Question

A filter is provided of order 3, find the roll-off rate.

(a) 6 dB/decade

(b) 60 dB/octave

(c) 60 dB/decade

(d) 3 dB/decade

This question was posed to me in an online quiz.

My question is from Frequency Filters in section Op-amps and its Applications of Analog Circuits

Answer 1

The correct answer is (c) 60 dB/decade

To explain: Roll-off rate is the rate at which the gain of a filter decreases outside the pass-band. Roll of rate is increased as the order increases. For an nth order filter, roll-off rate is 20xn dB/decade.