Constraint-aware robustness insertion for optimal noise-tolerance enhancement in VLSI circuits

Reliability of nanometer circuits is becoming a major concern in today\´s VLSI chip design due to interferences from multiple noise sources as well as radiation-induced soft errors. Traditional noise analysis/avoidance and manufacturing testing are no longer sufficient to handle the dynamic interactions between various noise sources and unpredictable operational variations. Therefore, "robustness insertion" has been adopted as the supplementary approach to ensure high circuit reliability through on-line protections. However, the related design overhead is not always acceptable, especially for cost/timing-sensitive designs. In this paper, we present a novel "constraint-aware robustness insertion" methodology protect the sequential elements in digital circuits against various noise effects. Based on a configurable hardening sequential cell design and an efficient sequential cell robustness estimation technique, an optimization algorithm is developed to search for the optimal protection scheme under given timing and area constraints. Experiment results demonstrate that the proposed methodology is able to achieve a high degree of noise-tolerance while keeping the protection cost within limit.