Design of a High-Power and High-Efficiency GaN-HEMT VCO Based on an Inverse Class-F Amplifier

TL;DR

This paper presents a novel GaN-HEMT VCO design utilizing an inverse class-F amplifier and a coupled-line coupler, achieving high power and efficiency suitable for wireless power transmission.

Contribution

It introduces a high-power, high-efficiency GaN-HEMT VCO with a novel frequency-tunable resonator and precise feedback control, advancing microwave source technology.

Findings

Achieved 74.5% efficiency at 2.44 GHz

Output power of 40.2 dBm at 2.44 GHz

Operates effectively in the 2.41-2.45 GHz range

Abstract

This letter proposes a high-power and high-efficiency GaN-HEMT voltage-controlled oscillator. The VCO consists of a coupled-line coupler, an inverse class-F amplifier, and a novel frequency-tunable stepped-impedance resonator. Using a harmonic control circuit and a parasitic parameter compensation circuit, the power amplifier operates in the inverse class-F state to achieve high efficiency. The feedback circuit uses a coupled-line coupler instead of the traditional coupling capacitor to control feedback power precisely. The measurement results show that the VCO with an oscillation frequency of 2.41-2.45 GHz achieves a maximum conversion efficiency of 74.5% at 2.44 GHz and an output power of 40.2 dBm. It is a candidate for the microwave source in a wireless power transmission system.