Low-leakage asymmetric-cell SRAM

Abstract

We introduce a novel family of asymmetric dual-Vt SRAM cell designs that reduce leakage power in caches while maintaining low access latency. Our designs exploit the strong bias towards zero at the bit level exhibited by the memory value stream of ordinary programs. Compared to conventional symmetric high-performance cells, our cells offer significant leakage reduction in the zero state and in some cases also in the one state albeit to a lesser extend. A novel sense-amplifier, in coordination with dummy bitlines, allows for read times to be on par with conventional symmetric cells. With one cell design, leakage is reduced by 7X (in the zero state) with no performance degradation. An alternative cell design reduces leakage by 40X (in the zero state) with a performance degradation of 5%.