Circuit tests based on the linear relationships between changes in node voltages

Fault diagnosis in analog circuits can be based on changes in node-voltages. The changes in node-voltages are shown to be linearly related to changes in the component parameters. A fault dictionary diagnosis method was then developed using the linear relativity among the increments of node-voltages. Unlike traditional dictionary methods, the new method can diagnose single faults, multiple faults, catastrophic faults, and parametric faults and can be used for both DC and AC tests. For AC tests, the value extension is extended from real space to complex space.