Aggressive Runtime Leakage Control Through Adaptive Light-Weight $V_{\rm th}$ Hopping With Temperature and Process Variation

The increasing leakage power consumption and stringent thermal constraint necessitate more aggressive leakage control techniques. Power gating and body biasing are widely used for standby leakage control. Their large energy overhead for performing mode transition is the major obstacle for more aggressive leakage control. Temperature and process variation (TV/PV) further magnify the overhead problem, leading to so-called “corner case leakage control” problem. Light-weight V_th hopping (LW-VH) is a candidate technique to tackle the energy overhead problem. This paper demonstrates the application of LW-VH on microarchitectural- and RTL-level idleness exploitation with adaptive control techniques for TV/PV compensation. Adaptive LW-VH shows 30% average saving on total CPU leakage at microarchitectural level, and 4% to 15% leakage saving at RTL level. By combining all the techniques proposed in this paper, a three-tier aggressive leakage control system is introduced to fully exploit idleness at all levels.