Adaptive Voltage Model for Microwave Energy Harvest

In this paper, an ultra-low power, high-efficiency microwave rectifier based on adaptive voltage model is proposed. Targeting micro-watt power scenarios, the proposed model incorporates diode leakage loss and employs a power-adaptive turn-on voltage to accurately characterize the loss distribution and calculate the power conversion efficiency of diode. The maximum discrepancy between the model calculation and harmonic balance simulation is less than 1%. Guided by the theoretical calculations, the junction capacitance is optimized, and a trade-off between the turn-on voltage and leakage current is established to design a gallium nitride (GaN) Schottky barrier diode (SBD) tailored for ultra-low power rectification. A 2.4-GHz rectifier utilizing this GaN SBD is implemented, achieving a measured efficiency of 19.8% at an input power of -25 dBm. The performance of the high-efficiency rectifier validates the significance of the adaptive voltage model in guiding the design of ultra-low power harvesting systems.