An ultra low energy 9T half-select-free subthreshold SRAM bitcell

Operating both logic and memory at subthreshold supply voltages reduces energy dissipation for portable medical devices where battery life is critical. In this paper, we propose a 9T half-select-free subthreshold bitcell that has 2.05X lower mean read energy, 12.39% lower mean write energy, and 28% lower mean leakage current than conventional 8T bitcells at the TT_0.4V_27C corner. Our bitcell also supports the bitline interleaving technique that can cope with soft errors.