Study On High Efficiency Gan Doherty Power Amplifier

RF power amplifier is one of the key components of the wireless transmitter system,who decides the performance and the energy consumption of a system.In order to improve the spectrum efficiency,the high PAPR modulation methods are widely used in modern wireless communication systems,they put forward higher requirements on the performance of the power amplifier.The study of enhancing the efficiency of power amplifier has been popular for a long time.Reasons are as follows: first,in the transmitting chain,the power amplifier consumes the most energy of the system,it will cause a huge waste of energy if the PA efficiency is low.Second,the low DC to RF conversion efficiency will result to a huge heat in the PA,thus increasing the thermal design cost of the system,and reduce the reliability of the system.Therefore,study the methods of efficiency improving technology is of great significance for the entire wireless communication system.Doherty power amplifiers are widely used in modern wireless communication system for its large dynamic range.This article mainly studied the GaN based Doherty amplifier and class F amplifier works at S-band.First studied the classical active load-pull characteristics of the DPA,analyzed the main influencing factors of the turn-on time of peaking power amplifier,and draw the “back–off efficiency space”(BOES)of the dual-input DPA accordingly.Secondly,studied the high efficiency class-F PA theory and design methods,designed a class-F amplifier working at 2.1GHz.Third,to further enhance the efficiency and extend the dynamic range of the DPA,an asymmetric dual-input class-F Doherty power amplifier was proposed in the article.By validation,the proposed class-F DPA can improve the efficiency and dynamic range of the DPA significantly.The PAs designed in this article were all fabricated and tested.The testing results were compared to the simulation results and the relating problems and conclusions were analyzed.The study in this article has important guiding significance for the following PA design.