A Statistical Approach to Area-Constrained Yield Enhancement for Pipelined Circuits under Parameter Variations

Abstract

Under inter- and intra-die parameter variations, delay of a pipelined circuit follows a statistical distribution. Hence, a pipelined circuit suffers yield loss with respect to violation of target delay constraint unless an overly pessimistic worst-case design approach is followed. We propose a statistical approach for pipeline design to enhance yield with respect to a target delay under an area budget. Right choice of the number of pipeline stages to enhance yield under an area constraint is addressed using simple statistical yield models. Next, individual stages are designed for maximizing yield under area constraint for the stages. Once the independently optimized stages are combined to form a pipeline, we propose a final global optimization step to improve pipeline yield with no area overhead, based on a concept of area borrowing. Optimization results show that, the proposed statistical design approach for pipeline improves the overall yield up to 12% over conventional design for equal area.