High-Power Dual-Band RF Rectifier With Multifocus GaN Techniques for WPT Applications

This article presents a spatially adaptive dual-band rectifier leveraging multifocus gallium nitride (GaN) techniques, specifically designed for high-power wireless power transfer (WPT) applications. To address the challenges of watt-level power handling, frequency-specific performance optimization, and high RF-to-dc conversion efficiency, two custom-fabricated GaN Schottky barrier diodes (SBDs) are codesigned with dedicated matching networks for their respective frequency bands. For low-frequency operation at 0.875 GHz, a quasi-vertical GaN-on-Si SBD is developed, achieving a high breakdown voltage of 145 V and a near-ideal ideality factor of 1.03, ensuring both watt-level robustness and high efficiency under low-power excitation, which is particularly critical for sub-GHz IoT scenarios. For high-frequency operation at 5.8 GHz, a GaN-on-SiC SBD with a Y-shaped anode features a breakdown voltage of 205 V and an ultralow junction capacitance of 0.19 pF, extending the cutoff frequency while maintaining excellent power stability. A compact band-optimized matching network incorporating short-circuited stubs enables efficient impedance transformation across both frequency bands. The proposed rectifier achieves a peak RF-to-dc efficiency exceeding 65% at input powers above 6.3 W across both bands. This work addresses the unmet need for rectifiers capable of watt-level RF-to-dc conversion using frequency-specific GaN SBDs. The key contribution lies in the device-circuit codesign of high-power GaN rectifiers, which has not been previously demonstrated.