A High-Density Subthreshold SRAM with Data-Independent Bitline Leakage and Virtual Ground Replica Scheme

A 10T SRAM cell with data-independent bitline leakage and a virtual-ground replica scheme allows 1k cells per bitline in subthreshold SRAMs. Reverse short-channel effect is used to improve writability, offer higher speed, reduce junction capacitance, and decrease circuit variability. A 0.13mum, the 480kb SRAM test chip shows a minimum operating voltage of 0.20V.