# Analog Filters Design

This set of Digital Signal Processing Multiple Choice Questions & Answers (MCQs) focuses on “Design of IIR Filters from Analog Filters”.

1. What is the duration of the unit sample response of a digital filter?
a) Finite
b) Infinite
c) Impulse(very small)
d) Zero

2. Which of the following methods are used to convert analog filter into digital filter?
a) Approximation of Derivatives
b) Bilinear transformation
c) Impulse invariance
d) All of the mentioned

3. Which of the following is the difference equation of the FIR filter of length M, input x(n) and output y(n)?
a) y(n)=∑M+1k=0bkx(n+k)
b) y(n)=∑M+1k=0bkx(n−k)
c) y(n)=∑M−1k=0bkx(n−k)
d) None of the mentioned

4. What is the relation between h(t) and Ha(s)?
a) Ha(s)=∫∞−∞h(t)e−stdt
b) Ha(s)=∫∞0h(t)estdt
c) Ha(s)=∫∞−∞h(t)estdt
d) None of the mentioned

5. Which of the following is a representation of system function?
a) Normal system function
b) Laplace transform
c) Rational system function
d) All of the mentioned

6. For an analog LTI system to be stable, where should the poles of system function H(s) lie?
a) Right half of s-plane
b) Left half of s-plane
c) On the imaginary axis
d) At origin

7. If the conversion technique is to be effective, the jΩ axis in the s-plane should map into the unit circle in the z-plane.
a) True
b) False

c) Inside unit circle

8. If the conversion technique is to be effective, then the LHP of s-plane should be mapped into _____________
a) Outside of unit circle
b) Unit circle
c) Inside unit circle
d) Does not matter

9. Physically realizable and stable IIR filters cannot have linear phase.
a) True
b) False

10. What is the condition on the system function of a linear phase filter?
a) H(z)=z−NH(z−1)
b) H(z)=zNH(z−1)
c) H(z)=±zNH(z−1)
d) H(z)=±z−NH(z−1)

11. If the filter is in linear phase, then filter would have a mirror-image pole outside the unit circle for every pole inside the unit circle.
a) True
b) False

12. What is the order of operations to be performed in order to realize linear phase IIR filter?
(i) Passing x(-n) through a digital filter H(z)
(ii) Time reversing the output of H(z)
(iii) Time reversal of the input signal x(n)
(iv) Passing the result through H(z)
a) (i),(ii),(iii),(iv)
b) (iii),(i),(ii),(iv)
c) (ii),(iii),(iv),(i)
d) (i),(iii),(iv),(ii)

13. When an application requires a linear phase filter, it should be an FIR filter.
a) True
b) False