Research On High Efficiency Power Amplifier Design Based On X-Parameter Model

With the development of a new generation of wireless communication systems,the market has put forward higher requirements for its core module,radio frequency power amplifier(RFPA).The PAs need to have the characteristics of high output power,high efficiency,and broad bandwidth at the same time.In order to improve the performance of PAs and simplify the design procedure,electronic design automation(EDA)tools have been widely used.The transistor models have built a bridge between EDA tools and PA design,and the accurate transistor models are the basis of highquality and high-efficiency design of PAs.X-parameters,as a behavioral model based on a black-box architecture,have higher prediction accuracy and modeling efficiency than traditional equivalent circuit models and physical-based models.Especially in the saturated nonlinear region of the device,the X-parameter model shows a strong prediction ability of the nonlinear characteristics.However,its application for PA circuit design is still insufficient.The purpose of this thesis is to study the design of various types of high-efficiency PAs based on X-parameter models,to establish a methodology for the application of behavioral models in different types of PA designs,and to verify the feasibility.First,the X-parameter model of a 10 W Gallium nitride(Ga N)high electron mobility transistor(HEMT)is extracted based on broadband load pull technique,and a multi-octave PA is designed and fabricated based on this model using a Chebyshev low-pass topology.The output power of the PA is maintained between 39.5 d Bm-42.4d Bm with a gain greater than 11 d B,and a drain efficiency higher than 60% from 0.7GHz to 2.3 GHz,and the drain efficiency reaches 73% around 2 GHz.Then,a narrow-band Doherty power amplifier(DPA)with an operating frequency in the range of 1.4 GHz-1.6 GHz is designed and fabricated based on the extracted Xparameter model,which lays the foundation for the design of continuous broadband DPA.An X-parameter model including package plane and current plane information,which suitable for continuous broadband DPA design is extracted,and a continuous broadband DPA based on post-matching technology is designed and measured.The saturation output power of the DPA is 44.3 d Bm in the range of 1.1 GHz-1.8 GHz,and the saturation drain efficiency exceeds 68%,while the 6 d B OBO efficiency exceeds51% and the gain is maintained greater than 9 d B.Finally,a load modulation balanced amplifier(LMBA)design procedure based on X-parameters is studied and proposed.By extracting the transistor model,control PA model and balanced PA model based on load-pull X-parameters,a detailed design procedure of LMBA based on X-parameters is given.The designed and fabricated LMBA achieves a saturated output power of 43.2 d Bm at 1.3 GHz-1.6 GHz with a drain efficiency of over 73% and a 9 d B-10 d B OBO efficiency of still over 52%.