A minimal universal test set for self-test of EXOR-Sum-of-Products circuits

Abstract

A testable EXOR-Sum-of-Products (ESOP) circuit realization and a simple, universal test set which detects all single stuck-at faults in the internal lines and the primary inputs/outputs of the realization are given. Since ESOP is the most general form of AND-EXOR representations, our realization and test set are more versatile than those described by other researchers for the restricted GRM, FPRM, and PPRM forms of AND-EXOR circuits. Our circuit realization requires only two extra inputs for controllability and one extra output for observability. The cardinality of our test set for an n input circuit is (n+6). For Built-in Self-Test (BIST) applications, we show that our test set can be generated internally as easily as a pseudorandom pattern and that it provides 100 percent single stuck-at fault coverage. In addition, our test set requires a much shorter test cycle than a comparable pseudoexhaustive or pseudorandom test set.