An Adaptive Radio Frequency Energy Harvester Operating over −30 to 0 dBm Input Range for IoT Applications

Radio-frequency (RF) energy harvesting for Internet of Things (IoT) nodes must combine low-power sensitivity, efficient conversion over variable input levels, and a stable load supply. This paper presents a 900 MHz adaptive harvester that integrates complementary three-phase and varactor-based ladder rectifiers with self-powered, voltage-based path selection, dual undervoltage lockout, storage control, and capacitive buck–boost regulation. The ladder rectifier supports low-input-power harvesting, while the three-phase rectifier provides higher efficiency as input power increases. Post-layout simulations of the GF 22FDX implementation investigate −30 to 0 dBm within an active area of 0.017 mm2. Under matched 50 kΩ conditions, the higher-efficiency envelope of the individual rectifier curves extends the predicted interval with power conversion efficiency (PCE) ≥ 15% from 17.0 to 25.8 dB. Sensitivity is −11 dBm at 1 V, and peak PCE is 24% at −5 dBm and 1.9 V. The power management unit targets 0.6 V across 50 kΩ, with stored energy supporting delivery when harvested power is insufficient. Converter settling times range from approximately 0.2 µs in boost mode to a maximum of 3.6 µs in buck mode. These results demonstrate a compact architecture combining adaptive RF conversion with coordinated power delivery for IoT sensing.