VHF频段模拟预失真器的设计

发布时间：2018-06-21 02:41

本文选题：非线性 + 三阶互调系数　；参考：《华中科技大学》2015年硕士论文

【摘要】：随着世界的飞速发展,无线通讯业务全面普及,使得无线通讯系统的要求越来越高。功率放大器是其中很重要的部分,它的性能会影响到整个系统的性能。当功率放大器的输出功率大到一定程度的时候,将会产生明显的非线性失真,非线性失真会限制功率放大器的工作性能,从而影响整个系统的性能,所以改善非线性失真对提高功率放大器性能和系统整体性能有重要意义。论文分析了功率放大器非线性特性产生的原因,简单介绍了放大器非线性特性的衡量指标,研究对比了常见的线性化技术。在此基础上提出了模拟预失真器的整体技术指标,对各种实现方案进行了详细对比,提出了采用双环模拟预失真结构的设计方案。其中第一个环路提取预失真信号,第二个环路用于预失真信号相位和幅度的调节。基于双环模拟预失真结构,对频段在279.3 MHz~289.5MHz的模拟预失真器进行了设计,并对其中的关键器件进行了详细的设计与仿真。在上述设计基础上制作了一款模拟预失真器,对其各个器件性能进行了测试,测试结果表明各个器件性能均能达到预期要求。同时针对VHF频段的功率放大器,进行了单环测试、双环测试和功率放大器与模拟预失真器的级联测试,结果显示,功放的非线性指标得到了明显改善,其中三阶互调系数(IMD3)改善了10d B以上。
[Abstract]:With the rapid development of the world, wireless communication services are widely used, which makes the requirement of wireless communication system more and more high. Power amplifier is an important part of it, its performance will affect the performance of the whole system. When the output power of the power amplifier reaches a certain degree, there will be obvious nonlinear distortion, which will limit the performance of the power amplifier and affect the performance of the whole system. Therefore, improving nonlinear distortion is very important to improve the performance of power amplifier and system as a whole. In this paper, the causes of nonlinear characteristics of power amplifiers are analyzed, the measurement indexes of nonlinear characteristics of power amplifiers are introduced, and the common linearization techniques are studied and compared. On this basis, the overall technical specifications of analogue predistorter are put forward, and various realization schemes are compared in detail, and a design scheme using double loop analog predistortion structure is proposed. The first loop extracts the predistortion signal and the second loop is used to adjust the phase and amplitude of the predistortion signal. Based on the double loop analogue predistortion structure, the analog predistorter with frequency band of 279.3 MHz / 289.5 MHz is designed, and the key devices are designed and simulated in detail. On the basis of the above design, an analogue predistorter is fabricated, and the performance of each device is tested. The test results show that the performance of each device can meet the expected requirements. At the same time, single loop test, double loop test and cascade test of power amplifier and analogue predistortor are carried out for VHF power amplifier. The results show that the nonlinear index of power amplifier is improved obviously. The third order Intermodulation coefficient (IMD 3) was improved over 10 dB.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN722.75

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