Frequency Filters – 2 MCQ’s

This set of Analog Electronic Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Frequency Filters – 2″.

1. Find which one is a sallen-key topology.




2. Considering a second-order Butterworth LPF using an op-amp, where damping factor = 1.414 find the value of R3, given the following circuit. (R2=5kΩ)

a) 6.71 kΩ
b) 4.22 kΩ
c) 2.93 kΩ
d) 5 kΩ

3. For the following circuit, R2=220kΩ, R1=10kΩ, find the maximum gain and the phase shift at the cutoff frequency.

a) Maximum gain = 22, Phase shift = 45°
b) Maximum gain = 23, Phase shift = 135°
c) Maximum gain = 22, Phase shift = 225°
d) Maximum gain = 23, Phase shift = 45°

4. A first-order Butterworth low pass filter is an interconnection of ____________ and ___________
a) Single low pass RC circuit, Voltage follower
b) Low pass RC circuit, Band-pass RC circuit
c) Low pass RC circuit, LC feedback
d) Single low pass RC circuit, Power amplifier

5. Find the cutoff frequency for the following circuit. (R1=R2=20kΩ)

a) 25 kHz
b) 3987 rad/sec
c) 2500 Hz
d) 25000 rad/sec

6. Given a second-order Butterworth HPF, find the maximum gain magnitude.
a) 1.586 dB
b) 4 dB
c) 2.66 dB
d) 1 dB

7. Which of these is incorrect for a band-stop filter?
a) An adder is required when designing it using LPF and HPF
b) LPF and HPF are connected in parallel
c) The HPF cut-off frequency should be much higher than LPF cut-off frequency
d) The LPF and HPF are connected in series

8. Consider the following circuits.

If a band-pass filter is created by using the

above two circuits in cascade, find the correct relation from the choices below.
a) R4C2 >> R1C1
b) R4C2 << R1C1
c) R6R5 = R2C3
d) R4C2 = R1C1

9. Which of these is wrong for an all-pass filter?
a) It is used for phase equalization in a communication system
b) It is used in landline communication
c) Its phase shift is -2tan-1RC, between 0 to -180°
d) It can be made using a single op-amp

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