This article presents an automatic system that is able to dynamically restore the output power capability of a power amplifier (PA) under variable loading scenarios. This is accomplished by dynamically adapting the supply voltage, VDD, of the PA according to the developed theoretical model. To dynamically vary VDD, a GaN dc-dc converter, based on the commercial EPC 9067 Demo Board, was used. The load is measured using an impedance meter, which is based on the slotted line principle and was specifically designed for low insertion loss. This impedance meter also generates a load-dependent pulsewidth modulated signal that controls the dc-dc converter switching, regulating VDD. The prototype was designed for 3.55 GHz and tested with CW and modulated signal excitations, being able to compensate the output power degradation under variable loading conditions inside a 2.1 voltage standing wave ratio circle. For a constant gain compression level, the average efficiency degradation over the tested range of impedances is less than 5%, and the average power improvement is 0.7 dB. The worst case measured output power of the PA is compensated from 37.0 to 39.9 dBm, which corresponds to a 2.9 dB improvement. Using a modulated signal excitation, the peak envelope power, which is compressed by almost 3 dB without VDD compensation, is restored, and the average output power is improved by 0.6 dB. The system can track the load and adjust VDD with a worst case step-up delay of 25 ms.

中文翻译：

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用于在可变负载情况下校正 PA 输出功率的动态电源电压控制


本文介绍了一种自动系统，能够在可变负载情况下动态恢复功率放大器 (PA) 的输出功率能力。这是通过根据开发的理论模型动态调整 PA 的电源电压 VDD 来实现的。为了动态改变 VDD，使用了基于商用 EPC 9067 演示板的 GaN DC-DC 转换器。使用阻抗计测量负载，该阻抗计基于槽线原理，专为低插入损耗而设计。该阻抗计还生成一个与负载相关的脉宽调制信号，用于控制 DC-DC 转换器开关，调节 VDD。该原型设计用于 3.55 GHz，并使用 CW 和调制信号激励进行测试，能够补偿 2.1 电压驻波比圆内可变负载条件下的输出功率下降。对于恒定增益压缩水平，在测试的阻抗范围内的平均效率下降小于 5%，平均功率改进为 0.7 dB。最坏情况下测得的 PA 输出功率从 37.0 dBm 补偿到 39.9 dBm，相当于提高了 2.9 dB。使用调制信号激励，可以恢复在没有 VDD 补偿的情况下压缩了近 3 dB 的峰值包络功率，并且平均输出功率提高了 0.6 dB。该系统可以跟踪负载并调整 VDD，最坏情况下的升压延迟为 25 ms。