High-Efficiency Rectification Characteristics at 2.4 GHz With AlGaN/GaN GADs for Microwave WPT

We have demonstrated high-efficiency rectification characteristics of a diode using a AlGaN/GaN high-electron mobility transistor (HEMT) for microwave wireless power transfer (WPT). For diode operation of the device, the gate electrode and one of the ohmic electrodes of a normally off AlGaN/GaN HEMT were short-circuited, which was called as a gated-anode diode (GAD). The fabricated GAD showed a high current density of 390 mA/mm with a low turn-on voltage of$+$0.6 V and a high breakdown voltage over 75 V. The GAD exhibited a 2.4-GHz RF-to-DC conversion efficiency of 96% at an input power of 23 dBm, where the inputs were tuned up to third-order harmonic frequencies using an automated tuner. This result represents state-of-the-art efficiency performance in rectifiers at the 2.4-GHz band.