Fast static test compaction and its application to test generation for synchronous sequential circuits

Much research effort has been devoted to developing high quality automatic test pattern generators for synchronous sequential circuits, but it remains to be a challenging task. The main problem faced by sequential circuit automatic test pattern generation (ATPG) systems is how to achieve high fault coverages within in a reasonable time while keeping the length of the test sequence short. Because the test sequence length directly affects the cost of testing, to reduce the test sequence length without sacrificing the fault coverage is an important issue to reduce the cost of testing and to reduce the test application time.; In this thesis, several static test sequence compaction algorithms are developed to effectively reduce the test sequence length without reducing the fault coverage. Our test compaction methods greatly accelerate the vector restoration based compaction technique. We use parallel vector restoration, reverse order restoration and radix reverse order restoration techniques to speedup the vector restoration process while keeping the high compaction level. A two phase compaction scheme is proposed to further improve the compaction level achieved by the restoration based compaction.; Based on fast static compaction techniques, a new property based ATPG system for synchronous sequential circuits is developed. It uses fast static compaction, test sequence extension using hold method and several other techniques to generate test vectors. The experiments on benchmark circuits show that the proposed method is very effective in generating short sequences in a short time while achieving very high fault coverages.; Finally, we studied the ATPG techniques to improve the defect coverage of the generated test sequences. Two methods have been used to improve the defect coverage, i.e. test generation using bridging fault model and n-detection test sequence generation for stuck-at fault. From our experiments, the test sequences generated by the bridging fault test generator are more effective than n-detection test sequence to detect bridging defects.