An efficient wakeup scheduling considering resource constraint for sensor-based power gating designs

Power gating has been a very effective way to reduce leakage power. One important design issue for a power gating design is to limit the surge current during the wakeup process. Normally, a wakeup scheduling is required to control turn-on times of sleep transistors. In this paper, we adopt a voltage sensor to compare pre-designed reference voltages with the virtual ground voltage and use the comparison result to determine turn-on times of sleep transistors. Special properties and optimizations of using voltage sensors are discussed. Since a wakeup scheduling with fast wakeup time may require significant hardware resources, we propose a new wakeup scheduling formulation which considers the trade-off between wakeup times and hardware resources. Our experimental results show that with small increases on wakeup times, we can reduce significant hardware resources for a power gating design.