Butterworth fourth order low-pass filter | Download Scientific Diagram
Bessel Filter Design | Hackaday
Lowpass, Bandpass and Highpass Filter Calculators
I need to design a second order active filter low-pass Rauch structure of Bessel. Design data: f-cut = 15 Hz; C1 = 50 pF. More info in img - Electrical Engineering Stack Exchange
Low Pass Filter Calculator
Dale's Homemade Robots - Lowpass and Highpass Filter Calculator