What is Integrated circuit?
An '''integrated circuit''' (more often called an '''IC''', '''microchip''', '''silicon chip''', '''computer chip''', or '''chip''') is a single piece of specially prepared [[silicon]] (or another [[semiconductor]]) into which an electronic circuit is etched using [[photolithography]]. Silicon chips can contain [[logic gate]]s, [[central processing unit|computer processors]], [[computer memory|memory]] and special devices. The chip is very fragile and so is normally surrounded by a [[plastic]] package to protect it. Electrical contact with the chip is provided through tiny wires that connect the chip to larger metal pins that stick out of the package. An IC has two main advantages over discrete circuits: cost and performance. Cost is low, because millions of transistors can be put onto one chip instead of building a circuit with single transistors. Performance is higher since the components can operate more quickly and use less power. ICs are designed for different purposes. For example, a chip may be designed just for a [[calculator]], which can only work as a calculator. Integrated circuits can be classified into [[analog signal|analog]], [[digital signal|digital]] and mixed signal (both analog and digital on the same chip). ICs are found in many household items such as radios, computers, and telephones, and many others.[[File:DIP package sideview.PNG|thumb|left|Side view of [[dual in-line package]] (DIP)]] [[File:PQFP 44L.gif|thumb|left|Picture of Plastic Quad Flat Pack (PQFP)]] == Invention == An early attempt at combining multiple electronic devices into a single package was the Loewe 3NF [[vacuum tube]] in 1926. This integrated vacuum tube contained almost all of the components needed to build a [[radio]] receiver. At the time, radio receivers were [[tax]]ed based on the number of tubes they contained, so combining everything into a single tube resulted in a lower tax. In 1958 and 1959, two people had the idea for a semiconductor integrated circuit at almost exactly the same time. Transistors had becom