Efficient Wakeup Scheduling Considering Both Resource Usage and Timing Budget for Power Gating Designs

Power gating has been a very effective way to reduce power leakage. Normally, wakeup scheduling is required to control the turn-on times of sleep transistors to limit the surge current during the wakeup process. In this paper, a voltage sensor is adopted to compare the virtual ground voltage with the predesigned reference voltages, and use the result to determine the turn-on times of sleep transistors. We then propose a novel wakeup scheduling formulation that considers the tradeoff between wakeup times and hardware resources incurred by the voltage sensor. To address this problem, on the one hand, an efficient algorithm is proposed to find a wakeup scheduling with minimum wakeup time under the resource constraint. On the other hand, the algorithm to find a wakeup scheduling with minimum resource usage under the timing budget is presented. Experimental results show that with little increase in wakeup times, our algorithm can achieve significant hardware resource reduction for power gating designs.