Fast and Disturb-Free Nonvolatile Flip-Flop Using Complementary Polarizer MTJ

Nonvolatile flip-flop (NVFF) using spin-transfer torque magnetic tunnel junctions (STT-MTJs) has been proposed to enable line-grain power gating systems. However, the STT-MTJ-based NVFF (STT-NVFF) may not perform fast backup and disturb-free restore operations. We propose a new NVFF using complementary polarizer MTJ (CPMTJ) to alleviate these limitations. Our proposed NVFF exploits the CPMTJ structure for fast- and low-energy backup operation. The estimated backup delay is less than 10 ns in 7-nm node FinFET technology with CPMTJ size of 12 nm × 33 nm in a rectangular shape. Furthermore, during the restore operation, CPMTJ provides guaranteed disturb-free sensing, since the disturb torque from the two complementary pinned layers of CPMTJ cancels each other. The simulation results show 2 times improvement in the backup delay with higher restore-disturb margin compared with STT-NVFF.