Techniques for evaluating harmonic distortion in class-AB output stages: A tutorial

In this paper, we discuss and provide a detailed tutorial of four different methods for analytically evaluating the harmonic distortion in class-AB stages. All the methods are suitable for pencil-and-paper analysis and are based on modeling the stage with a specific non-linear function. We analyze them in details and extend some of them for predicting harmonic distortion behavior in a wide range of input signal amplitude. Comparisons made by means of simulations, reveal that some methods are more precise than others but require more computational effort. On the contrary, some of them are simple to use but are less precise. Moreover, some are more appropriate for predicting HD2 and others for HD3, only. Results of the present paper may be used by designers to choose the more efficient method for analyzing distortion in class-AB stages.