Comparative Study on SRAMs for Suppressing Both Oxide-Tunneling Leakage and Subthreshold Leakage in Sub-70-nm Leakage Dominant VLSIs

In this paper, we compare 4 SRAM circuits. They are the conventional ´SRAM1´, ´SRAM2´ with power switches on VSs line, ´SRAM3´ with switches on VDD line, and ´SRAM4´ with switches on VDD and Vss lines, respectively. Among 4 SRAMs, SRAM2 shows the smallest amount of leakage, because its subthreshold leakage is most suppressed by its BODY and DIBL effects. To reduce the oxide-tunneling leakage more, ´SRAM5´ with lowering of its precharge voltage is considered in this paper. Compared with SRAM2 without lowering of the precharge voltage, the amounts of leakage of SRAM5 are suppressed by 27.2%, 16.8%, and 6.3%, respectively, at -25degC, 25degC, and 100degC