Question

Which of the following pairs of M and N will give a perfect match?

(a) 3,6

(b) 3,4

(c) 3,5

(d) 4,5

This question was addressed to me in an international level competition.

Asked question is from Pade Approximation Method topic in division Digital Filters Design of Digital Signal Processing

Answer 1

Right answer is (d) 4,5

For explanation: When M is increased from three to four, we obtain a perfect match with the desired Butterworth filter not only for N=4 but for N=5, and in fact, for larger values of N.