A generalized fault diagnosis method in dynamic analogue circuits

Fault diagnosis of analogue circuits is essential for analogue and mixed-signal systems testing and maintenance. A new method is proposed in this paper for multiple fault diagnosis of linear analogue circuits in frequency domain. The Woodbury formula is applied to the modi9ed nodal equation to construct the fault diagnosis equation, which relates the limited measured circuit responses with the multiple faults inside the circuit in a linear way. A recently developed ambiguity group locating technique is modi9ed here to identify the faulty parameters directly. Computation cost is reduced compared to combinatorial search in traditional fault veri9cation methods. Only one node is needed for voltage measurement, but multiple excitations on accessible nodes are required for fault identi9cation. Parameter evaluation can provide the exact solution to the deviated values of faulty parameters. The faulty parameter deviations can have any 9nite values. Example circuits are provided to illustrate the proposed method. Two other methods for multiple analogue fault diagnosis sharing the same mechanism as the method proposed in this paper are also briecient. Copyright ? 2002 John Wiley & Sons, Ltd.