Compact test sets for high defect coverage

摘要

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 single-line stuck-at model may need to be augmented so as to derive test sets that detect each modeled fault more than once. In this work, we report on test pattern generators for combinational circuits that generate 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 experimentation, defect coverage is measured by the coverage of surrogate faults, using a framework proposed earlier. Within this framework, we show that the defect coverage does not have to be sacrificed by test compaction if the test set is computed using appropriate test generation objectives. Moreover, two test sets generated using the same test generation objectives, except that compaction heuristics were used during the generation of one but not the other, typically have similar defect coverages, even if the compacted test set is significantly smaller than the noncompacted one. Test generation procedures and experimental results to support these claims are presented.