Sallen-Key Active Butterworth High Pass Filter Calculator

Enter value and click on calculate. Result will be displayed.


Ra = Filter Resistor
Rb = Filter Resistor
Ca = Filter Capacitor
Cb = Filter Capacitor
(Ca = Cb)
Ca = Sqrt(2) / [2 × 3.14 × Cutoff Frequency × Capacitor]
Cb = Ra / 2

Cutoff Frequency:

(Enter any one value - Ra or Rb or Capacitor)

Resistor Ra:
Resistor Rb:
Capacitor (Ca = Cb):

A Sallen-Key Active Butterworth High-Pass Filter Calculator is a tool used to design a high-pass filter with a Butterworth response, ensuring a maximally flat gain in the passband.

How It Works
The calculator helps determine:

Resistor values (R1, R2)
Capacitor values (C1, C2)
Cutoff frequency (fc)
Operational amplifier (Op-Amp) configuration
Formula for a 2nd-Order Sallen-Key High-Pass Filter
The cutoff frequency is given by:



For a Butterworth response (maximally flat), the component values are chosen to achieve a damping factor (Q = 0.707).

Key Features
Blocks low-frequency signals while allowing high-frequency signals to pass.
Achieves -3 dB attenuation at cutoff frequency.
Uses an Op-Amp for active filtering, eliminating inductors.
Commonly used in audio applications, data communication, and sensor signal processing.