Integrated Circuit

What is Integrated Circuit?

Integrated Circuits are usually

called ICs and popularly known as a silicon

chip, computer chip or microchip.

• Integrated Circuit, tiny electronic circuit

used to perform a specific electronic

function, such as amplification.

 

• It is usually combined with other

components to form a more complex

system.

Electronic Components?

Miniaturized Active Devices:

1. Transistors

2. Diodes

Miniaturized Passive Devices:

1. Capacitors

2. Resistors

-> It is formed as a single unit by diffusing impurities into single-crystal

silicon, which then serves as a semiconductor material.

• Several hundred identical integrated circuits (ICs) are made at a time on a thin

wafer several centimeters wide, and the wafer is subsequently sliced into individual

ICs called chips.

Who invented ICs?

It seems that the integrated circuit was

destined to be invented. Two separate

inventors, unaware of each other's

activities, invented almost identical

integrated circuits or ICs at nearly the

same time.

1958: Invention of the Integrated Circuit

As with many inventions, two people had the idea for an integrated circuit at almost the same time. Transistors had become commonplace in everything from radios to phones to computers, and now manufacturers wanted something even better. Sure, transistors were smaller than vacuum tubes, but for some of the newest electronics, they weren't small enough.

1958: Invention of the Integrated Circuit

But there was a limit on how small you could make each transistor, since after it was made it had to be connected to wires and other electronics. The transistors were already at the limit of what steady hands and tiny tweezers could handle. So, scientists wanted to make a whole circuit -- the transistors, the wires, everything else they needed -- in a single blow. If they could create a miniature circuit in just one step, all the parts could be made much smaller.

1958: Invention of the Integrated Circuit

One day in late July, Jack Kilby was sitting alone at Texas Instruments. He had been hired only a couple of months earlier and so he wasn't able to take vacation time when practically everyone else did. The halls were deserted, and he had lots of time to think. It suddenly occurred to him that all parts of a circuit, not just the transistor, could be made out of silicon. At the time, nobody was making capacitors or resistors out of semiconductors. If it could be done then the entire circuit could be built out of a single crystal -- making it smaller and much easier to produce. Kilby's boss liked the idea, and told him to get to work. By September 12, Kilby had built a working model, and on February 6, Texas Instruments filed a patent. Their first "Solid Circuit" the size of a pencil point, was shown off for the first time in March.

But over in California, another

man had similar ideas…

1958: Invention of the Integrated Circuit

In January of 1959, Robert Noyce was working at the small Fairchild Semiconductor startup company. He also realized a whole circuit could be made on a single chip. While Kilby had hammered out the details of making individual components, Noyce thought of a much better way to connect the parts. That spring, Fairchild began a push to build what they called "unitary circuits" and they also applied for a patent on the idea. Knowing that TI had already filed a patent on something similar, Fairchild wrote out a highly detailed application, hoping that it wouldn't infringe on TI 's similar device.

All that detail paid off. On April 25, 1961, the

patent office awarded the first patent for an

integrated circuit to Robert Noyce while Kilby's

application was still being analyzed. Today,

both men are acknowledged as having

independently conceived of the idea.

IC Types

In the early days of integrated circuits, only a few transistors could be placed on a chip, as the scale used was large because of the contemporary technology, and manufacturing yields were low by today's standards. As the degree of integration was small, the design was done easily. Over time, millions, and today billions, of transistors could be placed on one chip, and to make a good design became a task to be planned thoroughly. This gave rise to new design methods.

Integrated circuits are often classified by the number of transistors

and other electronic components they contain:

• SSI (small-scale integration): Up to 100 electronic components per

chip

• MSI (medium-scale integration): From 100 to 3,000 electronic

components per chip

• LSI (large-scale integration): From 3,000 to 100,000 electronic

components per chip

• VLSI (very large-scale integration): From 100,000 to 1,000,000

electronic components per chip

• ULSI (ultra large-scale integration): More than 1 million electronic

components per chip

Classification

Integrated circuits can be classified

into analog, digital and mixed

signal (both analog and digital on

the same chip).

DIGITAL INTEGRATED CIRCUITS

Digital integrated circuits can contain anything from one to millions

of logic gates, flip-flops, multiplexers, and other circuits in a few

square millimeters. The small size of these circuits allows high speed,

low power dissipation, and reduced manufacturing cost compared

with board-level integration. These digital ICs,

typically microprocessors, DSPs, and micro controllers, work using

binary mathematics to process "one" and "zero" signals.

ANALOG INTEGRATED CIRCUITS

Analog ICs, such as sensors, power management circuits,

and operational amplifiers, work by processing continuous signals.

They perform functions like amplification, active

filtering, demodulation, and mixing. Analog ICs ease the burden on

circuit designers by having expertly designed analog circuits available

instead of designing a difficult analog circuit from scratch.

MIXED SIGNAL

ICs can also combine analog and digital circuits on a single chip to

create functions such as A/D converters and D/A converters. Such

circuits offer smaller size and lower cost, but must carefully account

for signal interference.

Merits or Advantages of IC

The integrated circuits offer a number of advantages over those made by interconnecting discrete components. These are summarized as follows:

1. Extremely small size—thousands times smaller than discrete circuit. It is because of fabrication of various circuit elements in a single chip of semi-conductor material.

2. Very small weight owing to miniaturized circuit.3. Very low cost because of simultaneous production of hundreds of similar

circuits on a small semiconductor wafer. Owing to mass production an IC costs as much as an individual transistor.

4. More reliable because of elimination of soldered joints and need for fewer inter-connections.

5. Low power consumption because of their smaller size.6. Easy replacement as it is more economical to replace them than to repair

them.

The integrated circuits offer a number of advantages over those made by interconnecting discrete components. These are summarized as follows:

7. Increased operating speeds because of absence of parasitic capacitance effect.

8. Close matching of components and temperature coefficients because of bulk produc¬tion in batches.

9. Improved functional performance as more complex circuits can be fabricated for achieving better characteristics.

10. Greater ability of operating at extreme temperatures.11. Suitable for small signal operation because of no chance of stray electrical

pickup as various components of an IC are located very close to each other on a silicon wafer.

12. No component project above the chip surface in an IC as all the components are formed within the chip.

Demerits or Disadvantages of

IC

The integrated circuits have few limitations also, as listed below :

1. In an IC the various components are part of a small semi-conductor chip and the individual component or components cannot be removed or replaced, therefore, if any component in an IC fails, the whole IC has to be replaced by the new one.

2. Limited power rating as it is not possible to manufacture high power (say greater than 10 Watt) ICs.

3. Need of connecting inductors and transformers exterior to the semi-conductor chip as it is not possible to fabricate inductors and transformers on the semi-conductor chip surface.

4. Operations at low voltage as ICs function at fairly low voltage.5. Quite delicate in handling as these cannot withstand rough handling or

excessive heat.

The integrated circuits have few limitations also, as listed below :

6. Need of connecting capacitor exterior to the semi-conductor chip as it is neither convenient nor economical to fabricate capacitances exceeding 30 pff Therefore, for higher values of capacitance, discrete components exterior to IC chip are connected.

7. High grade P-N-P assembly is not possible.8. Low temperature coefficient is difficult to be achieved.9. Difficult to fabricate an IC with low noise.10. Large value of saturation resistance of transistors.11. Voltage dependence of resistors and capacitors.12. The diffusion processes and other related procedures used in the fabrication

process are not good enough to permit a precise control of the parameter values for the circuit elements. However, control of the ratios is at a sufficiently acceptable level.

THE END

• Daniella Glean• Jayzel Gabutero• Jena Gonzales• Michael Gomez