Optimal Design Method And Application Of Doherty Power Amplifier With 3-port Network Based On Multi-objective Evolutionary Algorithm

Optimization algorithms and their use in the field of electronic information have emerged as one of the current research hotspots and development trends with the growth of computer and intelligent computing technologies.Among them,the multi-objective evolutionary algorithm has strong modeling ability and is convenient to solve complex engineering problems,and has been widely used in the field of actual engineering design.The Doherty power amplifier is a highefficiency power amplifier widely used in wireless communication network systems,and its performance has an important impact on the data transmission rate and energy efficiency of the system.The output combining network of the Doherty power amplifier is the core component that determines its working efficiency and output power,and its essence is a 3-port network.This thesis investigates the optimal design of the output network of Doherty power amplifier by using the 3-port network analysis method based on the multi-objective evolutionary algorithm,with the goal of streamlining the design process of the output combining network of Doherty power amplifier and improving overall performance.The following is a summary of this thesis’ s primary research content:1.A multi-objective evolutionary algorithm based on improved evolutionary operators and decomposition methods was studied to address the issue of insufficient algorithm diversity and low convergence speed caused by the use of basic genetic operators to randomly select parents to generate offspring in multi-objective evolutionary algorithms based on decomposition and apply the competitive evolution operator mechanism,iteratively update the population using the mixed decomposition approach to improve the overall performance of the algorithm,and apply it to the optimal design of the Doherty power amplifier output network.In order to verify the performance of the improved algorithm,the multi-objective test function is used to test,and the performance between the improved algorithm and the existing algorithm is compared and analyzed.It can be seen from the test results that the improved multi-objective evolutionary algorithm has good solution set distribution and faster convergence speed,which is more suitable for complex practical engineering problems.2.A general design approach of a 3-port output network suitable for Doherty power amplifiers is investigated in light of the issues of complex structure,laborious procedure,and relatively low performance in the design of traditional Doherty power amplifiers.First,the required S-parameters for the 3-port output network are calculated based on the power ratio and impedance conditions at saturated output and power back-off.Secondly,the topology structure of the output network is selected,the objective function is set according to the 3-port S parameters,and the output network is optimally designed by using the multi-objective evolutionary algorithm and calling the ADS simulation software.The proposed method can simplify the design process of Doherty power amplifier,which is beneficial to improve the efficiency and increase the power back-off range.In order to verify the proposed method,a Doherty power amplifier operating at 1.68 GHz frequency is designed and implemented.The test results show that the power back-off range of the amplifier reaches 10 d B back-off,and the corresponding efficiency is 60%.The method used meets the optimization design requirements of the Doherty power amplifier.3.An optimum approach of designing a Doherty output network with an irregular circuit topology is put forth in order to satisfy the design requirements of a wider bandwidth and high efficiency Doherty power amplifier.The method adopts the irregular circuit structure of curved and folded lines.First,the modeling simulation of the irregular circuit is carried out by using the multi-objective evolutionary algorithm and invoking HFSS simulation software.Secondly,the simulation data is output to the ADS simulation software through the application program structure for co-simulation and optimization of the 3-port network.In order to verify the design method,a high-efficiency Doherty power amplifier in the 1.2-2.8 GHz frequency band is designed and implemented using an irregular circuit structure as the output network.The test results show that the saturation output power of the designed amplifier is about 43.1-44.1d Bm,the saturation efficiency is about 50.1-73.4%,and the efficiency at 6d B power back-off is about 50.1-55.0%,which verifies the feasibility of designing the output network of the Doherty power amplifier using irregular structure combined with a multi-objective evolutionary algorithm and effectiveness.