question bank-antenna wave and propogation

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EC2353 ANTENNA AND WAVE PROPAGATION DEPARTMENT OF ECE

ST.JOSEPH'S COLLEGE OF ENGINEERING

ELECTRONICS AND COMMUNICATION ENGINEERING

VI-SEM

EC 2353-ANTENNA AND WAVE PROPAGATION

QUESTION BANK

UNIT-IELECTROMAGNETIC RADIATION AND ANTENNA FUNDAMENTALS

PART-A (2 Marks)

1.What is retarded potential?

If an alternating current is flowing in a short element, the effect of current is not feltinstantaneously at a distant point, but only after some interval equal to the time required for the fields to propagate some distance. So the fields obtained after retardation time areknown as retarded fields. They are very important in radiation calculation.2. Define an alternating current element.

If ‘dl’ be the infinitesimal length of a short dipole, ‘I’ be the current then ‘I dl’ is calledas the current element. Since this element generates alternating current it is called as

alternating current element.3.Distinguish between power and directive gains.

The power gain is the ratio of radiation Intensity in a given direction to the average totalinput power. But the directive gain is the ratio of Radiation Intensity in a specifieddirection to the Average radiation intensity.4.Define directivity of an antenna?

It is the value of directive gain in the direction of its maximum value. It is the ratio of power radiated from the test antenna to the power radiated from the isotropic antenna.5.What do you mean by effective aperture of an antenna?

An effective aperture is defined as the ratio of the power delivered to the load to theincident power density.6.Distinguish between standing wave antennas and travelling wave antennas?

Linear antennas that exhibit current and voltage standing wave patterns formed byreflections from the open end of the wire are referred to as standing wave or resonantantennas. But, Antennas whose current and voltage distributions are represented by one or more travelling waves, usually in the same direction are referred to as travelling wave or non-resonant antennas. They have uniform distribution of currents and voltages and thiscan be achieved by proper termination.7.Define the radiation resistance of an antenna? What is the importance of this

quantity?

It is the radiated power being dissipated in fictious resistance. It is defined as the ratio of

power radiated by the antenna o the square of the current at the feed point.8.What is the power gain of an antenna?

The power gain is the ratio of radiation Intensity in a given direction to the average totalinput power.9.What is self-impedance of an antenna?

The impedance at which the transmission line is carrying the RF current from thetransmitter to the antenna is known as the self-impedance.10.Define radiation intensity and directive gain.

Radiation Intensity in a given direction is defined as “ The power radiated from anantenna per unit solid angle”.

ST.JOSEPH’S COLLEGE OF ENGINEERING 1 ISO 9001:2008




The directive gain is the ratio of Radiation Intensity in a specified direction to theAverage radiation intensity.11.Write short note on effective length of antenna.

The effective length of an antenna is used to indicate the effectiveness of an antenna asa radiator or collector of electro magnetic energy. It is the actual height that is responsible

for radiation or reception.12.What is the relationship between gain and effective area of an antenna?

The gain is directly proportional to the effective area of an antenna.Go = K.DGo = α(4π⁄ λ2) Aem

Where α is the effectiveness ratio of an antenna.13.Define the bandwidth of an antenna.

The band width of antenna is defined as “ The range of frequencies within which the performance of the antenna, with respect to some characteristics [input impedance, beam,width, polarization, side lobe level, gain etc.] Confirms to a specified standard14.What do you mean by an isotropic radiator?

It is a hypothetical loss less radiator having equal radiation in all directions. E.g. pointsource15.Define the directive gain of an antenna.

The directive gain is the ratio of Radiation Intensity in a specified direction to theAverage radiation intensity.16.State the reciprocity theorem.

If an emf is applied the terminals of an antenna no: 1, and the current is measured at theterminals of another antenna no: 2, then an equal current both in amplitude and phase can

be obtained at the terminals of antenna no: 1. If the same emf is applied to the terminals of antenna no: 2.

17. Define the antenna efficiency. Antenna efficiency is defined as the ratio of power radiated to the total input power supplied by to the antenna and is denoted by η.

[ ]

ceresisloss Rceresis Radiation R

R R I

R I

plied power Total

radiated power

l r

l r

r

tantan

sup 2

2

==

+

==η

18. What is meant by polarization?

It refers time varying behaviours of the electric field strength vector at some fixed pointand it also refers the direction of the electric vector in relation to the direction of

propagation.

19. Define beam width.It is defined as the angular width (in degrees) of the major lobe between two directions

at which the radiated power in one half of the maximum power.20.Distinguish between monopoles and dipoles.

Monopole antenna is the vertical antenna of height H = L/2 fed against an infinitelylarge perfectly conducting plane has the same radiation characteristics above the plane asdoes the dipole antenna of length ‘L’ in free space.

A dipole antenna is a straight radiator, usually fed in the centre and producing amaximum of radiation in the plane normal to the axis.





21. What are Maxwell's equations?

The Maxwell’s equations are used for the prediction of the existence of electromagneticwaves and are based on the fundamental laws of (i) Faraday’s law (ii) Amperes circuitallaw (iii) Gauss law (iv) Displacement current law.22. Define power gain.

The power gain is the ratio of radiation Intensity in a given direction to the average totalinput power.23. What do you understand by static, induction and radiation field produced by an

antenna?

The field terms which vary inversely as the cube of the distance [α 1/r3] are known aselectrostatic fields. They are important only near the current elements and does notcontribute anything for radiation.Induction field: The field term that varies inversely as the square of the distance [α 1/r 2] isknown as induction field. It predominates at points close to current element where distanceis small.Radiation field: The field term that varies inversely as distance “r” is called as radiation

fields or “far fields” that accounts for the radiation of electromagnetic waves fromthe current element.

24. Define beam solid angle.

The beam solid angle is defined as the solid angle through which all the power of theantenna would flow if its radiation intensity were constant for all angles within the solidangle.25. Distinguish between resonant antenna and travelling wave antenna.

Linear antennas that exhibit current and voltage standing wave patterns formed byreflections from the open end of the wire are referred to as standing wave or resonantantennas. But, Antennas whose current and voltage distributions are represented by one or

more travelling waves, usually in the same direction are referred to as travelling wave or non- resonant antennas. They have uniform distribution of currents and voltages and thiscan be achieved by proper termination.26. What is induction and radiation field of a radiating field?

Induction field: The field term that varies inversely as the square of the distance [α 1/r 2]is known as induction field. It predominates at points close to current element wheredistance is small.Radiation field: The field term that varies inversely as distance “r” is called as radiationfields or “far fields” that accounts for the radiation of electromagnetic waves from thecurrent element.27. What is radiation resistance of antenna? What is its value for half wave dipole and

quarter wave monopole?It is the radiated power being dissipated in fictious resistance. It is defined as the ratio

of power radiated by the antenna to the square of the current at the feed point. The valuefor half wave dipole is 73Ω and for quarter wave monopole is 36.54Ω.28. Differentiate directive gain and power gain.

The power gain is the ratio of radiation Intensity in a given direction to the average totalinput power. But the directive gain is the ratio of Radiation Intensity in a specifieddirection to the Average radiation intensity.29.Define a short dipole.

A dipole antenna is a straight radiator, usually fed in the centre and producing a





maximum of radiation in the plane normal to the axis.30. Sketch the different antenna field zones.

R

R < 0.62 [ √D3 / λ ] ⇒ 0.62 √D3 / λ <R <2 D2 / λ R> 2D2 / λ Reactive near field Fresenel Region Fraunhofer region

31. Write down the expression for the retarded vector and scalar potentials of current

element with sinusoidal variation.

r

c

r t dl I

H

r c

r t dl I

E

rad

rad

λ

ω θ

λ

ω θ π

2

)(cossin

)(cossin60

−

=

−

=

32.What is Fresnel and Fraunhofer region of radiation?

Fresnel region is defined as the region of the field of an antenna between reactive near field and the far field region.

R D

R ⇒ 0.62 √D3 / λ <R <2 D2 / λ R> 2D2 / λ

Fresnel region Fraunhofer patternFraunhofer region is defined as that region of the field of an antenna where the angular field distribution is essentially independent of the distance from the antenna.

PART-B (16 Marks)

1. Derive the expressions for the fields radiated by an alternating current element.2. (a) Obtain general expressions for the electric and magnetic fields of oscillating electric

dipoles.(b) Explain self impedance and mutual impedance of an antenna.

3. Show the directivity of an alternating current element is 1.76dB.4. Derive the expression for the radiated field from hertzian dipole.5. Obtain the expression for the field produced by an alternating current element and

hence calculate the radiation resistance.6. (I) Completely specify the normalized radiation pattern with respect to field intensity

and polarization of an antenna.(ii) Write a short note on half power beam width.


D

D

D




7. i. calculate the radiation efficiency of an antenna if the input power is 100W and the power dissipated in it is 1W.ii. Discuss on linear, elliptical and circular polarization of antenna.

8. Explain the following antenna characteristics:i. Bandwidth

ii. Antenna temperatureiii. Effective aperture9. Explain the following antenna characteristics:

i. Radiation resistanceii. Directivityiii. Effective length

10. Write notes on the following:i. Isotropic antennaii. Antenna radiation patterniii.Half power beam widthiv.Front to back ratio

UNIT-IIWIRE ANTENNAS AND ANTENNA ARRAYS

PART-A (2 Marks)

1. Why are arrays used?

Antenna array is an arrangement of several individual antennas so spaced and phasedthat their individual electric field contributions combine in one preferred direction andcancel in all other directions to get greater directivity.2. What is a uniform linear array?

A linear antenna array in which the elements are fed with current of equal magnitude anduniform progressive phase shift along the line is called uniform linear array.

3. Differentiate between resonant and non-resonant antenna.Linear antennas that exhibit current and voltage standing wave patterns formed byreflections from the open end of the wire are referred to as standing wave or resonantantennas. But, Antennas whose current and voltage distributions are represented by one or more travelling waves, usually in the same direction are referred to as travelling wave or non- resonant antennas. They have uniform distribution of currents and voltages and thiscan be achieved by proper termination.4.What is Beverage antenna? Sketch its directional pattern.

This is a non-resonant antenna – in which there is no standing wave- suitable for reception of long wave signals. It is based on the principle of tilting of wave front of thedirect ray due to absorption of energy by the surface over which the wave passes.

5.What is the effect of earth on the radiation of antennas?Effects of earth modifies following

(i). Currents flowing in reflecting surface. (ii). Radiation pattern6.What is null beam width and 3dB beam width?

Null beam width is the angular width of major lobe between two directions at which theradiation becomes zero and the 3dB beam width is the angular width of major lobe betweentwo directions at which the radiated power is one half of the maximum power.7.Distinguish between standing wave antennas travelling wave antennas.

Linear antennas that exhibit current and voltage standing wave patterns formed byreflections from the open end of the wire are referred to as standing wave or resonant





antennas. But, Antennas whose current and voltage distributions are represented by one or more travelling waves, usually in the same direction are referred to as travelling wave or non- resonant antennas. They have uniform distribution of currents and voltages and thiscan be achieved by proper termination.8.Explain pattern multiplication .

It is stated that as “ The total field pattern of an array of non isotropic but similar sourcesis the multiplication of the unit radiation pattern and group radiation pattern”.9. Distinguish between null beam width and half power beam width?

Null beam width is the angular width of major lobe between two directions at which theradiation becomes zero and the 3dB beam width is the angular width of major lobe betweentwo directions at which the radiated power is one half of the maximum power.10.Mention the types of antenna arrays.

There are four types of antenna arrays: (i) Broad side array (ii) End fire array (iii)Collinear array (iv) Parasitic array.11. Define array factor

The factor by which the antenna array increases the field strength over that of a single

element radiating the same total power is called array factor.12.what is a broad side array?

The simplest array consists of a number of dipoles of equal size, equally spaced along astraight line with the dipole fed in the same phase from the same source. Such anarrangement is called broad side array.13. For three element binomial array give the values of currents through elements

and the radiation pattern.

n = 3; 1:2:3 = 1:2:11,2,3 are elements and 1,2,1 are corresponding values of currents

1 : 2 : 114. What is end fire array?

In the end fire array each element is fed with same magnitude but different phase andthis phases progressive from left to right.15. Why binomial array is advantageous?

The secondary lobes can be eliminated entirely, if the following two conditions aresatisfied

(i) Spacing between two consecutive radiating sources does not exceed λ/2 and(ii) The current amplitudes of radiating sources are proportional to the coefficients of the successive terms of the binomial series.

16.What is Dolph-chebychev array?

It is an array designed to make a compromise between binomial array and linear array. It provides a narrowest beam width for a given side lobe level and vice versa.17.What is the principle of super directive arrays?

An array whose directivity is larger than the directivity of same size is super directivityarray. Inserting more number of elements within a fixed length can form this array.18. Write short notes about Binomial array.


21 3




It is an array in which the current amplitudes of radiating sources are proportional to thecoefficients of the successive terms of the binomial series.

19. Give some applications of loop antennas.

i). They are seldom employed for transmission in radio communication, it is mostly usedas a receiving antenna, where antenna efficiency is not important.

ii). They are also used in radio direction finding (RDF) applications.20.What is loop antenna?

The loop antenna is radiating coil of any convenient cross section of one or more turnscarrying radio frequency currents. It may assume any shape like rectangular, square,triangular, hexagonal and circular loop. Most popular out of this being square and circle.21.What is Night effect in loop antenna?

A loop antenna will give correct bearings only when no horizontally polarized downcoming waves are present. The reason for this is that such waves induce voltages in thehorizontal members of the loop that do not cancel out when the plane of the loop is

perpendicular to the bearing angle of the radio wave. The result is then either false bearingor an indistinct minimum or both. This action is termed as right effect because the effect of

the horizontally polarized waves reflected by the ionosphere is much greater at night thanduring the day.22.Mention the antennas used in medium frequency range.

Loop antennas and Tower antenna.23.What is mean by capacitance hat?

The capacitance hats are installed at the top of the vertical radiator to increase theelectrical length of how frequency antenna. It also helps in improving radiation resistanceand hence the antenna efficiency.24.Explain the principle of a tower radiator.

It is a vertical radiator operating with an optimum height from the earth. It si used to provide maximum ground wave radiation i.e radiation in the horizontal direction for thestandard broadcast band from 535khz to 1605khz, it is customary to employ a groundedvertical tower or tower radiator.25.What is the principle of Adcock antenna?

Replacing the loop antenna with an Adcock antenna can eliminate the night error. Thecircuit is designed in such a way that the horizontally polarized waves do not affect theAdcock antenna. In this antenna the voltage induced in the two horizontal parts due tohorizontally polarized down coming sky waves are of same magnitude and phase andhence cancelled out.

PART-B (16 Marks)

1. Derive an expression for the bandwidth between first nulls for a broadside array of n

elements.2. (a) Derive the expression for the field produced by uniform linear array and obtain theexpression for the beam width of broadside array.(b) What is multiplication of pattern? Give examples for its use.

3. (a) Derive an expression for the beam width of end fire array.(b) How can be the secondary lobes reduced in size in binomial arrays?

4. (a) Obtain the array factor of a binomial array for 6 isotropic radiators.(b) Discuss the effect of earth on radiation pattern of antennas.





5. Obtain the expression for field and radiation pattern produced by a two element arrayof isotropic radiators with distance of separation λ and currents of equal magnitudewith phase shift of 1800.

6. (a) Explain the concept of binomial array.(b) Explain the methods of excitation of antennas.

7. Derive the expressions for the fields at a far point due to a small loop antenna. Explainan application of loop antenna.8. Determine the radiation resistance and directivity of half wave dipole.9. Discuss on the radiation pattern, radiation resistance and directivity of monopole.10. Derive the expressions for field components and hence for radiation resistance of half wave dipole antenna.11.From the first principle derive the expressions of electric field and magnetic field of a

short dipole.UNIT- III

APERTURE ANTENNAS

PART A (2 marks)

1.State Babinets theorem.In optical physics, Babinets princple states that if the field at any point behind the plane

having a screen is added to the field at the same point when complimentary screen issubstituted would equal the field at the point when no screen is present.2.What is slot radiator? What is its operating principle?

When a slot in a large metallic plane is coupled to an R.F source, it behaves like a diploeantenna mounted over a reflecting surface. The slot is coupled to a feed line in such amanner that E-field lies along the short axis of the slot .3.What is a Cassegrain feed for parabolic reflectors?

In this fed system primary radiator [Horn A] is put at the opening of vertex of parabolodereflector ‘B’. The secondary feed of the cassegrain system is hyperboloid reflector ‘H’whose focus F coincides with focus of the parabola reflector ‘B’ .4.Mention some microwave antenna.

i). Parabolic reflector ii). Lens antenna iii). Horn antenna5.Distinguish between sectorial horn and pyramidal horn.

A rectangular wave guide flared out in only one plane makes a sartorial horn. It flaresout width wise so that width ‘w’ of the mouth in larger than the width of the wave guide.

The rectangular wave guide flared out in both planes forms a pyramidal horn. Since itflares out in both directions, the width w’ > w and as well as h’ >h.6.Mention the different types of lens antenna.

Dielectric lens antenna, Metallic lens antenna, Zoned lens antenna, Stepped lens antenna.

7. State uniqueness theoremUniqueness theorem states that , for a given set of sources and boundary conditions in alossy medium , the solution to Maxwell’s equations is unique.8. What is the main advantage of Cassegrain reflector configuration?

• The main advantage is that the primary feed horn and the associated receiver or transmitter can be located conveniently behind the main reflector.

• The necessity of running long transmission lines or waveguides is also eliminated.• Since the horn feed is kept behind the main reflector , one can afford to have a

much larger aperture for the horn.





9.What is the main dis advantage of Cassegrain reflector configuration?

The main dis advantage of Cassegrain reflector configuration is the large aperture blockage by the sub-reflector .

Hence, Cassegrain reflector configuration is used only for very large aperture antennashaving gain greater than 40dB.

10. What are the drawbacks of lens antenna?• Due to the reflection at the dielectric-air interface, a matching quarter wave

transformer is required which limits the band width of the lens antenna to the bandwidth of the matching device.

• A lens antenna is generally heavy and bulky.11. What is ‘zoning’ in lens antenna?

Zoning is a method used to reduce the bulk of the antenna. The lens is divided into several circular zones and the dielectric material is removed from each zone such thatthe electrical path length between adjacent zones differs by an integer multiple of a wavelength.12. What are the two methods of ‘zoning’ in dielectric lens antenna?

zoning the non-refracting surface , zoning the refracting surface13. State Snell’s law of refraction.

2tan

1tan

,

sin

sin

2

1

2

1

regionof t consdielectricrelative

regionof t consdielectricrelative

refractionof angleincidenceof angle

r

r

t i

r

r

i

t

=∈

=∈

==

∈

∈=

θ θ

θ

θ

14. Give the applications of lens antenna.

They are used in the higher end of the microwave spectrum and millimetre wave

frequencies.15. Mention any three aperture antennas.

Horn antenna, slot radiator,Lens antenna16. What is the dual parameter of J and E?

Dual parameter of J is M, Dual parameter of E is H

17. What is a pyramidal horn?

The rectangular wave guide flared out in both planes forms a pyramidal horn. Sinceit flares out in both directions, the width w’ > w and as well as h’ >h.18. What is a sectoral horn?

A rectangular wave guide flared out in only one plane makes a sartorial horn. Itflares out width wise so that width ‘w’ of the mouth in larger than the width of the wave

guide.19. What is a corner reflector?

A corner reflector is made up of two flat-plate reflectors joined together to form acorner. The corner reflector is generally used in conjunction with a dipole or dipole arraykept parallel to the corner line. Corner reflector gives a higher directivity.20. Mention any three curved reflector shapes?

Parabolic, Parabolic cylinder, HyperboloidPART-B (16 marks)

1. i. State and explain uniqueness theorem.ii. Give an account on aperture antennas.





2. Explain the following principles:i. Field equivalence principleii. Duality principle

3. Explain the Cassegrain reflector configuration and mention its advantages anddisadvantages.

4. Explain the construction and special features of various types of Horn antenna.. 5. Explain the following antennai. Slot radiator.ii. Parabolic dish.

6.Explain the construction and special features of lens antenna.7. Explain the construction and special features of sectoral Horn antenna.8. Explain the construction details and application of any two aperture antenna.9. Discuss on the feeding mechanisms of parabolic dish antenna.10. Write notes on the following:

i. Pyramidal Horn antenna ii. Zoned lens antennaUNIT IV

SPECIAL ANTENNAS AND ANTENNA MEASUREMENTSPART A (2 marks)

1.Give some applications of rhombic antenna.

The applications of Rhombic antennas arei). HF transmission ii). HF reception

2.What is the reason for using Yagi antenna in TV broadcast reception? Yagi antenna is essentially a fixed frequency device i.e frequency sensitive and a

bandwidth of about 3% is obtainable. This much bandwidth is sufficient for TV reception.3.What is Wide Band antenna? Give example.

Antennas which maintain certain required characteristics like gain, front to back ratio,SWR, Polarization input impedance and radiation pattern over wide range of frequenciesare called wide band or broad antennas. Log periodic antenna is a broadband antenna.4.What are parasitic elements and where are they used?

Reflector and director are passive elements which are not connected to the feeder linedirectly, but they are simply grounded and are called parasitic elements. The parasiticelements receive their excitation from the nearby driven element. They are used in Yagiuda array for TV reception.5.What is log periodic antenna?

Log periodic antenna is a broadband antenna, it has number of dipoles of differentlengths. The performance of the system is periodic as the logarithmic function of frequencythat results the name.

6.What is folded dipole antenna? What is its input impedance?Folded dipole has got a versatile quality of providing any desired input impedance byincreasing the number of elements and selecting lengths of dipole.Its input impedance is 292Ω.7.Explain the concepts of parasitic elements.

Reflector and director are passive elements which are not connected to feeder linedirectly and are called parasitic elements. The parasitic elements receive heir excitationfrom the voltages induced in them by the current flow in the driven element. The phase andcurrents flowing due to the induced voltage depend on spacing between the elements andupon the reactance of the elements.





8.Differentiate between director and reflector.

The length of the reflector is greater than the length of the Active or driven element and both are placed very close to each other. But the length of the Director is smaller than thelength of the driven element and is placed apart from each other.9.What is the principle of V antenna?

Two long wires are arranged in the form of ‘V’, since two wires are super imposed, thefields along the axis of the antenna become doubled while the field normal to the axis areneutralized. So the resultant field pattern is bi-directional. The two ends may be terminated

by connecting a 500Ω resistor between each end to ground in order to get the unidirectional pattern.10.What is Helix antenna?

Helical antenna is broadband VHF and UHF antenna to provide circular polarizationcharacteristics. It is used in extra terrestrial communication in which satellite relays etc. areused.11.What are the diff types of antenna used in at very high frequency?

Yagi uda antenna, Log periodic antenna and Slot antenna.12. Describe the slotted line technique for impedance measurement.

This method is used for measuring the unknown input impedance at high temperatures.It makes use of voltage or current standing wave ratio (VSWR) i.e. the ratio between twovoltage or current minima and the reference point at which impedance is going to bemeasured.13.How the radiation resistance of a given antenna can be measured.

The radiation resistance of a given antenna can be measured using reflection coefficientmethod.14.Write short notes on measurement of antenna pattern.

• For pattern measurement , the antenna is used in the receive mode. The

antenna is kept at a distanceλ

2

2 D R > transmitting electromagnetic energy

, so that it produces a plane wave at the location of the receive antenna.• The receive antenna is rotated , keeping the position of the transmit antenna

unaltered.• The field pattern, phase pattern, polarization pattern, etc, are measured using

the same arrangement but with different sensors to measure thecorresponding parameters instead of the received power.

15. What is the condition required when gain of an antenna is measured by

comparison method ?

It is important that the secondary antenna and associated transmitter should be stableirrespective of frequency. There should not be any variation in the frequency of radiated

power in the direction of primary antenna throughout the measurement.16. What is the input impedance of folded dipole antenna?

Input impedance of folded dipole antenna is 292 ohms

17. Give the typical dimensions of 3 element Yagi-Uda antenna.





λ

λ

λ

482.0:

442.0:

47.0:

element reflector theof Length

element director theof Length

element driventheof Length

18. What is the effect of number of directors on the directivity of Yagi-Uda antenna?

As the number of directors increases, the directivity also increases.

19. Give the application of Turnstile antenna.Turnstile antenna is used for transmitting Television signals.

20.What is the antenna used for mobile and wireless hand set applications?Give

reason.

Helical antenna operating in the normal mode is used for mobile and wireless hand setapplications.

A normal mode helical antenna is compact and has an omni directional radiation pattern in the plane normal to the axis of the helix.

PART-B (16 marks)

1. With suitable diagrams explain how gain and half power beam width of anantenna can be measured.

2. i. Explain a method of determining the impedance of antenna. ii. How radiation pattern and hence beam width of antenna is determined?3 i. Describe the voltage standing ratio method of measuring antenna impedance.

ii.Reflection coefficient of an antenna is measured to be .12012.0o

∠ If thecharacteristic impedance of the measurement system is 50Ω, calculate theantenna impedance.

4. Explain the typical construction of an anechoic chamber.5. Explain the construction, radiation pattern and features of the rhombic

antenna.6. Justify how the log-periodic antenna can be used as a wide band antenna, by

explaining its method of operation.7 .i. Explain the construction and features of micro strip antennas.

ii. Design a rectangular micro strip antenna with dielectric constant of substrateas 2.2, h=0.1588 cm so as to resonate at a frequency of 10 GHz.8. Explain the working of biconical antenna and derive the expression for inputimpedance.9. Explain the construction, radiation pattern and features of helical antenna.10. i. Describe the construction and working principle of Yagi-Uda antenna.

ii. Calculate the dimensions of a Yagi-Uda antenna that has a directivity of 12dB at 145MHz.11. Explain the construction, radiation pattern and features of turnstile antenna.

12. Write notes on:i. V antennaii. Spiral antenna

13. Why a large bandwidth and high impedance is required for a TV Rx antenna.Describe an antenna used for this purpose.

UNIT – V

RADIO WAVE PROPAGATION

PART A (2 marks)

1.Write down the Sommer field equation.





Eg = A (Eo / r)

Where, Eo is the field strength of ground wave at the surface of the earth at unitdistance from the transmitting antenna neglecting earth losses.

Eg is gound field strengthr is distance between transmitting antenna.

A is Attenuation factor 2.Why is diversity reception necessary?

Due to the general fading, there is a considerable variation in the strength of short wavesignals received by common receivers through ionosphere. The diversity receiving systems

provide a high and intelligible level of received signals at all times.3.What is sun spot cycle?

The sun has a 11 year cycle (sun spot cycle) over which its output varies tremendously.Although the light are slight, but the solar output of ultra-violet rays, coronae, Hares,

particles radiation and sun spots may vary fifty fold over that period.4.Mention the various ionosphere layers.

D layer, E,F1 and F2 layers are various ionospheric layers.5.What are the different types of fading encountered in the sky wave propagation?What are the ways to overcome this effect?

Selective fading, Interference fading, Absorption fading, Polarization fading and Skipfading are the different types of fading.

Using exalted carrier reception can reduce the selective fading. The interference can beminimized either by space diversity or frequency diversity. The best way to minimizefading is diversity reception.6.What is duct propagation?

The ground surface and atmospheric layer form a duct or sort of “leaky wave guide”which guides the electromagnetic wave between its walls. When frequency is high, theregion where the refractive index is usually high, traps the energy and causes it to travelalong the earth surface as happens in a wave-guide. This type of propagation is called duct

propagation.7.What is magneto-ionic splitting?

The earth magnetic field splits up the incident radio waves into two components of theordinary and the extraordinary waves. The two waves have elliptical

polarization and rotate in opposite direction. They have different energyabsorption and velocities. The phenomenon of splitting of wave into twodifferent components by the earth’s magnetic field is called as magneto-ionicsplitting.

8.Define critical frequency.

The highest frequency of wave that will be reflected from a given layer is known ascritical frequency of the given layer fc = 9 √ N max Where N max --- Maximum electron density

9. Explain diversity reception.

The basic principle behind the diversity system is to duplicate some part of the signal or system in the hope that even if one part experiences a deep fade or distortion, the other partmay not. 10.What is optimum working frequency?





The frequency normally used for ionospheric transmission is known as the optimumworking frequency. It is chosen to be about 1.5% less than MUF. It is also known asoptimum Traffic frequency.11.Define virtual height.

Virtual height of an Ionospheic layer may be defined as the height to which a short pulse

of energy sent vertically upward and travelling with the speed of light would reach takingthe same two ways travel time as does the actual pulse reflected from the layer.12.Give the range of convergence of and frequency range of ground wave, sky wave

and space wave propagation modes.

The ground wave propagation takes place up to 2MHz. Sky wave propagation issuitable for short waves of frequency from 2MHz to 30MHz. Space wave communicationis used from 30MHz onwards.13.What do you mean by gyro frequency?

In ionospheric layer the vibration of electron will make a path of very narrow ellipse dueto the smaller amplitude of vibration. The tendency continues until the frequency islowered o appoint at which cyclotron resonance occurs and then the electrons will follow a

spiral path of steadily increasing radius along with the velocity also increases. This occursat 1400 KHz cycle is termed as Gyro frequency.14.How are critical frequency and max usable frequency related?

The maximum usable frequency and critical frequency can be related by the equation of f MUF = f c √(1+(D/2h)2)

Where f MUF = Maximum usable frequencyf c = Critical frequencyD = propagation distance , h = Height of the ionosphere layer

15.What do you mean by selective fading.

Selective fading produces serious distortion of modulated signals. Since the fading is

frequency selective, it is just possible for adjacent portion of a signal to fade independently,although their frequency separation is only a few dozen hertz.16.What is mean by wave tilt in ground wave propagation?

The ground or surface wave will be attenuated due to ground attenuation i.e. due todiffraction and tilt in the wave front. As the wave progress over the curvature of the earth,the wave front starts gradually tilting more and more. This increase in the tilt of wavecauses more short circuit of the electric field component and hence the field strength goeson reducing, ultimately at some appreciable distance from the transmitting antenna, thesurface wave dies because of the losses.17.What are the different ionosphere layers? Give its approximate heights and

electron densities.

The different layers of ionospheric region, corresponding height and electron density aregiven below:LAYER HEIGHT ELECTRON DENSITY

1. D –region 50-90 km 1014 –1016 /cm3

2. Normal E –region 90-140 km 105 – 4.5 x 105 during day5 x 103 – 104 during nighttime

3. Sporadic region 90-130 km Ten times to that of normal E -region4.F1 layer 140 – 250 km 2 x 105 – 4.5 x 105

F2 layer 250 – 400 km 3 x 105 – 2 x 106

18.What is the effect of earth’s magnetic field in sky wave propagation?





In Ionosphere, the electrons are set in motion by the electric field of the radio wave andthe earth’s magnetic field, and then exert a force on the vibrating electrons producingtwisting effect on their paths. This reacts on the incident radio waves.19.What is scatter propagation?

Forward scatter propagation or simply scatter propagation is of practical importance at

VHF, UHF and microwaves. UHF and microwave signals were found to be propagatedmuch beyond the line of sight propagation through the forward scattering in thetropospheric irregularities. It uses certain properties of troposphere and is also known asTroposcatter.20.What is MUSA system? What is its underlying principle?

MUSA system is employed during diversity reception, which is used to avoidSynchronous or general fading. Although rhombic arrays may be used in all types of diversity reception, but a more elaborate system of diversity reception is known as MUSAsystem in short wave reception.

Since the system consists of many antenna units and the vertical directivity of entiresystem is steerable i.e. adjustable and hence it is called as Multiple Unit Steerable Antenna.21.What are the causes for abnormalities in the ionosphere.

i).Sudden ionospheric disturbancesii). Ionospheric stormsiii).Sun spot cycleiv).Tides and winds in the Ionospherev).Fadingvi).Whistlesvii) Ionospheric Cross-modulation

viii).Atmospheric Noise22.Write short notes about ground wave propagation.

The ground wave propagation is due to ground wave, which is guided along thesurface of the earth. The waves must be vertically polarized to prevent short-circuiting of electric component. Since the earth’s attenuation increases with increase of frequency,ground wave propagation is limited up to 2Mhz only. It is suitable daytime local broadcast.23.How the virtual height can be measured?

• Virtual height can be measured using ionosonde.• Ionosonde is the instrument used to measure the virtual height of the

ionosphere. This instrument transmits an RF pulse vertically in to theionosphere from the ground. This pulse is reflected from the ionosphere and isreceived by the ionosonde.

• The time delay between the transmit and the receive pulse is measured which is

a measure of the virtual height of the ionosphere.PART-B (16 marks)

1. i. Explain the important features of ground wave propagation.ii. Explain the concept of super refraction.

2. i. Obtain the expression for the field strength of space wave signal.ii. Describe the need for diversity reception & typical schemes.

3. Establish the following relationship in ionosphere propagationf c = √81 NmaxWhere: f c – critical frequency & Nmax – max ionisation density.





4. i. Explain how ionosphere layers are formed.ii. Obtain an expression for the critical frequency of an ionospheric layer.

5. Bring out the important features of ground wave propagation, sky wave propagation & ionosphere propagation of radio waves mentioning the areas of application.

6. i. Obtain the expression for the range of space wave propagation.ii. Describe the characteristic features of various layers in the ionosphere.7. Why radio waves passing through ionosphere are attenuated ? State briefly the factors

which Influence the degree of attenuation.8. What does “The Effective Radius” of earth mean? Discuss the effect of

changes in Atmosphere on space wave propagation.9. Explain the following:

i.Tropospheric scatteringii. Effect of earth’s magnetic field in the ionosphere

10. i. Derive the expression for refractive index of the Ionosphere(neglectingEarth’s magnetic field effects)

ii. Explain the characteristics of different ionized regions of Ionosphere, drawing thestructure above the earth.

11. i. Show that the radius of curvature of wave path is function of rate of change of dielectric constant (or) refractive index with height in space wave

propagation.ii. Explain ground wave propagation and obtain expression for field strength.





St.Joseph’s College of Engineering

Department of Electronics and Communication Engineering

EC 2352: COMPUTER NETWORKS VI SEMESTER

UNIT I: DATA COMMUNICATION

1.Define the term data communication.

Data communication is the exchange of data between two devices through some form of transmission medium.2.Mention the fundamental characteristics of data communication systems.

(i) Delivery: The system must deliver data to the correct destination. Data must also bereceived by the intended device or user and only by that device or user.

(ii) Accuracy: The system must deliver data accurately. Data that have been altered intransmission and left uncorrected are unusable.

(iii) Timeliness: The system must deliver data in a timely manner. Data delivered late areuseless.3.Mention the components of Data communication system.

1.Message , 2.Sender, 3.Medium, 4.Protocol , 5.Receiver.4.What’s a computer network?

A computer network is a set of devices connected by media links. The links connectingthe devices are called as communication channels. Its size, its ownership, physical architecture andthe distance it covers determine the type of network.5.Give the classifications of computer networks.

1.LAN , 2.WAN ,3.MAN6.List out uses of computer networks.

1. To store & manipulate information, 2.Make decisions & manipulate data.3.Move information from one system to another.7.Mention the advantages of having computer networks.

Sharing of resources, Exchange of data within a company, Flexible work environment.8.What’s meant by line configuration?

It refers to the way two or more communication devices attach to a link. A link is a physical communication pathway that transfers data from one device to another.Two different types of line configurations are: 1.Point-to-point 2.Multipoint9.What’s meant by Topology of a network?

Topology refers to the way a network is laid out, either physically or logically. Thetopology of a network is the geometric representation of the relationships of all links and linkingdevices to each other. There are 5 basic topologies possible:(1) Mesh (2) Star (3) Tree (4) Bus (5) Ring10.What’s a hub?

In star topology each device has a dedicated point-to-point link only to a central controller called as hub. The hub acts as an exchange (i.e.) if one device wants to send data to another, itsends data to another, it sends the data to the controller, which then relays the data to the other

connected device.11.What’s an active hub?

An active hub contains a repeater, which is a hardware device that regenerates the received bit pattern before sending them out. Repeating strengthens transmissions and increases distance asignal can travel.12.What’s meant by transmission mode?

It defines the direction of signal flow between two linked devices. There are 3 types of transmission modes:

1.Simplex: Unidirectional communication.2.Half-duplex: Bi directional, but not simultaneous utilization of link.3.Full-duplex: Bi directional, simultaneous utilization of link.





13.What’s a LAN?

LAN is a data communication network within a building, plant (or) campus (or) between nearby buildings.

14.What’s MAN?A data communication network system covering an area the size of a town or city.

15.What’s WAN?

A data communication network spanning states, countries or the whole world.16.What’s protocol?

A set of rules that govern all aspects of information for communication.17.What’s a standard?

A standard that provides a model for development that makes it possible for a product to work regardless of individual manufacturer.18.Mention the types of conversion of data.

1.Digital-to-digital 2.Digital-to-analog 3.Analog-to-digital 4.Analog-to-analog.19.Distinguish BIT RATE and BAUDRATE.

Bit rate – No.of bits per second. Baud rate – No.of signal units per second.20.List mechanisms of modulating digital data into analog signal .

1.Amplitude-shift-keying (ASK).2.Fequency-shift-leying (FSK) 3.Phase-shift-keying (PSK)21.List analog-analog modulation techniques.

1.Amplitude modulation.2.Frequency modulation. 3.Phase modulation.22.What’s meant by DTE and DCE?

DTE (Data Terminal Equipment) – source for binary digital data.DCE (Data Circuit terminating equipment) – receives data from a DTE and changes it into a form

appropriate for network transmission. Also performs the reversetransformation.23.Give the necessity for interface standards DTE-DCE interfaces.

They try to define the mechanical, electrical, functional characteristics of the connection betweenDTE & DCE.24.What’s a modem?

The most familiar type of DCE is a MODEM. A device, which consists of a modulator & ademodulator. It converts digital signal into an analog signal and vice versa.25.List the design factors for transmission media.

1.Bandwidth 2.Transmission impairments 3.Interference 4.Numberof receivers.26. What are the Advantages of distributed processing?

In distributed processing a task is divided among multiple computers. Instead of a single largemachine being responsible for all aspects of a process each separate computer handles a subset.

Advantages of distributed processing

1. Security/encapsulation 2.Distributed databases 3.Faster problem solving4. Security through redundancy 5. Collaborative processing

27. Distinguish between a peer-peer relationship and a primary-secondary

relationship.• Peer-to-peer relationship: The devices share the link equally.• Primary-Secondary relationship: One device controls traffic and the others must transmit through

it. 29. What are advantages of a multipoint connection over a point-to-point connection?

• In multipoint connection more than two specific devices share a single link • The capacity of the channel is shared spatially or temporally• But in point-to-point connection a dedicated link is provided between two machines

30. Which OSI layers are the network support layers?

1. Physical layer 2. Data link layer 3. Network layer 31. What is the difference between network delivery and Transport layer delivery?





• Network layer delivery: The network layer is responsible for the source-to-destination delivery of a packet. It treats each packet independently, even though they belong to the same message.

• Transport layer delivery: The transport layer is responsible for source-to-destination (end-to-end)delivery of the entire message.

32. List the layers of the OSI model

1. Physical layer 2.Data link layer 3.Network layer 4.Transport layer 5.Session layer

6.Presentation layer 7.Application layer 33. What are the responsibilities of the session layer?

1. Dialog control: The session layer allows two systems enter into a dialog2. Synchronization: The session layer allows a process to add checkpoints into a stream of data to

achieve synchronization between sender and receiver.

34. What are the responsibilities of the presentation layer?1. Translation: The presentation layer is responsible for interoperability between the different

encoding methods used in different computers. The presentation layer at the sender changes theinformation from its sender-dependent format into a common format. The presentation layer atthe receiving machine changes the common format into its receiver-dependent format.

2. Encryption/Decryption: To carry sensitive information, a system must be able to assure privacy. Encryption means that the sender transforms the original information to another form

and sends the resulting message out over the network. Decryption reverses the original processto transform the message back to its original form.3. Compression: Data compression reduces the number of bits to be transmitted.

35. How do the layers of the TCP/IP protocol suite correlate to the layers of the OSI model?

• The TCP/IP protocol suit is made of five layers: Physical, data link, network, transport andapplication.

• The first four layers provide physical standards, network interface, internetworking, and transportfunctions that correspond to the first four layers of the OSI model.

• The three topmost layers in the OSI model are represented in TCP/IP by a single layer called theapplication layer.

36. How does NRZ-L differ from NRZ-I?

S.No NRZ-L NRZ-I

1 Nonreturn to zero, level encoding Nonreturn to zero, invert encoding2 A positive voltage represent bit 0 &

A negative voltage represent bit 1(or vice versa)

An inversion of the voltage level represent bit 1A bit 0 is represented by no change

3 Synchronization i s not p rovided for a longstream of 0s or 1s in the data

NRZ-I is superior to NRZ-L due to thesynchronization provided by the signal changeeach time a bit 1 is encountered.

4 Example

Time

37. What is the purpose of a null modem?

• Null modem is used to connect two compatible DTEs (Computers) in the same building.• It provides the DTE-DTE interface without the DCEs. (modems)• A null modem is an EIA-232 interface that completes the necessary circuits to fool the DTEs at

either end into believing that they have DCEs and a network between them.


0 1 0 0 1 1 1 0 1 0 0 1 1 1 0




38. Mention the disadvantages of OSI model.1. Bad timing 2. Bad technology 3. Bad implementation 4. Bad politics

PART B

1.What is the use of Layered Architecture? Describe Briefly the OSI Layers that are the responsible for thefollowing

i)Determining the best path to route packets (6)ii) Providing End- to –End communication with reliable service (6)iii) Providing node to node communication with reliable service (4)

2. Describe Briefly the ISO-OSI Layers in detail (16)3. Explain briefly the different types of Guided and Unguided transmission media used for datacommunication (16)4. Explain the different types of Topologies in detail (16)5. What does the term Modem stand for? Explain different types Modems. (16)6. Write short notes on Analog to analog Encoding method (16)7. Explain briefly the Digital to analog Encoding method (16)8. With suitable example explain Digital to digital Encoding method (16)9. Describe the data pins of Null modem (16)10.Explain the RS232 Interface in detail. (16)

UNIT-II: DATA LINK CONTROL AND PROTOCOLS

1.What are the three main functions of the data link layer?

• Line discipline: It coordinates the link system; it determines which device can send and when it cansend.

• Flow control: It coordinates the amount of data that can be sent before receiving acknowledgement.• Error control: It allows the receiver to inform the sender of any lost or damaged frames and

coordinates the transmission of those frames by the sender.2.What is the mechanism of stop and wait flow control?

In stop and wait method of flow control, the sender waits for an acknowledgement after every frameit sends. Only when an acknowledgement has been received the next frame is sent.3.What is the mechanism of sliding window flow control?

In the sliding window method of flow control the sender can transmit several frames before needingan acknowledgement. The receiver uses a single acknowledgement to confirm the receipt of multiple dataframes.4. List out the different types Flow Control Schemes

a) Stop and Wait Flow Control b) Sliding Window Flow Control5.An ACK 3 in sliding window flow control (window size of 7) means that frame three is next operated

by the receiver. 6.ARQ stands for automatic repeat request.

7.Why are asynchronous protocols losing popularity?

The asynchronous protocols have inherent slowness hence they are replaced by higher speedsynchronous mechanism.8.What is piggybacking?

Piggybacking means combining data to be sent and acknowledgement of the frame received in onesingle frame.9.How are synchronous protocols classified? What is the basis of the classification?

Synchronous protocols can be classified into two groups depending upon the interpretation of framesas

• Character-oriented protocols: interprets a transmission frame as a succession of characters• Bit-oriented protocols: interprets a transmission frame as a succession of individual Bits.





10.Name and discuss briefly the bits in the HDLC control field.

I-frame0 P/F N(r)S-frame1 0 P/F N(r )U-frame

1 1 P/F code• P/F - poll / final bit has meaning only when set to 1.• N(s) - sequence number of frame sent.• N(r) - sequence number of next frame expected.• Code - code for supervisory or unnumbered frame.

11.How do character –oriented protocols convey control information?

In character oriented protocol the control information is conveyed in the form of an existingcharacter encoding system, eg. ASCII characters.12.HDLC is an acronym for High Level Data Link Control.

13.BSC is a character-oriented protocol.

14.How are data-link protocols divided into classes? What is the basis of the division?

Data-link protocols are classified into two groups depending on the type of transmission as

1.Asynchronous protocols 2. Synchronous protocols15.Name the five categories of U-frames.

The five categories of U-frames areMode setting, Unnumbered exchange, Disconnection, Initialization mode, Miscellaneous

16.Name the four types of S-frames.

Receive ready, Receive not ready, Reject, Selective reject17.The shortest frame in the HDLC protocol is usually the management frame.

18.What are the two main methods for error control?

1. Stop and wait 2. Sliding window19.What is the use of p/f bit in the HDLC frame?

The poll/final bit has meaning only when set. The bit is called poll bit when data is transmitted from primary station to secondary station and is called final bit when data is transmitted from secondary station to primary station.

20. In what way sliding window flow control is more efficient than stop andwait flow control?

• The disadvantage of stop and wait flow control is inefficiency and slow.• In situations where the bit length of the link is greater than the frame length, the facility of the link is

not utilized efficiently in stop and wait flow control.• Efficiency can be greatly improved by allowing multiple frames to be in transit at the same time.

This method is implemented in sliding window flow control.• To keep track of which frames have been acknowledged, each is labeled with a sequence number.

21. Define data transparency.Data transparency in data communication is the ability to send any combination of bits as data.

22.What is Bit stuffing? Apply Bit Stuffing for the given data: 011011111111111111110010

• Bit stuffing is the process of adding one extra 0 whenever there are five consecutive 1s in the data sothat the receiver does not mistake the data for a flag.• The bit stuffed data is 011011111011111011111010010

23. Give examples for asynchronous data link protocols

1. XMODEM 2. YMODEM 3. ZMODEM 4. BLAST 5. KERMIT24. Draw the HDLC frame format.

Flag Control Address Data FCS FlagFlag value: 01111110FCS: Frame Control Sequence25. What are the advantages of FDDI over a basic Token Ring?

S.No FDDI Token Ring





1 Data rate: 100Mbps 4 & 16Mbps only2 Access method: Timed Token passing. In

this method each station may send asmany frames as it can within its allottedaccess period.

Access method is Token passing: In this method, eachstation is permitted to send only one frame in its turn.

3 Transmission of Real time information

( S-frame ) is possible

Not possible

4 FDDI is implemented as a dualring. Data is transmitted alongthe primary ring.

The secondary ring makes FDDIself-healing

Whenever a problem occurs onthe primary ring, the secondarycan be activated to complete datacircuits and maintain service.

In Token ring, one disabled or disconnectednode could stop the flow of traffic around theentire network.

To solve this problem each station isconnected to an automatic switch that requireextra hardware.

26. Why is there no AC field in the 802.3 frame?

Access control (AC) field in token ring frame specify the priority level to each station, sothat each station sends data during its turn.

But CSMA/CD access method does not specify priority level for any station. So there is noAC field in the 802.3 frame.

27. What types of transmission media are used in LANs?

Types of LANs1. Wired LAN2. Wireless LAN

Transmission media in Wireless LAN is radio wave Transmission media in Wired LAN are

1. Coaxial cable2. Unshielded Twisted Pair cable (UTP)3. Shielded Twisted Pair cable (STP)4. Fiber optic cable

28. What is the difference between base band and broadband?

S.No Base band Broadband1 The word base specifies a digital signal The word broad specifies an analog

signal.2 The different standards are 10Base-5, 10Base-2,

10BaseT, 100Base-T, 1Base-5The only one specification for

broadband is 10 Broad-36Where the first number indicates the data rate and the lost number defines the maximumcable length.

29. The PDU is a product of the LLC sublayer

a) 802.3 frame b) 802.5 frame c) PDU d) Preamble30. FDDI is an Acronym for Fiber Distributed Data Interface.

31. Suppose there is heavy traffic on both a CSMA/CD LAN and a Token Ring LAN. A station on

which system is more likely to wait longer to send a frame? Why?

A station on a CSMA/CD LAN is more likely to wait longer to send a frame than a Tokenring LAN. Because there is no way to predict either the occurrence of collisions or thedelays produced by multiple stations attempting to capture the link at the same time inCSMA/CD LANs.

But in Token ring, each station may transmit only during its turn and may send only oneframe during each turn.

32. Why are services such as DQDB and SMDS used in MANs?

A Metropolitan area network(MAN) is a network designed to extend over an entire city. When LANs of a single enterprise are distributed over a larger area, however, privately

owned connecting infrastructure is impractical. Most organizations find that even if they could get permits to lay cable on public land, a

better alternative is to use the services of existing utilities.





So, services such as DQDB and SMDS are used in MANs.33. How are slots generated in DQDB?

Head stations in the dual bus configuration of DQDB generate the empty slots in whichtransmitting station drops data into it and the intended destination station reads the data. .

The slot is the 53-bytes information, which consists of 48 bytes payload and 5 bytes header.34. Why was the slot size chosen to be 53 bytes in DQDB?

To make compatible with the size of a cell in Asynchronous Transfer Mode (ATM), the slotsize in DQDB was chosen to be 53 bytes.35. What is the use of HUB?

A HUB is a central controller in a star topology. Each device has a dedicated point-to-point link only to the hub. When a station sends a frame to a hub, the frame is sent out from all ports and every station

will receive it.36. What is CSMA/CD?

CSMA/CD is the access method used in an Ethernet. It stands for Carrier Sense Multiple Access with Collision Detection. Collision: Whenever multiple users have unregulated access to a single line, there is a

danger of signals overlapping and destroying each other. Such overlaps, which turn thesignals into unusable noise, are called collisions.

In CSMA/CD the station wishing to transmit first listens to make certain the link is free,then transmits its data, then listens again. During the data transmission, the station checksthe line for the extremely high voltages that indicate a collision.

If a collision is detected, the station quits the current transmission and waits a predetermined amount of time for the line to clear, then sends its data again.

37. What is FDDI and its use?

FDDI is a LAN Protocol standardized by ANSI & ITU-T. It stands for Fiber Distributed Data Interface. It supports data rate of 100 Mbps and provides a high-speed alternative to Ethernet and

Token Ring. It specifies timed token passing access method and dual ring configuration.

38. What does IEEE 10 Base 5 standard signify?

It is Ethernet standard. The number 10 signifies the data rate of 10 Mbps and the number 5 signifies the maximum

cable length of 500 meters. The word Base specifies a digital signal with Manchester ecoding.

39. What is token ring?

Token ring is a LAN protocol standardized by IEEE and numbered as IEEE 802.4. In a token ring network, the nodes are connected into a ring by point-to-point links. It supports data rate of 4 & 16 Mbps.

Each station in the network transmits during its turn and sends only one frame during eachturn.

The mechanism that coordinates this rotation is called Token passing. A token is a simple placeholder frame that is passed from station to station around the ring.

A station may send data only when it has possession of the token.40.Differentiate 1000base SX and 100 Base FX.

S.No Feature 1000 Base SX 100 Base FX.

1 Type Gigabit Ethernet Fast Ethernet2 Data rate 1 Gbps I00 Mbps.3 Medium Optical fiber Optical fiber 4 Signal Short-wave laser Laser 5 Max. Distance 550m 2000m6 Encoding 4B/5B 8B/10B

41.Name and explain the functions of the timers used in FDDI

Token Rotation Timer (TRT): The TRT runs continuously and measures the actual timetaken by the token to complete a cycle.





Token Holding Timer (THT): The THT begins running as soon as the token is received.Its function is to show how much time remains for sending asynchronous frames once thesynchronous frames have been sent.

42. What is daisy chaining in Ethernet?

StarLAN allows as many as 10 stations to be linked, each to the next, in a chain in whichonly the leading device connects to the hub.

This mechanism is called daisy chaining in which the range of the StarLAN can beincreased. The StarLAN is 1 Base 5 Ethernet.

43. What is the need for MAC sublayer in LANs?

Project 802 has split the data link layer into two different sublayers3. Logical Link Control (LLC)4. Medium Access Control (MAC).

MAC sublayer resolves the contention for the shared media. It contains the synchronization, flag, flow and error control specifications necessary to

move information from one place to another, as well as the physical address of the nextstation to receive and route a packet.

It is the lower sublayer of the data link layer.44. Differentiate Collision and Congestion.

Collision: Whenever multiple users have unregulated access to a single line, there is adanger of signals overlapping and destroying each other. Such overlaps, which turn thesignals into unusable noise, are called collisions.

Congestion: Congestion in a network may occur if users send data into the network at arate greater than that allowed by network resources.

Congestion may occur because the switches in a network have a limited buffer size to storearrived packets before processing.

Congestion in a network is a problem that must be avoided because it decreases throughputand increases delay.

PART B

1. With neat diagram explain the various Flow Control Mechanisms available in Data link layer (16)2. With neat diagram explain the various Error Control schemes available in Data link layer (16)

3. Briefley explain Station types, Configurations, Modes of Communications and Frame Format of HDLC.4. With neat diagram explain the access method, Electrical specification, Implementation and Frame formatof IEEE 802.3 Standard in detail.5. With neat diagram explain the access method, Electrical specification, Implementation and Frame formatof IEEE 802.4 Standard in detail.6. With neat diagram explain the access method, Electrical specification, Implementation and Frame formatof IEEE 802.5 Standard in detail.7. Explain the various features of Wireless LAN Standard.8. With suitable example, explain the working principle of Cyclic Redundancy Check 9. With suitable example, explain any one Error Detecting and Correcting Scheme.10.What is SONET? Explain the SONET Devices, Layers, and Types of Headers with neat diagram.

Unit – III NETWORK LAYER

1. Define address space.

Total number of address used by the protocol.2.what is the address space of IPv4?

232= 4,294,967,2963.change the following IPv4 address from binary notation to dotted decimal notation.

10000001 00001011 00001011 11101111

129.11.11.2394.What is netid and hostid used in classful addressing?

Portion of the IP address that identifies the network is called netid and portion of the IP address thatidentifies the host or router is called hostid5.What are the restrictions in classless addressing?





The number of addresses needs to be a power of 2; the mask needs to be included in the address todefine the block; starting address must be divisible by the number of address in the block.6.How many types of addresses available in IPv6?

Unicast, multicast and anycast7.What is the address space of IPv6?

2128

8. What is address mapping?Mapping a logical address to physical address or vice versa.

9.What is static mapping?

Involves the creation of a table that associates a logical address with a physical address.10.What are the limitations in the static mapping?

A machine can change its NIC; physical address of a machine changes everytime (LocalTalk) and amobile computer can move from one physical network to another.11.What is proxy ARP?

A router represents a set of hosts. When an ARP request seeks the physical address of any host in theset, the router sends its own physical address, This creates a subnetting effect.12.What is RARP?

Reverse ARP is a form of dynamic mapping in which a given physical address is associated with alogical address.

13. What is the use relay agent in BOOTP?It is router that helps send local BOOTP requests to remote servers.

14.How many data bases are used in DHCP ?

Static database: to store the permanent IP addresses assigned to hosts.Dynamic database: to store temporary IP addresses.

15.What is reverse mapping?

Mapping physical address to the logical address.16. What is the need for reverse mapping?

A diskless ststion is just booted and an organization does not have enough IP address.17. What is IGMP?

Internet group management.IGMP is an integral part of IP layer in all hosts and routers that supportmulticasting.18. What is MBone?

Multicast backbone network.The network formed by inter connected set of mrouter.19.What is autonomous sytem?

A group of networks and routers under the authority of a single administration.20.What is Interdomain routing?

Routing between autonomous sytemsPart – B

1.Explain ARP in detail.2.Explain BOOTP and DHCP in detail.3.Explain ICMP in detail.4.Explain IGMP in detail.

5.Explain Distance vector and Link state routing algorithm in detail.6. Consider a network using the link state algorithm and assume that router A receives the following link state packets from other routers in the network.

LSP from node Neighbor node (link cost)

B A(4) C(8) D(15) E(6)C A(5) B(8) D(1) E(2)D B(15) C(1) E(10)E A(16) B(6) C(2) D(10)

Construct the network topology from this table. From the topology you have constructed, use Dijkstra’salgorithm to compute the shortest path from node A to all nodes in the network.7.Explain DVMRP in detail.

UNIT IV. TRANSPORT LAYER.





1.How is repeater different from an amplifier?

An amplifier cannot discriminate between the intended signal & noise; it amplifies equallyeverything fed to it. A repeater does not amplify the signal; it regenerates it; when it receives a weakenedor corrupted signal, it creates a copy bit for bit, at the original strength.

2.What is the function of a router?

• Routers are specialized computers, which determine the best path for a particular transmission.

• Routers operate in the physical, data link, & network layers of the OSI models.• Routers relay packets among multiple interconnected networks. They route packets from one

network to any of a number of potential destination networks on an internet.3.What is the function of a gateway?

• A gateway is a protocol converter. Gateways potentially operate in all seven layers of the OSImodel.

• A router by itself transfers, accepts, & relay packets only across a network using similar protocols.• A gateway, on the other hand, can accept a packet formatted for one protocol and convert it to

packet formatted for another protocol, before forwarding it.• A gateway is generally software installed within a router.

4.What are the most popular routing algorithms?

1. Distance vector routing.

2. Link state routing.5.What are the X.25 layers? How does each relate to OSI model?

X.25 specifies three layers:1. Physical layer-It uses X.21 protocol.2. Frame layer-It uses a bit oriented protocol called LINK ACCESS PROCEDURE,

BALANCED (LAPB).3. Packet layer- It uses packet layer protocol.

Figure shows the relationship between X.25 layers & OSI layers6.Distinguish between the X.25 & Frame relay?

Feature X.25 Frame Relay

Data rate Fixed BurstyError control Available Not availableFlow control Available Not available

Multiplexing At the network layer At the data link layer Congestion control Not necessary Necessary

7. There is no sequence numbers in frame relay. Why?

• Frame Relay is a virtual circuit network.• In the virtual circuit network, the relationship between all packets belonging to a message or session

is preserved. A single route is chosen between sender and receiver at the beginning of the session.• When the data are sent, all packets of the transmission travel one after another along the route. So,

there is no sequence numbers in frame relay.8. ATM multiplexes cells using Asynchronous TDM

a) Asynchronous FDM c) Asynchronous TDM b) Synchronous FDM d) Synchronous TDM.

9. The VPI of an NNI is 12 bits length.

10.Which is more efficient, circuit switching or virtual circuit switching? Why?• Virtual circuit switching is more efficient than circuit switching.• In circuit switched connection, the links that make a path are dedicated. They cannot be used by

other connections.• In a virtual circuit connection, the links that make a route can be shared by other connections.

11. What are the three switching methods?

Circuit switching Packet switching andMessage switching.12. The PSTN is an example of a circuit switched network.

13. What are the two popular approaches to packet switching?

1. The datagram approach. 2.The Virtual circuit approach.





14.What is the fundamental difference between the circuit switching and packet switching?

Feature Circuit switching Packet switching

Dedicated copper path Required Not requiredBandwidth available Fixed Dynamic

Potentially wasted bandwidth Yes NoStore-and-forward transmission No YesEach packet follows the same route Yes NoCall setup Required Not neededWhen can congestion occur At setup time On every packet

15.What is meant by virtual path?A virtual path (VP) provides a connection or a set of connections

between two switches. Think of a virtual path as a highway that connects

two cities. Each highway is a virtual path.16. What is the major difference between Nonadaptive and adaptive routing Algorithm?

• Nonadaptive Routing: In nonadaptive routing algorithm, once a path to a destination has been

selected, the router sends all packets for that destination along that one route. The routing decisionsare not made based on the condition or topology of the networks.• Adaptive Routing: In adaptive routing algorithm, a router may select a new route for each packet

(even packets belonging to the same transmission) in response to changes in condition and topologyof the networks.

17. What is primary difference between N-ISDN and B-ISDN?

S.No N-ISDN B-ISDN

1 Narrowband ISDN Broadband ISDN2 It supports data rate of 64Kbps to

1.544Mbps.It supports data rate of 600Mbps.

18. Give two differences between connection-oriented and connection-less services.

S.No Connection-oriented service Connectionless service

1 It is modeled after the telephone system It is modeled after the postal system2 To use a connection-oriented network service,

the service user first establishes a connection,uses the connection, and releases theconnection.

To use a connectionless network service, theservice user selects the route and sends the packets.There is no connection establishment andtermination.

3 The packets are delivered from the source tothe destination in the correct order.

The network transfers each packet of data to thedestination one at a time, independently of theother packets.

4 Example:Remote login & Digitized voice transmission

Example:Electronic junk mail & Registered mail

19. What is Socket Address?

Socket Address is a combination of IP address and port Address20. What are the types of Socket

Stream Socket, Packet Socket, Raw SocketPART B

1. What are the advantages of using UDP over TCP2. Discuss with a neat diagram of UDP Segment3. Describe the steps required for data communication for a connection oriented

protocol4. Explain about TCP Congestion control in detail5. Explain the steps involved in computing checksum for an UDP Datagram6. What is Silly window Syndrome?7. List and Discuss the states used in the TCP Connection management finite state

machine8. Explain How TCP Flow control works





9. Explain in detail the various techniques to improve QoS

UNIT V: APPLICATION LAYER

1.Define the term graceful close?It is the service provided by the session layer to ensure that the dataexchange is complete before the session closes.2.What is the relation between plaintext and ciphertext?

• The original message is called plaintext.• The encrypted message is called ciphertext.

3. What are the two categories of encryption/decryption methods? What is themain difference between the categories?

1. Conventional methods: In this method, the encryption key and

the decryption key are the same and secret.

2. Pubic key methods: In this method, the encryption and

decryption algorithms are completely different functions and the

keys are different. Every user has the same encryption

algorithm and key. The decryption algorithm and key are kept

secret. Anyone can encrypt information, but only an authorized

receiver can decrypt it.

4. What is the concept behind substitutional character-level encryption?a. It is a simplest form of character-level encryption.

b. In monoalphbetic substitution (Caesar Cipher), each

character is replaced by another character in the set.c. The monoalphabetic encryption algorithm simply adds a number to the ASCII code of the

character; the decryption algorithm simply subtracts the same number from the ASCII codeof the character.

5. What is relative compression?d. Relative compression is the method of reducing the number of bits. It is also called as

differential encoding.e. This method is extremely useful for sending video. Commercial TVs send 30 frames of 0s

and 1s every second. However, usually there is little difference between consecutiveframes.

f. So, instead of sending an entire frame, in this differential encoding method only thedifference between consecutive frames are sent.

g. The small differences can be encoded into small steams of bits.

6.What is statistical compression?h. Statistical compression is one of the lossless data compression methods.i. This method uses short codes for frequent symbols and long codes for infrequent symbols.

In this way, the length of the total data is reduced tremendously. j. The three common encoding systems using this principle are Morse code, Huffman

encoding and Lempel-Ziv-Welch encoding.

7.What is run-length encoding?k. Run-Length encoding is one of the lossless data compression methods.l. When data contain strings of repeated symbols, the strings can be replaced by a special

marker, followed by the repeated symbol, followed by the number of occurrences.m. The symbol being repeated is called the run symbol and it follows the marker. The number

of occurrences, which is called length, is placed after the run symbol in the compresseddata.

n. This run-length encoding method can be used in audio and video.





8.An example of lossy compression is JPEG

a. Differential encoding b. Lempel-Ziv-Welch encodingc. Run-Length encoding d. JPEG

9.Encryption and decryption are functions of the presentation layer.

10.How is a secret key different from a private key?

The secret key is also called a private key. It is available only with authorized customers who

can view their account.11.In the public key encryption, the private key is used for decryption 12.How many keys are needed for a sender and a receiver in secret key encryption?

• Two keys are needed for a sender and a receiver.• A sender (customer) uses one public key and one secret key• A receiver (the bank) uses one secret key and one public key

13. How do authentication and access authorization differ?

• Authentication means verifying the identity of a sender. This technique tries to verify thatthe message is coming from an authentic sender and not an imposter.

• Access authorization is that the host gives permission only to users who have valid details.

14.Which factors needed for a secure network are handled by the digitalsignature?

• The concept of digital signature is similar to that of signing

transaction document when we do business with a bank.

• In network transactions we cannot personally sign the

request for withdrawal. However we can create the

equivalent of an electronic or digital signature by the way we

send the data.

15.What are the objectives of CMIS?Fault management, Accounting management, Configuration and name management, Performance

management, Security management16.What are the specific services provided by CMISE ?

Management association services , Management notification services, Management operation services17.What are the classifications of Encryption methods?

• Encryption methods fall into two categories1. Conventional methods 2. Public key methods

• Conventional method can be classified into two types1. Character-level encryption 2. Bit-level encryption

18.What is the use of mail transfer agent?

• A Message Handling system has two subsystems.1. User Agent: It allows people to read and send email.2. Message or Mail transfer agent: It moves the messages from source to

destination.

• The user agents are local programs that provide a command-based, menu-based or graphicalmethod for interacting with the email system.

• The mail transfer agents are typically system daemons that run in the background and moveemail through the system.

• MTAs are like the different departments of a post office.19.What is a virtual terminal and how is it used in remote access?

• A virtual terminal is an imaginary terminal with a set of standards characteristics that every hostunderstands. It is a software version of a physical terminal.

• A terminal that wishes to communicate with a remote host communicates to its local host. Thelocal host contains VT software that translates the request or data received from the actualterminal into the intermediary format used by the virtual terminal.





• The reformatted data travel over the network to the remote host. The remote host passes thetransmission to its own VT software, which transforms it from its VT format into the formatused by the remote host’s own terminals.

• Therefore the remote host receives the input as if from a local host.20.What is Digital Signature?

Digital signature is basically authentication technique based on public keyencryption/decryption.

21.What is cryptology?

The art of devising ciphers (Encryption) and breaking (Decryption) them is collectivelyknown as cryptology.

22.List the services offered by the session layer.• To coordinate connection and disconnection of dialogs between applications.• To provide synchronization points for data exchange.• To coordinate who sends when.• To ensure that the data exchange is complete before the session closes.

PART B

1. Explain RSA in detail with an example2. With neat diagram explain DES Algorithm in detail3. Write short notes on i) FTP ii) HTTP iii)SMTP4. Explain the followings related with FTP i) Connections and communications ii)

Commands5. Explain the followings related with HTTP i) Messages ii) Headers6. List and discuss the different types DNS Records7. With Relevant example discuss Substitution Ciphers8. Explain the different types of Authentication Protocols9. What is the need of Digital Signature? Explain the different types to generate

Digital Signature





ST. JOSEPH`S COLLEGE OF ENGINEERINGQUESTION BANK

SUB: PRINCIPLES OF MANAGEMENT SUB CODE : MG 2351BRANCH: ECE SEMESTER – VI

UNIT – IPart A (Each question carries 2 marks)1. Define Management.

Management is the process of designing and maintaining an environment inwhich individuals, working together in groups, accomplish their aims effectivelyand efficiently.According to Koontz and Weilhrich "Management is process of designing andmaintaining of an environment in which individuals working together in groups,efficiently and efficiently attain the organizational goals."

2. State the Functions of Manager.

P – Planning

O – OrganisingS – StaffingD – DirectingCO – CoordinatingR – ReportingB – Budgeting

3. What are the various skills required by a manager?

Managers require three kinds of skillsTechnical Skill – Knowledge of and proficiency in working with tools and

technologyHuman Skill – Ability to work with peopleConceptual Skill – Ability to recognize important element in a situation and

understand relationship among elements4. Write some characteristics of Management

Management is a continuous process. 2) Managers use the resources of theorganisation both physical as well as human to achieve the goals. 3) Managementaims act achieving the organisation goals by ensuring effective use of resources.

5. Define Productivity.

It implies effectiveness and efficiency in individual and organizational performance.Productivity = Outputs

Inputs (within a time period, quality considered)6. What is Effectiveness & Efficiency ?

Effectiveness is the achievement of objectives and Efficiency is the achievement of the ends with the least amount of resources. Effectiveness is doing right things &efficiency is doing things rightly.

7. What are management levels?

Top level management. 2) Middle level management. 3)Lower level management.8. Write some important functions of top level management .

To formulate goals and policies of the company. 2) formulate budgets. 3) To appointtop executives.





9. What is social responsibility?

Social responsibility is the part of the management to initiate actions to protect theinterest

of the society.10. Write Fayol's fourteen principles of management .

1) Division of work. 2) Authority and Responsibility. 3) Discipline. 4) Unity of command. 5) Unity of direction. 6) Subordination of Individual interest to generalinterest. 7) Remuneration. 8) Centralisation 9) Scalar chain. 10) Order. 11)Equity. 12) Stability of Tenure. 13) Initiative. 14) Esprit de Corps.

11. What is scalar chain?

The instructions and orders should be sent from the top management to thelower management.

12. Explain: Management is both —A science and an art.

Management is a science because it contains general principles. It is also an art because it requires certain personal skills to achieve desired results.

13. What is Esprit-de-corps?

It means ‘Unity is strength’In an organization, amongst the employees there should be harmony and

unity.14. List out the claimants of the business enterprise.

1) Shareholders. 2) Employees. 3) Customers. 4) Creditors. 5) Suppliers. 6) Government15. What are the major contributions of Taylor?

The major contributions of F.W.Taylor are as follows• He developed the principle of division of labor/work • He developed method study• He advocated time study

• He developed certain principles to breakup each job into small independentelements

• He developed the concept of fair day’s work • He proposed the functional organization

16. Write some important functions of top level management.

To formulate goals and policies of the company. 2) formulate budgets. 3) To appointtop executives.17. What is time study?

Time study refers to the measuring of (under controlled conditions) the timefor completing a particular process using specific materials and techniques.

This will be useful in arriving at a scientific standard for each work task inthe marketing process.18. Define partnership

Under the Indian Partnership Act of 1932, Partnership is defined as – “therelation between persons who have agreed to share the profits of a

business carried on by all or by any one of them acting for all”.19. What do you mean by ‘unity of command’?

‘Unity of command’ is an important principle proposed by Henry Fayol. Thisimplies that an employee should receive orders from one superior only.

20. What is centralization?





The organization is centralized when the power is concentrated in the hands of few people.Part B(Each question carries 16 marks)

1. Explain the Functions of Management.2. Discuss whether Management is a Science or Art.

3. Explain Systems approach to Operational Management.4. Explain the Henry Fayol’s principles of management?5. Explain the contributions of FW Taylor.6. Explain forms of business organizations.7. State the characteristics of a company.8. Differentiate between public limited company and private limited company.9. Discuss partnership firm, it characteristics , types., advantages and disadvantages.10. Explain the evolution of management thought.UNIT – II

Part A (Each question carries 2 marks)

1. Definition of planning

The determination of what is to be done, how and where it is t be done, who is todo it and how results are to be evaluated.

2. Types of planning

Short range and long range planning repeated and single use planning and

functional planning

3. What are the Qualities of good plan?

Simple , logical, flexible, practical, stable and it must be complete and integrated4. What are Rules ?

Statement of expected results expressed in quantitative terms.5. Define Procedure

It is a series of related task that up the chronological sequence and the establishedway of performing the work to be accomplished.

6. Define Budget.

Statement of expected results expressed in quantitative terms.7. Define Objectives.

Objectives are goals established to guide the efforts of the company and each of itscomponents

8. What is MBO ?

Process where by the superior and subordinate of an organization jointlyidentify its common goal, define each individual’s major areas of responsibility interms of results expected of him and use this measures as guides for operating the

unit and assessing the contribution of each if its members9. what is TOWS matrix ?

It is a conceptual frame work for systematic analysis, which facilitates matching theexternal threats and opportunities with the internal weakness and strength of theorganization.

10. Define Strategy.

Determination of basic long term objectives and of courses of action and allocationof resources to achieve these aims.

11. What are Policies ?





Verbal, written, or implied overall guide setting up boundaries that supply thegeneral limits and direction in which managerial action will take place.

12. State different strategies of Porter’s generic strategy.Overall cost leadership strategy, differentiation strategy and focused strategy

13. Define Planning Premises.

Anticipated environment in which plan are expected to operate. They includeassumptions or forecasts of the future and known conditions that will effect theoperation of plans

14 Define MIS

MIS is more advance technology for solving its basic requirements. MIS used for decision making in the various functional areas of business.

15. Explain the terms decision-making. It is a process of selection from a set of alternative courses f action which is thoughtto fulfill the objectives of the decision problem more satisfactory than others.

16. What are the difference between PERT and CPM

S. No. CPM PERT1. It is activity oriented PERT is event oriented2. CPM is planning device It is control device3. It estimates only one time It estimates three times4. It is a deterministic model It is probabilistic model

17 What are classification of budget?

a) Functional classification- Sales, production, cash, capital and master budget b) Time classification- Short, current and long term budgetc) Activity level- Fixed and flexible budget

18. What is zero base budget?

Initially the budget is designed from a zero base. The main element is ZBB is futureobjective orientation.19. What is DSS ?

DSS –use computers to facilitate the decision making process of semi structuredtasks

20. Benefits of planning

Emphasis on objectives, minimizes uncertainty, facilitates control, improvescoordination, secure economy, encourage innovation and improve competitivestrength

Part B (Each question carries 16 marks)

1. Discuss the Nature of Planning.

2. Explain the Steps in Planning.3. Explain Various elements of Plans .4. Explain Purpose of Planning.5. Explain the Process of MBO.6. Discuss the Advantages and Disadvantages of MBO.7. Explain Strategic Planning Process.8. Explain Tows Matrix.9. Explain Portfolio Matrix.10. Suggest some recommendations to make strategies successful. UNIT III





1. Define Organizing?

Organising is the process of identifying and activities required to attain the objectives,delegating < creating responsibility and establishing relationships I people to work effectively.

2. Mention any four characteristics of an organization.

a. Common objectives b. Specialisation or Division of Labour c. Authority of structured. Group of persons

3. List out the steps involved in organization process.

a. Determination of activities b. Grouping of activitiesc. Assignment of Dutiesd. Delegation of authority

4. Mention the various principles involved in organization.

1. Principle of unity of objective2. Principle of division of work or specialization3. Principle of efficiency4. Principle of span of control

5. Differentiate between formal and informal organization.

SI no. Point of view Formal organisation Informal organisation

1. Origin It is created deliberately andconsciously by the frames of theor anisation.

It is created spontaneouslynaturally.

2. Purpose It is created for achievinglegitimate objectives of theor anisation.

It is created by members of theorganisation for social and

s cholo ical satisfaction.3. Nature Planned and official Unplanned and unofficial.

4. Size It may quite large. It may be small size.

6. Mention the three categories of relationships in span of management.

a. Direct single relationship b. Direct grouprelationshipsc. Cross relationship

7. State the important factors in determining an effective span of management.

1. Capacity of superior 2. Capacity of subordinates3. Nature of work 4. Type of technology5. Delegation of authority

8. What are the types of departmentation ?

1. Departmentation by function.2. Departmentation by Territory or Geography.3. Departmentation by Customers.4. Departmentation by equipment or process.





5. Departmentation by product or service.

9. State the advantages of departmentation by function.

Advantages:

1. It is most logical, scientific, time proven and natural method of departmentation.2. It provides specialization of work which makes maximum utilization of manpower

and other resources.3. It ensures proper performance control.4. It facilitates delegation of authority and therefore, reduces the burden of top executives.

10. State the disadvantages of departmentation by function.

Disadvantages:

1. There is a tendency for overspecialization. The department managersare experts in handling the problems in their department alone. They may not beable to understand the problem of other departments.

2. Functional departmentation discourages communication across functions so that theworkers develop a narrow technical point of horizontal conflicts.

3. It increases the workload and responsibility of the departmental heads.4. It does not offer any scope for training for the overall development of manager.

11. Give a note on departmentation by customers.

This type of departmentation is preferred when the needs of customers are different innature. Big organizations provide special services to different types of customer.

12. What is departmentation by product?

Departmentation By Product Or Service:In this case, the units are formed according to the product. It is more useful in multi-line

corporations where ] expansion and diversification, manufacturing and mark characteristics of the product are of primary concern.

13. Define authority."Authority is the right to give orders and the power to exact obedience".

14. List out the sources of authority.

a. Formal authority theory b. Acceptance Authority Theory , ;

c. Competence theory15. What is line authority?

Line authority is the direct authority which a superior exercises over a number of subordinates to carry out orders and instructions. In an organizing process, authority isdelegated to the individuals to perform the activities.

16. What is staff authority?

A staff person assists the line people in attaining their objectives. Staff authority is purelyadvisory. Types of staff authority are a) Advisory staff authority, b) Compulsory staff authority& c) Concurrent staff authority.

17. State the types of organizational charts.

a) Vertical or Top-to-Bottom chart b) Horizontal or Left-to-right chartc) Circular or concentric chart

18. What is departmentation by process?

Departmentation By Process Or Equipment:Under this type of departmentation, activities are grouped on the basis of production





processes or equipment involved.19. What is Performance Appraisal? What are the different methods/techniques of

Performance appraisal?

Performance Appraisal is evaluating the actual performance of the employee for determining the compensation and identifying the potential of the

employees.Methods/Techniques of Performance Appraisal:(i) Trait-based appraisal: (job knowledge, leadership, judgment, ability,initiative, loyalty): Graphic scale method, ranking method, grading system,forced distribution method, check list method, Critical incidentmethod, group appraisal(ii)Appraisal by results: MBO, Behaviorally Anchored Rating(BARS),Assessment Centre, 360 degree performance appraisal.

20. What are various stages of staffing Process?


1. What are the factors determining span of Management?2. What are the various types of departmentation?3. Discuss the factors determining the degree of decentralization of Authority.4. What are various problems in organizing?

5. What are the various factors affecting staffing.6. Describe Selection Process.7. What are Methods of Performance Appraisal ?8. Describe departmentation by process and state its advantages and

disadvantages?10. Distinguish between formal and informal organization.11. Explain the various sources of recruitment. What are their advantages and

disadvantages?UNIT – IV



Enterprise plans

Organization plans

Number and kindsof managersrequired

Manager inventory

Analysis of present andfuture needsfor managers

Externalsources

Internalsources

RecruitmentSelectionPlacementPromotionSeparation

AppraisalCareer Strategy

Training&Development

External environment




1. Define Leading.

it is a process of influencing people so that they will contribute to organization andgroup goals.

2. Define Motivation .It is a process of stimulating people to action to achieve/ accomplish desired goals.

3. . Democratic leaderHe consults with subordinates on proposed actions and decisions and encourages

participation from them..4. Define Job Enrichment.

it attempts to make a job more varied by removing the dullness associated with performing repetitive operations

5. What is QWL?

Increasing productivity and reducing inflation and as a way of obtaining industrialdemocracy and minimizing labor disputes.

6. Define Leadership.Art or process of influencing people so that they will strive willingly and

enthusiastically towards achievement of the goal .7. What are the Styles of Leadership ?

Autocratic,Democratic and Free-rien8. Define Communication.

Transformation of ideas from one person to another.9. What are the various types of communication?

Formal,informal,vertical,horizontal,grapevine,written and oral communication.10. Country club management

Mangers have little or no concern for production. but are concerned for people11. Define Motivation

It is a process of stimulating people to action to achieve/ accomplish desired goals.12. Explain - Maslow’s Needs.

Physiological needs, Safety needs, Social needs, Self- Esteem needs and Self-actualization needs.

13. Define Incentives

An incentive is something which stimulates a person towards some determination14.what are Job content factors

Achievement, advancement, responsibility, respect, growth and development.15. Define Expectancy theory

force=Valance * Expectancy 16. what is Equity theory

Outcomes by a person Outcomes by another person------------------------------------ = -----------------------------------Inputs by a person inputs by another person

17. Define.Creativity

Ability and power to develop new ideas 18. what is Innovation.

Use of new ideas. 19. Define Brainstorming

Improve problem solving by finding new ideas and unusual solution20.. Define Leadership





Art or process of influencing people so that they will strive willingly andenthusiastically towards achievement of the goal

Part B (Each question carries 16 marks) 1. Explain some of theories of Motivation?2. Explain Likert’s Four System of Management.

3. Explain Managerial Grid.4. Describe Communication Process.5. What are the Barriers in communication and how they can be improved ?6. What are the qualities required for effective leadership?7. what are the essentials of good communication system?8. Explain the various theories of Leadership?9. what are the various types and networks of communication?10. What are the various techniques of Motivation?UNIT - V


1. what is control?

Control is the measurement and correction of performance in order to make sure theenterprise objectives and the plans devised to attain them are accomplished.

2. Give some critical points standards of control.

Cost standard, revenue standards, goals standards and program standards.3. What is concurrent control?

This control measures for taking corrective action while any programme meet anyobstacle in this activities.

4. State the difference between feedback and feed forward control technique?

S.No.

Feedback Feed forward

1. It measures only the output of the process

It measures the inputof the process

2. It is submissive approach It is aggressiveapproach

3. Less benefit More benefit5. Define Budget?

A Budget the expression of a firm’s plan is financial form for a period of time in tothe future.

6. Define budgetary control?

A system which uses budgets as a means of planning and controlling all aspects of producing and selling commodities and services.

7. Write the objectives of budgetary control?d) It aims at maximization of profitse) To plan and control the income and expenditure of the organizationf) To provide adequate working capital

8. What are classification of budget?

g) Functional classification- Sales, production, cash, capital and master budgeth) Time classification- Short, current and long term budgeti) Activity level- Fixed and flexible budget

9. What is zero base budget?





Initially the budget is designed from a zero base. The main element is ZBB is futureobjective orientation.

10. What are the difference between PERT and CPM

S. No. CPM PERT1. It is activity oriented PERT is event oriented

2. CPM is planning device It is control device3. It estimates only one time It estimates three times4. It is a deterministic model It is probabilistic model

11. Define MIS

MIS is more advance technology for solving its basic requirements. MIS used for decision making in the various functional areas of business.

12. Define productivity?

Productivity is a measure of how much input is required to produce a given output.13. Define OR?

OR is a systematic analysis of a problem through scientific methods, carried out byappropriate specialists, working together as a team, finding an optimum and themost appropriate solution to meet the given objective under a given set of constraints.

14. Define Linear Programming?

It is a mathematical technique in operation research and a plan of action solve agiven problem involving linearly related variables in order to achieve the laid downobjectives in the form of minimizing or maximizing the objective function under given set of constraints.

15. What is Inventory Control

Inventory control refers to the control of raw materials and purchased material instore and regulation of investment in them.

16. What is JIT ?Just in time inventory system, in this method the suppliers delivers the materials tothe production spot just in time to be assembled. This method reduces the cost of inventory.

17. What are objectives of value engineering?

a) It is a special type of cost reduction technique. b) Modify and improve product designc) Reduce the product costd) Increase the profite) Simplify the product

18. What is MNC?

Multinational corporation is an enterprise which own or control production or service facilities outside the country in which they are based.19. Write some advantages of MNCs?

f) It can promote quality product at low priceg) MNC leads to increase in production aggregate employment, exports and

imports of the required inputsh) It increases the government revenues.

20. What is work simplification?

It is the process of obtaining the participation of workers in simplifying their work through time study, motion study, work flow analysis and layout of work situation.





21. Define quality circles?

Quality circles are groups of people, from the same organizational area, who meetregularly to solve problems they experience at work. Members are trained insolving problems, in applying statistical quality control and working in groups.

22. What is preventive control?

It the method to develop better managers who will skillfully apply concepts,techniques and principles and who will look at managing the problems from system point of view, thus eliminating the unwanted results caused by poor management.

23.. What are the various forms of international business?

Exportation, licensing agreement, management contracts, Joint ventures andsubsidiaries.


1. Discuss the Control Techniques.2. Explain Operations Research Procedure.3. What are Techniques for improving productivity?4. Discuss the Principles of Preventive Control.

5. Explain the Global Theory of Management.6. What factors affect the Companies at International Level?7. Why do companies decide to go international? Also explain the merits and

limitations of multinational companies.8. Explain how companies go international and also explain how they effect

organization complexity and managerial involvement abroad.9…..Explain the functions of management at international level.10 . Discuss the various types of budgets





ST. JOSEPH’S COLLEGE OF ENGINEERING, CHENNAI-119

DEPARTMENT OF ECE

EC2354: VLSI DESIGN

UNIT I: CMOS TECHNOLOGY

PART-A

1. What are the advantages of SiO2 as a dielectric.

SiO2 has a relatively low loss & high dielectric strength, thus application of high gate fields is possible.2. State the 3 modes involved in the operation of an enhancement transistor

1. Accumulation mode 2.Depletion mode 3. Inversion mode.3. What is a field induced junction?

In a pn junction the n- type conductivity is brought about by a metallurgical process, ie the electronsare introduced into the semiconductor by the introduction of donor ions. In an inversion layer substrate junction, the n- type layer is induced by the electric field E applied to the gate .Thus this

junction instead of being a metallurgical junction is a field induced junction.4. What are the factors that influence the drain current.

• The distance between source and drain• The channel width• The threshold voltage Vt

• The thickness of the gate – insulating oxide layer • The dielectric constant of the gate insulator • The carrier(electron or hole) mobility, µ.

5. Define cut – off and saturated regions in the characteristics of an MOS transistor.

Cut – off current flow is essentially slow.Saturated region – Channel is strongly inverted and the drain current flow is independent of the drain

– source voltage.6. Define threshold voltage and state the parameters on which it is dependent on.

Vt can be defined as the voltage applied between gate & source of an MOS device below which Idseffectively drops to zero. It is a function of

• Gate conductor material• Gate insulation material

• Gate insulator thickness - channel doping• Impurities at the silicon insulator interface• Voltage between the source and the substrate,Vsb.

7. Define Body effect.

• The threshold voltage Vt is not constant with respect to the voltage difference between thesubstrate and the source of the MOS transistor.

• So, when several MOS devices are connected in series, the threshold voltage is increased due tovoltage difference between the substrate and the source. This effect of body or substrate voltageis called body effect.

8. What is channel length modulation?

• When an MOS device is in saturation, the effective channel length is decreased such that, L eff =L - Lshort .

Where Lshort = √ 2(εsi /qNa) (Vds – (Vgs – Vt))• The reduction in channel length increases the W/L ratio, thereby increasing β as the drain

voltage increases.9. Define noise margin. Illustrate how it can be obtained from the transfer characteristics of a

CMOS Inverter.

Noise margin is a parameter that allows us to determine the allowable noise voltage on the input of agate so that the output will not be affected. The 2 common parameters are NMH & NML Where

NML = | VILmax – VOLmax| and NMH = | VOHmin – VIHmin|VIHmin=minimum HIGH input voltage

VILmax = maximum LOW i/p voltageVOHmin = minimum HIGH o/p voltage





VOLmax = maximum LOW o/p voltage10. Define rise time( tr ).

Tr is the time for a waveform to rise from 10% to 90% of its steady state value.11. Define fall time ( tf )

Time for a waveform to fall from 90% to 10% of its steady state value.12. Define delay time,td.

Time difference between input transition and 50% output level .This is the time taken for a logictransition to pass from input to output. Fig 4.18 (a) Page 207 Weste.13. What is latch-up?

Latch-up is the shorting of the VDD & VSS lines in CMOS fabrication process due to parasitic circuiteffect.Latch-up results in chip self-destruction or system failure.14. How is a capacitor created in CMOS fabrication process?

Capacitors are created in the CMOS fabrication process by adding at least one extra layer of polysilicon.Between the two polysilicon layers, a second thin-oxide layer is required.15. List the materials used for masks in IC technology.

Photoresist, Polysilicon, Silicon dioxide,Silicon nitride16. What are the advantages of twin tub process?

Used for protection against latch-up

Provides separate optimization of p-type & n-type transistors17. How is resistor created in CMOS fabrication process?

If Polysilicon is left undoped, it is highly resistive. This property is used to build resistors.A resistive metal such as nichrome me be added to produce high value & high quality resistors.The resistor accuracy might be improved by laser trimming the resulting resistors on each chip to some

predetermined test specification.18. What is BiCMOS?

BiCMOS is the combination of bipolar & CMOS transistors.To reduce the delay times of the highly loaded signals (microprocessor busses) and to provide better

performance for analog functions the bipolar devices (npn or pnp) can be added to MOS transistors or vice versa.19. What are the advantages of SOI process?

There is no latch-up

There are no body-effect problems No field-inversion problemsLower substrate capacitances provide the possibility for faster cirecuits.20. What is the objective of the layout rules?

To obtain a circuit with optimum yield in as small an area as possible without compromising reliabilityof the circuit.21. What are the types of layout design rules?

• Micron rule,Lambda based rule22. What is guard ring?

p+ diffusion in the P-substrate and n+ diffusion in the n-well are called guard rings that are used to collectinjected minority carriers.When they are implemented in a structure, the n+ guard ring must be tied to VDD and the p+ guard ringmust be connected to VSS.Guard rings must be included in the fabrication process to prevent I/O latch-up.23. What is scribe line?

The scribe line is a specifically designed structure that surrounds the completed chip and is the point atwhich the chip is cut with a diamond saw.The construction of the scribe line varies from manufacturer to manufacturer.24. What is passivation or overglass?

• This is a protective glass layer that covers the final chip. Openings are required at pads andany internal test points.

25. List the two techniques that can be used to prevent latch-up

• Latch-up resistant CMOS process,Layout techniques26. What are the types of oxidation?





• Wet Oxidation: The oxidizing atmosphere contains water vapor • Dry Oxidation: The oxidizing atmosphere is pure oxygen

27. What are the advantages of EBL pattern generation?

EBL: Electron Beam LithographyPatterns are derived directly from digital dataThere are no intermediate hardware images

Different patterns may be accommodated in different sections of the wafer without difficulty.Changes to patterns can be implemented quickly.28. What are the types of etching process?

• Isotrophic etch,Fully anisotrophic etch,Preferential etch29. What are the types of interconnect?

Metal interconnectPolysilicon/Refractory interconnectLocal interconnect30. What is a thinox ?

Thinox is an active mask formed which defines the areas where thin oxide are needed to implementtransistor gates and allow implantation to form P or N-type diffusions for transistor source/drain regions.31. How is the channel stop implant made?

Channel stop implant is made by doping the P-substrate in areas where there are no N-transistors P + usinga photo resist mask.32. List the four main CMOS technologies

i. N-well processii.P-well processiii. Twin-tub processiv. Silicon on insulator.

PART-B

1. (a) Explain the operation of a CMOS inverter clearly indicating the variousregions of operation.(12)

(b) List the advantages of Lambda based design rules as compared to micron based design rules.(4) (Apr’05)

2. (a).Discuss the aspects of MOS transistor threshold voltage.(8)

(b) Derive the VTC of CMOS inverter. (8) (Apr’05)3. (a). Discuss the operation of s CMOS inverter with diagrams.(8)(b) Discuss the mead Conway design rules for the silicon gate NMOS process.(8)

4. Briefly describe the working principles & characteristics of NMOS device withnecessary diagrams.(16) (Nov ’04)

5. Explain the various steps involved in the P-well CMOS process with necessarydiagrams (Nov ’04)

6. (i) Draw and explain the n-well process (10)(ii) Explain the twin tub process with a neat diagram (6) (Nov’07)

7. (i) Discuss the origin of latch up problems in CMOS circuits with necessary diagrams. Explain theremedial measures. (10)(ii) Draw and explain briefly the n-well CMOS design rules. (6) (Nov’07)

8. Explain the various features of CMOS technology (May 09)9. Discuss the steps involved in IC fabrication process (16) (Nov09)10. Describe n- well process in detail (16) (Nov 09)11. Explain with neat diagrams the SOI process and mention its advantages.12. i) How are circuit elements implemented in IC’s? (8)

ii) Explain about CMOS interconnects with diagrams (8) (Nov 08)UNIT II:CIRCUIT CHARACTERIZATION AND SIMULATION

PART-A

1. What are critical paths ?

Critical paths are logic paths that require attention to timing details. Designers use a timing analyzer to find the slowest path in a logic design. Quick delay estimation is essential to design critical paths.

2. List the levels affecting critical path.





The architectural / micro architectural level, the logical level, the circuit level,and the layout level.

3. Why floor planning is of great importance in VLSI?

Delay is dependent on the layout. The floor plan determines the wire lengths that can dominate thedelay.

4. What is propagation delay time tpd?

It is the maximum time from the input crossing 50% to the output crossing 50%. It is also called asMax-time.5. What is contamination delay time tcd?

It is the minimum time from the input crossing 50% to the output crossing 50%. It is also called asMin-Time.

6. What are the depending factors for delay of a logic gate?

a. Width of the transistors in the gate. b. Capacitance of the load that must be driven.

7. How do you determine gate and diffusion capacitance?

Gate capacitance can be determined from the transistor width form the schematic and diffusioncapacitance depends on the layout.

8. Give the equation for elmore delay model. N N

t pd= ∑ R n-i Ci = ∑ Ci ∑ R ji i=1 j=1

R n-i = Node in the ladder of resistance R n-i between the node and a supply.9. Define logical effort.

Logical effort is defined as the ratio of input capacitance of the gate to that of the input capacitanceof an inverter that can deliver the same output current. It is independent on the size. It helps toestimate the delay of the entire path quickly based on the parasitic and logical delay of the path.

10. What is electrical effort?

It is the ratio of load capacitance to input capacitance. It is also called as the fan-out. This dependson the size.

11. What is parasitic delay?

The parasitic delay of the gate is the delay of the hate when it drives zero load. It can be estimatedwith RC delay models.

12. Give the equations that express the delay of a logic gate.d= f + p , p=> Parasitic delay, f => Effort delay/ Stagg effortf d= g.h , g => Logical effort , h=> electrical effort/Fan-out

h=Cout / Cin, Cout => Capacitance of the external load being driven.

Cin=> Input capacitance of the gate.13. What is path delay?

It is the sum of delays of each stage. It is the sum of the path effort delay D f and path parasitic delayP.

D= Σ di = Df + P , where Df = Σ fi & P= Σ Pi14. Give the factors that give rise to static power dissipation.

a. Sub-threshold conduction through off transistors. b. Tunneling the current through gate oxide.c. Leakage through reverse biased diodes.d. Contention current in the ratioed circuits.

15. Give the factors that produce dynamic power dissipation.a. Charging and discharging of load capacitance.

b. Short term current when both PMOS and NMOS networks are partially ON .16. Give the formula for static power dissipation

Pstatic = Tstatic VDD

17. Write the formula for dynamic power dissipation.Pdynamic=C VDD

2 f sw

C=> Load capacitanceVDD=> High potential / power f sw => average frequency





18. How do we reduce dynamic power?

Activity for reduction, Reduction of the inter connect switching capacitance and Chooselower power supply /operating frequency.

19. What is wire pitch?

The sum of the width and the spacing from their neighbors is called the wire pitch.20. What is aspect ratio?

The thickness to width ratio is called aspect ratio.21. What is cross talk?

In modern VLSI processors, transistors switch much faster. The wires are packed very closelytogether and thus a large fraction of their capacitance is to their neighbors. When one wire switches,it tends its neighbor through capacitive coupling. This effect is called cross talk.

22. Why does interconnect increase delay?

1. The wire capacitance adds loading to each gate.2. Long wires have significant resistance that contributes distributed RC delay or flight time.

23. List the hard errors that cause integrated circuits to fail permanently.

Electro migration, Self heating, Latch up, Overvoltage failure, Circuit pitfalls24. What is MTBF and FIT?

MTBF is the mean time between failures. FIT is the failure in time, the number failures that wouldoccur every thousand hours per million devices.

25. What is infant mortality?Soon after birth, systems with weak or marginal components tends to fail. This period is calledinfant mortality.

26. What are the effects of self heating?

1. Hot wires exhibit greater resistance and delay.2. Self-heating causes temperature induced electro migration problems in bidirectional wires.

3. Brief pulses of high peak currents may even melt the inter connect.27. What do you mean by latch up in CMOS technology?

CMOS chips develop law resistance path between VDD and GND causing catastrophic melt down.The phenomenon called latch up occurs when parasitic bipolar transistor formed by the substratewell and diffusion turn on. With proper layout procedures latch up problems can be easily avoided.

28. Give the types of scaling in CMOS technology.

Transistor scaling, Interconnect scaling29. What do you mean by SPICE?

SPICE is a Simulation Program with Integrated Circuits Emphasis. It solves the non linear differential equations describing components such as transistors, capacitors and voltage sources.

30. What does the two letters in units denote in SPICE?

The first character indicates the order of magnitude and the second letter indicates a unit for humanconvenience and is ignored by SPICE.

31. What is threshold voltage?

The threshold voltage is defined as the values of Vgs below which Ids becomes zero. In the realtransistor characteristics, sub-threshold current continues to flow for Vgs < Ids. The threshold voltagevaries with L,W, Vds and V bs .

PART B

1. Discuss in detail about the various delay models in CMOS technology.2. What is meant by power dissipation? Derive an expression for static power dissipation anddynamic power dissipation.3. Explain interconnect in detail.4. Explain in detail about Device models.5. Discuss in detail about hard errors and soft errors in VLSI technology?6. Write notes on logical effort and transistor sizing.7. Explain low power design.8. Explain the various circuit pitfalls that cause chips to fail.9. Find the rising and falling propagation delays of an AND- OR- INVERT gate using the Elmoredelay model. Estimate the diffusion capacitance based on a stick diagram of the layout.10. Draw a 3- input NAND gate with its gate and diffusion capacitance. Assume all diffusion nodesare contacted.





UNIT III: COMBINATIONAL AND SEQUENTIAL CIRCUIT DESIGN

PART-A

1. What is a transmission gate.

A transmission gate consists of an n- channel transistor and a p – channel transistor with separategate connections and common source and drain connections. It gives good transmission of both logic1 and logic 0.

2. Why is the transmission of logic 1 degraded as it passes through a nmos pass transistor.When S = 1 (Vdd) , and Vin = 1 the pass transistor begins to conduct and charges the CL towardsVdd.Initially Vin is at ahigher potential than Vout, the current flows through the device. As voltageot the load approaches Vdd – Vtn, the n- device begins to turn – off. Vtn is the n- transistor bodyeffected threshold .. Thus the transmission of logic 1 is degraded.

3. What is a tristate inverter.

A tristate inverter is got by cascading a transmission gate with an inverter. When c = 0 and –c = 1,the output of the inverter is in a tristate condition.

4. Draw the structure & symbol of a CMOS tri - state inverter.

5. Write the equation for total static power dissipation.

nPs = ∑ leakage current X supply voltage

1n = no: of devices.

6. What is a pass transistor ? What are its advantages ?Pass transistor is similar to a buffer.

Advantages of pass transistor are(i) occupies less space,because any logical operation can be realized with

lesser number of MOS transistors(ii) No direct path between VDD and Gnd. So,amount of power dissipation

is lesser under stand by condition.7. How latch up problems can be rectified in CMOS fabrication process ? (Nov ’04)

CMOS/bulk devices have parasitic bipolar transistors can cause latch up,a condition in which highcurrents exist between VDD & Gnd.

One method of preventing Latch up consists of decreasing the current gainsof the parasitic transistors. If the product of the two current gains of both transistors is less than unity,f/b is not self sustaining & the device cannot latch. The current gain of the vertical pnp tr is determined

by the process design & can be reduced by using buried layers of n+ material under the n wells.The tendency of CMOS / bulk devices to latch up is reduced by putting guard rings around the

p&/or n wells & making frequent contacts to the rings. This reduces the parasitic resistance values.8. What is a transmission gate ? Realize a 2-input XOR gate using transmission gates.

(Apr ’05)





9. What is a pull – down device (nov 09)

10. What are the disadvantages of CMOS transmission gates? Draw the symbol for

transmission gate.

Disadvantages of CMOS transmission gate are(iii) Require more area than NMOS pass circuits(iv) Require complemented control signalsT.G symbol

11. Give a brief description about NAND implementation of a MUX circuit.

MUX consists of switched paths.NAND implementation uses depletion devices to short circuitundesired connections while using enhancement mode devices to form the switches that exertcontrol. MUX is defined by the locations of the ion implants required to form the depletionmode transistors. (1)

Diagram (1)

A’ A B’ B

I0

I1

I2

I3





12. Draw the structure of 2:1 CMOS MUX.

13. What is meant by scaling ?

Scaling of MOS transistor is concerned with systematic reduction of overall dimensionsof the devices as allowed by the available technology, while preserving the geometric ratiosfound in the larger devices.

14. Is D-flipflop applicable for counter applications ? Why ?

D-latch is not an edge triggered storage element because the output changesaccording to the input, ie, latch is transparent, when the clock is high. Due tothis transparency property, it is unsuitable for counter applications.

15. List the disadvantages of dynamic logic.

(v) Logic function is implemented by the NMOS pull down network.(vi) Less no. of transistors required.(vii) Noise margin doesn’t depend on transistor ratios(viii) Consumes only dynamic power.(ix) Faster switching speeds.

16. What is meant by domino logic ?

Domino logic module consists of a PE logic block followed by an Inverter. This ensures that allinputs to the next logic block are set to 0 after the precharge period. So, only the possible transitionduring the evaluation period is the 0-1 transition.

17. Draw the switch logic arrangement for CMOS 3-input NOR gate.

18. Draw 2-input MUX gate using transmission gates.





19. Write down the Expression for the total propogation delay in an n bit carry bypass Adder.

T p = tset up + M tcarry + (N/M-1) t bypass + M tcarry + tsum.20. What is the total time delay for a ripple carry Adder.

Tadder = (N-1) tcarry + tsum.21. List the different considerations for designing a Ripple carry adder.

(i) Propogation delay of ripple carry adder is linearly proportional to N.(ii) It is important to optimize tcarry than tsum.(iii) Inverting all i/ps to a full adder results in inverted values for all o/ps.

22. What are the draw backs of a static adder circuit.

(iv) Consumes large area.

(v) Circuit is slow.23. Why is static adder circuit slow ?

A static adder ckt is slow as,(i) long chains of series PMOS transistors are present in both carry & Sum generation

circuit.(ii) Intrinsic load capacitance of the Co signal is large & consists of 2 diffusion & 6 gate

capacitances plus the wiring g capacitances.(iii) Carry generation ckt requires 2 inverting stages per bit.

(iv) Sum generation ckt requires an extra logic stage24. What is the advantage of Dynamic adder design?

Reduced capacitance of dynamic circuitry results in substantial speed up over staticimplementation.

25. List the advantages of two phase clocking scheme.(Nov ’04)

(i)No chance of race conditions occurring in the circuit(ii) No timing errors due to races or Hazards or clock skew(iii) two phase clocking schemes are popular due to its simplicity & reliability(iv)Design procedures are also simple

PART B

1. What is a pass transistor ? What are their limitations ? Why ? Explain howtransmission gates are built and their principle of operation. (16) (Apr ’05)2. Construct a 8 to 1 multiplexer using CMOS devices. Give necessaryexplanation.(8)3. Explain why the transmission gate of logic 1 is degraded as it passed througha n MOS pass transistor (4) (Apr ’05)4. Explain Pass Transistor and transmission gates with neat sketches. (8)5. Design CMOS NOR gate, NAND gate and NOT gate.6. Discuss the operation of a CMOS latch (6) (Nov’07)7. Implement the following function using CMOS

f(A,B,C) = A’BC + AB’C + ABC’ (8)UNIT IV: CMOS TESTING

PART-A

1. List some typical defects in the manufacturing of IC.

• Layer to layer shorts• Discontinuous wires• Thin – oxide shorts to substrate or well.• Nodes shorted to ground or power





• Nodes shorted to each other • Inputs floating• Outputs disconnected

2. What are SA0 & SA1 faults.

When anode in a circuit is permanently at logic 1 or 0 due to thin oxide shorts , ie the n – transistor gate to Vss or the p – transistor gate to Vdd or meta to metal shorts. The SA0 or SA1 Fault occurs.

3. Define observability and controllability.

Observability: The observability of a particular internal circuit node is the degree to which one canobserve that node at the outputs of an integrated circuit. Controllability : It is the measure of the easeof setting an internal node to 1 or 0 state via primary inputs. A well designed circuit should have allnodes easily controllable.

4. What is fault sampling?

Fault sampling is one of the approaches to fault analysis. It is used in the circuit where it isimpossible to fault every node in the circuit. In this approach, nodes are randomly selected andfaulted.

5. What is a sensitized path?

In D – alg one objective is to propagate a fault at a particular node to one or more primary o/p This path to the o/p pin is called a sensitized path.

6. What are primary i/p’s and o/p’s?

A primary output(Po) is adirectly observable signal ,such as a pad or a scan o/p .A primary input isone that can be directly set via a pad or some other means.

7. State the 3 types of fault simulation process.

1. Serial simulation 2. Parallel simulation 3. Concurrent simulation.8. What is delay fault testing.

In the case of a high powered NAND gate composed of paralleled n - & p – transistors, if an open ckt occurs as in fig 7.10 pg 483 Weste the gate would stillfunction but with increased pull down time. This is a delay fault.

9. What is ILA testing.

An iterative logic array is a collection of identical logic modules . An ILA is C – testable if it can betested with a constant number of input vectors independent of the iteration count. An ILA is I -testable if a particular fault that occurs in any module as a result of an applied input vector is

identical for all modules in an ILA.10. What are the advantages & disadvantages of IDDQ.

As IDDQ is based on quiescent current measurement which is time consuming, the tests must berun slower than normal ,thus increasing the test time. However this technique gives a form of indirect massive observability at little overhead.

11. What are the various connections of a Test Access Port.(TAP).

The TAP has 4 or 5 single bit connections. They are• TCK(the test clock input) – used to clock tests into & out of chips.• TMS ( The test mode select) – used to control test operations.• TDI ( the test data input) – used to input test data to a chip.• TDO ( test data output) used to output test data from a chip.

It also has an optional signal• TRST( The test Reset Signal) used to synchronously reset the TAP

controller: also used if a power – up reset signal is not available in thechip being tested.

12. Describe the test architecture of a boundary scan using TAP.

Fig 7.25 pg 502 . Basic test architecture consists of • The TAP interface pins• A set of test data registers to collect datafrom chip• An instruction register to enable test inputs• A TAP controller, which interprets instructions & controls the flow of

data.13. What is a TAP controller.





The TAP controller is a 16 state FSM that proceeds from state to state based on TCK & TMSsignals. It provides signals that control the test data registers & instruction registers.

14. Explain BYPASS ,EXTEST, SAMPLE /PRELOAD.

The instruction registers has to decode 3 instructions they are.BYPASS – This instruction is represented by an IR having all zeroes in it. It isused to bypass any serial data registers in a chip with a 1 – bit register. This

allows specifis chips to be tested in a serial scan scan chain without having toshift through the accumulated SR stages in all the chips.EXTEST – This allows for the testing of off chip circuitry & is represnted by all ones in the IR.SAMPLE /PRELOAD: - This instruction places the boundary scan register in the DR chain andsamples or preloads the chip i/os.

15. What is a test DR.

The test data registers are used to set the inputs of modules to be tested and to collect the resultsof running tests.

16. What are boundary scan registers?

The boundary scan register is a special case of a data register. It allows circuit boardinterconnections to be tested, external components tested, and the state of chip digital I/Os to besampled.

17. What is the aim of adhoc test techniques?

Reducing the combinational explosion of testing18. Distinguish functionality test and manufacturing test.

Functionality test is used to confirm the function of a chip as a whole whereas manufacturing testsare used to verify that every gate operates as expected.

19. List the typical manufacturing defects.

Layer to layer shorts ,discontinuous wires,missing or damaged vias, shorts through the thin gate oxideto the substrate or well

20. What is ATPG.

Automatic Test Pattern Generation is a testing tool which can achieve excellent fault coverage21. What is IDDQ testing.

It is a method of testing for bridging faultsPART-B

1. Explain the different fault models.

2. Explain system level test techniques. (16) (Nov’07)3. What is self test.4. Explain how serial scan testing is implemented.5. Design a block diagram of a test generator for an 8 x 4 K static RAM.6. What is a programmable logic device? Explain the implementation of a

Boolean function using AND OR arrays. Give appropriate diagrams for a suitable example.(16)(Apr ’05)

7. Explain the chip level test techniques. (16) (Nov’07)8. Explain with diagram the design strategies for testing the

CMOS devices.(Nov 08)9. Explain in detail Scan based test techniques (16)10. Discuss the 3 main strategies for testability. (16)11. i) Explain in detail Boundary – Scan test.

ii) Enumerate on physical faults with examples.12. i) Explain Built – in self test.

ii) Describe the testing techniques at chip level and at system level.13. Explain the importance of system level test techniques.

UNIT V: SPECIFICATION USING VERILOG HDL

PART -A

1. Write the syntax for switch primitive instantiation.

• Syntax: switch_name instance_name(output, data, control_input);• Example: nmos n1 (out, data, control);





pmos p1 (out, data, control);cmos c1 (out, data, ncontrol, pcontrol);

2. List out different data types in verilog.

• Net type: It represents a physical connection between structural elements. Ex: wire• Register type: It represents an abstract data storage element. It is assigned values only within an

always statement or an initial statement. Ex: reg3. Give the symbol, Truth table and syntax of bufif1.

Truth table:Control input

Input

0 1 x Z0 z 0 L L1 z 1 H Hx z x x xz z x x x

Syntax: bufif1 n1 (out, input, control);Symbol:4. Give the structural coding of an Half adder

module HA (a, b, sum, carry)input a, b;output sum, carry;xor (sum, a, b);and (carry, a, b);

endmodule

5. What are the types of modeling in verilog?

• Structural,Data flow,Behavioral6. What is HDL?

• HDL: Hardware Description Language• HDL is a standard language to describe the operations of digital circuits.

7. Name two types of HDLs.

• Verilog• VHDL: Very High Speed Integrated Circuits Hardware Description Language.8. What is module?

• A module is the description of a unit that performs some function.• The basic unit of description in verilog.• It describes the functionality or structure of a design.• It describes the ports through which it communicates with other modules.

9. What is the difference between initial and always statement?

• Initial statement: It executes only once.• Always statement: It executes in a loop i.e. it is executed repeatedly.

10. What is inter-statement delay?

• Inter-statement delay: The delay by which a statement’s execution is delayed.

• Example: sum = (A^B)^C;#4 carry = A&B + A&C + B&C;

• The delay in the second statement specifies that the execution of the assignment is to bedelayed by 4 time units, and then executes the second assignment.

11. What is intra-statement delay?

• Intra-statement delay: The delay between computing the value of the right-hand sideexpression and its assignment to the left-hand side.

• Example: Sum = #3 (A^B)^C;• The delay in this statement means that the value of the RHS expression is to be computed

first, wait for 3 time units, and then assign the value to the sum12. List any two capabilities of verilog.





• Primitive logic gates such as AND, OR & NAND are built-in into the language.• Flexibility of creating a user-defined primitive (UDP). This UDP can be either combinational or

sequential logic primitive.13. What are the types of event control?

• Regular event control (edge-triggered )• Named event control• Event OR control• Level-sensitive timing control

14. What is value set?

• Verilog supports four values to model the functionality of real hardware.

Value levels Conditions in hardware circuit01xz

Logic 0, falseLogic 1, trueUnknown valueHigh impedance

15. Define net.

• Net is a data type that represents a physical connection between structural elements.• Its value is determined from the value of its drivers.• The default value to a net is Z.• Nets are declared with the keyword wire.

• It can be declared as scalar or vector.16. Write the syntax for gate primitive instantiation.

Gate_name instance_name (out, in_1, in_2, in_3, …….);Example: and g1 (c, a, b);

or g2 (c, a, b);17. Define a port. How is it declared?

• Ports are interface terminals that allow a module to communicate with other modules.These corresponds to the input and output points on a library cell.

• All ports must be declared within a module lisiting.• Unidirectional port can be declared as

input in_1, in_2;output out_1, out_2;

• Bidirectional port can be declared asinout IO_1, IO_2;

18. Define an identifier.

• Identifiers are names of modules, variables, and other objects that can be used in the design.• Identifiers consist of upper & lower case letters, digits 0 through 9, the underscore

character( _ ) and the dollar sign ($).• The first character must be a letter.

19. What is UDP?

• User Defined Primitives are self-contained and do not instantiate other modules or primitives.

• UDP declaration: primitive UDP_name (port list);• Two types of UDP: 1. Combinational, 2. Sequential

20. List the types of Gate delay

• The signal propagation delay from any gate input to the gate output can be specified using agate delay.

• The gate delay can be specified in the gate instantiation itself.• Types of gate delay.

rise delay, fall delay, turn-off delay21. What are the types of structural modeling?





• Switch instantiation (at the transistor level),Gate instantiation (at the gate level)• Module instantiation (to create hierarchy),UDP instantiation (at the gate level)

22. What are the types of procedural assignment?

(i) Blocking Procedural assignment:

• A procedural assignment in which the assignment operator is an “=” is a blocking procedural assignment.

• The assignment statement is executed before the next statement is executed.• Blocking assignment statements are executed in the order they are specified in a

sequential block.(ii) Non-blocking procedural assignment:

• In a non-blocking procedural assignment, the assignment symbol “<=” is used.• It allow scheduling of assignment without blocking execution of the statements

that follow in a sequential block.23. What is the difference between reduction operator & bitwise operator?

• Reduction Operator: It performs a bitwise operation on a single vector operand and yield a1-bit result.

• Bitwise Operator: It performs bitwise operation between two vector operands and yieldvector result.

• Example A=4’b1010; B=4’b1101;Z=A&B = 4’b1000 -------------- Bitwise AND operationZ=&A=1’b0 ---------------- Reduction AND operation

24. What is replication operator?

• Replication operator is used to concatenate the same number to the specified number of times.

• Example: A=4’b1010; Z= 2 A=8’b1010 1010• In the above example, 2 is the replication constant that specifies how many times to

replicate the 4-bit number A inside the bracket.PART-B

1. Explain the design hierarchies2. Explain Behavioral RTL modeling.

3. Write notes on priority encoder.4. Explain how a CMOS D – FLIP –FLOP is constructed .5. (i) Construct a full adder ckt. And give its verilog HDL coding.

(ii) Write the behavioral description for a full adder .6. (i) List the various data objects in Verilog HDL and explain with examples.(6)(ii)Write the Verilog HDL behavioral and structural description of 4 to 1 MUX (10)

7. Write the Verilog code to simulate a positive edge triggered D FF with synchronous reseti/p:

(i) Using IF statement(ii) Using WAIT—UNTIL statement.(16) (APR ‘05)

8. Write the Verilog HDL structural description of full adder and explain (8) (APR ‘05)9. (i) Give a Verilog structural gate level description of a bit comparator. (10)(ii) Give a brief account of timing control and delay in verilog (6) (Nov’07)

10. (i) Give a Verilog structural gate level description of a ripple carry adder.(10)a. Write a brief note on the conditional statements available in verilog. (6) (Nov’07)

11. a) i) With a neat flow chart explain the VLSI design flow.ii) Explain the syntax of conditional statements in verilog HDL with examples

12. a) i) Explain in detail Behavioural and RTL modeling.ii) Write the program using verilog HDL to implement a Full adder ckt.

13. Explain in detail any 5 operators used in HDL.14. i) Write the verilog code for 4 bit ripple carry adder.(10)ii) Give the structural description for priority encoder using verilog (6)15. i) Write a verilog program for 3 to 8 decoder in gate level description(12)ii) What are the differences between behavioural and RTL modeling? (4)





16. Write a verilog program for 8 bits full adder using one bit full adder. The one bit full adder should be written in behavioural modeling.

17. Explain various features of gate level modeling and switch level modeling.(16)

question bank-antenna wave and propogation

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