A Selective replacement method for timing-error-predicting flip-flops

The aggressive technology scaling brings us new challenges, such as parameter variations, soft errors, and device wearout. They increase unreliability of transistors and thus will become a serious problem in SoC designs. To attack these problems, spatial redundancy is commonly utilized. Based on the spatial redundancy, a lot of dual-sensing flip-flops (FFs) are proposed. These FFs require additional circuits consisting of a redundant FF and a comparator. Thus, they suffer large area overhead. In order to reduce the area overhead, this paper proposes a selective replacement method. We focus our attention on a timing-error-predicting FF, named canary FF and evaluate the selective replacement method. We apply it to two commercial processors, Toshiba´s MeP and Renesas Electronics´s M32R. In the case of MeP, the area overhead is reduced from 55% to 11%.