Push Pull Amplifier Voltage Gain

The push-pull stage of an amplifier usually has voltage gain of 1 also known as unity, and therefore it is also known as a source follower. It is usually the power output stage designed to drive a load such as a loudspeaker, and therefore it provides the necessary current gain. In the example circuit diagram above, section A consists of an op amp, which produces the voltage gain and amplification of the signal. Section B is responsible for biasing the MOSFETs and to reduce cross-over distortion that usually occurs in a push-pull circuit. Finally, Section C is the push-pull stage, which produces the necessary current gain to drive a loudspeaker.

In the example circuit above, we make use of an inverting amplifier to provide a gain of -4.7. We can calculate this using the basic gain formula for inverting op amps. The total gain of the amplifier remains as -4.7 because the final push-pull stage usually has a gain of unity. Realistically, though, it is usually between 0.6 and 1.