sallen-key active butterworth high pass filter calculator

enter the value and click "calculate", the calculation 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 × capacitance]
Cb = Ra / 2

enter a value:

cutoff frequency:

calculation result:

(enter any value - ra or rb or capacitor)

resistor ra:
resistor rb:
capacitor (ca = Cb):
sallen-key active butterworth high pass filter calculator

it was through this circuit type that the sallen-key filter was introduced

1955 el key, mit lincoln laboratory.

this circuit uses two resistors, two capacitors, and a unity-gain buffer amplifier to produce a very low-pass response. this filter topology is also called a voltage-controlled voltage source (vcvs) filter.

sallen-key filtering is a simple active filter based on an op amp stage that is ideal for filtering audio.

this is one of the most widely used filter topologies. one reason for its popularity is that this configuration has minimal dependence of the filter performance on the op amp performance. 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, resulting in good processability.

a serious drawback is that the filters are not easily adjustable.

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

capacitance ca: 2.250000nf

capacitance cb: 1.125000nf
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