Self-exercising checkers for unified built-in self-test (UBIST)

An original built-in self-test (BIST) scheme is proposed aimed at covering some of the shortcomings of self-checking circuits and applicable to all tests needed for integrated circuits. In this scheme, self-checking techniques and built-in self-test techniques are combined in an original way to take advantage of each other. The result is a unified BIST scheme (UBIST), allowing high fault coverage for all tests needed for integrated circuits, e.g., offline test (design verification, manufacturing test, maintenance test) and online concurrent error detection. An important concept introduced is that of self-exercising checkers. The strongly code-disjoint property of the checkers is ensured for a very large class of fault hypotheses by internal test pattern generation, and the design of the checkers is simplified