A subthreshold single ended I/O SRAM cell design for nanometer CMOS technologies

Lowering supply voltage is an effective technique for power reduction in memory design, however traditional memory cell design fails to operate, as shown in [3], [10], at ultra-low voltages. Therefore, to operate cells in the subthreshold regime, new cell structures needs to be explored. Towards this, we present a single-ended I/O (SEIO) bit-line latch style 7-transistor static random access memory (SRAM) cell (7T-LSRAM) as an alternative for nanometer CMOS technology which can function in ultra-low voltage regime. Compared to existing 6-transistor (6T) cell or 10-transistor cell design, the proposed cell has 2X improved read stability and 36% better write-ability at lower supply voltage. Furthermore, the 7T-LSRAM has improved process variation tolerance. The area analysis shows that there is 18% increase in area penalty compared to the standard 6T cell, however the improved performance and process variation tolerance could justify the overhead.