Calculate from first principles the maximum power efficiency

Calculate, from first principles, the maximum power efficiency of a class B power amplifier which has a sinusoidal signal. Assume that the output transistors operate ideally(treat as two terminal device-o/p circuit only).

Solution

Class B power Amplifier

If the collector current flows during the half cycle of the signal only , the power amplifier is known as class B amplifier.

For this operation Q point must be located at cutoff.

The derivation of the efficency of class B amplifier is shown below.