A UNIFORM APPROACH TO MIXED-SIGNAL CIRCUIT TEST

Owing to the analogue nature of many industrial processes and the incr easing use of microprocessor techniques, many circuits nowadays carry mixed (digital and analogue) signals. As complexities of these circuit s increase, the testability of mixed-signal circuits has become an imp ortant issue that must be dealt with by both design and test engineers . A systematic api,roach to study the testability of mixed-signal circ uits is urgently needed, because current ad hoc methods cannot efficie ntly handle increasingly complex and ever-changing circuits. In this p aper we develop a uniform and systematic approach to the mixed-signal circuit testability problem. The approach is based on a recently devel oped theory of discrete event systems. It is suitable for the followin g tasks: (i) checking the testability of a circuit; (ii) computing the minimum test set; (iii) finding the fault coverage; (iv) dividing a c ircuit into testable modules. (C) 1997 by John Wiley & Sons, Ltd.