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The CLASS OF OPERATION of a transistor amplifier is determined by the percent of time that
current flows through the transistor in relation to the input signal.
In CLASS A OPERATION, transistor current flows for 100% (360º) of the input signal. Class A
operation is the least efficient class of operation, but provides the best fidelity.
In CLASS AB OPERATION, transistor current flows for more than 50% but less than 100% of the
input signal.
