Normally bipolar junction transistors, diodes and field effect transistors are commonly used electronics component in electronic circuit. These components are interconnected along with required resistors and capacitors to form an electronic circuit. This type of circuit is known as discrete circuit as each of the components can be separated from the circuit as when required. Nowadays there is a new trend of producing electronic circuit where on a semiconductor wafer numbers of diodes, transistors, and capacitors are permanently fabricated.
As the components in this type of electronic circuit are not separable that is integrated on the semiconductor wafer, this circuit is commonly referred to as an Integrated Circuit. IC is also popularly known as chip or microchip. The number of transistors that we have been able to fit into an IC has rapidly increased since their creation, doubling approximately every 2 years. This phenomenon is known as Moore’s Law, and is often cited as an explanation for the exponential growth of technology over the last 50 years.
History of Integrated Circuits
This technology was invented in the year of 1950 the by Jack Kilby of Texas Instruments USA and Robert Noyce of Fairchild Semiconductor USA. The first costumer to this new invention was the US Air Force. In the year 2000 Jack Kilby won the Nobel Prize in Physics for miniaturized electronic circuits.
One and a half years after Kilby demonstrated his IC design, Robert Noyce of Fairchild Semiconductor Limited came up with his own integrated circuit. His model solved many practical problems which Kilby’s device had. It was made up of silicon where as Kilby’s was made up of germanium. Jack Kilby and Robert Noyce both received US patents for their part of work on integrated circuits. After several years of legal issues both companies wisely decided to cross license their technology and created a huge global market.
Types of Integrated Circuits
Like electronic circuit, ICs can also be categorized as digital IC and analog IC based on their applications.
In this type of ICs, the input and output both signals are continuous. The output signal level depends upon the input signal level and the output signal level is a linear function of input signal level. Linear ICs or analog ICs are most commonly used as audio frequency amplifier and radio frequency amplifier. Op amps, voltage regulators, comparators and timers are also well-known examples of linear ICs or analog ICs.
The logic Gates, such as AND gate, OR gate, NAND gate, XOR gate, flip flops, counters; microprocessors are some well-known examples of digital ICs. These ICs operate with binary data such as either 0 or 1. Normally in digital circuit, 0 indicates 0 V and one indicate +5 V.
The main components of an IC are transistors. These transistors may be bipolar or field effect depending upon the applications of ICs. As the technology is improving day by day, the number of transistors incorporated in a single IC chip is also increasing. Depending upon the number of transistors incorporated in a single chip, the ICs are categorized in five groups. Namely,
|i)||Small Scale Integration (SSI) where the number of transistors incorporated in a single IC chip is up to 100.|
|ii)||Medium Scale Integration (MSI) where the number of transistors incorporated in a single IC chip is from 100 to 1000.|
|iii)||Large Scale Integration (LSI) where the number of transistors incorporated in a single IC chip is from 1000 to 20,000.|
|iv)||Very Large Scale Integration (VLSI) where the number of transistors incorporated in a single IC chip is from 20,000 to 10,00,000.|
|v)||Ultra Large Scale Integration (ULSI) where the number of transistors incorporated in a single IC chip is from 10,00,000 to 1,00,00,000.|
Depending upon the active devices used in ICs, it can be further classified as bipolar ICs and unipolar ICs. In bipolar ICs the main components are bipolar junction transistors, whereas in unipolar ICs the main components are field effect transistors or MOSFETs.
IC Manufacturing Process
There are two types of IC manufacturing technologies one is monolithic technology and other is hybrid technology. In monolithic technique, all electronic component and their interconnections are manufactured together into a single chip of silicon. This technology is applied when identical ICs to be produced in large scale. Monolithic ICs are cheap but reliable.
In hybrid ICs, separate components are attached on a ceramic substance and interconnected by wire or metallization pattern.
Advantages of Integrate Circuit or IC
- It is quite small in size practically around 20,000 electronic components can be incorporated in a single square inch of IC chip.
- Many complex circuits are fabricated in a single chip and hence this simplifies the designing of a complex electronic circuit. Also it improves the performance.
- Reliability of ICs is high
- These are available at low cost due to bulk production.
- ICs consume very tiny power.
- Higher operating speed due to absence of parasitic capacitance effect.
- Very easily replaceable from the mother circuit.