自适应低通滤波器的设计  

Design of the Adaptive Low-pass Filter

作　　者：马胜前[1] 冉兴萍[1] 范满红[1] 张维昭[1] 

机构地区：[1]西北师范大学物理与电子工程学院,甘肃省原子分子物理与功能材料重点实验室,甘肃兰州730070

出　　处：《压电与声光》2013年第2期245-249,共5页Piezoelectrics & Acoustooptics

基　　金：国家自然科学基金资助项目(61162017,20927004);甘肃省教育厅基金资助项目(1101-03)

摘　　要：提出了一种自适应低通滤波器的结构和实现方法,输入信号预处理并整形后产生频率信号,频率信号经频率电压转换(F/V)电路转换成电压信号,再将该电压信号输入到模拟乘法器MLT04和电流反馈运算放大器AD844为核心构成的压控低通滤波电路。通过该电压信号调节滤波器的截止频率,从而实现滤波器频率的自动跟踪。介绍了设计原理,推导出设计公式并设计了自适应二阶低通滤波器电路。经过测试,输入信号的频率为100Hz～10kHz,实测结果与理论符合良好。改变F/V电路的定时电阻的阻值,电路工作频率可扩展到100kHz。This paper presents the structure and implementation of an adaptive low-pass filter. After the input signal is pre-processed and shaped, the frequency signal is generated; the frequency signal then is converted into volt- age signal through F/V circuit. Then the voltage signal is input into the voltage-controlled low-pass filter circuit which is mainly constituted by the analog multiplier MLT04 and the current feedback amplifier AD844. The cutoff frequency of the low-pass filter can be adjusted by the voltage signal, thus the frequency of the filter can be tracking atuomatically. In this paper,the design principle is introduced in detail,the design formulas are derived and the cir- cuit of second order from tracking low-pass filter is given. When the input signal ~ s frequency is in the range of 100 Hz to 10 kHz,the measured results are in good agreement with the theoretical results. If the value of timeing re- sistance in the F/V circuit is changed,the operating frequency of the filter can be extended to 100 kHz.

关 键 词：自适应滤波器 电流反馈运放 自跟踪 压控低通滤波器 

分 类 号：TN713[电子电信—电路与系统]