DiCER: Distributed and cost-effective redundancy for variation tolerance

Increasingly prominent variational effects impose imminent threat to the progress of VLSI technology. This work explores redundancy, which is a well-known fault tolerance technique, for variation tolerance. It is observed that delay variability can be reduced by making redundant paths distributed or less correlated. Based on this observation, a gate splitting methodology is proposed for achieving distributed redundancy. We show how to avoid short circuit and estimate delay in dual-driver nets which are caused by gate splitting. A spin-off gate placement heuristic is developed to minimize redundancy cost. Monte Carlo simulation results on benchmark circuits show that our method can improve timing yield from 59% to 72% with only 0.3% increase on cell area and 2.2% increase on wirelength on average.