Guide to Anti-aliasing Filter Basics

Abstract: In a sampled data system, frequency components greater than half the sampling rate \"alias\" (shift) into the frequency band of interest. Most of the time, aliasing in an undesirable side effect, so the \"undersampled\" higher frequencies are simply filtered out before the analog-to-digital (AD) stage. But sometimes, the undersampling is deliberate and the aliasing causes the AD system to function as a mixer.

This application note discusses the different filtering requirements for a sampled data system. It describes aliasing and the types of filters that can be used for anti-aliasing.