A hierarchical analog test bus framework for testing mixed-signal integrated circuits and printed circuit boards

Progress in analog circuit testing has been hindered by the lack of structured design-for-testability methodologies. With the increasing complexity of analog/mixed-signal circuits, test program development time is now a major obstacle in achieving shorttime-to-market, while production testing cost is a prominent factor in total production cost. TheAnalog Autonomous Test is a structured design-for-testability scheme for analog circuits. Originally developed for testing analog circuits at chip level, AAT extends naturally to cover testing of mixedsignal integrated circuits mounted on printed circuit boards. With the addition of an analog test bus to PCBs, testability for analog components (bothcore circuits andglue circuits) can be improved, in a manner similar to that achieved for digital boards by the IEEE 1149.1 boundary scan scheme. Details on the implementation of thisAnalog Autonomous Test Bus, both at chip level and board level, are presented here. Its limitations and potential applications are also discussed.