BIST-Based Low Power Test Vector Generator and Minimizing Bulkiness of VLSI Architecture

Abstract

In several pseudorandom built-in self-test (BIST) circuits, the applied test vectors will be generated by a linear feedback shift register (LFSR). This type of test pattern generator (TPG) may generate some repeated test patterns, which unnecessarily increases the test power without contributing much to the fault coverage. Based on the vast designs of TPG engine, the chip area also increases by contributing for the overall power consumption of the IC. This paper presents an approach called low power — bit complements test vector generation (LP-BCTVG) technique with bipartite (half fixed) and bit insertion (either 0 or 1) techniques. In order to reduce the test power, the LP-BCTVG inserts appropriate intermediate vectors in between consecutive test vectors generated by LFSR circuit. Hence, the application of final output vectors of LP-BCTVG circuit over circuit under test decreases the test power compared with LFSR-based BIST. By complementing the output bits of LP-BCTVG, we can reduce the bulkiness of TPG engine approximately by half. This further contributes to the reduced IC size. The obtained simulation results prove that this technique can reduce the overall test power consumption along with better fault coverage when compared with LFSR-based BIST and other recent methods. Here, the proposed approach has been tested on several ISCAS’85, ISCAS’89 and ITC’99 benchmark circuits.