Operational amplifier is a kind of analog integrated circuit, can be used for addition, subtraction, multiplication, division, power, root and other operations, the key word of its function lies in operation.
Differential amplifier circuit can be composed of discrete components, can also be composed of operational amplifiers (simply put, the differential amplifier circuit at this time is a typical application circuit of operational amplifiers), the core is to amplify the differential mode signal, that is, the difference between two input values.