A 65-nm Reliable 6T CMOS SRAM Cell with Minimum Size Transistors

As minimum area SRAM bit-cells are obtained when using cell ratio and pull-up ratio of 1, we analyze the possibility of decreasing the cell ratio from the conventional values comprised between 1.5-2.5 to 1. The impact of this option on area, power, performance and stability is analyzed showing that the most affected parameter is read stability, although this impact can be overcome using some of the read assist circuits proposed in the literature. The main benefits are layout regularity enhancement, with its consequent higher tolerance to variability, cell area reduction by 25 percent (with respect to a cell having a cell ratio of 2), leakage current improvement by a 35 percent, as well as energy dissipation reduction and a soft error rate per bit improvement of around 30 percent.