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

Enter your values:

Cutoff Frequency:


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

Resistor Ra:
Resistor Rb:
Capacitor (Ca = Cb):
Sallen-Key Active Butterworth High Pass Filter Calculator

The Sallen-Key filter was introduced by this circuit type

1955 E. L. Key, MIT Lincoln Laboratory.

This circuit produces an extremely low pass response using two resistors, two capacitors and a unity gain buffer amplifier. This filter topology is also known as a voltage-controlled voltage source (VCVS) filter.

Sallen-Key filtering is a simple active filter based on an op amp stage, which is ideal for filtering audio frequencies.

This is one of the most widely used filter topologies. One of the reasons for its popularity is that this configuration has minimal dependence on the performance of the filter on the performance of the op amp. Another advantage of this structure is that the ratio of the maximum and minimum resistance values to the maximum and minimum capacitance values is very low, which is good processability.

A serious disadvantage is that the filter is not easily tuned.

A low-pass filter is a filter that passes low-frequency signals and attenuates signals with frequencies above the cutoff frequency.

Usage example
Input data: Cutoff frequency: 10KHz

Click "Calculate" to output the results

Resistance (Ra = Rb): 10.00000Kohm

Capacitor Ca: 2.250000nF

Capacitor Cb: 1.125000nF

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