Page "Low-pass filter" Paragraph 21

* A second-order filter attenuates higher frequencies more steeply.

The Bode plot for this type of filter resembles that of a first-order filter, except that it falls off more quickly.

For example, a second-order Butterworth filter will reduce the signal amplitude to one fourth its original level every time the frequency doubles ( so power decreases by 12 dB per octave, or 40 dB per decade ).

Other all-pole second-order filters may roll off at different rates initially depending on their Q factor, but approach the same final rate of 12 dB per octave ; as with the first-order filters, zeroes in the transfer function can change the high-frequency asymptote.

See RLC circuit.