Integrated Circuits

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An integrated circuit (IC) is a semiconductor wafer. Sometimes it is called a chip, microchip or microelectronic circuit. Thousands of resistors, capacitors and transistors are fabricated using integrated circuits. An IC can also function as an amplifier, oscillator, computer memory or microprocessor.

Integrated circuits are the fundamental building blocks of all modern electronic devices. They are an integrated system of multiple miniaturized and interconnected components implanted into a thin substrate of semiconductor material.

A single IC may contain thousands or millions of transistors, resistors, capacitors or diodes. It may also contain additional components, interconnected through a complex web of semiconductor wafers, silicon and other materials. Each component is usually small or microscopic. The resulting circuit, mostly a monolithic chip, is also tiny. It might only occupy a few square millimeters or centimeters of space.

Computer processors which usually contain millions or billions of transistors, capacitors and logic gates connected together to form complex digital circuits are common examples of modern-day ICs. But all ICs are not processors.

History and Evolution

Transistor was invented in 1947 setting the stage for the modern computer age. It got its name from the combination of words ‘transfer’ and ‘resistor’.

Each circuit contained discrete transistors, capacitors and resistors. Each transistor came in a separate plastic package in the early days. Owing to the large size of the components, early ICs were only able to hold a few of them wired together on the circuit board. 

Development of solid-state electronics over the years made it easier to reduce the size of components. In the 1950s, Jack Kilby and Robert Noyce found ways to lay thin paths of metal on devices making them function as wires. Finding a solution to the problem of wiring between small electrical devices initiated the beginning of the development of modern IC.

Modern ICs: Design and construction


Integrated circuits have progressed rapidly with faster speeds, greater capacity and smaller sizes over the past 50 years. 

The latest integrated circuit is all one piece, rather than simply mounting on it, the individual components are directly implanted into the silicon crystal. Modern integrated circuits are unbelievably complex, they are capable of holding billions of transistors and other components on a single piece of material. A fusion of wafers is known as a die. Semiconductor wafer which constitutes the IC is fragile and contains several intricate connections between its many layers. An IC depends on multiple levels of abstraction. 

It becomes impossible to position and connect each component individually as there will be millions or billions of components on one single chip itself. Dies will be too small to solder and connect to. Hence designers make use of a special-purpose programming language for creating small circuit elements. They combine them to progressively increase the size and density of components on the chip to meet application requirements. 

ICs are packaged in such a way that delicate and tiny dies are turned into black chips. It forms the basis of several devices including computers, smartphones, cars, washing machines, toasters and microwaves.

Types of Integrated Circuits


Depending on their intended application, ICs can be linear (analog), digital or at times combination of both. 

Depending on the input signal level, analog or linear ICs will have continuously variable output. Such ICs will be able to attain an infinite number of states. The output signal level becomes a linear function of the input signal levels in such types of ICs. Ideally when the instantaneous input is graphed against the instantaneous output, the plot takes the shape of a straight line.

Analog ICs make use of only a few components and are simple in nature.

Audio-frequency (AF) and radio-frequency (RF) amplifiers are examples for linear ICs. Temperature sensor makes use of analog ICs as well. If programmed accordingly, Linear ICs can be used to turn various devices on or off, once the signal reaches a particular value. These devices include air conditioners, heaters and ovens.

Digital ICs do not operate over a continuous range of single amplitudes. They function only at a few discrete levels. Logic gates are the fundamental building blocks of digital ICs. They work with binary data, with signals having only two different states, namely low (logic 0) and high (logic 1).

Digital ICs are used in computers, modems and frequency counters. 

A mixed IC makes use of both analog and digital design principles.It functions as digital-to-analog converter, analog-to-digital converter and clock/timer IC. 

Microprocessors and ICs


Microprocessors are the most complicated types of ICs. They are capable of performing billions of operations per second. When it comes to a computing device, the microprocessor will contain the central processing unit (CPU) which helps in running the computer or graphics processing unit (GPU) which helps in rendering images and videos. A single microprocessor will contain billions of interconnected transistors. All of those transistors will perform specific logic functions based on instructions from the clock.

The transistors perform the logic functions they are supposed to perform as the clock changes state. The clock’s frequency helps in determining the speed of these functions.

Microprocessors consist of different kinds of predetermined memory locations for storing information.

  • A permanent register will store preprogrammed instructions for various operations.
  • A temporary register will store numbers to be operated on, and the results of an operation.
  • Counter will contain the memory address of the next instruction.
  • Stack pointer includes the address of the last instruction put into stack memory.
  • Memory address register will contain the location of the data to be worked on. 

ICs have made our lives infinitely better. A modern laptop is way powerful and about 100 times smaller than the first computer developed in the 1940s. The ENIAC ran on 18,000 vacuum tubes and was as large as three to four double-decker buses. 

Hence the IC was key to our progress!


Read more:Nanotechnology

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 Answer) Depending on their intended application, ICs can be linear (analog), digital or at times combination of both. 

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