Linear integrated circuit is an integrated circuit based on amplifier. The word "linear" means that the response of the amplifier to the input signal usually presents a linear relationship. Later, this kind of circuit includes many nonlinear circuits such as oscillator, timer and data converter, as well as the circuit combining digital and linear functions. Because the information processed involves continuously changing physical quantities (analog quantities), people also call this kind of circuit analog integrated circuit.

A new development in linear circuits is the use of MOS technology to manufacture audio filters. Its principle is switched capacitor method, that is, the capacitor is alternately connected to different voltage nodes in the circuit with a switch to transmit charges, so as to produce equivalent resistance. This technology is especially suitable for MOS process (see switched capacitor filter). On the other hand, due to the application of analog sampling technology, MOS technology has been able to produce high stability operational amplifiers and high-precision digital to analog and analog to digital converters. The combination of these two technologies opens up a broad prospect for the large-scale integration technology of analog information processing and communication equipment subsystems.

In terms of manufacturing process, most linear integrated circuits are manufactured by standard bipolar process. In order to obtain high-performance circuits, some modifications or additional manufacturing processes are sometimes made on the basis of standard processes, so as to make various components and devices with different performances on the same chip.

According to the functions and applications of circuits, linear integrated circuits can be roughly divided into:

1. General circuit, including operational amplifier, voltage comparator, voltage reference circuit and regulated power supply circuit;

2. Industrial control and measurement circuit, including timer, waveform generator, detector, sensor circuit, phase-locked loop, analog multiplier, motor drive circuit, power control circuit, analog switch;

3. Data conversion circuit, including digital to analog converter, analog to digital converter, voltage frequency converter;

4. Communication circuit, including telephone communication circuit and mobile communication circuit;

5. Consumer circuits, including television circuits, video recorder circuits, and audio circuits. In fact, there are many other circuits, such as medical circuits such as cardiac pacemakers.

On the other hand, due to the increasing development of large-scale integration technology and computer-aided design and measurement technology, the design of linear circuits is developing from traditional standard units to custom integrated circuits with complex functions.