Low Standby Power Capacitively Coupled Sense Amplifier for wide voltage range operation of dual rail SRAMs

摘要

Dual Rail SRAMs are widely used to enable Dynamic Voltage and Frequency Scaling (DVFS) in SRAMs where array voltage cannot be scaled down. DVFS operating points are limited by maximum differential supported between two supplies of the SRAM. To extend gains of DVFS, we propose a Low Standby Power - Capacitively Coupled Sense Amplifier (LSTP-C2SA) that enables further lowering of periphery supply in Dual Rail SRAMs without leading to SRAM cell instability. We present a design method to optimally size the coupling capacitance in LSTP-C2SAs. Designs with LSTP-C2SA are shown to consume 43% lesser read power in DVFS operation at 0.4V in 28nm UTBB FD-SOI when compared to an implementation with standard latch sense amplifier. Silicon measurements confirm LSTP-C2SA functionality at 0.35V.