摘要
采用三阶环路滤波器的四阶频率合成器比三阶频率合成器能够更好的改善频率合成器的频谱杂散性能,但增加的极点会使得环路滤波器中电阻电容值的优化设计更为复杂。通过对系统的相位裕度、环路带宽、零极点频率等环路参数之间的关系,提出了一种无源环路滤波器优化设计的估算方法,并给出仿真流程。方法从相位裕度和环路带宽出发,通过指定零点和第二个非零极点所需要提供的参考毛刺的衰减程度来得出环路滤波器的各个原件值,简化了优化计算过程。
Four-order frequency synthesizer with three-order loop filter has a better performance in suppressing reference spurs than three -order frequency synthesizer, however, the added pole point makes the calculation of optimization values of capacitors and resisters of loop filter more complex. In this paper, a new calculating approach of passive loop filter of four-order charge pump-phase locked loop frequency synthesizer with simulation procedure is clearly introduced to simplify design process greatly based on relation of loop parameters, such as phase margin, band-width,pole point,zero point and so on. The novel approach starts with phase margin and loop bandwidth, and educes the optimization elements values of loop filter easily through the appointed zero point and the needed attenuation provided by the second nonzero pole point.
出处
《计算机仿真》
CSCD
2008年第5期294-297,共4页
Computer Simulation
关键词
电荷泵锁相环
相位裕度
环路带宽
行为级建模
Charge pump-phase locked loop
Phase margin
Loop bandwidth
Behavioral modeling
