Function Design And Confirmation Of Power Amplifier Digital Pre-Distortion On The MATLAB

A RF power amplifier is an indispensable component in wireless communication for amplification of signal power.RF power amplifiers can improve the signal power,but cause memory nonlinear distortion simultaneously,Therefore,it is particularly critical to solve the memory nonlinear distortion of the amplifier.Digital predistortion has the advantages of being efficient and easy to implement,making it a common way to solve this problem.In this paper,SYSGEN platform is used to realize a digital predistortion system with simple structure and improved power amplifier distortion.The main contents include:First,study the characteristics of the PA and the main technology of DPD.Through the theoretical analysis and MATLAB simulation comparison of several learning structures,indirect learning structure is chosen.LMS algorithm which is simple and less costly to implement and calculate is selected by comparing three classical identification algorighm models.The memory polynomial model is selected after comparing several predistorter models.Under the consideration of resource cost and performance,the realization scheme of memory depth 3 and non-linear order 5 has been chosen.Second,build a digital predistortion system in the SYSGEN platform according to the selected model and parameters.The signal source,predistorter,amplifier model,quadrature modulation/demodulation,data buffer and predistortion algorithm modules are built.And by using the MCode module in SYSGEN,the.m file can be called directly to calculate the predistortion algorithm and return the tap weight vector,which greatly improves the efficiency of modeling.Thirdly,the overall function of the link is verified by the software radio platform independently developed by ourselves.Through the internal loopback of the FPGA,FMC board loopback,the power amplifier loopback to test the improvement effect of DPD.The output's ACLR of the power amplifier is lower than-45 d B which meets the require of 3GPP.The output ACLR of amplifier signal meets the requirements of 3GP which proves that the design of using SYSGEN is basically correct.