Self-dual parity checking-A new method for on-line testing

Self-dual parity checking as a modification of ordinary parity checking is proposed in this paper. This method is based on the newly introduced concept of a self-dual complement of a given Boolean function. The parity prediction function f_p of ordinary parity checking is replaced by the self-dual complement δ_p of this function such that the module-2 sum of the outputs of the monitored circuit and of δ_p is an arbitrary self-dual Boolean function h. Because of the large number of possible choices for h as an arbitrary self-dual Boolean function, the area overhead for an optimal self-dual complement δ_p is small. Alternating inputs are applied to the circuit; the output h is alternating as long as no error occurs. The fault coverage of this method is almost the same as for parity checking. The usefulness of the proposed method is demonstrated for MCNC benchmark circuits