1)   Filter Wiz PRO 5.0
Active filter design software for lowpass, highpass, bandpass and bandstop electronic filters using resistors, capacitors and op amps. Provides Butterworth, Chebyshev, Elliptic and Bessel Approximations to order 20, with a variety of circuit choices.

 2)   Filter Wiz Lite 1.08
Active filter design software for lowpass, highpass, bandpass and bandstop electronic filters using resistors, capacitors and op amps. Provides Butterworth, Chebyshev, Elliptic and Bessel Approximations to order 10, with a variety of circuit choices.