Radio frequency (RF) power amplifiers are an integral part of many academic, medical, and industrial applications. For many of these applications, the RF power needs to quickly transition from one level to another. For switched-mode amplifiers, one way to achieve this is with an out-phasing modulation technique. This power control technique, however, presents its own disadvantages, including poor light-load efficiency and an increase in overall system size. In this paper, we present an alternative power modulation method to create a high-efficiency high-speed RF amplifier system. This control technique utilizes two mechanisms, modular on/off and phase-shifting. In modular on/off, a different number of sub-circuits are turned “on” or “off” to crudely adjust the output power. In phase-shifting, the smallest sub-circuit of the whole system is phase-shifted away from the rest of the circuit to fine-tune the output power. This system's performance is first compared with existing out-phasing systems via circuit simulation. Then, an actual circuit implementation with a 13.56-MHz, 1500-W RF amplifier is demonstrated. A 93% dc-to-RF efficiency is achieved at full load, and above 80% efficiency is maintained all the way down to 7% load.

中文翻译：

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用于高速射频功率调制的模块化ON / OFF和相移

射频（RF）功率放大器是许多学术，医学和工业应用中不可或缺的一部分。对于许多此类应用，RF功率需要快速从一个电平过渡到另一个电平。对于开关模式放大器，一种实现方法是采用异相调制技术。然而，这种功率控制技术具有其自身的缺点，包括较差的轻载效率和整个系统尺寸的增加。在本文中，我们提出了一种替代性的功率调制方法，以创建一个高效的高速RF放大器系统。该控制技术利用两种机制，模块化开/关和相移。在模块化开/关中，不同数量的子电路被“接通”或“关断”以粗略地调节输出功率。在相移中 整个系统中最小的子电路与电路的其余部分相移，以微调输出功率。首先通过电路仿真将该系统的性能与现有的异相系统进行比较。然后，演示了使用13.56MHz，1500W RF放大器的实际电路实现。满载时，DC-RF效率达到93％，一直到7％的负载，始终保持80％以上的效率。