Complementary Class B push-pull power amplifier or transformerless power amplifier

Complementary Class B push-pull power amplifier

or

transformerless power amplifier

Class B push-pull amplifier uses 2 transfomer which make it bulky and costly .To avoid using transformer complementary symmetry class B is used

It consist of  NPN and PNP transistor >During positive  half cycle of input ,$Q_1$ conducts and $I_{c1}$ flows from $V_{cc1}$ through $R_L$ .During negative half cycle of input $Q_2$ conducts and $I_{c2}$ flows from $V_{cc2}$ through $R_L$ .Thus we get a complete amplified waveform of input across $R_L$