筛选器基础知识： 消除锯齿

摘要：在采样的数据系统中，超过一半采样率"别名"(改变)到感兴趣的频段的频率分量。大多数情况下，消除锯齿的不良副作用，所以"取样不足"更高的频率只是筛选之前的A/D阶段。但有时，欠采样是故意，消除锯齿会导致A/D系统作为一个混音器功能。

Maxim>AppNotes>Filtercircuits(analog)Keywords:filterbasics,antialiasing,filterrequirements,filtering,sampleddatasystemJan11,2002APPLICATIONNOTE928FilterBasics:Anti-AliasingAbstract:Inasampleddatasystem,frequencycomponentsgreaterthanhalfthesamplingrate"alias"(shift)intothefrequencybandofinterest.Mostofthetime,aliasinginanundesirablesideeffect,sothe"undersampled"higherfrequenciesaresimplyfilteredoutbeforetheA/Dstage.Butsometimes,theundersamplingisdeliberateandthealiasingcausestheA/Dsystemtofunctionasamixer.Thisapplicationnotediscussesthedifferentfilteringrequirementsforasampleddatasystem.Itdescribesaliasingandthetypesoffiltersthatcanbeusedforant