【作者】 冷永清；

【导师】 曾云；

【作者基本信息】 湖南大学 ， 微纳器件与集成， 2013， 博士

【摘要】 全球无线通信技术的迅速发展增加了无线通信系统中收发机的市场需求，并对收发机的性能提出了更高的要求。在整个无线通信系统中，功率放大器作为发射机关键组件，其带宽、输出功率、效率和工作温度等性能将严重影响系统的整体功能。功率放大器中最主要、最关键的部分是功率晶体管。现在用于功率放大器的功率器件主要有硅-横向扩散金属氧化物半导体器件、砷化镓、磷化铟和碳化硅材料的器件等，由于受到材料本身物理特性的限制，不能满足应用的需求,发展新型材料的功率器件迫在眉睫。作为第三代半导体材料代表，宽禁带氮化镓（GaN）材料凭借其优异的电学和热学性能成为研究热点。宽禁带半导体GaN高电子迁移率晶体管（HEMT）器件具有高击穿电压、大电流密度、高功率密度、低噪声及良好的频率特性，在高效、高频、宽带、大功率无限通信系统中具有广泛的应用前景。GaN高电子迁移率晶体管物理特性及其在功率放大器中的应用是目前功率器件的前沿研究内容，具有重要的研究价值和实际意义。本论文即针对GaN高电子迁移率晶体管的特性及其在功率放大器中的应用进行研究。研究GaN HEMT器件的小信号模型，根据现有的器件和实验条件，提出了一种小信号等效电路模型，采用直接提取法提取小信号参数，给出了详细的参数提取流程，对比了模型仿真与实际测量的S参数，验证了模型的准确性。基于AgilentADS大信号非线性模型中的EEHEMT1模型，建立了GaN HEMT的大信号非线性模型，并对直流模型进行了改进，引入了膝点电压随栅源电压的变化特性，通过仿真和测量数据的对比，证明了模型的准确性和可用性。设计并实现了一种基于GaN HEMT器件的新型宽带平衡功率放大器，分别从宽带匹配、宽带耦合器、偏置电路和热设计等方面对GaN HEMT放大器进行了设计，并制作和测试了实物电路，使用输入/输出端的最优化匹配网络结构，获得高的效率和大的带宽，验证了设计的正确性。同时，针对GaN HEMT器件输入、输出端最佳阻抗特性，研究了分别使用于输入/输出端的最优化匹配网络的结构和设计方法，并给出了设计实例加以验证。研究晶体管输出电容对E类功率放大器性能的影响，证明了在微波频段，晶体管的输出电容会破坏零电流切换（ZCS）和零电流导数切换（ZCDS）条件，输出电容的增加会导致放大器效率和输出功率的下降，输出电容限制了E类功率放大器的工作频率。为了消除晶体管大输出电容对E类放大器工作频率的限制，提出了多频点电感补偿法，用以消除大输出电容的影响，进行了详细的理论推导。提出了两种多频点微带补偿电路结构，可有效地消除晶体管输出大电容对工作频率的限制，并进行了详细的理论分析和参数计算公式推导。通过对理想功率放大器的ADS仿真，验证了微带补偿电路理论分析的正确性。基于该电路结构设计并测试了一款并联电路E类功率放大器，优良的测试结果证明了该电路结构能有效地提高E类放大器工作频率，克服晶体管输出电容对工作频率的限制，显著地提高了放大器的综合性能。提出了一种具有有限扼流电感的逆E类功率放大器电路结构，进行了详细的理论分析和公式推导，并与其他类型E类功率放大器做了详细的性能对比。基于该电路结构设计并测试了一款逆E类功率放大器，谐波平衡仿真和实验测试结果证明了理论分析的正确性和拓扑结构的合理性。为了使有限扼流电感逆E类功率放大器更好在微波频段应用，提出了有限扼流电感逆E类功率放大器的传输线近似结构，并制作和测试了工作频率为3GHz的逆E类功率放大器实例，采用有效扼流电感的谐波抑制作用，利用和补偿管芯漏极电感和输出电容，有效提高了输出功率和效率，获得了良好的测试结果，证明了该电路技术可以广泛地应用于微波频段的高效率功率放大器设计。更多还原

【Abstract】 The rapid development of the global wireless communication technologiesincreases the market demand for transceiver of a wireless communication system andgives higher performance requirements of the transceiver. In the entire wirelesscommunication system, the power amplifier is the critical components of thetransmitter, whose performances, such as bandwidth, output power, efficiency andworking temperature, severely affect the overall fuction of the system. The powerdevice is the most important and critical part of the power amplfier, such as the deviceof silicon-lateral deffusion metal oxide semiconductor, GaAs, InP and SiC, etc. Due tothe physical charactristics limitations of the materials themselves, they can not meetthe needs of the application, and the development of new materials using for powerdevices is extremely urgent. As the behalf of the third generation of semiconductormaterial, GaN, which is a wide-bandgap semiconductor material, become a hotresearch topic due to its excellent electrical and thermal properties. The advantageouscharacteristics of GaN HEMT are well known and documented. These include highbreakdown voltage, high current carrying capability, high power density and highfrequency of operation. These attributes make GaN HEMT well suited for present andfuture wireless communication systems. It is a cutting-edge research that is thephysical characteristics of the high electron mobility transistor of GaN and itsapplication in the power amplfier. The research has important value and practicalsignificance. The dissertation focuses on the research on the characteristics of highelecton mobility transistor using GaN and its application in power amplifer.To study the small signal model of GaN HEMT. A small-signal equivalent circuitmodel is proposed, and a direct extraction method with detailed parameter extractionprocess is given to extract the small signal parameters. The accuracy of the model isverified by the comparison of the simulated and measured S-parameter. A large-signalnonlinear model, whose DC model is improved by considering the impact of thegate-source voltage on the knee voltage, is established for GaN HEMT based onEEHEMT1(the ADS large-signal nonlinear model). The accuracy and usability of thelarge-signal nonlinear model is proved by the comparison of the simulated andmeasured data.A design procedure and implementation for a broadband balanced PA has beenpresented from several aspects; wideband matching, broadband couplers, bias circuit and thermal design. A wideband balanced PA is fabricated based on GaN HEMTdevices. Measured results are in agreement with design expectations showing highefficiency and large bandwidth. The excellent results obtained verify the correctnessof the design method.The effects of a transistor output capacitance is analyzed for performance of aClass-E power amplifier. The output capacitance of the transistor is found to destroythe ZCS and ZCDS conditions of a Class-E power amplifier. The increase of theoutput capacitor will cause the decline of the amplifier efficiency and output power.And the maximum operation frequency of the Class-E PA is found to be affected bythe transistor’s output capacitance. In order to eliminate the limitation on themaximum operation frequency caused by the transistor’s output capacitor, amulti-frequency inductance-compensation method is proposed to eliminate the impactof large output capacitance. The theoretical derivation is carried out in detail, and thecorrectness of the theoretical analysis is proved by simulation results.Two transmission-line compensation circuits is developed, considering theapplication of the multi-frequency inductance-compensation technology in themicrowave band, to effectively eliminate the limitation on the opertation frequency ofthe transistor output capacitance. Analytical expressions are derived to determine thevalues of the required circuit elements in detail. The proposed circuit has beensimulated and the predicted behavior is substantiated by measurements results. Basedon the theory developed, a class-E PA has been designed, fabricated and measured.The agreement between simulation and measured data, taken together with ease offabrication demonstrates the validity and advantage of the proposed capacitivecompensation network. The restriction on operating frequency imposed by thetransistor’s increased output capacitance is eliminated, and the comprehensiveperformance of the power amplifier is significantly improved.An inverse Class-E power amplifier with finite D.C. feed inductance is propesedand analyzed. A set of design equations are derived in order to obtain the values of thecircuit components and evaluate the major performance parameters. As analyticalsolutions of the resultant circuit equations are cumbersome, the performance of theproposed inverse class-E PA is analyzed using numerical simulations, tables, andgraphs. The advantages of an inverse Class-E amplifier are compared with otherclass-E PA. The proposed PA has been simulated and the predicted behavior has beensubstantiated by measurements. The agreement between simulation and measured data,demonstrates the validity of the proposed PA. In order to make it better in the microwave band applications, a transmission-line topology is proposed of theinverse class-E power maplifier. A3-GHz inverse class-E power amplifier instancehas been designed, fabricated and measured. Due to the effective harmonicsuppression, the using and compensation of the transisitor drain inductor and outputcapacitor, the output power and efficiency are effectively improved. Excellentmeasured results prove that the circuit technology can be widely used in the design ofthe microwave-band high-efficiency power amplifier.更多还原