# 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 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 |

Equivalent block diagram:

Vi→ | 2πfc1 s+2πfc1 | → | (2πfc2)^{2}s ^{2}+2ζ(2πfc2)s+(2πfc2)^{2} | →Vo |

Transfer function block diagram: