Research Of Rf Power Amplifier Modeling And Digital Predistortion Based On Decomposition Vector Rotation Technology

In recent years,wireless communication rapid development requires more and more high transmission datarate,the bandwidth and peak-to-average ratio of signals as well as the array scale of signal chain are increasing continuely.So power amplifiers(PAs)are requested to be high efficiency and linearity in the complicated situation.In order to solve these problems,high-efficiency RF PA architectures such as Envelope Tracking(ET)technology and Doherty PA have been developed.Meanwhile,5G systems contain the Multi-input Multiple-output(MIMO)array of multiple PAs.However,Digital Predistortion(DPD)is one of the most promising linearization technologies of PA due to its high integration,good linearity and low cost.Based on the technology and theory of Decomposed Vector Rotation(DVR)model,the nonlinear characteristics of ET PA and the delay in MIMO transmitter scene have been reseached.Two modified DVR models were proposed for the modeling and DPD of the ET PA and multi-channel PA delay scenarios.Firstly,the nonlinear characteristics of the ET PA with distinct characteristic at different power levels were analyzed.The real value time-delay support vector regression(SVR)based model was applied to the modeling of ET PA operating frequency range from 1.6 GHz to 2.6 GHz.On this basis,combined with DVR technology,a modified SVR model for the ET PAs was proposed,which can achieve better accuracy than original SVR based model,and the influence of hyperparameters on the modeling performance of SVR model was discussed.The DPD with the proposed model of the ET PA was implemented.Almost 20 dB improvements in Normalized Mean Squared Error(NMSE)can be achieved by using the proposed model to DPD,and the Adjacent-Channel Power Ratio(ACPR)is also reduced from-30.2 dBc /-30 dBc to-49.7 dBc /-47.1 dBc,which meets the basic requirements of DPD that ACPRs should be less than-45 dBc.Secondly,the multi-channel time delay problem of Over-the-Air(OTA)feedback architecture in the MIMO system was researched.Two experimental platforms were set up to test different time delays in single amplifier and dual amplifiers respectively.A comparative study of different digital predistortion models was presented to compare the performance of three classic Volterra models with enhanced piecewise technique.An improved DVR model was proposed for multi-channel delay,which shows 1 dBc improvement on ACPRs and 1 dB improvement on NMSE after DPD compared to the original DVR model...