Push–pull output: Difference between revisions

Revision as of 23:30, 10 September 2021

Revision as of 23:32, 10 September 2021

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A conventional amplifier stage which is not push–pull is sometimes called [[Single-ended triode|single-ended]] to distinguish it from a push–pull circuit.

In analog push–pull power amplifiers the two output devices operate in [[antiphase]] (i.e. 180° apart). The two antiphase outputs are connected to the load in a way that causes the signal outputs to be added, but distortion components due to non-linearity in the output devices to be subtracted from each other; if the non-linearity of both output devices is similar, distortion is much reduced. Symmetrical push–pull circuits must cancel even order harmonics, like f22f, f44f, f66f and therefore promote odd order harmonics, like (f1)f, f33f, f55f when driven into the nonlinear range.

A push–pull amplifier produces less [[distortion]] than a single-ended one. This allows a [[Power amplifier classes#Class A|class-A]] or [[Power amplifier classes#Class AB|AB]] push–pull amplifier to have less distortion for the same power as the same devices used in single-ended configuration. [[Power amplifier classes#Class AB|Class AB]] and [[Power amplifier classes#Class B|class B]] dissipate less power for the same output than class A; distortion can be kept low by [[negative feedback]] and by biassing the output stage to reduce crossover distortion.