with filter calculator pro you can calculate the parameters or components of a passive RL, RC, LC, Butterworth, Bessel, Chebyshev, and active filter. Filter calculator has the following features: RC filter calculations RL filter calculations LC filter calculations Passive Butterworth filter calculations (2,3,4, and 5 pole Butterworth filter) Active Butterworth, Bessel, Chebychev filter calculations Notch filter Passive cross over design Band pass filter filter design is suitable for the desig