Question

What is the roll-off rate of single order filter?

(a) 20dB/decade

(b) 5dB/octave

(c) 40dB/decade

(d) 10dB/octave

I had been asked this question by my college director while I was bunking the class.

This is a very interesting question from General Frequency Consideration topic in portion Transistor Biasing and Low Frequencies of Analog Circuits

Answer 1

Correct option is (a) 20dB/decade

Easy explanation: At lower and higher frequencies the gain is decreasing. This fall or decrease in gain is known as roll-off rate. It is commonly specified in dB/octave or dB/decade. For a single order filter, the roll-off rate is 6dB/octave or 20dB/decade.