信号源及DDS杂散分析.doc

信号源及dds杂散分析 目  录中文摘要1前言11 模拟信号源与dds系统性能特点比较11.1 模拟信号源的类型及特性11.1.1 rc正弦波振荡电路11.1.2 lc正弦波振荡电路21.1.3 石英晶体振荡器 31.2 dds系统原理及特性41.3 两者比较52 dds的杂散来源62.1 相位截断误差分析72.2 幅度量化误差分析93 对于dds杂散信号抑制的分析103.1 rom幅度表压缩103.2 加扰技术 113.3 改进的dds电路结构 13结论14参考文献15英文摘要15致谢 16 信号源及dds杂散分析 摘要：信号源是电子系统中重要的组成部分。随着电子技术的不断发展,对信号源的要求越来越高，传统的模拟信号源已经远远不能满足要求，而直接数字合成技术的出现，给现代电子技术带来了新的生机。但因其数字化本身的特点，仍存在输出频带范围有限，输出杂散大的缺点。因此，解决这方面的问题就显得尤为重要。本文分析了dds系统与模拟信号源系统的电路特征，研究了它们各自的性能特点，并对两者进行了比较；探讨了dds杂散的来源，主要来源有3个：相位截断误差，幅度量化误差和数模转换器的非理想特性；重点对dds的相位截断杂散信号和幅度量化杂散信号进行了分析，得到1些关于其频谱特征和杂散水平的规律性结论，并提出了相应的抑制杂散的方法。关键词：直接数字频率合成；模拟信号源；相位截断；幅度量化；杂散抑制siganal source and the analysis of dds spur abstract: the signal source is an important part in the electronic system. along with continuous development of the electronic technical, the request of the signal source is more and more high and the traditional simulant signal source coundt satisfy the request any more. the emergence of direct digital frequency synthesis has brought much vitality for modern electronic science and technology. but because of the numeral characteristics by itself, the dds still has the weakness of limited scope for the equency broad and miscellaneous spur. therefore, the problem to resolve this aspect seems to be much importance. this article analyzes characteristic of dds and simulant signal source system, studys their function characteristics and carries on the comparison to both while the analysis of dds is more in detail. there are three main sources of spurious signal in dds: the truncation of the phase accumulator bits in the sine rom, the finite precision of the sine samples stored in the rom, and the digital to analog conversion. in this article the front two are emphatically studyed to get some regular conclusion referring to its frequency chart characteristic and spur level. at the end, corresponding technique to reduce the spur is introduced.key words: the direct digital frequency synthesis; simulant signal source; phase truncation; quantization of rank ; reduction of spur.前言高精度的信号源在现代电子系统中占有10分重要的地位,它是进行科学研究、开发研制新产品、各种测试和实验必不可少的工具之1，在通信、电子、控制、雷达、测量、教学等领域应用10分广泛。1般要求频率稳定度高，大的功率输出动态范围，良好的输出频率响应，应具有调制功能，频谱纯度高，频率、相位、幅度可程控，精度高等特点。因此传统的模拟信号源已经远远不能满足要求，而直接数字合成技术（direct digital frequency synthesis简称dds或ddfs）的应用，产生了全数字化的信号源，以数字为基础的程控化、智能化的信号源，不仅性能指标有了质的飞跃，功能也更为强劲，操作更加简便。dds技术是近年来迅速发展起来的1种新型的频率合成技术,它具有频率改变速度快、频率分辨率高、相位连续以及可灵活产生波形等特点。近几年超高速数字电路的发展以及对dds的深入研究，dds