A Novel FeFET Differential Bit-Cell With Hybrid Volatile and Non-Volatile Memory Modes

Abstract

Non-volatile SRAM (nvSRAM) designs have been investigated to address the high leakage power of CMOS-based SRAM and the large write latency of emerging non-volatile memory (eNVM) technologies. However, prior nvSRAM designs that combine SRAM with eNVM devices typically require backup and restore (B\&R) operations and incur significant cell-area overhead. Here, we propose a differential memory bit-cell consisting of a pair of cross-coupled ferroelectric field-effect transistors (FeFETs) and a pair of access transistors, resulting in a four-transistor (4T) structure, which is smaller than conventional 6T SRAM and many prior nvSRAM designs. The proposed bit-cell can be configured to operate in either volatile or non-volatile mode by adjusting the write conditions. In the non-volatile mode, the proposed nvSRAM achieves a store power of 0.13~$μ$W with a 2~ns store time, and no explicit B\&R operation is required. The proposed bit-cell can also be viewed as a cross-coupled gain cell, enabling further applications.