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: