Testing of differential cascade voltage switch (DCVS) circuits

The problem of testing differential cascode voltage switch (DCVS) circuits is analyzed. These circuits have several potential applications in fault-tolerant, highly available system design due to their inherent self-checking capability. It is shown how concurrent (online) testing of DCVS circuits, which is very effective under single transistor fault assumptions, can be performed. The impact of multiple faults of DCVS circuits is examined, and analytical results are derived. These results indicate that periodic offline tests on DCVS circuits are necessary in order to achieve high multiple-fault coverage. Single-fault test sets and/or pseudorandom vectors were successfully used in the offline tests to detect many of the multiple faults which reduce the efficiency of online tests. The results show the need for a comprehensive mixed-test strategy combining offline and online tests for DCVS circuits