Composition of operational amplifiers

Usually, the circuit of an operational amplifier consists of four parts: input stage, intermediate stage, output stage, and bias circuit:

1. Input stage

The input stage is a key part of improving the quality of operational amplifiers. Usually, the input resistance of the input stage is high, and a differential amplification circuit is used. There are two input terminals in phase and in phase, which can reduce zero drift and suppress interference signals.

2. Intermediate stage

The function of the intermediate stage is to amplify the voltage, usually consisting of a common emitter amplifier circuit.

3. Output stage

The output stage is connected to the load and requires low output resistance, strong load carrying capacity, and the ability to output large voltage and current. It is often composed of complementary symmetrical circuits or emitter outputs.

4. Bias circuit

The function of a bias circuit is to provide a stable bias current for each stage of the circuit, which will determine the static working point of each stage and is often composed of various constant current source circuits.