| The radio power amplifier aims to amplify the radio modulation signal,what is a necessary part of the radio-frequency unit in communication system.As a very important device,the quality of power amplifier can influences the performance of the whole communication system,meanwhile,it also decides the power dissipation of the system.So,the research of the efficiency of the power amplifier always is a hotspot in related fields.There are so many technique can enhance the efficiency of the power amplifier,but the Doherty power amplifier gets the good graces from researchers and engineers,because of a lot of advantages,such as its easy construction,adjustment and it need not digital command circuits.According to the basic theory of the Doherty power amplifier,this thesis designs and makes two different base station Doherty power amplifiers work in S-band.The thesis introduces the related acknowledge of power amplifier and the basic theory of Doherty power amplifier firstly.And then,the performance targets of the drive-stage,symmetrical and asymmetrical Doherty power amplifiers is set on the basis of the reality.Secondly,according to the performance targets,the drive-stage power amplifier is designed and tested by ADS simulate software.Then,designs and tests the power divider,the main power amplifier,the auxiliary power amplifier and combined these parts as a symmetrical power amplifier.After test,the symmetrical power amplifier gets 12 dB gain,the Power Added Efficiency(PAE)is about 40% at the max output power,and the PAE reaches 37% when the output power back-off is 5dB.Contrast with the performance targets,this power amplifier meets the design targets,and it gets outstand efficiency.Lastly,after concluded the problems during the design and the test of symmetrical power amplifier,the asymmetrical power amplifier is designed and tested.During this design,the problems that appeared in design symmetrical one is avoided.And complete the steps of processing and test.The test result shows that the gain over 13 dB,the PAE is 42% at the max output power,and the PAE reaches 35% when the output power back-off is 7dB.After test these two Doherty power amplifiers,contrast performance data,it is easy to found that test results is similar with theory analysis.It is got that asymmetrical power amplifier have some advantages in power back-off area. |
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