Equivalent Circuits of Linear Active Four-Terminal Networks*

Abstract

The art of equivalent network representation has grown very considerably since its inception by Dr. G. A. Campbell. In his paper “Cissoidal Oscillations” which was published in 1911 he proved that any passive network made up of a finite number of invariable elements and having one pair of input terminals and one pair of output terminals is externally equivalent to an unsymmetrical T or II network. From this modest beginning the field of applications of the equivalent circuit concept has steadily expanded so that by now the whole field of linear passive circuit theory has been subjected to equivalent circuit interpretation.