Analogue fault diagnosis of active networks via bias modulation

A new branch fault location technique for active networks is proposed, which requires a single excitation source at one test frequency. Diagnosable branch-diagnosis equations are constructed by modulating the bias of nonlinear devices in the network. The constraints on the bias transitions and test frequency are addressed for a general network where q network elements are modulated or q bias transitions are used. A network element whose value is varied externally (i.e. by test equipment) is defined as a modulated element. An example of the proposed technique applied to a two-stage cascade amplifier is given.