Welcome to the IIR and FIR Filters Laboratory. Choose a signal to filter, then choose the parameters of your filter. Note that the second cutoff frequency will only be used with a bandpass or stopband filter. Also, the second cutoff frequency must be greater than the first cutoff frequency if it is to be used. In addition to the choices on this page, there are several other specific examples available to help you answer the questions in the Exercises section of this laboratory.