Compaction of pass/fail-based diagnostic test vectors for combinational and sequential circuits

Abstract

Substantial attention is being paid to the fault diagnosis problem in recent test literature. Yet, the compaction of test vectors for fault diagnosis is little explored. The compaction of diagnostic test vectors must take care of all fault pairs that need to be distinguished by a given test vector set. Clearly, the number of fault pairs is much larger than the number of faults thus making this problem very difficult and challenging. The key contributions of this paper are: 1) to use techniques for reducing the size of fault pairs to be considered at a time, 2) to use novel variants of the fault distinguishing table method for combinational circuits and reverse order restoration method for sequential circuits, and 3) to introduce heuristics to manage the space complexity of considering all fault pairs for large circuits. Finally, the experimental results for ISCAS benchmark circuits are presented to demonstrate the effectiveness of the proposed methods.