Test Vector Omission for Fault Coverage Improvement of Functional Test Sequences

Test vector omission was introduced as a static test compaction procedure for functional test sequences. Experimental results indicated that it can also increase the fault coverage accidentally when it is applied to a sequence that does not detect all the detectable target faults. However, this capability was not explored directly. It is important since test vector omission provides a smaller search space for functional test sequences than any existing approach to sequential test generation. This paper describes a branch-and-bound procedure for test vector omission whose goal is to find functional test sequences for faults that are not detected by a given sequence. Experimental results for benchmark circuits demonstrate that the procedure provides a cost-effective addition to a simulation-based sequential test generation procedure.