Design of a 5.8 GHz GaN HEMT Class-F Rectifier Using Voltage Doubler

In this study, the design and measurement results of a 5.8 GHz GaN HEMT Class-F rectifier using a voltage doubler were proposed. The proposed rectifier employed a voltage doubler for high-output dc voltage characteristics and applied the technique of opening the third-harmonic impedance to an input-matching network to obtain high-efficiency characteristics. A GaN HEMT bare chip with a high breakdown voltage and wide bandgap was used as a diode, which enabled stable operation at a high input power. Four methods of electrically connecting a bare chip to a PCB were proposed, and fabrication and measurements were conducted to verify the optimal electrical connection method. At 5.8 GHz, with an input RF power of 32 dBm and load resistance of 1,000 Ω, the fabricated rectifier exhibited RF-dc conversion efficiency of over 55 % in all methods. Maximum efficiency of 69 % was obtained in a circuit in which the cathodes of series and parallel diodes were connected to the PCB with bond-wires, and the anode of the parallel diode was connected to the PCB with through-wafer via.