Anticausal analysis of feedback amplifiers

This paper discloses a technique for the direct analysis of linear active circuits, avoiding the solution of simultaneous equations. This is done by representing the circuit in such a way that the signal variables (currents and voltages) are determined sequentially: we only allow a signal variable to depend upon previously determined signal variables, not upon signal variables yet to be determined. Such a circuit is representable by a cascade signal flow graph, a graph containing no feedback loops. Not all circuits can be so represented, of course, but the number which can is expanded by the technique to be described to include most feedback amplifier configurations. This simplification in linear amplifier analysis allows us to trace a clear path from rough design approximations to exact computer analysis. The extension of the analysis to include the effect of nonsaturating nanlinearities is indicated but not developed here.