Testable design of GRM network with EXOR-tree for detecting stuck-at and bridging faults

A new testable realization of generalized Reed-Muller (GRM) expression with tree implementation of the EXOR-part is presented. This solves an open problem of designing an EXOR-tree based GRM network that admits a universal test set. For an n-variable function, the proposed design can be tested by (2n+8) test vectors, which are independent of the function and the circuit-under-test (CUT). Excepting a few intergate bridging faults in the EXOR-tree, it detects all other single bridging (both OR-and AND-type) and all single stuck-at faults. The EXOR-part is designed as a tree of depth (/spl lceil/log/sub 2/s/spl rceil/ +1), where s is the number of product terms in the given GRM expression. This reduces circuit delay significantly compared to cascaded EXOR-part. Further, for several benchmark circuits, the test set is found to be much smaller than those of the earlier tree-based designs.