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1、SelectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointselectionParagraaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesTSelectionParbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
2、agraphFoLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointse11111111111111111111111111111111lectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPoctionParagraphFormatLineSpaci2222222222222222222222ngLinesToPoints2SelectionParagraphFormatLineSp
3、acingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointselectionParagraphFccccccccccccccccccccccccccccccccccccccccccccccccccccccccormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPoctionParagraSelec SelectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFor
4、matLineSpacingLinesToPointselectionParagraaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesTSelectionParbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbagraphFoLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLi
5、nesToPointse11111111111111111111111111111111lectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPoctionParagraphFormatLineSpaci2222222222222222222222ngLinesToPoints2SelectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointsele
6、ctionParagraphFccccccccccccccccccccccccccccccccccccccccccccccccccccccccormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPoctionParagraSelec 基于 FPGA 的 DDS 正弦波信号源设计 内容摘要：频率合成技术在现代电子技术中具有重要的地位。在通信、雷达和导航等设备中， 它可以作为干扰信号发生器；在测试设备中，可作为标准信号源，因此频率合成器被人们称 为许多电子系统的“心脏”。直接数字频率合成（DDSDigital
7、 Direct Frequency Synthesis）技术是一种全新的频率合成方法，是频率合成技术的一次革命。本文主要分析了 DDS 的基本原理及其输出频谱特点，并采用 VHDL 语言在 FPGA 上实现。对于 DDS 的输出频谱， 一个较大的缺点是：输出杂散较大。针对这一缺点本文使用了两个方法加以解决。首先是压 缩 ROM 查找表，在相同 ROM 容量的情况下，压缩后相当于把 512 点查找表扩展为 2048 点，过 采样的引入提高了 DDS 输出谱的纯度。其次，采用了相位随机抖动技术，引入了 M 序列作为 DDS 采样输出的相位随机抖动，这个方法把原来的均匀查表抽样变成为伪随机非均匀抽样
8、，使 得 DDS 输出谱的杂散分量白化，同样使输出频谱纯度得到提高。本文最后用频谱分析仪做了 相关实验测试，在实验上验证了设计思想。 关键词：DDS FPGA VHDL M 序列 频谱 SelectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointselectionParagraaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaphFormatLineSpacingLinesToPointsSelectionParagrap
9、hFormatLineSpacingLinesTSelectionParbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbagraphFoLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointse11111111111111111111111111111111lectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPoctio
10、nParagraphFormatLineSpaci2222222222222222222222ngLinesToPoints2SelectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointselectionParagraphFccccccccccccccccccccccccccccccccccccccccccccccccccccccccormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLin
11、esToPoctionParagraSelec SelectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointselectionParagraaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesTSelectionParbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
12、bbbbbbbbbbbbbbbbbbbbbbbbagraphFoLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointse11111111111111111111111111111111lectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPoctionParagraphFormatLineSpaci2222222222222222222222ngLinesToPoints2Select
13、ionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointselectionParagraphFccccccccccccccccccccccccccccccccccccccccccccccccccccccccormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPoctionParagraSelec 1 TheThe realizationrealization ofof DDSDDS w
14、ithwith VHDLVHDL andand itsits highhigh purepure spectrumspectrum researchresearch Abstract；The frequency synthesis technology has the important status in the modern electronic technology. In equipment such as correspondence, radar and navigation, it may work as the unwanted signal generator; In the
15、 test facility, may work as the standard signal source, therefore the frequency synthesizer is called by the people as “the heart“ of many electronic systems .DDSDigital Direct Frequency Synthesis technology is one brand-new frequency synthetic method, is a frequency synthesis technology revolution.
16、 This paper analyzes the basic principle of DDS and its output frequency spectrum characteristic, and realizes it with VHDL language on FPGA. In regard to the output frequency spectrum of DDS, a shortcoming is: The output spurious is bigger. In view of this shortcoming this article uses two methods
17、to solve. First compress the ROM search table, in the same capacity of ROM, it is equal to expand 512 searches tables to 2,048 after the compression, the introduction of over sampling enhance the spectrum purity of DDS output. Then utilize the phase random dither technology, use the M sequence as th
18、e phase random dither of the DDS sampling output .this method causes evenly look up table sampling turn to for pseudo-random non- even sampling, it make the output spurious component of DDS change to white noise, similarly enhance purity of the output frequency spectrum to This article finally used
19、the spectrum analyzer to do the correlation experiment test, has confirmed the design thought at the experiment. SelectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointselectionParagraaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaphFormatLineSpacingLinesToPoi
20、ntsSelectionParagraphFormatLineSpacingLinesTSelectionParbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbagraphFoLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointse11111111111111111111111111111111lectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLine
21、SpacingLinesToPoctionParagraphFormatLineSpaci2222222222222222222222ngLinesToPoints2SelectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointselectionParagraphFccccccccccccccccccccccccccccccccccccccccccccccccccccccccormatLineSpacingLinesToPointsSelectionParagraph
22、FormatLineSpacingLinesToPoctionParagraSelec SelectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointselectionParagraaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesTSelectionParbbbbbbbbbbbbb
23、bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbagraphFoLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointse11111111111111111111111111111111lectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPoctionParagraphFormatLineSpaci2222222222222222222222ng
24、LinesToPoints2SelectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointselectionParagraphFccccccccccccccccccccccccccccccccccccccccccccccccccccccccormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPoctionParagraSelec 2 KeyKey wordswords: Digi
25、talDigital DirectDirect FrequencyFrequency SynthesisSynthesis FPGAFPGA VHDLVHDL M M sequencesequence SpectrumSpectrum SelectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointselectionParagraaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaphFormatLineSpacingLines
26、ToPointsSelectionParagraphFormatLineSpacingLinesTSelectionParbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbagraphFoLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointse11111111111111111111111111111111lectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphForma
27、tLineSpacingLinesToPoctionParagraphFormatLineSpaci2222222222222222222222ngLinesToPoints2SelectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointselectionParagraphFccccccccccccccccccccccccccccccccccccccccccccccccccccccccormatLineSpacingLinesToPointsSelectionPara
28、graphFormatLineSpacingLinesToPoctionParagraSelec SelectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointselectionParagraaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesTSelectionParbbbbbbbb
29、bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbagraphFoLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointse11111111111111111111111111111111lectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPoctionParagraphFormatLineSpaci2222222222222222222
30、222ngLinesToPoints2SelectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointselectionParagraphFccccccccccccccccccccccccccccccccccccccccccccccccccccccccormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPoctionParagraSelec 3 目 录 一、频率合成技术概述及 DD
31、S 性能特点 4 4 （一） 频率合成技术概述4 （二） DDS 特点 5 二、DDS 基本原理6 6 （一） 波形存储器基本原理6 （二） DDS 基本原理 6 （三） DDS 设计中的参数选择 8 （四） 小结8 三、DDS 的 VHDL 语言实现9 9 （一） EDA 技术与 VHDL 语言 .9 （二） DDS 的 FPGA 实现方法 10 （三） 开发平台.10 （四） 基本 DDS 的 VHDL 实现与仿真10 四、 提高输出频谱纯度的方法与实验验证 14 （一） DDS 的频谱纯度提高方法简述 .14 （二） 相位随机抖动原理与 VHDL 实现15 （三） 频谱纯度提高的实验验证
32、.20 五、程序下载及硬件调试 2020 （一） FPGA 的配置和下载 20 （二） 调试与程序固化.21 六、结束语 2121 SelectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointselectionParagraaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesTSel
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34、22222222222222222222ngLinesToPoints2SelectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointselectionParagraphFccccccccccccccccccccccccccccccccccccccccccccccccccccccccormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPoctionParagraSelec Sel
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36、aphFoLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointse11111111111111111111111111111111lectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPoctionParagraphFormatLineSpaci2222222222222222222222ngLinesToPoints2SelectionParagraphFormatLineSpaci
37、ngLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointselectionParagraphFccccccccccccccccccccccccccccccccccccccccccccccccccccccccormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPoctionParagraSelec 4 七、致谢 2222 参考文献 2222 附录 2323 （一） 各组成模块的 VHDL 程序 .23 SelectionParagraphF
38、ormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointselectionParagraaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesTSelectionParbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbagraphFoLineSpacing
39、LinesToPointsSelectionParagraphFormatLineSpacingLinesToPointse11111111111111111111111111111111lectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPoctionParagraphFormatLineSpaci2222222222222222222222ngLinesToPoints2SelectionParagraphFormatLineSpacingLinesToPointsS
40、electionParagraphFormatLineSpacingLinesToPointselectionParagraphFccccccccccccccccccccccccccccccccccccccccccccccccccccccccormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPoctionParagraSelec SelectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLines
41、ToPointselectionParagraaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesTSelectionParbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbagraphFoLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointse1111111
42、1111111111111111111111111lectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPoctionParagraphFormatLineSpaci2222222222222222222222ngLinesToPoints2SelectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointselectionParagraphFcccc
43、ccccccccccccccccccccccccccccccccccccccccccccccccccccormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPoctionParagraSelec 5 基于 FPGA 的 DDS 正弦波信号源设计 一、频率合成技术概述及 DDS 性能特点 （一）（一） 频率合成技术概述 频率合成是指由一个或多个频率稳定度和精确度很高的参考信号源通过频率域的线形运 算，产生具有同样稳定度和精确度的大量离散频率的过程。实现频率合成的电路叫频率合成 器，频率合成器是现代电子系统的
44、重要组成部分。它在很多领域都有很广泛的应用。如在通 信、雷达、导航、遥控摇测、电子对抗、以及现代化的仪器仪表的领域，都可以看到频率合 成器的身影，由于它应用领域的广泛，所以人们对它进行了深入的研究。到现在为止，已经 发展到了第三代频率合成技术。 随着电子技术的不断发展，对频率合成器的要求越来越高，频率合成器的主要性能指标 有： 1 输出频率范围 频率范围是指频率合成器输出最低频率和输出最高频率之间的变化范围，它包含中心频 率和带宽两个方面的含义。 2频率稳定度 频率稳定度是指在规定时间间隔内，频率合成器输出频率偏离标定值的数值，它分长期， 短期和瞬间稳定度三种。 3频率间隔 频率间隔是指两个输
45、出频率的最小间隔，也称频率分辨率。 4频率转换时间 频率转化时间是指输出由一个频率转换到另一个频率的时间。 SelectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointselectionParagraaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesTSelectionParbbb
46、bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbagraphFoLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointse11111111111111111111111111111111lectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPoctionParagraphFormatLineSpaci22222222222222
47、22222222ngLinesToPoints2SelectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointselectionParagraphFccccccccccccccccccccccccccccccccccccccccccccccccccccccccormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPoctionParagraSelec SelectionParagr
48、aphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointselectionParagraaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesTSelectionParbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbagraphFoLineSpa
49、cingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointse11111111111111111111111111111111lectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPoctionParagraphFormatLineSpaci2222222222222222222222ngLinesToPoints2SelectionParagraphFormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPointselectionParagraphFccccccccccccccccccccccccccccccccccccccccccccccccccccccccormatLineSpacingLinesToPointsSelectionParagraphFormatLineSpacingLinesToPoctionParagraSelec 6 5频率纯度 频率纯度以杂散分量和相位噪声来衡量。杂散又称寄生信号，分为谐波分量和非谐波分 量两种。主要由频率合成过程中的非线形失真产生