基于GaN HEMT的高效率Doherty功率放大器设计  

Design of High Efficiency Doherty Power Amplifier Based on GaN HEMT

作　　者：张志维 程知群[1] 刘国华[1] ZHANG Zhi-wei;CHENG Zhi-qun;LIU Guo-hua(Key Laboratory of RF Circuit and System,Ministry of Education,Hangzhou Dianzi University,Hangzhou 310018,China)

机构地区：[1]杭州电子科技大学射频电路与系统教育部重点实验室,杭州310018

出　　处：《微波学报》2020年第2期28-31,共4页Journal of Microwaves

基　　金：国家自然科学基金(61871169);射频电路与系统教育部重点实验室开放基金(KFJJ201807)。

摘　　要：通过分析传统Doherty功放的负载调制网络存在的带宽限制和晶体管输出电容对于效率的影响问题。利用改善阻抗变换比和补偿载波功放晶体管的输出电容的方法提出一种新型负载调制网络,使用GaN HEMT晶体管并基于此网络设计完成了一款高效率的Doherty功率放大器。该Doherty功率放大器采用不等分结构设计。此外,采用阶跃式阻抗匹配方法设计主辅功放的输入输出匹配网络来拓展Doherty功放的工作带宽。测试结果显示,在2.8~3.2 GHz频段内,饱和输出功率达到45 dBm,饱和漏极效率65%~73.18%。功率回退6 dB时,漏极效率在45%~50%之间,功率回退9 dB时,漏极效率在38.94%~44.68%之间。This paper analyzes the bandwidth limitations of the traditional Doherty power amplifier’s load modulation network and the effect of transistor output capacitance on drain efficiency.A novel load modulation network is proposed by improving the impedance conversion ratio and compensating the output capacitance of the transistor.Based on this network,a high efficiency Doherty power amplifier is designed and fabricated.The Doherty power amplifier is designed in an unequal power structure.In addition,the step-impedance matching method is used to design the input and output matching network of the main and auxiliary amplifiers to expand the working bandwidth of the Doherty amplifier.The test results show that the saturated output power reaches 45 dBm and the saturated drain efficiency is 65%-73.18%in the 2.8-3.2 GHz band.When the power is backed off by 6 dB,the drain efficiency is between 45%-50%,and when the power is backed off by 9 dB,the drain efficiency is between 38.94%-44.68%.

关 键 词：高效率 GAN HEMT 新型负载调制网络 DOHERTY功率放大器 不等分结构 

分 类 号：TN722.75[电子电信—电路与系统]