A Scalable Algorithmic Framework for Row-Based Power-Gating

Leakage power is a serious concern in nanometer CMOS technologies. In this paper we focus on leakage reduction through automatic insertion of sleep transistors for power gating in standard cell based designs. In particular, we propose clustering algorithms for row- based power-gating methodology which is based on using rows of the layout as the granularity for clustering. Our clustering methodology does timing and area constraint driven power-gating in contrast to only timing driven power-gating as proposed in the previous works. We present two distinct clustering algorithms with different accuracy-efficiency trade-off. An optimal one, which exploits a 0-1 or binary integer programming approach, and a heuristic one, which resorts to an implicit enumeration of the layout rows. Results show that, for all the benchmarks, the leakage power savings, as compared to previous techniques, are more than 75% when we have the same timing constraints but half sleep transistor area and at least 60% when area constraint is set at one fourth. We also show that we can perform clustering with no speed degradation and achieve maximum leakage power savings up-to 83%.