Page "Electronic amplifier" Paragraph 35

In class-AB operation, each device operates the same way as in class B over half the waveform, but also conducts a small amount on the other half.

As a result, the region where both devices simultaneously are nearly off ( the " dead zone ") is reduced.

The result is that when the waveforms from the two devices are combined, the crossover is greatly minimised or eliminated altogether.

The exact choice of quiescent current, the standing current through both devices when there is no signal, makes a large difference to the level of distortion ( and to the risk of thermal runaway, that may damage the devices ); often the bias voltage applied to set this quiescent current has to be adjusted with the temperature of the output transistors ( for example in the circuit at the beginning of the article the diodes would be mounted physically close to the output transistors, and chosen to have a matched temperature coefficient ).

Another approach ( often used as well as thermally tracking bias voltages ) is to include small value resistors in series with the emitters.