Topological Evaluation Of The Null Return Difference In Feedback Amplifier Theory

摘要

Like the general return difference, the general null return difference is defined as the ratio of the two functional values assumed by the second-order cofactor of the elements as sociated with the input and output terminals of the indefinite-admittance matrix of a feed back amplifier under the condition that the element of interest assumes its nominal value and the condition that the element assumes its reference value, It is shown that this alge braic definition is entirely consistent with the classical physical formulation of the null return difference. Topological formulas are presented for the null return difference and the sensitivity functions in terms of the directed-tree and directed-two-tree products in the associated digraph of the amplifier.