Question

Which of these is not true for a class B amplifier?

(a) It has zero DC bias

(b) They have an efficiency less than that of class A amplifiers

(c) The quiescent power dissipation is zero

(d) The conduction angle is only 180°

I had been asked this question in an interview for internship.

Query is from Push-Pull Class B Amplifier topic in section Power Amplifier of Analog Circuits

Answer 1

Right option is (b) They have an efficiency less than that of class A amplifiers

To explain I would say: The class B amplifier has zero DC bias as the transistors are biased at cut-off only. Each transistor conducts when the input is greater than the base-emitter voltage. The conduction angle is only 180° for this amplifier. They have higher efficiency than class A amplifiers.