基于抗混叠滤波的LTC1569-7低频特性探究  

Exploration of Low Frequency Characteristics of LTC1569-7 Based on Anti-Aliasing Filter

作　　者：李霞[1] 马喜宏[1] 任勇峰[1,2] 贾兴中[1] LI Xia;MA Xihong;REN Yongfeng;JIA Xingzhong(State Key Laboratory of Electronic Testing Technology of North University of China,Taiyuan 030051,China;Science and Dynamic Testing of Education Key Laboratory Instrument of North University of China,Taiyuan 030051,China)

机构地区：[1]中北大学电子测试技术重点实验室,太原030051 [2]中北大学仪器科学与动态测试教育部重点实验室,太原030051

出　　处：《电子器件》2019年第5期1221-1224,1241,共5页Chinese Journal of Electron Devices

摘　　要：LTC1569-7是十阶集成开关电容低通滤波器,具有外围电路简单、频率控制精度高以及频带外衰减大的优点,广泛应用于抗混叠滤波场合。针对LTC1569-7使用中出现的问题进行探究,当截止频率低于16 kHz、3.68 kHz、900 Hz(1、4、16分频)时,频带外衰减不理想,且输入频率在截止频率32倍及其整数倍附近会产生混叠,同时还存在开关噪声。在LTC1569-7的前端搭建二阶低通滤波电路,可以消除混叠,在LTC1569-7后端搭建二阶低通滤波电路可以消除频带外衰减不理想情况以及开关噪声,使得LTC1569-7更好地应用于抗混叠滤波中。LTC1569-7 is a ten-order integrated switch-capacitor low-pass filter.It has the advantages of simple circuit,high precision of frequency controlling and big out-of-band attenuation.It is widely used in anti-aliasing filter applications.When the cutoff frequency is lower than 16 kHz,3.68 kHz,900 Hz(division of 1,4,16),the out-of-band attenuation is not ideal.Aliasing occur if the input frequency is 32 and its integer multiple times the cutoff frequency,and LTC1569-7 has switching noise.A second-order low-pass filter circuit can be built on the front end of the LTC1569-7 to eliminate aliasing.These problems occurred in the use of LTC1569-7 are exploreded.A second-order low-pass filter circuit can be built at the LTC1569-7 back end to eliminate the undesired out-of-band attenuation and switching noise,making the LTC1569-7 applied well to anti-aliasing filter.

关 键 词：抗混叠滤波 开关电容滤波器 LTC1569-7 二阶低通滤波 带外衰减 混叠 开关噪声 

分 类 号：TN713.92[电子电信—电路与系统]