可调信号发生器的FPGA实现

文档编号:DZXX363 文档字数:23701,页数:60 附任务书

摘  要
 信号发生器是一类非常重要的电子仪器，在做实验、进行产品研制和调试以及系统测试中都是必不可少的，而传统的信号发生器性能是非常有限的，满足不了有些用户的要求。直接数字式频率合成技术DDS是新一代的频率合成技术，它采用数字控制信号的相位增量技术，具有频率分辨率高，频率切换快，频率切换时相位连续和相位噪声低以及全数字化易于集成等优点而被广泛采用。近几年超高速数字电路的发展以及对DDS的深入研究，DDS的最高工作频率以及噪声性能己接近并达到锁相频率合成器相当的水平。随着这种频率合成技术的发展，现已广泛应用于通讯、导航、雷达、遥控遥测、电子对抗以及现代化的仪器仪表工业等领域。
 在理论上对DDS的原理及其输出信号的性能进行了分析，采用FPGA实现了
任意波形发生器，能够产生三角波、锯齿波、正弦波和方波始终波形。在设计频率调制电路时采用了频率字运算单元和相位累加器相结合的结构，该方法既可实现宽带线性调频，又可实现非线性调频。利用了Verilog 硬件描述语言和ModelSim软件完成了模块的设计与性能验证，结果满足设计要求。

关键词： Verilog HDL； 任意波形发生器；DDS 直接数字频率合成

Abstract
 Signal generator is very important in modern electronic instruments. In the experiments，product development and debugging and system testing is essential，and the traditional signal generator performance is very limited，can not meet the requirements of some users. Direct Digital Synthesis is the new generation of frequency synthesis technology，it uses the numerical control signal the phase increase technology，has the frequency resolution high，the frequency cuts quickly，when frequency cut the phase continuously low as well as the entire digitization is easy with the phase noise to integrate and so on the merit is widely used. In recent years the super velocity digital circuit development as well as to the DDS thorough research，the DDS highest operating frequency as well as the noise performance approached and achieves the phase-lock frequency synthesizer suitable level. Along with this kind of frequency synthesis technology development，already widely applied to the communication，the navigation，the radar，remote control telemetering，electronic countermeasure as well as modernized do main and so on instrument measuring appliance industry.
 The thesis analyses the principle of DDS and the performance of output signals. An arbitrary waveforms generator which can generate the triangle waveform, saw tooth waveform, FM, PM, AM, burst waveform and other waveforms is designed with FPGA. Arbitrary waveforms can be downloaded to the arbitrary waveforms generator via serial port of PC. The structure that combines a phase accumulator with frequency word calculation unit is used to design the frequency modulation circuit. This structure can not only realize broad band linear frequency modulation, but also nonlinear frequency modulation. The design and debugging of hardware and the software are finished.

 Key words： Verilog HDL；Arbitrary waveforms generator；Direct Digital Frequency Synthesis；

目录
Abstract V
第1章  绪 论 1
1.1课题研究的背景、目的、意义 1
1.2频率合成技术概述 1
1.3直接频率合成技术的特性 3
1.4国内外波形发生器的发展状况 4
1.5本文内容 6
第2章  FPGA和开发环境、仿真工具简介 8
2.1 FPGA简介 8
2.2 Verilog HDL硬件描述语言简介 9
2.3 Quartus II开发软件简介 9
2.4 ModeSim仿真软件 10
2.5 FPGA设计流程 11
第3章 DDS技术相关原理 15
3.1 DDS基本原理 15
3.2 DDS基本结构 16
3.2.1基于CORDIC算法的DDS结构 16
3.2.2基于RAM查找表的DDS结构 17
3.3 DDS的误差分析 19
3.3.1理想DDS的谱分布 20
3.3.2 DDS的相位噪声 22
第4章 波形发生器的FPGA的实现 23
4.1 DDS设计流程 24
4.2相位累加器的设计 25
4.3地址产生器的设计 26
4.4波形寄存器的设计 27
4.4.1波形ROM的设计 27
4.4.2波形数据的产生 31
4.4.3波形RAM的设计 34
4.5地址分配器和数据选择器的设计 35
4.6 DDS模块和单片机接口设计 38
第5章 DDS模块的仿真 42
5.1 testbench的介绍 42
5.2固定波形的仿真实现 42
结论 45
致谢 46
参考文献 47
附录1 48
附录2 52

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