COMPACT TEST SETS FOR HIGH DEFECT COVERAGE

It was recently observed that, in order to improve the defect coverage of a test set, test generation based on fault models such as the sing le-line stuck-at model may need to be augmented so as to derive test s ets that detect each modeled fault more than once. In this work, we re port on test pattern generators for combinational circuits that genera te test sets to detect each single line stuck-at fault a given number of times, Additionally, we study the effects of test set compaction on the defect coverage of such test sets. For the purpose of experimenta tion, defect coverage is measured by the coverage of surrogate faults, using a framework proposed earlier. Within this framework, we show th at the defect coverage does not have to be sacrificed by test compacti on if the test set is computed using appropriate test generation objec tives. Moreover, two test sets generated using the same test generatio n objectives, except that compaction heuristics were used during the g eneration of one but not the other, typically have similar defect cove rages, even if the compacted test set is significantly smaller than th e noncompacted one. Test generation procedures and experimental result s to support these claims are presented.