FPGA-based Implementation Of Adaptive Filter

This article focus on the analysis of the key performance indicators such asconvergence rate, offset, tracking, robustness, computational requirements analysis,structural and numerical characteristics of two algorithms of the family ofadaptive-process algorithms-LMS algorithm and recursive least squares algorithmbased on the study of the adaptive filter principles. And elaborated on the specificimplementation measures for implementation and application of adaptive filtersaccording the example of WCDMA Repeater broadband digital predistortion poweramplifier technology engineering practice in order to provide a reference forengineering technicians who want to use the general theory of adaptive filtering inengineering practice.According to the requirements of WCDMA Repeater broadband amplifierpredistortion technology, this paper first introduces the characteristic curve of poweramplifier, and illustrates the effect generated by the power amplifier characteristics onthe signal. and Then established the mathematical model on the basis of analysis ofamplifier characteristic curve for further study of predistortion. Then introduceddigital predistortion algorithms, and discuss the performance of the RLS and theQR-RLS algorithm under the mathematical principle after a brief introduction todigital predistortion techniques, that aimed to provide a theoretical basis for theselecting of the training algorithm of coefficient. And based on creating amathematical model of the entire digital pre-distortion system, the paper built asimulation model of the pre-distortion system using Simulink. The simulation resultsof the model not only verify the validity of mathematical models and algorithms usedin this paper but also determine the fixed-point scheme of implement of the adaptivefilter in FPGA through the fixed-point simulation which lay the foundation of furthertransform the digital pre-distortion system into FPGA realization. Then mainlydescribed the logical design of digital predistortion system in this paper,and alsopresent the overall structure of WCDMA Repeater digital predistortion system on thebasis of analysis of the implementation methods of the DPD system and thenrecommend the overall implement framework of this system in FPGA after completing the simulation analysis. And then discussed each module of the FPGAdesign and highlights the design of DPD filter and coefficients training modules.Upon complete the implementation of the DPD adaptive filter in FPGA, this paperachieve the goal of the verification of the FPGA implement of this system on theplatform built in Matlab and Modelsim. As can be seen by the verification result, theDPD FPGA-based implementation of the adaptive filter function correctly reached therequired design specifications.