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CLASS B AMPLIFIERS are biased so that collector current is cut off during one-half of the input
signal. Thus, for a class B operation, collector current will flow for approximately 180 degrees (half) of
the input signal.
The class B operated amplifier is used as an audio amplifier and sometimes as the driver- and power-
amplifier stage of transmitters.
CLASS C AMPLIFIERS are biased so that collector current flows for less than one-half cycle of
the input signal.
The class C operated amplifier is used as a radio-frequency amplifier in transmitters.
FIDELITY and EFFICIENCY are two terms used in conjunction with amplifiers. Fidelity is the
faithful reproduction of a signal, while efficiency is the ratio of output signal power compared to the total
input power.
The class A amplifier has the highest degree of fidelity, but the class C amplifier has the highest
efficiency.
A TRANSISTOR CONFIGURATION is the particular way a transistor is connected in a circuit. A
transistor may be connected in any one of three different configurations: common emitter (CE), common
base (CB), and common collector (CC).
