A brand new robust oriented near-threshold 8T SRAM design methodology

Nanometer SRAM design is challenging because of the ever increasing process variation reducing the precious noise margin. This is especially true when the supply voltage are aggressively scaling at the same time for reducing the total power consumption. Traditional 6-T transistors are not capable of working in this condition, and it requires more complicated 8-T SRAM structure. To preserve a reasonable yield a 8-T SRAM must be designed by very carefully tuning the the threshold voltages of transistors. In contrast to 6-T SRAM design, the optimization of 8-T SRAMs is much less studied. In this paper, we propose a new 8-T structure and a comprehensive method for SRAM design relying on an efficient combination of performance optimization and yield analysis. Experiments show that traditional design which focuses only on optimizing the noise margins may lead to sub-optimal design which can not full fill the yield requirement. While the proposed yield oriented design method gives much better design which can be used in SRAM array design.