摘要
如何为开关电容滤波器(SCF)合理配置前置、后置滤波器,一直缺少系统的分析和说明。在研究SCF工作特性的基础上,提出了SCF前置、后置滤波器的设计方法。SFC前置、后置滤波器的主要设计参数是转角频率和衰减量。设计时,先根据系统要求确定衰减量,再根据选定的滤波器结构的衰减系数确定转角频率。用此方法,结合12位数据采集系统需要,以MAX295为核心设计了一个可程控低通滤波器。结果表明,MAX295的前、后置滤波器能以4档转角频率覆盖其10 Hz^50 kHz转角频率范围,前、后置滤波器的最小衰减量分别为-74 dB和-10 dB。
For a switched-capacitor filter（SCF）,it is important to configure its pre-filter and post-filter properly.There is a lack of systematic analysis and description for the problem.Based on the analysis of characteristics of SCF,a design method of pre-filter and post-filter for SCF was presented.Two design parameters of pre-filter and post-filter for SCF are cut-off frequency and attenuation.In designing a pre-filter or a post-filter,its attenuation should be determined according to system requirements first,and then its cut-off frequency should be determined according to the attenuation coefficient of a given filter structure.In this way,a programmable low-pass filter based on a MAX295 was designed for a 12-bit data acquisition system.The results show that the pre-filter and post-filter of the MAX295 could cover cut-off frequency range from 10Hz to 50kHz with 4 different cut-off frequencies,keeping minimum attenuation-74dB and-10dB respectively.
出处
《电子设计工程》
2011年第12期143-146,共4页
Electronic Design Engineering
