A complete logic BIST technology with no storage requirement

Mixed-mode BIST enhances test efficiency of digital circuits by combining the advantages of both pseudorandom and deterministic patterns. In order to apply the deterministic patterns, most traditional methods need to store some test data in external testers or on-chip memory. In this paper we present a novel mixed-mode BIST technique by which all deterministic patterns can be generated on chip in real time and thus requiring no storage device. By appropriately connecting some internal nets of the circuit under test to the inputs of the circuit, together with a set of pseudo-random patterns, this BIST scheme can reach full fault coverage in a very short time. Experimental results show that all irredundant stuck-at faults in each of the ISCAS85 benchmarks can be detected in less than 1000 test cycles with no storage space required.