Sallen-Key low-pass filter

The frequency point at which the capacitive reactance and resistance are equal is known as the cutoff frequency of a low pass filter. At cutoff frequency, the output signal is attenuated to 70.7% of the input signal value or -3dB of the input.

This passive RC low pass filter calculator calculates the cutoff frequency point of the low pass filter, based on the values of the resistor, R, and the capacitor, C, of the circuit, according to the formula fc= 1/(2πRC) .

Calculate cutoff frequency of low pass filter The cutoff frequency denotes the frequency at which the two values are equal, ie R = X_C . Thus, at a frequency above the cutoff frequency, X_C is less than R, at a lower frequency, X_C is greater than R.