A cm-Scale 2.4-GHz Wireless Energy Harvester With NanoWatt Boost Converter and Antenna-Rectifier Resonance for WiFi Powering of Sensor Nodes

The widespread use of WiFi in the 2.4-GHz ISM band creates the potential for RF powering using WiFi radios. This paper presents the design of a cm-scale RF-energy harvester including antenna, rectifier, and dc-dc boost converter for RF powering in the 2.4-GHz ISM band. The rectifier and boost converter are designed while considering cold-start operation and nanowatt-scale available power from the rectifier for RF incident power <;-33 dBm. Low-power design in the power management unit and converter leads to ~1-nW quiescent power. The harvester implementation in 65-nm CMOS occupies 1.6 mm
²
while the antenna occupies 1.27 cm
²
. The proposed design optimization approach leads to a sensitivity of -33 dBm in cold start and -36 dBm in the primary mode for 1-V output, translating to ~1.4x and ~2x improvement in range compared to prior art. Measurements using a commercial WiFi TX demonstrate the ranges of up to 1.25 m for 14-dBm output power with 1.3% TX duty-cycling in WiFi access-point mode, demonstrating the feasibility of powering sensors from RF power beacons in the 2.4-GHz ISM band as well as from background WiFi transmissions.