数字频率合成器的设计-毕业论文(设计).doc

PAGE 摘 要 频率合成器主要以频率合成技术，即一个或者多个具有高稳定度和高精确度的频率参源，通过在频率域中的线性运算得到具有同样稳定度和精确度的大量的离散频率的技术来完成的装置。它应用范围非常广泛，特别是在通信、导航、电子侦察、干扰与反干扰、遥控遥测及现代化仪器仪表中起了极其重要的作用。大多数使用的频率合成器采用的是锁相环(PLL)频率合成技术，但是该技术的频率转换速度已经接近其极限，要进一步改善的技术难度越来越大，而且分辨率较低。为了能够进一步提高跳频速率，提出了直接数字频率合成技术(DDS)。DDS采用全数字技术，具有频率分辨率高，频率转换时间快，输出频率可以很高而且稳定性好，相位噪声低等优点，这在无线电通信领域，尤其在雷达、航空航天和移动通信中都已显示了其巨大的优越性，并得到了广泛的应用。当然还有很多问题尚未很好的解决，其中最突出也最重要的问题就是相位噪声和杂散。 本文简要地阐述了频率合成技术、DDS发展历程及其优缺点，并对几种常用的频率合成器性能作了比较，概述了DDS的具体应用领域，论述了国内外DDS的发展现状。其中着重就DDS的结构和基本原理、相位噪声和杂散以及改善DDS杂散的方法等问题根据有关资料分析讨论，为进一步深入研究打下良好的基础。 【关键词】： 频率合成 DDS PLL 相位噪声 杂散? Abstract Frequency synthesizer mainly frequency synthesis technology, namely one or more with high stability and high accuracy, through the frequency and source of linear operations in the frequency domain with the same degree of stability and get the discrete frequency of accuracy of technology to complete device. It application range is very wide, especially in communications, navigation, electronic reconnaissance, interference and anti interference, remote telemetry and modern instruments plays an extremely important role. Most current use frequency synthesizer USES is phase locked loop (PLL) frequency synthesis technology, but the technology of frequency conversion speed is close to its limits, to further improve the technology, and increasingly difficult to a low resolution. In order to further improve the frequency hopping rate, puts forward direct digital frequency synthesis technology (DDS). By digital technology, DDS with frequency resolution is high, frequency conversion time quick, output frequency can is very tall and good stability, advantages, this phase noise in radio communication field, especially in radar, aerospace and mobile communications have shows its great superiority, and been widely used. And of course many problem has not been very good solution, one of the most prominent, and most important problem is phase noise and stray. This paper briefly expounds the spurious