Classes of Amplifier Operation

Class A: An amplifier's Class A operation means that at the all times the transistor operates in the active region.That implies that collector current flows for 360 degree of the ac cycle.

 Class B: The Class B operation of an amplifier means that collector current flows for only 1/2 of the cycle.A designer locates the Q point at cutoff. Then,only the positive half of ac base voltage can produce collector current.This reduces the wasted heat in Power transistors.

Class C: It means that collector current flows for less than 180 degree of the ac cycle.With class C operations, only part of the positive half cycle of ac base voltage produces collector current.