Reducing SRAM Power Using Fine-Grained Wordline Pulsewidth Control

Embedded SRAM dominates modern SoCs, and there is a strong demand for SRAM with lower power consumption while achieving high performance and high density. However, the large increase of process variations in advanced CMOS technologies is considered one of the biggest challenges for SRAM designers. In the presence of large process variations, SRAMs are expected to consume larger power to ensure correct read operations and meet yield targets. In this paper, we propose a new architecture that significantly reduces the array switching power for SRAM. The proposed architecture combines built-in self-test and digitally controlled delay elements to reduce the wordline pulsewidth for memories while ensuring correct read operations, hence reducing the switching power. Monte Carlo simulations using a 1-Mb SRAM macro in an industrial 45-nm technology are used to verify the power saving for the proposed architecture. For a 48-Mb memory density, a 27% reduction in array switching power can be achieved for a read access yield target of 95%. In addition, the proposed system can provide larger power saving as process variations increase, which makes it an attractive solution for 45-nm-and-below technologies.