code no: r22041 r10 set - 1 ii b. tech ii semester ... · pdf fileii b. tech ii semester...

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Code No: R22041

II B. Tech II Semester Supplementary Examinations Jan/Feb - 2015

ANALOG COMMUNICATIONS (Electronics and Communications Engineering)

Time: 3 hours Max. Marks: 75

Answer any FIVE Questions

All Questions carry Equal Marks

~~~~~~~~~~~~~~~~~~~~~~~~

1. An AM modulator consists of 500 kHz carrier with peak amplitude of 32V and a 12 kHz

modulating signal whose amplitude is sufficient to provide a 14V peak change in the amplitude

of the envelope. Determine the following:

i) Upper and lower side frequencies

ii) Modulation coefficient, percent modulation

iii) Maximum and minimum amplitudes of the envelope

iv) Draw the output envelope.

v) Draw the output frequency spectrum. (5×3M=15M)

2. a) Explain the time domain and frequency domain description of DSBSC.

b) Write short notes on Costas Loop. (8M+7M)

3. a) Explain how a balanced modulator is used to demodulate SSB signals?

b) Draw the circuit and explain the generation of SSB-SC wave using frequency discrimination

method? (7M+8M)

4. a) Define modulation index in FM. Discuss the separation of Narrow band FM and wide band

FM for various modulation indices.

b) Draw the phasor diagram of FM and compare it with AM? (9M+6M)

5. a) Derive necessary equations to show that the SNR will improve with pre- emphasis circuit?

b) Calculate the figure of merit for a SSB-Sc system. (7M+8M)

6. a) Draw the block diagram of phase modulated type FM transmitter and explain the significance

of each block?

b) Explain the classification of transmitters. (8M+7M)

7. a) What is an Amplitude Limiter? Explain its operation with a neat circuit Diagram.

b) Explain about image frequency and image frequency rejection of radio receiver. (8M+7M)

8. a) Explain with neat wave forms, how a PWM wave is converted into PPM wave.

b) Explain why a single channel PPM of system requires the transmission of synchronization

signal, where as a single channel PAM or PDM do not require the same. (9M+6M)

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1. a) Explain the need for modulation and also mention its advantages?

b) Explain about frequency division multiplexing. (8M+7M)

2. a) In an DSB-SC system the modulating signal is single tone sinusoid 10cos(2 10 )tπ which

modulates a carrier signal10cos(2 1000 )tπ . Plot the spectrum of the modulated wave?

b) How DSB-Sc can be generated using Balanced modulator. (8M+7M)

3. Describe the single tone modulation of SSB. Assume both modulating and carrier signals are

sinusoids. Write SSB equation and draw all the waveforms and spectrums. (15M)

4. a) Discuss the merits and demerits of AM and FM modulation techniques.

b) A carrier is frequency modulated by a sinusoidal modulating waveform of frequency 2 kHz

resulting in a frequency deviation of 5 kHz. What is the bandwidth occupied by the

modulated waveform? Also compute the new bandwidth, when the amplitude of the

modulating sinusoid is increased by a factor of 3 and its frequency is lowered to 1 kHz.

(8M+7M)

5. Calculate signal to noise ratio for SSB SC. Find its figure of merit. (15M)

6. a) Explain about AM transmitter. Why feedback is used in the AM transmitter and explain its

advantage?

b) Draw the block diagram of SSB transmitter and explain their principle of operation

(8M+7M)

7. a) Explain about double spotting and how it occurs.

b) Describe the general process of frequency changing in a super heterodyne receiver.

(7M+8M)

8. Discuss the generation and demodulation of PWM. (15M)

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1. In a nonlinear device, the output current 0i and the input i

v are related by the equation 3

0 1 1 3 1i a v a v= + , Where 1a and 3a are constants. Explain how these devices may be used to

provide i) a product modulator and ii) an amplitude modulator. (15M)

2. a) Explain the time domain description of DSB-Sc wave.

b) The modulating signal in an AM-SC system is a multiple tone signal given by

1 1 2 2 3 3( ) cos cos cosm t A t A t A tω ω ω= + + . The signal ( )m t is modulated by a carrier cosc c

A tω .

Write the equation of modulated wave. Plot the spectrum and find bandwidth. (8M+7M)

3. Define vestigial sideband modulation? Discuss the vestigial sideband modulation in time

domain and frequency domain? What are its advantages and applications? (15M)

4. a) Explain demodulation of FM signal with the help of PLL.

b) Compare the Narrow band FM and Wide band FM (7M+8M)

5. a) What is capture effect? Explain FM threshold effect.

b) Explain the equivalent model of a generalized communication system for noise calculation.

(7M+8M)

6. a) With the help of necessary block diagram describe the functioning of FM transmitters using

frequency stabilization scheme for the FM oscillator centre frequency?

b) What is the different classification of transmitters (9M+6M)

7. a) Explain the need for a mixer in a receiver and also explain its operation with neat circuit

diagram.

b) A superhetrodyne radio receiver is tuned to receive 1500 kHz carrier amplitude modulated

by a 5 kHz sinusoidal tone. Assuming the IF to be 455 kHz, identify the input and output

frequency components for the IF amplifier. The IF bandwidth is 10 kHz. (7M+8M)

8. a) Explain about single polarity and double polarity in PAM.

b) Distinguish between time division multiplexing and frequency division multiplexing

(7M+8M)

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1. a) Write the equation for Amplitude Modulation and define i) modulation index

ii) Percentage modulation iii) under-modulation and iv) over-modulation.

Also Explain why over modulation is undesirable.

b) The output of a diode envelope detector is fed through a dc blocking capacitor to an

amplifying stage, which has an input resistance of 10 k Ω . If the diode detector load resistor

is 5 k Ω , determine the maximum depth of sinusoidal modulation so that in the detector

negative peak clipping will not occur. (8M+7M)

2. a) Explain DSB-SC generation by using Balanced Ring Modulator.

b) Evaluate the effect of frequency and phase error in the demodulation of DSB-SC wave using

Synchronous detector (7M+8M)

3. a) Explain the phase discrimination method of generating SSB modulated waves with the help

of neat diagram.

b) Explain about envelope detection of VSB wave pulse carrier. (7M+8M)

4. a) Explain how FM is generated using Armstrong method.

b) What are zero crossing detectors? Explain how they can be used as FM demodulators.

(7M+8M)

5. a) Explain why Signal to Noise ratio is a Figure of Merit in case of performance of a

communication channel.

b) Calculate the figure of merit for a SSB-Sc system (7M+8M)

6. Describe the operation of direct FM transmitter and also explain two methods to up convert the

frequency of an angle modulated wave? (15M)

7. a) Differentiate between simple, delayed and amplified AGC and explain their operation with

the help of simple circuit diagrams.

b) Discuss briefly similarities and differences between AM and FM receivers. (8M+7M)

8. a) Write short notes on Time Division Multiplexing.

b) Draw the circuit for PPM demodulator and explain its operation. (8M+7M)

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Code No: R22026


CONTROL SYSTEMS (Com. to EEE, ECE, EIE, ECC, AE)


Answer any FIVE Questions All Questions carry Equal Marks

~~~~~~~~~~~~~~~~~~~~~~~~

Note: Provide ordinary and Semi log graph sheets

1. a) Why negative feedback is preferred in control systems? What are the characteristics of

negative feedback?

b) Explain the effects of feedback on i) stability ii) sensitivity iii) External disturbance

(6M+9M)

2. a) Explain how a two phase servomotor differs from a normal induction motor.

b) Reduce the given block diagram (figure 1) and hence obtain the transfer function ( )

.( )

C s

R s

c) Compare ac and dc servomotors. (3M+8M+4M)

3. a) Define the test signals i) Step ii) Parabolic iii) Impulse

b) What is the effect of derivative control on damping ratio, peak overshoot, steady state error

and rise time.

c) Consider the closed-loop system given by .2)(

)(22

2

nn

n

sssR

sC

ωξω

ω

++= Determine the values of

ξ and so that the system responds to a step input with approximately 5% overshoot and

with a setting time of 2 sec. (Use the 2% criterion). (3M+4M+8M)

4. a) Explain the effects of adding poles and zeros to G(s)H(s) on the root loci.

b) Sketch the root locus for 0<K< , for the system with the open loop transfer function

)22)(2(

)()(2 +++

=ssss

KsHsG (5M+10M)

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G1

H2 H1

R(s) C(s)

- -

-

Figure 1

+ + G2

+

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Code No: R22026

5. Sketch the Bode plots for the following transfer functions and determine the system gain K for

the gain crossover frequency to be 10 rad/s (15M)

)12.0)(1()(

2.0

++=

−

sss

KesG

s

6. a) Enlist the step-by-step procedure for the construction of Nyquist plots.

b) A system is given by )12)(1(

14)(

2 ++

+=

sss

ssG .Sketch the Nyquist plot and hence determine

the stability of the system. (5M+10M)

7. a) What is compensation? What are the different types of compensators?

b) What is a lag compensator, obtain the transfer function of lag compensator and draw pole-

zero plot?

c) Explain the different steps to be followed for the design of compensator using Bode plot?

(2M+3M+10M)

8. a) Explain the Concepts of Controllability and Observability?

b) Obtain the state transition matrix for the state model whose A matrix is given by

c) Enumerate the properties of state transition matrix? (5M+5M+5M)

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1. a) How are control systems classified?

b) Write the differential equations governing the behavior of the mechanical system shown in

figure 1 draw the mechanical network and obtain the transfer function. (6M+9M)

2. For the given electrical network Figure 2.

a) Obtain the signal flow graph

b) Compute the gain using the mason’s gain formula. (7M+8M)

3. a) What are the time domain specifications? Explain each of them.

b) A closed loop control system is represented by the differential equation

, where e = r-c is the error signal. Determine the undamped natural

frequency, damping ratio and percentage maximum overshoot for a unit step input.

(6M+9M)

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Code No: R22026

4. a) What do you mean by stability? Explain the qualitative and conditional stability?

b) Draw the complete root locus for )4)(2(

)()(++

=sss

KsHsG from the root locus plot, find

the range of values of K for which the system will have damped oscillatory response. Also,

determine the value of K for a damping ratio of ξ=0.5. (5M+10M)

5. a) Discuss the stability analysis from Bode plots.

b) Sketch the Bode plots for the following transfer functions and determine the system gain

K for the gain crossover frequency to be 10 rad/s (5M+10M)

)01.01)(1.01)(1()(

2

sss

KssG

+++=

6. a) What is the effect of adding a zero at origin to the to the open loop transfer

function on polar plot?

b) Sketch the polar plot of a system given by )12)(1(

1)(

2 ++=

ssssG . If the plot crosses the

real axis determine the corresponding frequency & magnitude (5M+10M)

7. a) What is lead compensator? When is it preferred?

b) Design a lag compensator that will provide a phase lag at 400 and alternation of 12 dB at 2

rad/sec. Determine its transfer function. (7M+8M)

8. a) Define i) State ii) State variable iii) State model

b) Construct the state model for a system characterized by the differential equation

.

c) Obtain the state transition matrix for the state model whose A matrix is given by

(3M+8M+4M)

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1. a) Explain the limitations of closed loop system over open loop system.

b) Find the transfer function for the following mechanical system: Shown in figure 2

c) Define the term ‘impulse response of a system. (4M+8M+3M)

2. a) For the system represented in the given Figure 4 , obtain transfer function

b) Write down the signal flow equations and draw the signal flow graph for the above

system. (8M+7M)

3. a) Derive the expressions for rise time, peak over shoot, settling time of 2nd

order system of unit

step input.

b) A unit feedback system is characterized by an open-loop transfer function )5(

)(+

=ss

KsG

Determine the gain K so that the system will have a damping ratio of 0.5. For this value of

K determine settling time, peak overshoot and times to peak overshoot for a unit-step input.

(6M+9M)

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Code No: R22026

4. a) A feedback system has an open loop transfer function

( ) ( )( )952 ++

=sss

KsHsG

Determine by use of the Routh criterion, the maximum value of K for the closed loop

system to be stable.

b) A unity feedback system has the following open loop transfer function

Determine the stability of the system in terms of the parameter K. (7M+8M)

5. a) What are steps involved in constructing the Bode plot for a given G(jω)H(jω).

b) Sketch the magnitude and phase Bode plots. Determine the gain crossover frequency,

phase crossover frequency, gain margin and phase margin. (5M+10M)

)025.01)(25.01(

)1(20)(

2sss

ssG

++

+=

6. a) Define Polar plot? Explain how you can determine relative stability using polar plots.

b) Sketch the polar plot of a system given by )12)(1(

13)(

++

+=

sss

ssG . If the plot crosses

the real axis determine the corresponding frequency & magnitude (5M+10M)

7. a) Write the transfer function of a lag compensator and draw its polar plot and frequency

response plots.

b) Design a lead compensator that will provide a phase lead of 350 and again of 6.5 dB at 2.8

rad/sec. What will be the transfer function of the lead compensator that will satisfy the

above requirement? (7M+8M)

8. a) Test the controllability and observability of the system described by

b) Solve the following differential equation by converting it into state variable form

Where y(0)=0, (0) = 0; u(t)=unit step input. (8M+7M)

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1. a) Distinguish between:

i) Linear and non linear control system

ii) Open loop and closed loop control systems

iii) Time invariant and time varying control systems.

Give an example for each of the above.

b) Find the transfer function of the following system show in figure.3 (8M+7M)

2. a) Derive the transfer function of an a.c. servomotor and draw its characteristics.

b) Explain the Synchro error detector with circuit diagram. (8M+7M)

3. a) What is the difference between type and order of a control system? Explain each with an

example?

b) The Figure 2 shows PD controller used for the system. Determine the value of Td so that

the system will be critically damped? Calculate it’s settling time? (5M+10M)

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4. a) Enumerate the limitations of Routh criterion. (5M+10M)

b) By means of the Routh criterion, determine the stability of the system represented by the

following characteristic equations. For systems found to be unstable, determine the number

of roots of the characteristic equation in the right half of the s-plane.

i) 0520102 234 =++++ ssss ii) 054322 23456 =++++++ ssssss

5. a) Define the following terms

i) Gain margin ii) Gain crossover frequency

iii) Phase margin iv) Phase crossover frequency v) Corner frequency

b) Sketch the magnitude and phase Bode plots. Determine the gain crossover frequency, phase

crossover frequency, gain margin and phase margin. (5M+10M)

)05.01)(5.01(

10)(

ssssG

++=

6. a) State Nyquist Stability Criterion? Explain the use of Nyquist Stability Criterion in the

assessment of relative stability of a system.

b) With the help of Nyquist plot assess the stability of a system )2)(1(

3)(

ssssG

++=

What happens to stability if the numerator of the function is changed from 3 to 30?

(7M+8M)

7. a) What is the purpose of using compensator? What is the basis for the selection of a particular

compensator?

b) Explain the design procedure of a lag-lead compensator in frequency domain. (5M+10M)

8. a) Test the observability of the system described by

b) For a system described by the state equation the response is

;

Determine the system matrix A and the state transition matrix Φ(t). (5M+10M)

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Code No: R22043


ELECTRONIC CIRCUIT ANALYSIS

(Com. to ECE, EIE)




~~~~~~~~~~~~~~~~~~~~~~~~

1. a) For a single stage common emitter transistor amplifier configuration, RS=10K and RL= 10K.

The h-parameter values are hfc= - 51, hic =1.1K Ω , hrc = 1, hoc = 25 µ A/V. Find AI; AV; AVS;

Ri, and Ro.

b) Draw the circuit of Darlington emitter follower. Explain why the input impedance is higher

than that of a single-stage emitter follower

2. a) Explain the advantages of negative feedback amplifiers.

b) What is linear analysis of feedback amplifiers? Illustrate with examples.

3. a) Draw the circuit of colpitts oscillator and explain its working. Derive the frequency of

oscillator and condition for sustained oscillation.

b) State and explain Barkhausen criterion.

4. a) When 2-stages of identical amplifiers are cascaded, obtain the expressions for overall

voltage gain and power gain.

b) List out various types of distortions that occur in transistor amplifiers. Discuss the causes for

each.

5. a) Show that in Hybrid - π model, the diffusion capacitance is proportional to the emitter bias

current.

b) What is the frequency range to consider Giacolletto model of a transistor at high frequencies?

What is the significance of fT in discussing the frequency range of a transistor at high

frequencies

6. a) What are the advantages of push-pull connection in AF power amplifiers?

b) Design a push-pull class B power amplifier to achieve maximum output power to a 10 Ω

load. The two transistors have the following ratings Pc(max) = 5W; VCE(max) = 45V.

IC(max) = 1A. Assume Necessary data.

7. Substantiate the necessity of the following in tuned amplifiers.

a) Heat Sinks

b) Stabilization circuits

8. Write short notes on the following:

a) 3-Pin IC fixed voltage regulators

b) Buck and Boost Switching regulators.

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Code No: R22043


ELECTRONIC CIRCUIT ANALYSIS

(Com. to ECE, EIE)




~~~~~~~~~~~~~~~~~~~~~~~~

1. For the emitter follower circuit as shown in Figure 1, calculate the quiescent voltage and

current for VCC=20 V, hfc = 1.3K Ω, hoc = 2.8 x 10-6

mhos and hrc is negligibly small.

Reactance of capacitance need not be considered at the frequencies of interest. If R1 = 27 Ω ,

R2 = 8.6 k Ω , RL= RE =500 Ω , Rs = 1k Ω , Rc=1.2 kΩ, Find the maximum undistorted peak-

to-peak output voltage.

2. a) Show that bandwidth increases with negative feedback.

b) Draw the block diagram of a single loop negative feedback circuit and explain each and every

block in detail.

3. Draw the block diagram of generalized LC oscillator and from that derive the frequency of

oscillation for a) Hartley Oscillator b) Colpitts Oscillator

4. Write short notes on:

a) Cascode amplifier b) Transformer coupled amplifier. c) Darlington pair

5. a) Draw the circuit of a Common Source FET amplifier. Derive an expression for the Voltage

gain at low frequencies. What is the maximum value of AV.

b) Draw the Common Source amplifier at Higher Frequencies and derive an expression for

voltage gain.

6. a) What is the difference between Class D amplifier and Class S amplifier

b) With a neat circuit diagram explain the operation of class AB power amplifier and mention its

advantages.

7. a) Discuss about the effect of Cascading Single tuned amplifiers on Band width.

b) What are the limitations of stagger tuned amplifiers?

8. a) Draw the circuit diagrams of series and shunt voltage regulators and explain their working.

b) What are the limitations of 3 terminal regulators?

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Code No: R22043


ELECTRONIC CIRCUIT ANALYSIS (Com. to ECE, EIE)




~~~~~~~~~~~~~~~~~~~~~~~~

1. a) State and prove Miller’s theorem and its dual.

b) Using linear analysis, derive expressions for voltage gain, input resistance of a CE amplifier

with Re.

2. a) Draw and explain the circuit of a voltage series feedback circuit.

b) What are types of amplifier circuits in any feedback systems? Discuss.

3. a) Derive frequency of oscillation of a Wien-bridge oscillator circuit with necessary diagrams.

b) What is the Condition for sustained oscillations and draw and explain the RC-phase shift

oscillators with Transistor.

4. a) Obtain the expressions for overall voltage gain, current gain and power gain of a two-stage

identical cascaded amplifier.

b) What are the advantages of Darlington pair? Explain with a neat diagram.

5. a) Discuss about various capacitances in a transistor at high frequencies.

b) Draw the common Drain Amplifier at high frequencies and derive expressions for voltage

gain, current gain.

6. Draw the circuit of class-B Power amplifier. Explain its operation and derive the expression for

efficiency of the amplifier by making necessary assumptions

7. a) Explain the operation of single tuned amplifier and derive the expression for Q factor.

b) What is staggering of tuned amplifiers? Discuss about its advantages and disadvantages.


a) positive and negative voltage regulators

b) series and shunt regulators.

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Code No: R22043


ELECTRONIC CIRCUIT ANALYSIS (Com. to ECE, EIE)




~~~~~~~~~~~~~~~~~~~~~~~~

1. a) With the help of circuit diagram and equivalent circuit of a common collector amplifier,

generate the expression for the overall input impedance of the pair

b) Explain how FET acts as voltage variable resistor.

2. a) What are the basic amplifiers used in a negative feedback system. Derive the relationship

between input and source resistance, output and load resistance of these basic amplifiers.

b) Show that input resistance increases with series mixing.

3. a) What do you mean by Barkhausen criterion? Give the Statement.

b) Draw the circuit diagram of FET based RC phase - shift oscillator and derive the expression

for frequency of Oscillations & condition for sustained Oscillations

4. a) Write short notes on Direct coupled and transformer coupled multistage amplifiers

b) With a neat circuit diagram analyze the two stage RC coupled JFET-CS amplifier.

5. a) Derive the expression for voltage gain of a common drain amplifier at high frequencies.

b) Derive an expression for fT of a single stage CE amplifier.

6. a) Explain the operation of transformer coupled power amplifier and derive an expression for

conversion efficiency.

b) What is cross over distortion? Explain how to eliminate this problem.

7. Derive an expression for ‘bandwidth’ and ‘quality factor’ of a capacitive coupled single

tuned amplifier in CE configuration. Make necessary assumptions and mention them.


a) three terminal IC voltage regulator.

b) over load voltage protection.

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Code No: R22042


ELECTRO MAGNETIC WAVES AND TRANSMISSION LINES (Com. to ECE, EIE)




~~~~~~~~~~~~~~~~~~~~~~~~~

1. a) Let V = xy2z, calculate the energy expended in transferring a 2µC point charge from

(1, - 1, 2) to (2, 1,-3).

b) State Gauss Law for electrostatic fields and obtain it in point form. (8M+7M)

2. a) For a current distribution in free space, A = (2x2y + yz)ax + (xy

2 - xz

3)ay - (6xyz – 2x

2y

2 )az

Wb/m. Calculate B and also show that divergence of A = 0 and divergence of B = 0.

b) State Biot-Savart’s law.

c) Applying Ampere’s law to obtain the expression for H due to a infinite line current assuming

symmetrical current distribution. (7M+2M+6M)

3. a) Check whether the following field is genuine EM field i.e whether it satisfies Maxwell's

equations. Assume that the fields exist in charge-free regions.

E = (3ρ2 cotΦ aρ +1/ρ (cosΦ)aΦ)sinωt

b) Write the Maxwell’s equations in point and integral forms.

c) Derive the expression for displacement current density. (7M+4M+4M)

4. a) Discuss about wave propagation in free space.

b) A plane wave propagating through a medium with εr=8 µr = 2 has E = 0.5e-z/3

sin(108t - βz)

ax V/m. Determine β, loss tangent, wave impedance, wave velocity. (8M+7M)

5. Explain the reflection by a perfect conductor at oblique incidence and obtain the expressions

for fields for both horizontal and vertical polarizations. (15M)

6. a) For parallel plane waveguide explain and analyze the concept of TE modes and obtain the

expressions for fields.

b) Define attenuation factor and obtain the attenuation factor for the TEM wave between

perfectly conducting parallel planes. (8M+7M)

7. a) A distortion less line operating at 120 MHz has R = 20 Ω/m, L = 0.2 µH/m, and C=63 pF/m.

i) Determine γ and Zo. ii) How far will a voltage wave travel before it is reduced to 20%

of its initial magnitude?

b) Derive the transmission line equations. (8M+7M)

8. a) Explain the steps involved in double stub matching.

b) A 75Ω transmission line is terminated by a load impedance ZL. If the line is 5λ/8 long,

calculate Zin when: (a) ZL = j45 Ω, (b) ZL = 25 - j65 Ω (8M+7M)

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1. a) In free space, V = x2y(z + 3) V. Find E at (3, 4, -6) and the charge within the cube

0 < x,y,z < 1.

b) Derive Laplace’s equation and express it in Cartesian and spherical coordinates. (8M+7M)

2. a) Applying Biot-Savart’s law and obtain the expression for H due to a infinite line current.

b) State the Maxwell’s equations for magnetostatic fields.

c) The y- and z-axes, respectively, carry filamentary currents 10 A along ay and 20 A along -az.

Find H at (- 3, 4, 5). (6M+3M+6M)

3. a) Check whether the following field is genuine EM field i.e. whether it satisfies Maxwell's

equations. Assume that the fields exist in charge-free regions. E = (1/r) sinθ sin(ωt-r)aθ b) Derive the electrostatic boundary conditions at the dielectric-conductor interface. (8M+7M)

4. a) Considering propagation of wave in good dielectrics from wave equations obtain the

expressions for attenuation, phase constants, wave velocity and intrinsic impedance of the

medium.

b) A lossy dielectric has an intrinsic impedance of 030200 ∠ Ω at a particular frequency. If, at

that frequency, the plane wave propagating through the dielectric has the magnetic field

component H = 10e-αx

cos (ωt-(1/2)x)ayA/m find E and α. Determine the skin depth and

wave polarization. (8M+7M)

5. a) Explain the reflection by a perfect conductor at normal incidence and obtain the expressions

for fields.

b) Explain the concept of total internal reflection and define Brewster angle. (8M+7M)

6. a) For parallel plane waveguide explain and analyze the concept of TM modes and write the

expressions for fields. Draw the distribution of fields between parallel planes for TM10

mode.

b) Define wave impedance and obtain wave impedances for TEM, TE and TM modes between

a pair of parallel planes. (8M+7M)

7. a) A telephone line has the following parameters: R = 40 Ω/m, G = 400 µS/m, L = 0.3 µH/m,

C = 0.5 nF/m. If the line operates at 10 MHz, calculate the characteristic impedance Zo and

velocity. Also find after how many meters will the voltage drop by 30 dB in the line?

b) Explain why loading is used in a transmission line. Classify loading schemes and explain

each one of them. (8M+7M)

8. a) Explain the steps involved in single stub matching.

b) A λ/2 line is terminated in Zr. Find the input impedance of the line.

c) What are the disadvantages of single stub matching and suggest a remedy. (7M+4M+4M)

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Code No: R22042






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1. a) Three point charges Q1 = 1 mC, Q2 = -2mC, and Q3 = 3 mC are respectively located at

(0, 0, 4), (-2, 5, 1) and (3, - 4, 6). Find the potential VP at P (-1, 1, 2) and also calculate the

potential difference VPQ if Q is (1, 2, 3).

b) Derive the expressions for conduction current and convection current. Also obtain point

form of Ohm’s law. (8M+7M)

2. a) If H = yax - xay A/m on plane z = 0, determine the current density and also verify Ampere's

law by taking the circulation of H around the edge of the rectangle,

Z = 0, 0 < x < 3, - 1 < y < 4.

b) State Ampere’s circuit law.

c) Applying Ampere’s law to obtain the expression for H due to a infinite sheet of current

assuming symmetrical current distribution. (7M+2M+6M)


equations. Assume that the fields exist in charge-free regions. E = (10/ρ) cos(ωt - 2ρ)aρ

b) Write the word statements of Maxwell’s equations and explain.

c) Explain Faraday’s Law. (7M+6M+2M)

4. a) Considering propagation of wave in good conductor from wave equations obtain the

expressions for attenuation, phase constants, wave velocity and intrinsic impedance of the

medium.

b) The magnetic field component of an EM wave propagating through a nonmagnetic medium

is H = 25 sin (2 X 108t + 6x) ay mA/m Determine the direction of wave propagation, the

permittivity of the medium, the electric field intensity. (8M+7M)

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Code No: R22042

5. a) Explain the reflection by a perfect dielectric at normal incidence and obtain the expressions

for fields, reflection and transmission coefficients.

b) Explain the reflection by a perfect dielectric at oblique incidence for perpendicular

polarization and obtain the expressions for fields, reflection and transmission coefficient

(15M)

6. a) Explain the propagation of TEM wave in a parallel plane wave guide and draw the sketch of

a TEM wave between parallel planes.

b) Define attenuation factor and obtain the attenuation factor for the TE wave between

perfectly conducting parallel planes. (8M+7M)

7. a) What is a loss less transmission line. For a loss less line obtain the expressions for γ, α, β, Zo.

b) A telephone line has R = 30 Ω/km, L = 100 mH/km, G = 0, and C = 20 µF/km. At f = 2 kHz,

obtain: the characteristic impedance of the line, the propagation constant and the phase

velocity. (8M+7M)

8. a) Explain the application of a λ/4 line as a quarter wave transformer.

b) A certain transmission line operating at ω = 106 rad/s has α = 6 dB/m, β = 1 rad/m, and

Zo = 60 + j40 Ω, and is 2 m long. If the line is connected to a source of 10 V, Zg = 40 Ω and

terminated by a load of 20 + j50 Ω, determine the input impedance and the sending-end

current. (8M+7M)

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Code No: R22042


ELECTRO MAGNETIC WAVES AND TRANSMISSION LINES

(Com. to ECE, EIE)




~~~~~~~~~~~~~~~~~~~~~~~~~

1. a) Define electric potential. Derive the relationship between electric potential and electric field

b) Derive continuity equation and explain the significance of relaxation using relevant

expressions. (8M+7M)

2. a) Planes z = 0 and z = 4 carry current K = -10ax A/m and K = 10ax A/m, respectively.

Determine H at (1,1,1) and H at (0, - 3,10).

b) Explain the terms magnetic scalar and vector potentials using relevant expressions.

c) State Ampere’s force law. (7M+4M+4M)


equations. Assume that the fields exist in charge-free regions. E = 40 sin(ωt + 10x)az

b) Derive the electrostatic boundary conditions at the dielectric- dielectric interface. (8M+7M)

4. a) Define polarization of a uniform plane wave. Discuss different types of polarizations using

relevant expressions and diagrams.

b) What is skin effect? Define skin depth.

c) A uniform plane wave propagating in a medium has E = 2e-αz

sin (108t - 3z) ay V/m.

If the medium is characterized by εr = 1, µr = 20, and σ = 3 mhos/m, find α, β, and H.

(4M+4M+7M)

5. a) Explain the reflection by a perfect dielectric at oblique incidence for parallel polarization and

obtain the expressions for fields, reflection and transmission coefficients.

b) State and prove Poynting theorem. (8M+7M)

6. a) Explain the characteristics of TE and TM waves.

b) Derive the relationship between phase velocity, the velocity with which the wave propagates

and free space velocities. (8M+7M)

7. a) A transmission line operating at 400 MHz has Zo = 80 Ω, α = 0.04 Np/m, β=1.5 rad/m. Find

the line parameters R, L, G, and C.

b) What is a distortion less transmission line? For a distortion less line obtain the expressions

for γ, α, β, Zo. (8M+7M)

8. a) Derive the relationship between input impedance of a shorted line, input impedance of a

open circuited line and characteristic impedance of the line. Obtain the input impedance of a

line terminated in characteristic impedance of the line.

b) Mention the salient features of a smith chart and discuss its use in transmission line theory

(8M+7M)

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Code No: R22021


PULSE AND DIGITAL CIRCUITS (Com. to EEE, ECE, ECC, BME, EIE)

Time: 3 hours Max Marks: 75



~~~~~~~~~~~~~~~~~~~~~~~~~

1. a) Obtain the response of an RC low pass circuit for a step input.

b) Draw the circuit diagram of RLC based ringing circuit and explain its operation.

2. a) Draw the basic circuit diagram of negative peak clamper circuit and explain its operation.

b) Draw the circuit diagram of slicer circuit using zener diodes and explain its operation with

the help of its transfer characteristic.

3. a) Define the transistor switching times:

i) delay time ii) rise time iii) storage time and iv) fall time.

b) Draw the circuit diagram of RTL logic gate and explain its operation with the help of truth

table.

4. a) Draw the circuit diagram of a fixed bias binary with speed up capacitors.

b) Explain the method of symmetrical triggering with relevant diagram.

5. Design a collector coupled monostable multivibrator employing two n-p-n silicon transistors

with 5 msec as its quasi stable state duration. Make reasonable assumptions.

6. a) Write the differences between the voltage and current time base generators?

b) Discuss the concept of Bootstrap Time Base Generator.

7. a) What is relaxation? With neat circuit diagram explain the principle of operation of a voltage

sweep circuit using UJT.

b) Define and explain the following terms: i) Phase delay and ii) Phase jitter

8. a) Explain a method of triggering a blocking oscillator with the help of circuit diagram.

b) With neat circuit explain operation of bi-directional sampling gate using transistors.

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Code No: R22021






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1. a) Obtain the condition for an RC high pass circuit to behave as a good differentiator.

b) What is a double differentiator circuit? Draw and explain its response to ramp input.

2. a) Draw the shunt clipper that clips the sine wave signal above +5V and explain its working

with waveforms.

b) Explain the response of the clamping circuit when a square wave input is applied under

steady state conditions.

3. a) With the help of neat wave forms explain the transition time of a diode.

b) Compare the Resistor Transistor and Diode Transistor logic families.

4. a) Explain the reason for the occurrence of overshoot at the base of normally ON transistor of

one shot. Derive an expression for overshoot.

b) Explain how a Schmitt trigger can be used as a comparator and as a squaring circuit.

5. Draw the circuit diagram of collector coupled transistor astable multivibrator. Explain its

operation and also derive an expression for the time period.

6. a) Explain how UJT is used for sweep circuit?

b) Draw the circuit diagram of Transistor Miller time base generator and give the requirement

of each component.

7. a) Explain the need for synchronization.

b) With neat circuit diagram and waveforms, explain the pulse synchronization of an astable

relaxation circuit.

8. a) Explain the operation of astable transistor blocking oscillator with diode control.

b) Differentiate different types of uni-directional diode sampling gate.

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Code No: R22021






~~~~~~~~~~~~~~~~~~~~~~~~~

1. a) Obtain the expression for the gain A and phase angle Φ of an RC low pass circuit. Sketch

the frequency response and find the expression for higher cutoff frequency.

b) A symmetrical square wave of 20V peak to peak amplitude with zero average value and with

a fundamental time period ‘T’ is given as input of an RC low pass circuit. Obtain the

expression for peak-to-peak value of the output signal.

2. a) Classify different types of clipper circuits. Give their circuits and explain their operation

with the aid of transfer characteristics.

b) State and prove clamping-circuit theorem.

3. a) Design the transistor switch for the following specifications: Vin= ±3Vsquare wave,

VCC=10V, IC=1mA, hFE=50. Assume Si transistor.

b) Why totem pole is used in DTL? Draw circuit diagram and explain a DTL gate with this.

4. a) Discuss symmetrical and asymmetrical triggering in case of bi-stable transistor

multivibrator.

b) Design a transistor Schmitt trigger circuit employing two n-p-n silicon transistors which

has its upper tripping point at 6V and lower tripping point at 4V. Assume that VCC=18V,

IC(sat)=4mA and hFE(min)=20.

5. a) Describe how the gate width T of an emitter coupled monostable multivibrator can be

linearly varied by adjusting the bias voltage V through a dc potentiometer.

b) Design an Astable Multivibrator to generate 5 kHz square wave.

The supply voltage VCC=10V, IC(sat)=10mA, hFE(min)=50 and assume Si transistors.

6. a) Explain how an inductor L can be used to improve the linearity of a simple RC sweep

circuit.

b) How does sync signal amplitude will affect frequency of operation of the sweep generator?

7. a) Explain the factors which influence the stability of a relaxation divider with the help of a

neat waveforms

b) Explain how the synchronization of a sweep circuit is achieved with symmetrical signals.

8. a) Explain the principle of operation of monostable blocking oscillator with base timing.

Sketch the current waveforms and derive an expression for current pulse width.

b) What is pedestal? How it effect the output of sampling gates?

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Code No: R22021






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1. a) What is low pass RC circuit? Derive an expression of output voltage for square wave input

and draw input-output characteristics of this circuit

b) Explain the operation of RC high pass circuit when exponential input is applied.

2. a) Derive the steady state response of a clamping circuit for a square wave input in which the

resistance Rs of the signal source is taken into account.

b) Design a diode clamper circuit to clamp the positive peaks of the input signal at zero level.

The frequency of the input signal is 500Hz.

3. a) Derive expressions for rise and fall time of a transistor in terms of the transistor Parameters

and operating currents.

b) Verify the truth table of RTL NOR gate with the circuit diagram of two inputs.

4. a) What are the basic techniques in the triggering of Bistable Multivibrator? Explain the

techniques with neat diagrams.

b) Design a self bias bi-stable multivibrator employing two p-n-p silicon transistors to

operate at a maximum frequency of 60Hz. Assume that VCC=15V, RC=2.2kΩ,

VCE(sat)=0.4V, VBE(sat)=0.95V, hFE=30 and the impedance of the trigger source RS=680Ω.

5. a) Explain the operation of a collector coupled transistor monostable multivibrator with the

help of a neat circuit diagram and waveform.

b) Write short notes on triggering of monostable multivibrators

6. a) With a neat circuit, explain a method of compensation used to improve the linearity of

bootstrap time base circuit.

b) Compare a transistor-switch sweep circuit with UJT sweep circuit with respect to sweep

speed and linearity of sweep.

7. a) What is phase jitter? Discuss the significance of it in a frequency divider.

b) A UJT sweep operates with VV=3V, Vp=16V and η=0.5. A sinusoidal synchronizing voltage

of 2V peak is applied between bases and the natural frequency of the sweep is 1 kHz, over

what range of sync signal frequency will the sweep remain in 1:1 synchronism with the sync

signal?

8. a) Derive an expression for the pulse width of a triggered transistor blocking oscillator

with base timings.

b) Derive the gain and control voltages of four diode sampling gate.

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Code No: R22023


SWITCHING THEORY AND LOGIC DESIGN (Com. to EEE, ECE, ECC, BME, EIE)




~~~~~~~~~~~~~~~~~~~~~~~~

1. a) Convert the following to binary and then to gray code.

i) 234516 ii) 123416 iii) 23458

b) Perform the following using BCD arithmetic.

i) 712910 + 771110 ii) 812410 + 812710

2. a) Show that both NAND gate and NOR gate are universal gates.

b) Simplify the following Boolean expressions to a minimum number of literals.

i) CBABA ++ ii) )]([ XZXYZYX ++

iii) CAABCCA ++ to three literals iv) )()( CDAABDCDBA +++ to one literal

v) ))()(( DCBACACA ++++ to one literal

3. a) Reduce the following expressions using K-map

i) CBCBACBAAB +++ ii) ABCCBAADCCAAB +++++

b) Obtain the simplified expressions in sum of products for the following Boolean functions

using K-map

i) ∑= )15,14,13,7(),,,( DCBAF ii) ∑= )15,14,13,12,3,2(),,,( zyxwf

4. a) Design a full adder with two half adders and OR gate.

b) Design a Excess-3 adder using 4-bit parallel binary adder and logic gates.

5. a) Distinguish between a multiplexer and a Demultiplexer.

b) Design a full adder using 8×1 MUX.

6. a) Differentiate between PROM and EPROM.

b) Tabulate the PLA programming table for the four Boolean functions listed below.

∑= )6,4,2,1,0(),,(1 mCBAf

∑= )7,6,2,0(),,(2 mCBAf

∑= )6,3(),,(3 mCBAf

∑= )7,5,3,1(),,(4 mCBAf

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Code No: R22023

7. a) Realize D Flip-Flop using JK Flip-Flop.

b) Realize a master slave JK Flip Flop using NAND gates and explain its operation and point

out how race condition is avoided.

8. a) A clocked sequential circuit is defined by the following state-table: Obtain minimal state

table.

b) Give proper assignment and hence design the circuit using T - Flip-Flops.

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Code No: R22023






~~~~~~~~~~~~~~~~~~~~~~~~

1. a) Convert the following to Decimal and then to Hexadecimal.

i) 32148 ii) 45678 iii) 101011012

b) Perform the subtraction with the following unsigned binary numbers by taking the 2’s

complement of the subtrahend.

i) 11010 – 10010 ii) 11011 – 1101 iii) 100 – 110000 iv) 1010100 – 1010100

2. a) Show that the dual of the exclusive-OR is equal to its complement.

b) Express the complement of the following functions in sum of min terms

i) ∑= )14,13,11,6,2,0(),,,( DCBAF ii) )7,6,3,0(),,( ∏=zyxF

3. a) The following function should be simplified using K-map

i) ∑= )7,5,3,1(),,( zyxf ii) ∑= )7,6,5,3,2,1(),,( zyxf

iii) ∑= )7,5,2,0(),,( zyxf

b) Simplify the following Boolean functions using K-map technique

∑= )31,29,27,26,25,24,16,11,10,9,8,7,4,0(),,,,( mEDCBAf

4. a) Implement full adder circuit using ROM and verify the working.

b) Realize a look ahead carry adder.

5. a) Implement the following function:

∑= )14,12,10,7,4,3,1,0(),,,( DCBAf Using i) 16×1 MUX ii) 4×1 MUX

b) Design a circuit to convert excess-3 code to BCD code using a 4-bit full adder.

6. a) What is the basic architecture of a PLA.

b) Implement the following two Boolean functions with a PLA

∑= )4,2,1,0(),,(1 mCBAF ∑= )7,6,5,0(),,(2 mCBAF

7. a) Design a Mod-6 synchronous counter using J-K flip flops.

b) Explain the following:

i) Race-around condition in flip flop ii) J-K Master slave flip flop

8. A clocked sequential circuit is provided with a single input x and single output Z. Whenever

the input produce a string of pulses 1 1 1 or 0 0 0 and at the end of the sequence it produce an

output Z = 1 and overlapping is also allowed.

a) Obtain State - Diagram.

b) Also obtain state - Table.

c) Find equivalence classes using partition method & design the circuit using D- flip-flops.

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Code No: R22023






~~~~~~~~~~~~~~~~~~~~~~~~

1. a) Convert the following to binary and then to gray code.

i) 12578 ii) 77710 iii) 99910

b) Convert the following.

i) AB16 = ( )10 ii) 12348 = ( )10 iii) 101100112 = ( )10 iv) 77210 = ( )16

2. a) What is a parity bit? How many types of parity are there? Why is odd parity used more often

than even parity?

b) i) Given BCAACthatshowCBAAB =+=+ ,

ii) ),)()(( DCBACACA ++++ Simplify.

3. Obtain the minimal expression for ∑= )15,13,12,9,8,7,6,5,3,2,1(mf using the tabular

method

4. a) Design a combinational logic to subtract one bit from the other. Draw the logic diagram

using NAND and NOR gates.

b) Give the NAND gate realization of full-adder.

5. a) Given a 32 x 8 ROM clip with an enable input, show the external connection necessary to

construct a 128 x 8 ROM with four chips and a decoder.

b) Design a 32:1 Multiplexer using two 16:1 and 2:1Multiplexers.

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Code No: R22023

6. a) What are the advantages and disadvantages of using a PROM as a PLD?

b) Implement the following Boolean functions using PAL.

∑= )13,12,10,8,7,5,2,0(),,,(1 mzyxwf

∑= )15,14,9,8,6,2,0(),,,(2 mzyxwf

∑= )15,14,8,0(),,,(3 mzyxwf

∑= )10,9,8,5,4,2,1,0(),,,(4 mzyxwf

7. a) Define the following terms as applied to flip flops.

i) Set-up time ii) hold time

iii) Propagation delay time iv) maximum clock frequency

b) Convert an SR flip flop into

i) T flip flop ii) JK flip flop iii) D flip flop

8. a) Convert the given Mealy Machine to Moore Machine.

b) A clocked sequential circuit with two inputs x and y and a single output Z is defined by the

following state diagram. Design the circuit using T flip-flop.

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Code No: R22023






~~~~~~~~~~~~~~~~~~~~~~~~

1. a) Perform subtraction with the following unsigned decimal numbers by taking 10’s

complement of the subtrahend. Verify the result.

i) 5250- 1321 ii) 1753 – 8640 iii) 20 – 100 iv) 1200 – 250

2. a) Derive the Boolean expression for a two input Ex-OR gate to realize with two input NAND

gates without using complemented variables and draw the circuit.

b) Reduce the circuit given in figure after simplification.

3. a) Define the following terms:

i) Prime implicant ii) Essential prime implicant

b) What are dominating rows & dominating columns?

c) Simplify the following Boolean functions using K-map technique

∑= )27,25,23,22,20,19,18,16,11,9,7,6,4,3,2,0(),,,,( mEDCBAf

4. a) Write the design steps of adder? Design half adder with NAND gates.

b) Design of full subtractor with two half subtractors and OR gate.

5. a) Explain how a 4-variable function can be realized using an 8:1 MUX.

b) Design 4 to 16 decoder using 2 to 4 decoders and basic gates.

6. a) Implement the following Boolean functions using PLA.

∑= )5,3,1,0(),,(1 mCBAf ∑= )7,5,3,0(),,(2 mCBAf

b) Give the comparison between PROM, PLA and PAL.

7. a) Design a 4-bit binary synchronous counter with D flip-flops.

b) Compare synchronous & asynchronous circuits

8. a) What are the Moore and Mealy machines? Compare them.

b) What are the capabilities and limitations of FSM?

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code no: r22041 r10 set - 1 ii b. tech ii semester ... · pdf fileii b. tech ii semester...

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