A fuzzy multiple signature compaction scheme for BIST

Compared to single signature analysis, checking multiple signatures yields smaller aliasing, easier fault coverage computation, shorter average test-time, and increased fault diagnosability. In conventional multiple signature (CMS) schemes, for a CUT to be declared good, at each check point, the signature obtained must match a specific reference. This strict one-to-one correspondence makes the CMS scheme complex to implement and expensive in terms of silicon area. The authors propose a fuzzy multiple signature compaction scheme in which the requirement for the one-to-one correspondence is removed. In the FMS scheme, for a CUT to be declared good, it suffices that the signature obtained at each check point correspond to any of a set of references