The name operational amplifier has been derived from the fact that it was originally developed for performing mathematical operations such as additions, subtractions, multiplication, division, integration, differentiation, etc. of electrical signals. Though the number and types of stages of commercially available operational amplifiers vary widely from one configuration to the other, a general configuration is demonstrated in Fig. 15.1 that has three stages cascaded together. It is usually referred to as operational amplifier (op-amp).
Figure 15.1 Block diagram of operational amplifier
The input stage ...