An automated runtime power-gating scheme

Abstract

An automated runtime power-gating scheme to reduce the leakage power in the active mode is presented in this paper. We propose a circuit that generates a sleep control signal from a clock-gating control signal automatically. By the combination of selective MT-CMOS scheme, the generated sleep control signal, and a novel flip-flop circuit with an additional latch function, a zero-wait transition from a sleep mode to an active mode is enabled. The additional latch function required for the zero-wait transition is achieved by only 6 transistors in addition to a conventional flip- flop. By the scheme, any design with the clock-gating scheme can be transformed automatically to a power- gated design while keeping the system operation the same in terms of the cycle accuracy. The scheme is applied to an MPEG4/H.264 audio/video codec and 21% power saving is achieved in the active mode while keeping the area overhead only 16% in a 90 nm CMOS design.