Static and dynamic stability improvement strategies for 6T CMOS low-power SRAMs

Abstract

The main contribution of this work is providing a static and dynamic enhancement of bit-cell stability for low-power SRAM in nanometer technologies. We consider a wide layout topology without bends in diffusion layers for the nanometer SRAM cell design to minimize the impact of process variations. The design restrictions imposed by such a nanometer SRAM cell design prevents from applying traditional read SNM improvement techniques. We use the SNM as a measure of the cell stability during read operations, and Qcrit to quantify the robustness against SEE during hold mode. The techniques proposed have a low impact on read time and leakage current while improving significantly the SNM. Moreover, the Word-line modulation technique has no impact on strategic cell parameters like area and leakage when in hold mode. Results obtained from both a commercial 65nm CMOS technology and a 45nm BPTM technology are provided.