# Digital (FIR and IIR) Filters

There are two types of digital filters in the LabWindows/CVI Advanced Analysis Library: Finite Impulse Response (FIR) filters and Infinite Impulse Response (IIR) filters. FIR filters have a linear phase response. IIR filters generally have a nonlinear phase response but offer much better amplitude response.

The particular type of filter you choose depends on the application. If you want a linear phase response, choose one of the FIR filters. If performance and better amplitude response are more important, choose an IIR filter. No matter what type of filter you choose, enter a sampling frequency and other cutoff frequencies when you design your filter. You can design a digital filter using a normalized sampling frequency. The LabWindows/CVI Advanced Analysis Library provides a sampling frequency parameter so that you do not need to normalize other frequencies.