Vector replacement to improve static-test compaction forsynchronous sequential circuits

Static-test compaction procedures for synchronous sequential circuits may saturate and be unable to further reduce the testsequence length before the test length reaches its minimum value, resulting in test sequences that may be longer than necessary. We propose a method to take a static-compaction procedure out of saturation and allow it to continue reducing the test-sequence length. The proposed method is based on the replacement of test vectors in the test sequence every time the compaction procedure reaches saturation. Test-vector replacement is done such that the fault coverage of the sequence is maintained. Experimental results using an effective static-compaction procedure demonstrate that reductions in test length can be obtained by the proposed vector replacement method