Ultra-low supply-voltage static random-access memory (sram) with 8-transistor cell with p and n pass gates to same bit lines

Abstract

An eight-transistor (8T) Static Random-Access Memory (SRAM) cell has four latch transistors, and pairs of n-channel and p-channel pass transistors in parallel to only one pair of bit lines. During read, only the read word line and the n-channel pass transistors are activated, but during a write both the read word line and an extra write word line are activated to turn on all four pass transistors. The cell is powered by VDDM, one threshold above the normal VDD power supply of the read sense and write drivers and interfaces. The bit lines are precharged to VDD but pulled up to VDDM by a latch of cross-coupled p-channel transistors. Any p-channel transistors that connect to the bit lines are driven inactive by VDDM. The read margin is largely decoupled from the write margin by two additional p-channel pass transistors and one extra word line versus a standard 6T cell.