基于LMF100的自动跟踪带通滤波器的设计与实现

Design and Realization of Automatic Tracking Band-Pass Filter Based on LMF100

开关电容滤波器较其他滤波器更易实现对信号频率的跟踪滤波.采用LMF100开关电容滤波器芯片和锁相环电路MC14046,研究与设计了一种简单实用的自动跟踪带通滤波器.该滤波器是一个四阶的由LMF100中两节工作模式1的二阶带通滤波器级联构成,使用MC14046锁相环和双BCD同步加计数器MC14518对输入信号产生100或50倍频脉冲作为LMF100的时钟,实现带通滤波器中心频率的自动跟踪.实验结果表明,该滤波器取得了较好的跟踪滤波效果.

In order to effectively eliminate the noise of the input signal in signal processing, it＇s necessary to design an automatic tracking filter. And it is easier to realize the tracking filtering of signal frequency with a switched capacitor filter than with other filters. The LMF100 switched capacitor filter and MC14046 PLL were adopted, and a simple practical automatic tracking band-pass filter was studied and designed. In the band-pass filter, the LMF100 constitutes a fourth-order filter by cascading two second-order band-pass filter sections with mode 1, and it uses the clock signal generated by the MC14046 PLL and the dual BCD up-counter MC14518 with a frequency of 100 or 50 times of the input signal frequency to realize the automatic tracking filtering at the central frequency. The experiment results have shown that the filter has a good tracking filtering effect.