Diagnosis of analogue nonlinear circuits in dc domain by using a tearing procedure

The diagnosis of analogue circuits has several drawbacks in comparison to its digital counterpart. In particular, the diagnosis in the dc domain has two main issues: the shifting of the dc bias point and the existence of multiple dc operating solutions. This paper is focussed on the change of the number of dc operating points due to faulty elements. It determines the change of the number of dc solutions either by the presence of active or passive faulty elements. The method developed detects this change by applying a tearing procedure in order to save computing time. The circuit representation yields a pair of matrices of the linear part and the nonlinear part (the BJTs) of the circuit. The structure of both matrices allows us to carry out a tearing procedure that speeds up the diagnostic method. It can be easily programmed and added to a CAD frame.