14.2 Differential and Common-Mode Operation
14.3 Op-Amp Basics
14.4 Practical Op-Amp Circuits
14.5 Op-Amp Specifications – DC Offset Parameters
14.6 Op-Amp Specifications – Frequency Parameters
14.7 Op-Amp Unit Specifications
14.8 PSpice Windows
After completing this chapter you will be able to:
- Explain the difference between common mode and differential mode operation
- Explain the operation of the basic op-amp
- Calculate the output voltage for a number of basic op-amp configurations
- Explain the terminology associated with the dc and ac performance of an op-amp
- Interpret manufacturers specification to determine op-amp performance
An operational amplifier, or op-amp, is a very high gain differential amplifier with high input impedance and low output impedance. Typical uses of the operational amplifier are to provide voltage amplitude changes (amplitude and polarity), oscillators, filter circuits, and many types of instrumentation circuits. An op-amp contains a number of differential amplifier stages to achieve a very high voltage gain.
Figure 14.1 shows a basic op-amp with two inputs and one output as would result using a differential amplifier input stage. Recall from Chapter 12 that each input results in either the same or an opposite polarity (or phase) output, depending on whether the signal is applied to the plus (+) or the minus (–) input.