Nonvolatile Flip-Flops Using FiCC for IoT Processors with Intermittent Operations

Recently, Internet of Things (IoT) are spread out in many fields. Some applications for an IoT request intermittent operations to extend their battery life. In this paper, we present a nonvolatile flip-flop (NV-FF) using FiCC (Fishbone-in-Cage Capacitor) suitable for IoT processors with intermittent operations. The NV-FF was fabricated in a 180 nm CMOS process technology. The area overhead caused by nonvolatility of the flip-flop is 29%. We confirmed that NV-FF is fully working at 65 MHz. The data retention time was approximately 155 minutes when the write time to the nonvolatile memory was 0.1 sec. and the reading voltage was set to 1.4 V. The simulation results indicate that the nonvolatile register file composed of the NV-FFs can reduce the energy consumption by 80.31% compared with a conventional register file when it operates 35 sec. per hour and hybernates in the remaining time.