Basic Concepts of the Integrated Operational Amplifier
1.1 OVERVIEW OF OPERATIONAL AMPLIFIERS
1.1.1 Brief History
Operational amplifiers began in the days of vacuum tubes and analog computers. They consisted of relatively complex differential amplifiers with feedback. The circuit was constructed such that the characteristics of the overall amplifier were largely determined by the type and amount of feedback. Thus the complex differential amplifier itself had become a building block that could function in different “operations” by altering the feedback. Some of the operations that were used included adding, multiplying, and logarithmic operations.
The operational amplifier continued to evolve through the transistor era and continued ...