摘要频率合成技术广泛应用于通信、雷达，电子对抗、航空航天、仪器仪表等领域。目前，常用的频率合成技术有直接模拟频率合成，锁相环频率合成和直接数字频率合成[1]。
直接数字频率合成器(DDS)是一种全数字化的频率合成器，它是以数字取样技术为基础，由相位累加器、ROM查找表、数模转换器和低通滤波器构成的频率合成器。直接数字频率合成技术具有频率分辨率高、频率切换速度快、频率切换时相位连续、相位噪声低等优点。数字量化所带来的误差一直是数字电路所面临的难题，本文采用32位的相位累加器，使精度得到很大的提高。
本文首先回顾了频率合成技术的历史，概括了直接数字频率合成技术的特点和在各个领域的应用，分析了使用FPGA实现DDS系统的意义和可行性；分析了直接数字频率合成技术的结构和输入输出之间的关系；对输出信号的频谱特性做出了详细分析，同时对杂散的主要来源以及抑制方法进行了探讨；介绍了Altera公司FPGA器件的开发和设计流程，并且对Verilog HDL语言的特点作了简要介绍，对本次设计所使用的EDA工具也作了简要介绍；接着用Verilog HDL语言实现了DDS系统各个模块的功能并进行了仿真，然后进行了综合仿真，产生了正弦波信号；最后对输出结果进行了分析。79746
毕业论文关键词: 直接数字频率合成；现场可编程门阵列；Verilog HDL
Abstract The technology of Frequency synthesis which contains of Direct Synthesis, Phase-locked Synthesis and Direct Digital Synthesis is widely used in the field of communication, radar, electronic confrontation, aeronautics, instrument and so on。
The direct digital frequeney synthesizer is a kind of fully digitized fequeney synthesizer, which based on digital sampling technology and consists of phase accumulator,ROM look-up table, digital to analog converter, and low pass filter。 It has the advantages of high frequency resolution,fast frequeney switching speed, the ability to maintaining constant phase while switch frequency,low phase noise。 The error brought by quantization has been the challenges facing digital circuit, the design use 32-bits phase accumulator, which greatly improved the accuracy 。
Firstly,the dissertation reviews the history of frequeney synthesis techniques,and summarized the characteristics of the direct digital frequeney synthesis techniques and application in all fields,and analysis the feasibility and significance of realizing the dircet digital frequeneyt technique based on Field
Programmable Gate Array(FPGA);Secondly, it analysis the structure of the direct
digital frequency analysis and the relationship between input and output, then analysis the spectrum characteristics of the output signal in detail,meanwhile it discusses the source of the stray and the method to inhibit the stray; Thirdly, it introduces the FPGA devices made by Altera company and the development
software and design process;Then,it designes each module of DDS system by VHDL+FPGA的DDS仿真与设计:http://www.youerw.com/zidonghua/lunwen_92336.html