Process Invariant Schmitt Trigger Based Static Random Access Memory Cell with High Read Stability for Low Power Applications

Low read stability and high leakage current are two major problems in Static Random Access Memory (SRAM) at the scaled CMOS technology node. This paper provides stability, leakage and process variation analysis of a Schmitt Trigger and read buffer based differential 10T (hereafter called ST3) SRAM cell. The ST3 cell provides improve read stability, tight Read Static Noise Margin (RSNM) distribution due to simultaneously implementation of Schmitt trigger and read buffer technique. Moreover, ST3 cell consumes low leakage current because of stack transistor technique. To evaluate the impact of process variation, Monte Carlo analysis is performed in Hspice using 32 nm Predictive Technology Model (PTM) with 30% threshold voltage variation. ST3 cell provides 6x (6x) higher RSNM, 29.5x (14.5x) less RSNM variability and 0.6x (0.98x) less leakage current as compared to conventional 6T SRAM cell at 0.9 V and 0.4 V respectively. The findings of this study indicate that ST3 cell may be an attractive choice for battery-operated applications such as implantable medical device and remote sensor at the nm technology node.