Question

If H(s) is the transfer function of a analog low pass normalized filter and Ωu is the desired pass band edge frequency of new low pass filter, then which of the following transformation has to be performed?

(a) s → s / Ωu

(b) s → s.Ωu

(c) s → Ωu/s

(d) None of the mentioned

I have been asked this question in an internship interview.

My query is from Frequency Transformations in the Analog Domain topic in portion Digital Filters Design of Digital Signal Processing

Answer 1

Correct option is (a) s → s / Ωu

The explanation is: If Ωu is the desired pass band edge frequency of new low pass filter, then the transfer function of this new low pass filter is obtained by using the transformation s → s / Ωu.