# Single Pole RC vs 2nd Order Butterworth LP Filter Responses

July 09, 2012

The calculator below computes the amplitude responses for the single-pole RC and the 2nd order Butterworth (Q=1/√2) low-pass filters.
Enter the relative frequency f/f3db and click Get Response:

 LP Filter Response f/f3db: Single Pole RC Filter V/Vo: 20log10(V/Vo): 2nd Order Butterworth Filter V/Vo: 20log10(V/Vo):

The graph below shows the magnitude of the transfer functions |H(f)| and the cumulative relative output voltage noise for each filter assuming a constant noise spectral density: