Statistical Stability Characterization of Schmitt Trigger Based 10-T SRAM Cell Design

In this paper, stability analysis of conventional 6-T SRAM cell and Schmitt trigger (ST) based 10-T SRAM cell with optimized sizing parameters has been performed and compared. The read stability, write ability, delay and dissipated power have been investigated. By using N-curve methodology a significant improvement of 4.49%, 5.13% and 28.65% in SVNM, SINM and WTI respectively was observed for Schmitt trigger (ST) based 10-T SRAM cell as compared to optimized 6T SRAM cell. Furthermore, the effects of supply voltage and temperature on conventional 6T SRAM stability in read and write operational mode have also been examined. Furthermore, both read delay and read current were investigated for ST based 10-T SRAM cell and found in desirable limits. It is also interesting to note that read delay is improved by 66%. Monte-Carlo simulation of the ST based 10-T SRAM cell circuit is carried out in order to find the deviation for power and the read current. The read current of the 10T topology is found to be 29.97μA with standard deviation of 4.55μA. Mean dynamic power for all process corners is also calculated by monte-carlo simulation of 4000 point each and deviation from the mean power was obtained. For simulation process 90nm technology node at 1V power supply was used on cadence virtuoso tool.