An 8T/Cell FeFET-Based Nonvolatile SRAM with Improved Density and Sub-fJ Backup and Restore Energy.

In normally-off instant-on applications, power-gating of the embedded memory is an effective way for higher power efficiency by preventing long-standby-time leakage energy. Recent efforts of nonvolatile SRAM (nvSRAM) design with in-cell NVM element backup provide an efficient way for both normal-mode computing and off-mode backup and restore (B&R) operations. For these efforts, circuit innovations are required to achieve optimal balance between B&R energy and area overheads. In this paper, we report a novel 8T/cell FeFET-based nvSRAM design that outperforms prior FeFET-based designs with higher density, while still maintaining the advantage of only sub-fJ energy for each B&R operation, 363x lower than the existing RRAM-based nvSRAM design. Compared with prior FeFET-based designs, this design reduces the B&R transistor count per cell from 4 to only 2, which leads to a significant total area overhead reduction of 11%.