MZZ-HVS: Multiple Sleep Modes Zig-Zag Horizontal and Vertical Sleep Transistor Sharing to Reduce Leakage Power in On-Chip SRAM Peripheral Circuits

Recent studies show that peripheral circuit (including decoders, wordline drivers, input and output drivers) constitutes a large portion of the cache leakage. In addition, as technology migrates to smaller geometries, leakage contribution to total power consumption increases faster than dynamic power, indicating that leakage will be a major contributor to overall power consumption. This paper presents zig-zag share, a circuit technique to reduce leakage in SRAM peripherals by putting them into low-leakage power sleep mode. The zig-zag share circuit is further extended to enable multiple sleep modes for cache peripherals. Each mode represents a trade-off between leakage reduction and the wakeup delay. Using architectural control of multiple sleep modes, an integrated technique called MSleep-Share is proposed and applied in L1 and L2 caches. MSleep-share relies on cache miss information to guide leakage control mechanism and switch peripheral circuit's power mode. The results show leakage reduction by up to 40× in deeply pipelined SRAM peripheral circuits, with small area overhead and small additional delay. This noticeable leakage reduction translates to up to 85% overall leakage reduction in on-chip memories.