| Radio frequency power amplifier(PA)is one of the most important modules in transmitting system.It has been widely used in radar,satellite navigation,and electronic countermeasure systems.With the improvement of wireless communication technology,the fifth generation communication technology(5G)is coming soon,which has higher requirements for power amplifiers in communication systems.As a large power consumption element,the amplifier will not only cause waste of resources,but also increase the cost of equipment operation and maintenance due to heat dissipation.Therefore,it is a key problem in RF field to realize high efficiency power amplifier under the environment of signal peak to average ratio(PAPR).In the main technologies of improving efficiency,the power amplifier of Doherty is favored by the production operators because the structure is simple and it can be maintained efficiently at a certain power return.This thesis focuses on the simulation and realization of Doherty structure power amplifier.Firstly,the thesis introduces the current research situation of power amplifier and the key technical index of power amplifier,and analyzes the basic theory of Doherty structure amplifier.Then,the index allocation is given and the design work of each amplifier of Doherty structure is completed with the simulation software ADS,and the feasibility of the design is verified by the layout simulation.Finally,based on the simulation results and testing platform,the power amplifier that meets the requirements is obtained.Its gain is 52 dB,the average output power(43dBm)is 32.7%,1 dB compression point is 53.6dBm,3 dB compression point is 54.7dBm,and the ACPR is-32dBc.All the above indexes meet the design requirements while retaining a certain margin.In this thesis,the actual engineering factors are also taken into account in the simulation design.Aiming at the selection of the power amplifier circuit,the standard for selecting the amplifier tube,matching capacitance and dielectric substrate is described.On the basis of the test platform,the debugging scheme of the final Doherty structure amplifier was elaborated,and the direction and purpose of the debugging were clarified.According to the difference between simulation results and physical test,the consistency analysis of power amplifier is made,which points out the optimization scheme and accumulates valuable experience for the future research of power amplifier. |
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