Spin Hall Effect-based Nonvolatile Flip Flop for Fine-grained Power Gating

Abstract

This paper presents a nonvolatile flip flop (NVFF) for fine-grained power gating with data retention. The proposed NVFF exploits the spin Hall effect (SHE) for low-power and high-speed data backup operations. In order to evaluate the performance of the proposed NVFF, a simulation framework was used that consists of a SPICE circuit simulator and a Landau-Lifshitz-Gilbert solver. This work investigates the effect of process variation on the backup-and-restore operations, and shows that the proposed NVFF can achieve <5ns backup and <2ns restore operations even under process variations in the transistor and spin Hall device. Compared to the conventional spin transfer torque–based NVFF, the proposed NVFF improves the break-even time by more than three times because of the high spin injection efficiency of SHE and the simple single-phase backup mechanism.