摘要
压控振荡器(VCO)是合成器中的关键器件之一,其噪声特性直接影响合成器的相位噪声和环路动态特性。在锁相合成器中,特别是宽带合成器中,对VCO采用附加锁频环进行稳频控制,明显地优化了合成器载频中远区的相位噪声,锁频环已成为先进合成器的关键技术。该文描述了锁频环(FLL)的原理,对锁频环的环路特性和相位噪声进行了理论分析,并以C波段合成器为例,给出了常规小数锁相环和小数锁相附加锁频环的实验研究结果。实验证明锁频环对优化合成器中远区相位噪声效果明显。
VCO is a key element in frequency synthesizer, and its noise influences phase noise and dynamic characteristic of frequency synthesizer directly. In frequency synthesizer, especially in wideband synthesizer, phase noise at the middle-far band from carrier frequency will be improved effectively by adding a frequency-locked loop（FLL） to VCO. The FLL has become a key technology in advanced frequency synthesizer. In this paper, the operational principle of FLL is described, its loop characteristic and phase noise are analyzed and discussed. At last, taking a C band frequency synthesizer as example, the experimental results of the fraction-N phase locked Ioop（FNPLL） and the FNPLL added with FLL are given, the experiment proves that FLL improve clearly the synthesizer phase noise at middle-far band.
出处
《雷达科学与技术》
2006年第6期373-376,共4页
Radar Science and Technology
基金
十五预研项目
关键词
频率合成
锁频环
相位噪声
压控振荡器
frequency synthesis
frequency-locked loop
phase noise
VCO
