Amplification and Amplifiers
Davide Bucci · 2017
This chapter discusses the amplification of low-frequency signals and focuses on circuits based on operational amplifiers. It first describes the working principles of operational amplifiers: in particular, focusing on some parameters specified in the data sheets quantifying their limits and non-idealities. The chapter then describes some of the most relevant limitations of real operational amplifiers. Knowledge of their influence in a circuit helps to understand the data sheets and select the best product in the huge catalogs proposed by the semiconductor companies. A useful way to vastly increase input impedances is to exploit the excellent input characteristics of operational amplifiers. In the circuit, the two inputs are directly connected to the inputs of the operational amplifiers. For this reason, once the correct biasing of the operational amplifiers is assured, inputs are extremely high impedance. The chapter ends with insulation amplifiers, which are very useful when security or electromagnetic compatibility issues are of primary importance.