Modern wireless communication systems with large bandwidth and high peak-to-average power ratios (PAPRs) have been and will continue to be in high demand. This puts a strain on the transmitter, which has to operate with its average power in the output back-off (OBO) region. The Doherty power amplifier (Doherty PA) was invented in 1936 as an alternative to the highly inefficient linear amplifiers used in radio transmitters. The Doherty PA has recently undergone a renaissance, becoming the PA architecture of choice for mobile radio base stations. The additional efficiency peak at the OBO point makes it ideal for high PAPR signals. However, the main drawback of conventional Doherty PAs is its narrow bandwidth, which significantly limits its applicability. Recently, broadband Doherty PAs have been realized using a technique called "post-matching" and have attracted much attention. In this paper, the operating principles of conventional and broadband Doherty PAs are reviewed, followed by an analysis of recently reported prototypes, current technical challenges, and application in 5G wireless communication systems. As a comparison, process technologies for the implementation of Doherty PAs are also surveyed.

中文翻译：

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宽带高效 Doherty 功率放大器

具有大带宽和高峰均功率比 (PAPR) 的现代无线通信系统已经并将继续受到高需求。这给发射器带来了压力，发射器必须在输出回退 (OBO) 区域以其平均功率运行。Doherty 功率放大器 (Doherty PA) 于 1936 年发明，作为无线电发射机中使用的效率极低的线性放大器的替代品。Doherty PA 最近经历了复兴，成为移动无线电基站的首选 PA 架构。OBO 点处的额外效率峰值使其成为高 PAPR 信号的理想选择。然而，传统 Doherty PA 的主要缺点是其带宽窄，这极大地限制了其适用性。最近，宽带 Doherty PA 已经使用一种称为“