Anti-Aliasing, Analog Filters for Data Acquisition Systems

This application note investigates the design of analog filters that reduce the influence of extraneous noise in data acquisition systems. These types of systems primarily utilize low-pass filters, digital filters or a combination of both. With the analog low-pass filter, high frequency noise and interference can be removed from the signal path prior to the analog-to-digital (A/D) conversion. In this manner, the digital output code of the conversion does not contain undesirable aliased harmonic information. In contrast, a digital filter can be utilized to reduce in-band frequency noise by using averaging techniques.