Integrated circuit (IC), sometimes called chip or microchip, is a semiconductor wafer on which thousands of micro resistors, capacitors and transistors are manufactured. An integrated circuit can function as an amplifier, oscillator, timer, counter, computer memory, or microprocessor. Specific ICs are classified as linear (Analog) or digital according to their intended applications.
Linear ICs have continuously variable outputs (theoretically, an infinite number of states can be obtained), depending on the level of the input signal. As the name suggests, the output signal level is a linear function of the input signal level. Ideally, when the instantaneous output is plotted against the instantaneous input, the curve will appear as a straight line. Linear ICs are used as audio (AF) and radio frequency (RF) amplifiers. Op amp is a common device in these applications.
The digital IC only works at several defined levels or states, rather than within a continuous range of signal amplitude. These devices are used for computers, computer networks, modems, and frequency counters. The basic building block of Digital IC is logic gate, which can process binary data, that is, signals with only two different states, which are called low (logic 0) and high (logic 1).
