基于数字预失真的功率放大器线性化技术研究与实现

发布时间：2018-08-26 19:37

【摘要】：随着电子技术的飞速发展,通信系统在有限频段内的可用信道数量越来越多,频谱利用率越来越高,这是因为在实际应用中广泛采用了线性调制的方式。这些调制方式的最大特点是提高了传输效率和频谱利用率,但同时要求系统具备较好的线性度,否则调制信号会产生交调失真、频谱扩展和邻道干扰,从而影响信号传输和通信质量。一般情况下,影响射频系统线性度的主要元件是功率放大器,它对整个系统的作用是很重要的,所以对它的非线性进行改善是很有必要的。本文主要就功率放大器的线性化技术进行探讨,首先对数字无线通信系统中存在的非线性问题进行分析,概括了研究现状。然后对功率放大器的特性作了介绍,分析了它的非线性对电子通信系统的影响,接着介绍了功率放大器的几种常用模型和线性化的技术方案,重点介绍了数字预失真技术。介绍了功率放大器非线性特性的提取与建模的方法,提出了基于ADS仪器互连平台的功放测试系统及测试方法,利用实测数据建立功放行为模型。主要研究了基于查找表的无记忆功率放大器预失真技术,在Matlab环境下进行了仿真分析,仿真结果表明,极坐标查找表算法能够很好的改善放大器的非线性失真,有效的抑制带外频谱扩展,降低邻道干扰。构建了数字预失真方案验证平台,用于对数字预失真方法或算法进行快速验证。最后基于物理实验平台,做了单载波WCDMA信号的预失真实验,其预失真效果很好。
[Abstract]:With the rapid development of electronic technology, the number of available channels in the limited frequency band is increasing, and the spectrum efficiency is becoming higher and higher. This is due to the widespread use of linear modulation in practical applications. The most important feature of these modulation schemes is that the transmission efficiency and spectral efficiency are improved, but at the same time the system is required to have better linearity, otherwise the modulation signal will produce intermodulation distortion, spectrum spread and adjacent channel interference. Thus affecting the signal transmission and communication quality. In general, the main component affecting the linearity of RF system is the power amplifier, which is very important to the whole system, so it is necessary to improve its nonlinearity. In this paper, the linearization technology of power amplifier is discussed. Firstly, the nonlinear problems in digital wireless communication system are analyzed, and the research status is summarized. Then, the characteristics of power amplifier are introduced, and the influence of its nonlinearity on electronic communication system is analyzed. Then, several common models and linearized technical schemes of power amplifier are introduced, with emphasis on digital predistortion technology. This paper introduces the method of extracting and modeling the nonlinear characteristics of power amplifier, and puts forward the test system and test method of power amplifier based on ADS instrument interconnection platform. The model of power amplifier behavior is established by using the measured data. This paper mainly studies the memoryless power amplifier predistortion technology based on look-up table, and makes simulation analysis in Matlab environment. The simulation results show that the polar coordinate look-up table algorithm can improve the nonlinear distortion of amplifier very well. The outband spectrum spread is effectively suppressed and the adjacent channel interference is reduced. A digital predistortion scheme verification platform is constructed for fast verification of digital predistortion methods or algorithms. Finally, based on the physical experiment platform, the predistortion experiment of single carrier WCDMA signal is done, and the effect of predistortion is very good.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN722.75

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