中文摘要：

基于可有效提高功放效率的Doherty理论,对两路非对称Doherty所存在的问题进行剖析,提出了一种嵌入内Doherty的三路Doherty（3-way Doherty）结构,并对该三路Doherty的工作状态和阻抗变换等基本理论作了细致描述与分析,最终结合多谐波双向牵引技术和双匹配技术,成功设计了一款平均输出功率为5 W的TD-LTE直放站三路Doherty功率放大器.中心频率2600MHz的仿真结果表明,平均输出功率处的三阶互调系数IMD3为-36dBc,增益Gp达10.6dB,功率附加效率PAE保持在56%左右,较普通AB类功放有近38%的提高,且在整个12dB回退范围内功率附加效率曲线相对平坦,符合现代功放高功率回退和高效率的设计要求,可以与数字预失真技术结合用于实际直放站中.

英文摘要：

Based on theory which can improve efficiency effectively of Doherty,this paper analyses the existing problems of 2-way asymmetric Doherty at first,then presents a novel 3-way Doherty structure that embeds a conventional Doherty inside.Theoretical analysis and detailed description of the working state as well as impendence transformation of the proposed Doherty are given.Finally,combining multi-harmonic bilateral pull technology and the dual match technology,a 3-way Doherty amplifier with 5W average power is designed for TD-LTE repeater application.The 2600 MHz simulation results of the 3-way Doherty yielded-36dBc 3rd-order intermediation（IMD3）,10.6 dB power gain（Gp）,with 56% power added efficiency（PAE） which is 38% higher than class B amplifier at average output power.Moreover,the curve among 12 dB back-off power is smooth relatively.On the one hand,this will answer the purpose of high power back and high efficiency.On the other hand,it lay the foundation for combination of the digital predistortion technique for repeater application.