This article presents a generalized theory and new design methodology for reverse-load-modulated dual-branch (RMDB) power amplifiers (PAs), which uses a current-biased transistor in the main branch to realize optimal load modulation without using the impedance transformers at the output of the PAs. Consequently, this topology offers a proper load modulation mechanism over a wider frequency bandwidth. Besides, smaller output matching network (OMN) footprint and lower loss are suitable features for monolithic microwave integrated circuit (MMIC) designs. The proposed theory can be applied for symmetrical and asymmetrical designs to realize different output power back-off (OPBO) ranges. The theory and design methodology were used to design the first MMIC RMDB PA. The broad bandwidth of this design (2.6–3.8 GHz) allows it to cover multiple bands in 4th-generation (4G) Long Term Evolution (LTE) and 5th-generation (5G) New Radio (NR) standards. Under continuous wave (CW) excitation, the experimental results show a drain efficiency (DE) higher than 58% at peak output power (POP) and 37% at 9 dB OPBO, over the whole frequency band.

中文翻译：

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应用于 4G/5G 宽带 GaN MMIC PA 设计的反向调制双分支功率放大器的理论和设计方法

本文介绍了反向负载调制双分支 (RMDB) 功率放大器 (PA) 的广义理论和新设计方法，它在主分支中使用电流偏置晶体管来实现最佳负载调制，而无需使用阻抗变压器PA 的输出。因此，这种拓扑在更宽的频率带宽上提供了适当的负载调制机制。此外，较小的输出匹配网络 (OMN) 占位面积和较低的损耗是单片微波集成电路 (MMIC) 设计的合适特性。所提出的理论可应用于对称和非对称设计，以实现不同的输出功率回退 (OPBO) 范围。该理论和设计方法被用于设计第一个 MMIC RMDB PA。此设计的宽带宽 (2.6–3. 8 GHz) 使其能够覆盖第 4 代 (4G) 长期演进 (LTE) 和第 5 代 (5G) 新无线电 (NR) 标准中的多个频段。在连续波 (CW) 激励下，实验结果表明，在整个频带上，峰值输出功率 (POP) 下的漏极效率 (DE) 高于 58%，而 9 dB OPBO 下的漏极效率 (DE) 高于 37%。