Q.Which of the power amplifiers Class A, Class B and Class C produces maximum distortion? Which is more suitable for faithful amplification? Where is Q-point fixed in case of class-AB amplifier?

The three parts follow from how much of the cycle each class conducts: less conduction means more distortion, and full-cycle conduction means faithful reproduction. …

[!TLDR]

Class C is the most distorted, Class A is the most faithful, and class-AB has its Q-point set just above cut-off.

The amount of distortion in a power amplifier depends on the portion of the input cycle for which the transistor conducts, decided by the Q-point:

1. Maximum distortion — Class C. Its Q-point is fixed below cut-off, so the transistor conducts for less than 180° of the cycle, delivering current only in narrow pulses. This heavily clipped output has the greatest distortion (a tuned tank circuit is needed to recover a sine wave).
2. Most suitable for faithful amplification — Class A. Its Q-point is at the centre of the active region, so collector current flows for the entire 360° and the output faithfully reproduces the input with least distortion. …