A fast and effective DFT for test and diagnosis of power switches in SoCs

Power switches are increasingly becoming dominant leakage power reduction technique for sub-100nm CMOS technologies. Hence, fast and effective DFT solution for test and diagnosis of power switches is much needed to facilitate faster identification of potential faults and their locations. In this paper, we present a novel, coarse-grain DFT solution enabling divide and conquer based test and diagnosis solution of power switches. The proposed solution benefits from exponential time savings compared to previously reported solutions. Our DFT solution requires only (2⌈log2m⌈ + 3) clock cycles in the worst case for test and diagnosis for m-segment power switches. These time savings are further substantiated by effective discharge circuit design, which eliminates the possibility of false test and hence significantly reducing the charge and discharge times. We validated the effectiveness of our proposed solution through SPICE simulations on a number of ISCAS benchmark circuits, synthesized using 90nm gate libraries.