Question

A class A power amplifier uses ______________

(a) Two transistors

(b) One transistor

(c) Three transistors

(d) Four transistors

The question was posed to me in a job interview.

The above asked question is from Class A Output Stage topic in section Differential and Multistage Amplifiers of Electronic Devices & Circuits

Answer 1

Right answer is (b) One transistor

To explain: In Class A amplifier, if the collector current flows all times during the full cycle of the input signal, the power amplifier is known as class A power amplifier. It is less used for higher power output stages, as it has poor efficiency. So it consists of only one transistor.