Test Patterns of Multiple SIC Vectors: Theory and Application in BIST Schemes

摘要

This paper proposes a novel test pattern generator (TPG) for built-in self-test. Our method generates multiple single-input change (MSIC) vectors in a pattern, i.e., each vector applied to a scan chain is an SIC vector. A reconfigurable Johnson counter and a scalable SIC counter are developed to generate a class of minimum transition sequences. The proposed TPG is flexible to both the test-per-clock and the test-per-scan schemes. A theory is also developed to represent and analyze the sequences and to extract a class of MSIC sequences. Analysis results show that the produced MSIC sequences have the favorable features of uniform distribution and low input transition density. The performances of the designed TPGs and the circuits under test with 45 nm are evaluated. Simulation results with ISCAS benchmarks demonstrate that MSIC can save test power and impose no more than 7.5% overhead for a scan design. It also achieves the target fault coverage without increasing the test length.