Design and Iso-Area Vₘᵢₙ Analysis of 9T Subthreshold SRAM With Bit-Interleaving Scheme in 65-nm CMOS

In this brief, a 9T bit cell is proposed to enhance write ability by cutting off the positive feedback loop of a static random-access memory (SRAM) cross-coupled inverter pair. In read mode, an access buffer is designed to isolate the storage node from the read path for better read robustness and leakage reduction. The bit-interleaving scheme is allowed by incorporating the proposed 9T SRAM bit cell with additional write wordlines (WWL/WWLb) for soft-error tolerance. A 1-kb 9T 4-to-1 bit-interleaved SRAM is implemented in 65-nm bulk CMOS technology. The experimental results demonstrate that the test chip minimum energy point occurs at 0.3-V supply voltage. It can achieve an operation frequency of 909 kHz with 3.51-W active power consumption.