A Non-Volatile Flip-Flop Circuit Using One MTJ and Reference Resistance

Non-Volatile Flip Flops (NVFF) using Magnetic Tunnel Junction (MTJ) enable non-volatile power gating and reduce leakage power. However, MTJ has a problem of high write energy. Conventional NVFFs write to two MTJs per NVFF because they read using the difference between the high and low resistance of the MTJs. However, it is not necessary to write to two MTJs, if they can be accurately read using one MTJ and a reference resistor whose resistance value is fixed between high and low resistance. In this study, we propose an NVFF circuit that has a reference resistor and writes to only one MTJ to reduce energy. We conducted circuit design and layout in the 65nm process technology. Simulation results demonstrated that the write energy was reduced by 58% while suppressing the area overhead to 5%.