高阶有源滤波电路的分析与设计  

Analysis and Design of High Order Active Filter Circuit

作　　者：刘欲燃 张祥 戴博文 梅静怡 马延楠 LIU Yuran;ZHANG Xiang;DAI Bowen;MEI Jingyi;MA Yannan(CRRC Zhuzhou Institute Co.,Ltd.,Zhuzhou,Hunan 412001,China)

机构地区：[1]中车株洲电力机车研究所有限公司,湖南株洲412001

出　　处：《控制与信息技术》2024年第2期99-104,共6页CONTROL AND INFORMATION TECHNOLOGY

摘　　要：在模拟采样电路中,为避免杂波对采样信号造成干扰,采样信号需经滤波器处理后再送入DSP,这样往往能降低对模拟采样通道的硬件要求。相比无源滤波器,有源滤波器的放大倍数和频率特性基本不会随着负载的变化而变化,因此在小信号处理电路中,有源滤波器的使用更为广泛。但在实际设计高阶有源滤波器时,经常出现理论计算值与仿真值不一致的情况,导致所生成的电路参数往往不能满足器件选型要求。为此,文章从2阶有源滤波器出发,首先对传递函数进行分析,发现是系统阻尼系数的变化导致了这一情况的发生;接着提出了两种解决方案,一种是通过改变系统增益进而影响系统阻尼系数,另一种是通过调节滤波电路中的两个电容的比值来调节系统阻尼系数;之后通过分析计算,给出了使用这两种方案组成高阶滤波器时各级2阶滤波电路需具备的系统阻尼。对采用所述方法设计的截止频率为100 kHz的4阶和8阶滤波器进行PSPICE仿真分析,结果显示,其截止频率仿真值分别为98.828 kHz和96.200 kHz,与理论计算值基本一致,验证了所提高阶滤波器设计方法的有效性。In analog sampling circuits,filters are essential for processing sampled signals before they are sent to DSP for further processing,to avoid clutter interference on them.This practice often reduces the hardware requirements for analog sampling channels.Compared to passive filters,active filters exhibit stable amplification and frequency characteristics with load changes.Therefore,they are more widely used in small signal processing circuits.However,designing high-order active filters often leads to discrepancies between theoretically calculated values and simulated outcomes,resulting in circuit parameters that fall short of the requirements of device selection.This study started from the analysis of second-order active filters,focusing on the transfer function,which revealed the cause of the above design annoyance,i.e.variations in the system damping coefficient.To address this challenge,two solutions were proposed to manipulate the system damping coefficient respectively by changing system gains and adjusting the ratio of the two capacitance values in filter circuits.Through further analysis and calculations,this study derived the system damping required for each second-order filter circuit within a high-order filter constructed using these two solutions.Furthermore,a PSPICE simulation analysis was performed using 4-order and 8-order filters with a cut-off frequency of 100 kHz designed following the proposed methodology.The resulting simulated cut-off frequency values of 98.828 kHz and 96.200 kHz,respectively,closely matched the theoretical calculations,verifying the effectiveness of the proposed design approach for high-order filters.

关 键 词：高阶有源滤波器 模拟采样 截止频率 PSPICE 阻尼系数 

分 类 号：O436[机械工程—光学工程]