Distortion analysis using signal flow graphs and Volterra series

This paper describes a graphical method of nonlinear circuit analysis. The method combines circuit analysis using driving-point impedances and signal flow graphs with distortion analysis using the Volterra series. The result is a method of distortion analysis which is more intuitive and flexible than traditional methods. The method is demonstrated in the analysis of a common-emitter amplifier in which the second- and third-order harmonic distortion ratios are determined. The method is also applied to comparing the distortion of different voltage buffer circuits based on an emitter follower and on a differential pair with unity gain feedback.