Analyzing N-Curve Metrics for Sub-Threshold 65nm CMOS SRAM

This paper examines the usefulness of N-curve metrics for a 65 nm SRAM cell operating in sub-threshold region. Various N-curve metrics are evaluated with changing power supply voltage, temperature, cell ratios, pull up ratios and oxide thickness. N-curve metrics are also evaluated considering the effect of intra die and inter die random threshold voltage variations. Results indicate that N-curve method provides better metrics in terms of SINM and WTI to assess the stability of SRAM operating in sub-threshold region and enables complete functional analysis.