Catastrophic Fault Diagnosis of a Certain Class of Nonlinear Analog Circuits

摘要

This paper deals, for the first time, with catastrophic fault diagnosis of nonlinear analog circuits containing bipolar and MOS transistors having multiple operating points (DC solutions). The faults are cuts of some connecting paths and short-circuits of some pairs of points. Simulation-before-test approach is applied for detection and identification of a single catastrophic fault. To build a fault dictionary, a diagnostic test is arranged based on DC analysis. In the discussed circuits having multiple DC solutions, the tested output voltage may assume different values for fixed value of the input voltage. This fact considerably complicates the fault diagnosis. The crucial point of the proposed approach is tracing large number of nonlinear multivalued input-output characteristics at different values of circuit parameters within their tolerance ranges. For this purpose an efficient and fast algorithm is developed, based on the theory known under the name a linear complementarity problem. To illustrate the proposed approach and show its efficiency, four numerical examples are given.