This article presents the frequency-locked high-power RF oscillator using a gallium nitride (GaN) high electron mobility transistor (HEMT) amplifier and phase-locked loop (PLL) for 2.4-GHz industrial, scientific, and medical (ISM) band applications. The proposed architecture exploits the GaN power amplifier in the positive-feedback loop, whereas the desired phase shift for the target oscillating frequency is regulated from the PLL. To the best of our knowledge, this work is the first to employ the frequency locking scheme for a high-power solid-state RF oscillator. A detailed analysis of the oscillation conditions and the efficiency is provided. The prototype circuit is implemented with hybrid phase shifters and a fractional- $N$ frequency synthesizer. The implemented RF oscillator circuit operates from 2.3 to 2.575 GHz and achieves a low phase noise of −131.8 dBc/Hz at a 1-MHz offset frequency. The power efficiency of the proposed oscillator reaches 58%, and the PLL incurs only 0.2% efficiency degradation.

中文翻译：

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具有43dBm输出功率和58％效率的锁频RF功率振荡器

本文介绍了使用氮化镓（GaN）高电子迁移率晶体管（HEMT）放大器和锁相环（PLL）的锁频大功率RF振荡器，适用于2.4 GHz工业，科学和医学（ISM）频段应用。所提出的架构在正反馈环路中利用了GaN功率放大器，而目标振荡频率的所需相移由PLL调节。据我们所知，这项工作是第一个将锁频方案用于大功率固态RF振荡器的工作。提供了对振荡条件和效率的详细分析。原型电路由混合移相器和小数分频器实现。 $ N $ 频率合成器。所实现的RF振荡器电路在2.3至2.575 GHz的频率范围内工作，并在1MHz的偏移频率下实现了-131.8 dBc / Hz的低相位噪声。所提出的振荡器的功率效率达到58％，而PLL仅导致0.2％的效率下降。