This article presents a design strategy to improve the bandwidth of the three-stage Doherty Power Amplifier (DPA) by controlling the phase difference between the dual RF inputs digitally. The theory also proposes multiple back-off reconfigurability without using tuning elements and extra circuitry. The proposed theory is validated by demonstration of a dual-input three-stage DPA which is designed and implemented using Wolfspeed’s GaN HEMT transistors. The measured results show a drain efficiency of 50.4 – 58% and 46.1 – 65.4% at 12 dB and 6 dB back-off respectively, over the frequency range of 550-900 MHz. Over this 350 MHz band, the drain efficiency is between 53.97% and 71.5% at saturation, corresponding to 48.3% fractional bandwidth. The measurement results also show that both the back-offs are reconfigurable by changing the drain bias of main and first auxiliary power amplifier. The modulated measurements are carried with a 10 MHz LTE signal with a PAPR of 11.75 dB. The high average efficiency of 51.6%, 54.9%, and 52.6% is reported at 600, 700, and 800 MHz, respectively, at an average power of around 30 dBm. The measurement results validate the theory proposed making the presented DPA as a potential candidate for future wireless transmitters.

中文翻译：

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具有后退可重配置功能的双输入数字控制宽带三级Doherty功率放大器

本文提出了一种设计策略，通过数字控制双RF输入之间的相位差来改善三级Doherty功率放大器（DPA）的带宽。该理论还提出了多种退避可重配置性，而无需使用调谐元件和额外的电路。通过使用Wolfspeed的GaN HEMT晶体管设计和实现的双输入三级DPA的演示，验证了所提出的理论。测量结果表明，在550-900 MHz的频率范围内，在12 dB和6 dB补偿下，漏极效率分别为50.4 – 58％和46.1 – 65.4％。在此350 MHz频带上，饱和时的漏极效率在53.97％至71.5％之间，对应于48.3％的分数带宽。测量结果还表明，可以通过改变主功率放大器和第一辅助功率放大器的漏极偏置来重新配置两个补偿。调制后的测量结果是通过具有11.75 dB的PAPR的10 MHz LTE信号进行的。据报道，分别在600 MHz，700 MHz和800 MHz时，平均功率为30 dBm时，平均效率高达51.6％，54.9％和52.6％。测量结果验证了提出的理论，使提出的DPA成为未来无线发射机的潜在候选者。