A new method for evaluating harmonic distortion in push-pull output stages

In this paper, a new method for analytically evaluating the harmonic distortion in push-pull stages by circuit inspection is introduced. It is based on modeling each push-pull device in the stage with different third order polynomials. The coefficients of these polynomials may be evaluated by straightforward measurements or by pencil-and-paper analysis of the real transcharacteristic of the stage. The resulting theory was validated by simulations and is able to predict the harmonic distortion behavior of a push-pull output stage over a wide range of input values.