Power amplifiers have been categorized under many classes:

Class A Power Amplifier

Class B Power Amplifier

Class AB Power Amplifier

Class C Power Amplifier

Class D Power Amplifier

Class E Power Amplifier

Class F Power Amplifier

An attribute of classical PAs is that both the input and the output waveforms are considered sinusoidal. Each PAs have their merits and drawbacks described briefly in the following questions.