Op Amp Active Filter MCQ [Free PDF] – Objective Question Answer for Op Amp Active Filter Quiz

1. An electrical filter is a

A. Phase-selective circuit
B. Frequency-selective circuit
C. Filter-selective circuit
D. None of the mentioned

Answer: B

An electric filter is often a frequency selective circuit that passes a specified band of frequencies and blocks or alternates the signal of frequencies outside this band.


2. Filters are classified as

A. Analog or digital
B. Passive or active
C. Audio or radio-frequency
D. All of the mentioned

Answer: D

Filters are classified based on the design technique (analog or digital), elements used for construction (active or passive), and operating range (audio or radio-frequency).


3. Why inductors are not preferred for audio frequency?

A. Large and heavy
B. High power dissipation
C. High input impedance
D. None of the mentioned

Answer: A

At audio frequencies, the inductor becomes problematic, as the inductors become large, heavy, and expensive.


4. The problem of passive filters is overcome by using

A. Analog filter
B. Active filter
C. LC filter
D. A combination of analog and digital filters

Answer: B

The active filters enclose as a capacitor in the feedback loop and avoid using inductors, this way inductor-less active filters are obtained.


5. What happens if inductors are used in low-frequency applications?

A. Enhance inductor usage
B. No losses occur
C. Degrades inductor performance
D. Low power dissipation

Answer: C

For low-frequency applications, more number of turns of wires must be used, which in turn adds to the series resistance degrading the inductor’s performance.


6. Find out the incorrect statement about active and passive filters.

A. Gain is not attenuated in an active filter
B. Passive filters are less expensive
C. Active filter does not cause loading of source
D. Passive filters are difficult to tune or adjust

Answer: B

Typically active filters are more economical than passive filters. This is because of the variety of cheaper op-amps and the absence of inductors.


7. What are the most commonly used active filters?

A. All of the mentioned
B. Low pass and High pass filters
C. Bandpass and Band reject filters
D. All-pass filters

Answer: A

All the mentioned filters use an op-amp as an active element and capacitors & resistors as passive elements.


8. Choose the op-amp that improves the filter performance.

A. µA741
B. LM318
C. LM101A
D. MC34001

Answer: B

LM318 is a high-speed op-amp that improves the filter’s performance through increased slew rate and higher unity gain-bandwidth.


9. Ideal response of filter takes place in

A. Passband and stopband frequency
B. Stopband frequency
C. Passband frequency
D. None of the mentioned

Answer: C

The ideal response indicates the practical filter response and it lies within the passband frequencies.


10. Which filter type is called a flat-flat filter?

A. Cauer filter
B. Butterworth filter
C. Chebyshev filter
D. Band-reject filter

Answer: B

The key characteristic of the Butterworth filter is that it has a flat passband as well as a stopband. So, it is sometimes called a flat-flat filter.

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