An approach to LFSR-based X-masking for built-in self-test

摘要

To make a given circuit BIST-ready, unknown values appearing at the input of a MISR must be treated. In this paper, an LFSR-based X-masking circuit is employed and a method of seed generation for the LFSR to mask unknown values effectively is proposed. The seed generation method utilizes a stuck-at fault ATPG equipped with test pattern compaction. Experimental results for ITC'99 benchmark circuits show that the proposed masking seed generation method can utilize the ability of the test pattern compaction and can reduce the number of masking seeds required for achieving complete fault coverage.