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Butterworth Filters

Butterworth Filters have one of the flattest passbands and moderate group delay.  A standard Butterworth filter's passband attenuation is: -3.01dB.  However, FilterSolutions allows the option of selecting any passband attenuation, in dB, that defines the filter’s cut-off frequency.

FilterSolutions also gives the designer the option of placing user-defined zeros in the stopband. A filter with stopband zeros is no longer a true Butterworth filter, but is still in the maximally flat filter family. Below are examples of Butterworth low-pass, high-pass, bandpass and bandstop filters, and the low-pass step response: