自适应前馈功放中控制系统的设计与实现

发布时间：2018-09-08 10:03

【摘要】：现代无线通信技术已经从只传输语音、文字发展到提供多媒体业务以及互联网接入服务,这对通信系统的传输速率提出了更高的要求。因此,为了增大数据吞吐量,提高频谱效率,现代的通信协议普遍采用复杂的非恒包络调制方式。然而这些调制信号的高峰均比会严重减低功放的效率,因此需要引入线性化技术对功放的线性度进行补偿。前馈功放有着工作频带宽,线性度好等优点,因此普遍使用于现代通信系统。然而前馈功放为开环系统,需要对环路的增益与相位进行精确的调节,以应对温度,器件老化等问题对系统性能的影响,因此需要自适应控制系统动态调节功放的参数。前馈功放的自适应控制方案有多种,每种方案都有各自的优缺点,因此需要设计者根据实际的应用环境与设计要求选择合适的控制方案,并根据实际的硬件调试自适应算法,以获得最优的线性化效果。本文主要讨论了宽带信号作为扩频信号的线性化方案的实现,研究成果基于前人的基础,并做了进一步的改进。本文第一章主要介绍了课题的研究背景以及研究的必要性。第二章主要介绍了射频功放的线性失真与非线性失真特性,并着重介绍了几种常见的非线性失真,并引入了多个指标衡量功放的非线性,如1dB压缩点、3阶截断点、邻信道功率比等。第三章简要介绍了几种常见的功放线性化技术,包括功率回退、反馈、前馈、预失真等,并分析了每种方法的优缺点。第四章介绍了自适应前馈功放系统的设计,包括直接检测以及诸如导频检测两种方案的具体实现方法。第五章介绍了前馈功放系统数字控制部分的设计与实现。第六章为实际系统的测试结果,并提出了未来改进的方向。
[Abstract]:Modern wireless communication technology has developed from only transmitting voice and text to providing multimedia services and Internet access services, which puts forward higher requirements for the transmission rate of communication systems. Therefore, in order to increase data throughput and improve spectral efficiency, complex non-constant envelope modulation is widely used in modern communication protocols. However, the peak to average ratio of these modulated signals will seriously reduce the efficiency of the power amplifier, so it is necessary to introduce linearization technology to compensate the linearity of the amplifier. Feedforward amplifier is widely used in modern communication systems because of its advantages of bandwidth and linearity. However, the feedforward power amplifier is an open-loop system, so it is necessary to adjust the gain and phase of the loop precisely to deal with the effects of temperature and device aging on the performance of the system, so it is necessary to adjust the parameters of the power amplifier dynamically by adaptive control system. There are many adaptive control schemes for feedforward power amplifier, and each scheme has its own advantages and disadvantages. Therefore, it is necessary for the designer to choose the appropriate control scheme according to the actual application environment and design requirements, and to adjust the adaptive algorithm according to the actual hardware. In order to obtain the optimal linearization effect. This paper mainly discusses the realization of the linearization scheme of wideband signal as spread spectrum signal. The research results are based on the previous research results and further improvements are made. The first chapter mainly introduces the research background and the necessity of the research. In the second chapter, the linear and nonlinear distortion characteristics of RF power amplifier are introduced, and several common nonlinear distortions are emphasized. Several indexes are introduced to measure the nonlinearity of the amplifier, such as the third order truncation point of 1dB compression point. Adjacent channel power ratio etc. In chapter 3, several common linearization techniques are briefly introduced, including power back, feedback, feedforward, predistortion and so on, and the advantages and disadvantages of each method are analyzed. Chapter 4 introduces the design of adaptive feedforward power amplifier system, including direct detection and pilot detection. The fifth chapter introduces the design and implementation of the digital control part of the feedforward power amplifier system. The sixth chapter is the test results of the actual system, and proposes the direction of improvement in the future.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN92;TP273

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