Battery-Less IoT Sensor Node with PLL-Less WiFi Backscattering Communications in a 2.5-μW Peak Power Envelope

A system on chip including 802.11b WiFi communications is introduced to demonstrate battery-less operation for low-cost mm-scale sensor nodes. µW peak power is enabled by PLL-less WiFi backscattering communications and event-driven frequency regulation to compensate environmental variations. A 180nm testchip integrating the entire signal chain from any of four sensor interfaces to wireless communications with a commercial WiFi router exhibits 2.5µW total power.