This paper demonstrates a 0.8-V rail-to-rail operational amplifier (op-amp) for ultra-low-power Internet-of-Things (IoT) sensor nodes. To suppress the leakage current in the logic part, a FinFET technology with 0.4-V threshold voltage (V-t), is chosen. To realize the rail-to-rail operation in the small common-mode (CM) voltage headroom, V-DD - V-t, a 4-stage chopper-stabilized topology with high-pass filters, multi-path hybrid-nested Miller compensation, and a push-pull output stage are introduced. A near-V-t amplifier is also introduced to the second stage to boost the gain. The fabricated op-amp shows 1-MHz Gain-Bandwidth in whole of the CM voltage range.