Theory And Design Research Of Broadband Class EF Doherty Power Amplifier

The development of mobile communication systems has placed increasing demands on the performance of power amplifier(PA).This thesis finds that the following deficiencies existed in Class EF PA:(1)the study of waveforms for Class EF PA is not comprehensive,and there is a lack of theoretical analysis and design methods for Class EF PA from the waveform perspective;(2)the existing design methods of Class EF PA have certain limitations,which make the design of Class EF PA difficult due to the impedance conditions;(3)the existing design methods of Class EF PA make it difficult to achieve broadband design,and there is also a lack of research on the theory and design methods related to "continuous EF PAs".In addition,no research has been found on the design of continuous Class EF PA for broadband applications in Doherty PA(DPA).The work in this thesis addresses the above issues.Firstly,the operating principle and impedance conditions of Class EF PA are analysed,and the drain waveform equation expressions are derived;secondly,the problem that the traditional factorial factor is not applicable to the broadband design of Class EF PA is studied,and the corresponding modified factorial factor is proposed to realize the continuous Class EF PA combining the continuity theory with Class EF PA,which solves the theoretical problem of broadband design of Class EF PA;finally,a new structure of DPA using continuous Class EF PA as carrier PA is proposed,and the broadband design of continuous Class EF PA applied to DPA is studied.The specific work of this thesis is as follows.1.Completion of the waveform theory study for Class EF PA.By analysing the switching operation mode of Class E PA and the harmonic tuning technique of Class F PA,the drain waveform equation expressions of Class EF PA are derived.A new idea is proposed to simplify the design process of Class EF PA based on odd harmonic impedance in the form of pure reactance.In order to verify the validity of the waveform theory,the Class EF PA operating at 2.9-3.03 GHz is designed with the power-added efficiency(PAE)of 67.8%～72.4% and the drain efficiency(DE)of 69.3%～75%.2.Completion of theoretical analysis and design study of continuous Class EF PA.By combining the continuum theory with the novel waveform theory for Class EF PA,a new factorial factor applicable to Class EF PA is derived by studying the limitations of the traditional factorial factor.A new research idea is provided for the design of broadband Class EF PA.The measurements of continuous Class EF PA show the DE is69.5%～76.2% in the frequency range of 2.4-3.8 GHz.3.The new structure and design method of broadband DPA is studied,and a new structure of broadband DPA based on continuous Class EF PA as carrier branch is proposed and completed.By adopting the post-matching structure to achieve impedance transformation,this research completes the theory and design methodology of broadband design for DPA.The test results of the example design for DPA following this method show that the DE is 69.8%～76.3% at saturation and 39.5%～48.2% at 6 d B setback in the frequency range of 2.5-3.8 GHz.