Performance evaluation of SRAM design using different field effect transistors

Abstract

SRAM (Static Random Access Memory) is one of the type of memory which holds the data bit without periodic refreshment. Compared with DRAM (Dynamic Random Access Memory) which requires periodic refreshment of data bit stored in it. Unlike Dynamic RAM, Static RAM uses a flip-flop circuit to store each data bit, whereas Dynamic RAM uses a capacitor to store the data bit. But capacitor has tendency of losing charge which requires periodic refreshment. Thus SRAM perform better and have more stability than DRAM especially in idle state. In this work, we analysed the performance of the SRAM cell which are built with different field effect transistors and calculated the Write and Read delays, PDP (Power Delay Product) and Static Noise Margin (SNM) for all types of transistors. SRAM cell which is based on the CNT technology with optimized parameters of CNT density, CNT diameter and CNTFET flat band voltage has the better performance and stability compared with other device technologies. Optimized CNTFET SRAM cell compared with the MOSFET based SRAM the write and read delays are improved by 85.8% and 94.3% respectively. All the simulations have been carried out using HSPICE tool for 32nm technology node.