Question 6A165

Class C amplifiers are biased significantly below cutoff, meaning plate current flows for less than 180 degrees of the input signal cycle. This deep bias ensures current only flows during the peak positive swing of the input, resulting in a narrow pulse of current. This mode of operation yields high efficiency but also high distortion. Because of the distortion, Class C amplifiers are primarily used in RF power amplifier stages that operate with a tuned circuit in the output. The resonant tank circuit "rings" to reconstruct the full sinusoidal waveform from the short pulses of current, making them suitable for constant-amplitude signals like CW or FM. * **Class A** amplifiers conduct for 360 degrees. * **Class B** amplifiers conduct for 180 degrees (at cutoff). * **Class AB** amplifiers conduct for more than 180 but less than 360 degrees.