| As the core component of the transmitter in the wireless communication system,the performance of the RF power amplifier directly affects the function of the whole system.The performance of power amplifier mainly includes two aspects of efficiency and linearity.The low cost of power amplifier is huge.When working,it needs to dissipate huge power and need larger heat sink and volume.Therefore,improving the efficiency of power amplifier is very important.On the other hand,the linearity of power amplifier is low,so useful signals will distort,weaken and spread spectrum during transmission,which will lead to the loss of signal quality.The improvement of efficiency and linearity of power amplifier has always been a hot spot of research by researchers,and its research has never been interrupted.Based on the Doherty framework,this paper studies the improvement of the efficiency and linearity of the RF power amplifier.The topic is of great practical value.First,based on the Doherty architecture,an efficient S band power amplifier is designed and designed.The efficiency of the power amplifier is 61.795%.By comparing with the AB power amplifier and the balanced power amplifier,the symmetrical Doherty power amplifier has the advantages of high efficiency.In order to improve the linearity,on the one hand,using asymmetric Doherty structure,by design and simulation,its linearity is better than that of symmetrical Doherty power amplifier.On the other hand,the analog predistorter is prepositioned in the symmetrical Doherty power amplifier circuit,and the three order intermodulation(IMD3)distortion is improved to 13.6dB.As well as the use of feedforward technology to improve the linearity of the symmetrical Doherty power amplifier,the improvement of the three order intermodulation(IMD3)distortion is 18.969 dB. |
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