MULTIPLE-FAULT DETECTION IN PARITY CHECKERS

Parity checkers are widely used in digital systems to detect errors wh en systems are in operation. Since parity checkers are monitoring circ uits, their reliability must be guaranteed by performing a thorough te sting. In this work, multiple fault detection of parity checkers is in vestigated. We have found that all multiple stuck-at faults occurring on a parity tree can be completely detected using test patterns provid ed by the identity matrix plus zero vector. The identity matrix contai ns 1's on the main diagonal and 0's elsewhere; while the zero vector c ontains 0's. The identity matrix vectors can also detect all multiple general bridging faults, if the bridgings result in a wired-AND effect . However, test patterns generated from the identity matrix and binary matrix are required to detect a majority of the multiple bridging fau lts which yield wired-OR connections. Note that the binary matrix cont ains two 1's at each column of the matrix.