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1、摘 要 I论文题目：论文题目：基于 DDS 的任意波形发生器研究 专专 业：业：控制理论与控制工程 研研 究究 生：生：王应丽 指导教师：指导教师：林青松 摘 要摘 要 目前，基于直接数字频率合成 (Direct Digital Frequency Synthesis 简称 DDS) 技术的任意波形发生器在设计上多采用 FPGA 结合微处理器芯片的形式。DDS部分功能由 FPGA 来实现，微处理器芯片用于完成控制功能，这种结构电路复杂，开发周期长，系统的软硬件升级也存在困难。可编程片上系统（SOPC）设计是一个崭新的、富有生机的嵌入式系统设计方向，嵌入式集成化设计正成为电子领域发展的一个重要方
2、向。本文利用 SOPC 技术研究在单片 FPGA 上实现任意波形发生器的可行性。 论文以 Altera 公司的 EP1C12 芯片为 SOPC 系统的载体，把任意波形发生器的 DDS 模块和软核处理器 Nios II 集成到单片 FPGA 芯片内部，设计了能够输出正弦波、方波、锯齿波、任意波、及扫频等波形的任意波形发生器。文中对DDS 最致命的缺点（输出频谱杂散大）进行了研究和分析，重点探讨了 DDS 的相位截断误差，采用了一种新的相位加扰技术来改善波形的输出杂散；同时，针对目前的任意波形发生器还不具备过零切换功能这一问题，提出了 DDS 的结构改进思路：采用两套双端口 RAM 结构，使其在波
3、形切换时实现过零切换，以保证波形的平滑输出。 文中首先探讨了 DDS 的工作原理，根据信号分析理论分析了 DDS 的输出频谱，并在 MATLAB 中对 DDS 的频谱杂散和采用随机序列来改善杂散后的输出频谱进行了仿真；然后在对任意波形发生器进行需求分析的基础上，确定了任意波形发生器的总体方案，阐述了任意波形发生器硬件电路板的设计与制作；接着，给出了 Nios II 处理器的构建与系统各部分在 FPGA 上的硬件描述语言（Verilog HDL）实现，完成了上下位机的软件设计和编写（上位机的基于LabVIEW 的人机界面以及下位机的基于软处理器核 Nios II 的波形产生软件）；最后，对实验结
4、果进行了分析，并提出了改进意见。 试验结果表明：所设计的基于 DDS 的任意波形发生器能够实现规则波和任意波形的输出，波形性能达到了设计要求；系统实现了过零切换功能，可以用在河南科技大学硕士学位论文 II要求波形连续平滑输出的特殊场合，解决了目前的任意波形发生器所存在的这一问题；采用 SOPC 技术在单片 FPGA 上实现任意波形发生器是可行的，可大大减化系统电路，具有集成度高、稳定性好和扩展性强等优点。 关关 键键 词：词：任意波形发生器，现场可编程门阵列，SOPC，直接数字频率合成，虚拟仪器 论文类型：论文类型：应用研究 摘 要 IIISubject: Research of Arbitr
5、ary Waveform Generator Based on DDS Specialty: Control Theory and Control Engineering Name: Wang Yingli Supervisor: Lin Qingsong ABSTRACT At the present time, the structure of FPGA(Field Programmable Gate Array) combined with microprocessor chip was frequently adopted in the design of the AWG(Arbitr
6、ary Waveform Generator) based on DDS(Direct Digital Frequency Synthesis). DDS module was realized in FPGA and the control function was finished by microprocessor. That structure has such defects as complicated hardware circuit, long developing period and difficult upgrade in both software and hardwa
7、re. The design of SOPC(System on a Programmable Chip) is a piece of new and vital research field for embedded system. At the same time, embedded and integrated design is becoming an important developmental orientation in electron field. This paper intended to study the feasibility of realizing Arbit
8、rary Waveform Generator in single FPGA chip by adopting SOPC technique. In this paper, the EP1C12 chip produced by Altera Ltd. was used as carrier of SOPC, the DDS module and Nios II processor was integrated into single FPGA chip, the finished Arbitrary Waveform Generator can output sine waveform, s
9、quare waveform, saw tooth waveform, arbitrary waveform and frequency sweep waveform. Also, the fatal defect of DDS (high spur of outputting spectrum) was studied and analyzed, the error caused by phase truncation was discussed and a new method that adding disturbance to phase was introduced to impro
10、ve the spur; simultaneously, aimed at the problem that present AWG has no function of switching signal at zero phase, a new way of DDS structure was put forwarded: two set of dual port RAM was designed, which was switched when the data of waveform table changed so as to guarantee the outputting wave
11、form is smooth. Firstly, the DDS working theory was discussed, the outputting spectrum of DDS was analyzed based on signal analytical theory, the simulation of spectrums spur of DDS and outputting spectrum after spur was improved by introducing random sequence was finished in MATLAB; secondly, the g
12、eneral design scheme of AWG was given on the base of making requirement analysis and the hardware circuit boards 河南科技大学硕士学位论文 IVdesign and manufacture was elaborate; then, the build of Nios II processor and the realization of all sections on FPGA in Verilog HDL was formulated, the softwares design a
13、nd programming of upper machine and down machine was finished; finally, the experimental results was analyzed and the concerned improving advice was given. The experimental result indicated that, the designed AWG based on DDS realized the output of regular waveform and arbitrary waveform, which met
14、the designed requirement. The system equipped with the function of switching waveform at zero phase, that make it can be used in some special occasion that need continue and smooth output waveform. The adoption of SOPC in the design of AWG is feasible, which enormously simplified the systems circuit
15、, made the system many merits like high integrated degree, fine stability, strong expansibility and so on. KEY WORDS：Arbitrary Waveform Generator, Field Programmable Gate Array, System on a Programmable Chip, Direct Digital Frequency Synthesis, Virtual Instrument Dissertation Type: Application Study 第 1 章 绪论 1第1章 绪论 第1章 绪论 1.1 国内外任意波形发生器的技术发展状况国内外任意波形发生器的技术发展状况 现代科学技术的飞速发展对信号源提出了越来越高的要求，主要表现在高分辨率，高输出频率，偶发信号波形等方面，例如雷达信号仿真测试，普通的波形发生器已经不能满足其需求，需要用到任意波形发生器。作为一种特殊信号源的任意波形发生器，其综合具有其它信号源波形生成能力，原理上可仿真任意波形，只要数字示波器或其它记录仪捕捉到的波形，任意波形发生器都可复制出，特别有用的是仿真单次偶发的信号，例如地震波形、汽车碰撞波形等等。除了可以模拟各种复杂信号，任意波形发生器还可对频率、幅值、相
