A CNTFET based stable, single-ended 7T SRAM cell with improved write operation

Abstract

Many researchers are working to improve the write operation in SRAM bit-cell for better write stability, low power dissipation, and minimal access time during the write process. However, the read and hold operation parameters should not be compromised to achieve these improvements. This paper presents a stable single-ended seven-carbon nanotube field-effect transistor (CNTFET) driven SRAM cell with improved write operation. The one-side inverter weakening approach for write and transistor decoupling for read operation leads to reduced dynamic power, low write delay, reduced leakage power, and improved stability. The proposed design is compared with conventional 6T (Conv6T) and three recently proposed designs, i.e., feedback-cutting 8T (feed-cut 8T), Low-power 8T and low-leakage 7T cell. The write delay and write PDP of the proposed design improve by 4.05×/3.58×/1.19×/1.21×and 11.11×/24.71×/2.96×/3.32×, respectively, compared to Conv6T/feed-cut 8T/ low-power 8T/ low-leakage 7T. Also, the read delay and read PDP of the proposed design improve by 1×/1.03×/1.72×/1.56× and 1×/1.03×/1.82×/1.77×, respectively, compared to Conv6T/feed-cut 8T/ low-power 8T/ low-leakage 7T. The leakage power of the proposed design is reduced by 1.08×/1.84×/0.46×/0.72× compared to Conv6T/feed-cut 8T/ low-power 8T/ low-leakage 7T. The noise margin of the proposed cell for hold/write/read operation is improved by 1.02×/1.05×/0.99×compared to the Conv6T design. The simulation was performed using Stanford University’s 32 nm CNTFET model on the cadence virtuoso platform.