A 12T Subthreshold SRAM Bit-Cell for Medical Device Application

A Schmitt Trigger based SRAM 12T bit-cell is proposed to operate under optimum-energy supply voltage for medical device application. Therefore, the design of medical device has been more and more important in the scope of today´s SoC design. As have shown in the simulation, there always exists an optimum-energy supply voltage point (Vopt) in the SoC system, which normally lies in weak sub-threshold or nearthreshold region. As a result, the robustness problem arises due to the low-power operation. Considering about this degraded robustness, structural change instead of the sizing change is considered in this paper. The proposed design has 45% improvement of the SNM compared to the conventional 6T SRAM bit-cell. Due to the wide hysteresis effect, the proposed design also exhibits more robust to process variations. Its hold margin is 30.2% greater than conventional 6T SRAM. The optimum-energy supply voltage of proposed array (256×16) is 400 mV. At the same time, the power consumption at 400 mV decreases to 16% compared to that at 1200 mV.