Teaching Difference Amplifier Concepts

A novel method of teaching the concepts associated with difference amplifiers is outlined. Departures from methods used in most textbooks consist of emphasis upon superposition of common and difference mode signals, and use of "Thevenin equivalent type" models for the difference amplifier. The well-known decomposition of an arbitrary signal into common and difference mode components is interpreted in terms of three separate independent sources, an observation which forms the basis of the superposition approach. The circuit models make use of dependent sources producing the various difference and common mode output voltage components relative to ground. The techniques outlined here seem to present the many concepts required for solving general difference amplifiler problems in a manner which is especially easy for students to understand and remember.