| The power amplifier（PA）,which occupies an important position in the wireless communication system,is now facing the technical requirements of wider frequency band,farther working frequency band and higher efficiency.In view of the needs of 5G communication,based on real frequency technology and phase periodicity theory,the thesis conducts researches on the design technology of broadband and dual-wideband Doherty power amplifiers（Doherty PA,DPA）.Firstly,The broadband matching of single transistor power amplifiers using realfrequency technology is studied.Secondly,due to the fact that only a few literatures of DPA designed with real-frequency technology can be obtained,it explores the difference between the real-frequency technology design of a DPA and a single transistor PA.Further studies also be conducted on the bandwidth expandation design of a DPA with realfrequency technology.Finally,the real-frequency technology combined with a new matching network structure proposed on the basis of phase periodicity theory is applied to design dual-frequency bands DPA and to study DPA’s bandwidth expansion.The specific works of the thesis are as follows:1.The design of broadband PA matching network based on real frequency technology is studied.three basic theoretical problems of mathematical characterization,network function optimization,and network synthesis of physically achievable matching networks are studied.The impacts of parameter changes on matching network structure,final optimization error and subsequent network synthesis are analyzed.As verification,the above studies are applied to design a wideband power amplifier operating at 2.1-5.1GHz.when the input power is 30 d Bm,the power-added efficiency is 60.1%～62.4%,and the gain is 9.2～10.38 d B.2.Research and design of wideband DPA based on real frequency technology.Focusing on the research of the instigation point impedance function of the matching network in the three states of the DPA,the joint design of the carrier and the peak power amplifier output matching network is realized,and the impedance matching in the three states is completed at the same time.In this way,the purpose of bandwidth expanding and efficiency improving in fallback area of the designed DPA can be achieved.The above studies are applied to design a wideband DPA.Its saturated drain efficiency is 55.5%～66%in 3.45-4.65 GHz,the saturated output power is 39.5～41.7 d Bm,the drain efficiency is36%～48% at 6.9-7.9 d B output power back-off,and the gain is 6.9～ 9.9 d B.3.A dual-wideband DPA based on phase periodicity theory is studied and designed.With analyzing of the DPA impedance change,a new matching network structure is proposed.As a result,the DPA with bandwidth expansion and dual-frequency function features can be designed and realized,and it is combined with the real-frequency technology.The test results show that the saturated output power is 40-41.8 d Bm in 2.35-3.35 GHz,the drain efficiency is 64%～70%,and the drain efficiency at 6 d B output power back-off is over than 40%.Saturated output power is 41～42.4 d Bm in the 4.2-4.9 GHz band,drain efficiency is 56%～66%,and 6 d B output power back-off efficiency is40%～48%.The simulation and test results show that the double wideband DPA has good performance. |
