3rd order Sallen-Key Low-pass Filter Design Tool

This page is a web calculator that design a 3rd order Sallen-Key low-pass filter. Use this utility to simulate the Transfer Function for filters at a given frequency, damping ratio ζ or values of R and C. The response of the filter is displayed on graphs, showing Bode diagram, Nyquist diagram, Impulse response and Step response.

Calculate the transfer function for 3rd order Sallen-Key low-pass filter with R and C values

Vi→

→Vo

Transfer function:
    Transfer function of 3rd order Sallen-Key low-pass filter


2nd order Sallen-Key low-pass filter tool, use also.

Calculate the R and C values for the Sallen-Key filter at a given frequency and damping ratio ζ

Vi→

→Vo

※ 3rd order filters are usually made from combinations of 1st and 2nd order filters following the equivalent block diagram.


Equivalent block diagram:

Vi→

2πfc1  s+2πfc1

→

(2πfc2)2  s2+2ζ(2πfc2)s+(2πfc2)2

→Vo

Transfer function block diagram: