A Highly Stable Low-Energy 10T SRAM for Near-Threshold Operation

This paper aims to explore the design of a novel highly stable low-energy 10T (SLE10T) SRAM cell for near-threshold operation. The latch core of the proposed design consists of a cross-coupled structure of a tri-state inverter and a standard inverter. The tri-state inverter is switched to the high-impedance mode during a write operation to temporarily float the data node, improving writability. In addition, read stability is equivalent to hold stability due to considering a separate path for read current flow, as well as a built-in read-assist scheme to force the ‘0’ storing node to ground. Leakage and dynamic power consumptions in the designed cell are reduced with the help of single-bitline structure and stacking of transistors. The simulation results in a 7-nm FinFET at a 0.5 V show that the SLE10T improves read stability by at least <inline-formula> <tex-math notation="LaTeX">$1.31\times $ </tex-math></inline-formula> compared to read-disturbance SRAMs and offers the second-highest writability, improvement of at least <inline-formula> <tex-math notation="LaTeX">$1.10\times $ </tex-math></inline-formula>. Leakage power dissipation is reduced in the SLE10T by at least <inline-formula> <tex-math notation="LaTeX">$1.10\times $ </tex-math></inline-formula>. Moreover, it improves read/write energy by at least <inline-formula> <tex-math notation="LaTeX">$1.01\times /1.03\times $ </tex-math></inline-formula>. However, the area of the SLE10T bitcell is <inline-formula> <tex-math notation="LaTeX">$0.02~\mu \text{m}^{2}$ </tex-math></inline-formula>, which is <inline-formula> <tex-math notation="LaTeX">$1.657\times /1.318\times $ </tex-math></inline-formula> larger than the conventional 6T/8T bitcell.