Non-Volatile Coarse Grained Reconfigurable Array Enabling Two-step Store Control for Energy Minimization

Non-volatile power gating introducing MTJ into a flip-flop is an attractive technique for IoT devices. However, the time required for a successful store operation to MTJs varies at non-volatile flip-flops (NVFFs) due to process and voltage variation. This paper describes implementation and real-chip evaluation of a non-volatile Coarse Grained Reconfigurable Array employing verify-and-retryable NVFF (VR-NVFF) circuits and two-step store (TSS) control by instructions of a microcontroller. Test chips fabricated in a 40nm CMOS/MTJ hybrid technology have demonstrated that the TSS approach using both 30ns/100ns store operations reduces power by 37-42% when running an image processing program at 100MHz.