1、I 摘 要 频率合成器是以一个或少量的高准确度和高稳定度的标准频率作为参考频率， 由此导出多个或大量的输出频率，这些输出的准确度与稳定度与参考频率是一致 的。在通信、雷达、测控、仪器表等电子系统中有广泛的应用。频率合成器有直接 式频率合成器、直接数字式频率合成器及锁相频率合成器三种基本模式，前两种属 于开环系统，因此是有频率转换时间短，分辨率较高等优点，而锁相频率合成器是 一种闭环系统，其频率转换时间和分辨率均不如前两种好，但其结构简单，成本低。 并且输出频率的准确度不逊色与前两种，因此锁相环频率合成已获得广泛的应用。 而 VCO 作为其中一个必不可少的重要部件,其质量可以左右整个环路的性能。
2、负阻 集成 LCVCO 由于具有工作频率高、波形好、频稳度高、相位噪声低、性能可靠等优 点,适于作为甚高频和特高频 VCO。 关键词：MC1648；锁相环；频率合成器 II Abstract The frequency synthesizer with high accuracy and high stability of the standard frequency of one or a few as the reference frequency, which leads to multiple or large amount of output frequency, accuracy
3、and stability of the output and the reference frequency is consistent. There are widely applied in communication, radar, measurement and control, instruments and other electronic systems. Frequency synthesizer has the direct frequency synthesizer, DDS and PLL frequency synthesizer in three basic mod
4、els, the former two belongs to the open loop system, so there is short frequency conversion time, resolution is higher, and the PLL frequency synthesizer is a closed loop system, the frequency conversion time and resolution is not as good as the first two good, but it has the advantages of simple st
5、ructure, low cost. And the output frequency accuracy inferior to the former two, thus PLL frequency synthesis has been widely applied. VCO is one of the essential components, the performance of quality around the whole loop. Negative resistance integrated LCVCO because of the high operating frequenc
6、y, a good waveform, frequency stability, low phase noise, high performance and reliable, suitable for VHF and UHF VCO. Therefore the PLL frequency synthesis based on MC1648. Key words：MC1648；PLL Frequency ；Synthesizer III 目 录 1 绪论 .1 1.1 研究背景和意义 .1 1.2 国内外研究现状 .1 1.3 研究主要内容和结构安排 .1 2 系统方案设计 .3 2.1 方案设计思想 .3 2.2 方案设计方法 .3 3 锁相环及频率合成器 .3 3.1 锁相环的结构及基本原理 4 3.2 锁相环路的各部件及其数学模型 5 3.2.1 鉴相器 .5 3.2.2 环路滤波器 .6 3.2.3 压控振荡器 .6 3.2.4 环路相位模型和基本方程 .7 3.3 频率合成器及其技术指标 8 3.3.1 频率范围 .8 3.3.2 .9 3.3.3 频率转换时间 .9
