This article proposes a new and compact symmetrical Doherty power amplifier (DPA) configuration that provides extended output-back-off (OBO) and enhanced load modulation. The concept of active harmonic control (AHC) is introduced to remedy the reduced-conduction-angle operation of the class-C auxiliary device, providing enhanced auxiliary current and power capability. Semianalytical study based on generalized load-modulation theory and large-signal simulation reveal that an optimal AHC can offer increased peak current ratio, improved load modulation, boosted output power, and power utilization factor (PUF). Besides, a new output combiner, with the inclusion of parasitic effect, is devised for ultracompactness and simplicity. For verification, a 11-dB-OBO 2-GHz symmetrical DPA based on GaN HEMT transistors is designed, fabricated, and measured. Excellent performance with drain efficiency of 74% (52%) is obtained at saturation (back-off of 11 dB). Moreover, a saturation power of 42.98 dBm is achieved, corresponding to an uplifted PUF of 1.25 (compared with conventional symmetrical DPA design). Under 20-MHz modulated signal (peak-to-average power ratio of 11 dB) excitation, the prototype exhibits average efficiency of 53.2% at an average output power of 32 dBm. The adjacent channel leakage power ratio (ACLR) is found to be -27.5 and -50.9 dBc before and after digital predistortion, respectively.

中文翻译：

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使用有源谐波控制的峰值电流比增强型紧凑型对称 Doherty 放大器设计


本文提出了一种新型紧凑型对称 Doherty 功率放大器 (DPA) 配置，可提供扩展的输出回退 (OBO) 和增强的负载调制。引入有源谐波控制（AHC）概念来纠正C类辅助设备导通角减小的问题，提供增强的辅助电流和功率能力。基于广义负载调制理论和大信号仿真的半解析研究表明，最佳 AHC 可以提高峰值电流比、改进负载调制、提高输出功率和功率利用率 (PUF)。此外，还设计了一种包含寄生效应的新型输出组合器，以实现超紧凑和简单性。为了进行验证，设计、制造和测量了基于 GaN HEMT 晶体管的 11dB-OBO 2GHz 对称 DPA。在饱和状态下（回退 11 dB），漏极效率达到 74% (52%)，具有出色的性能。此外，还实现了 42.98 dBm 的饱和功率，对应于 1.25 的 PUF 提升（与传统对称 DPA 设计相比）。在 20 MHz 调制信号（峰均功率比为 11 dB）激励下，原型在平均输出功率为 32 dBm 时表现出 53.2% 的平均效率。数字预失真前后的邻道泄漏功率比（ACLR）分别为-27.5 和-50.9 dBc。