Signature analysis with modified linear feedback shift registers (M-LFSRs)

A signature analysis technique that uses modified linear feedback shift registers (LFSRs) is presented. It is demonstrated that the modified-LFSR-based analyzers can be designed with significantly lower aliasing probability compared to conventional LFSRs of the same size. The methodology for their design is described. Analytic expressions for their aliasing probability, hardware requirements, and the average tet-time overhead are obtained and experimentally verified. Studies using several circuit-under-test responses corroborate the improvement in the aliasing probability for the same hardware (or reduction in hardware for the same aliasing probability) when the modified LFSRs are used. The extra test-time required by the modified LFSRs is found to be nominal (<5%) in a majority of instances.<
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