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Unit 5: Fundamentals of filters and operational amplifier - Practice Quiz

ECE131 — Basic Electrical And Electronics Engineering 60 Questions
0 Correct 0 Wrong 60 Left
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1 A low-pass filter allows which type of signals to pass through?

low-pass filter Easy
A. Low-frequency signals
B. Signals within a narrow band in the middle of the spectrum, while attenuating everything above and below that band
C. High-frequency signals
D. Only DC signals

2 A high-pass filter attenuates signals that are:

high-pass filter Easy
A. Above the cutoff frequency
B. At all frequencies equally
C. Below the cutoff frequency
D. Equal to the cutoff frequency

3 A band-pass filter is designed to:

band-pass filter Easy
A. Reject all frequencies
B. Pass only the lowest frequency
C. Pass a specific range of frequencies and reject others
D. Pass only DC voltage

4 An ideal operational amplifier has an input impedance that is:

operational amplifier abstraction- device properties of the operational amplifier Easy
A. Equal to
B. Negative
C. Zero
D. Infinite

5 An ideal operational amplifier has an output impedance of:

operational amplifier abstraction- device properties of the operational amplifier Easy
A. Infinite
B.
C. Equal to the input impedance
D. Zero

6 The open-loop voltage gain of an ideal op-amp is:

properties of operational amplifier Easy
A. Unity
B. Infinite
C. Exactly
D. Zero

7 In the virtual ground concept, the voltage at the inverting input of an ideal op-amp with negative feedback is approximately:

simple op amp circuits – virtual ground concept Easy
A. Equal to the supply voltage
B. Equal to the output voltage
C.
D. Infinite

8 The output of an inverting amplifier is:

inverting and non-inverting op-amp Easy
A. In phase with the input
B. Always zero
C. out of phase with the input
D. out of phase with the input

9 The voltage gain of an inverting amplifier with input resistor and feedback resistor is:

inverting and non-inverting op-amp Easy
A.
B.
C.
D.

10 The voltage gain of a non-inverting amplifier is given by:

inverting and non-inverting op-amp Easy
A.
B.
C.
D.

11 An op-amp summing amplifier produces an output proportional to:

op-amp as an adder and subtractor Easy
A. The product of the input voltages
B. The ratio of the input voltages
C. The sum of the input voltages
D. The difference of the input voltages

12 An op-amp subtractor circuit gives an output proportional to the:

op-amp as an adder and subtractor Easy
A. Square of the input voltage
B. Sum of two input voltages
C. Difference between two input voltages
D. Integral of the input voltage

13 An op-amp integrator produces an output that is the:

op-amp RC circuits – op-amp integrator Easy
A. Inverse of the input frequency
B. Integral of the input signal
C. Sum of two inputs
D. Derivative of the input signal

14 In a basic op-amp integrator circuit, the feedback element is a:

op-amp RC circuits – op-amp integrator Easy
A. Inductor
B. Capacitor
C. Diode
D. Resistor

15 An op-amp differentiator gives an output proportional to the:

op-amp differentiator Easy
A. Integral of the input signal
B. Average of the input signal
C. Peak value of the input signal
D. Rate of change of the input signal

16 In a basic op-amp differentiator circuit, the input element is a:

op-amp differentiator Easy
A. Capacitor
B. Transistor
C. Resistor
D. Inductor

17 An active high-pass filter differs from a passive one because it includes an:

active high pass filter Easy
A. Additional transformer
B. Operational amplifier for gain
C. Extra ground connection
D. External battery only

18 An active band-stop filter is designed to:

active band stop filter Easy
A. Pass only a narrow band of frequencies
B. Reject a specific range of frequencies
C. Amplify only DC signals
D. Pass all frequencies equally

19 Compared to passive filters, active filters generally offer:

active filter Easy
A. Lower cost always
B. Gain greater than unity
C. No need for a power supply
D. The ability to work only at DC

20 When used as a comparator, an op-amp output switches based on:

op-amp as a comparator and its application in anti-lock braking systems Easy
A. The frequency of the input
B. The capacitor charge time
C. The resistor tolerance in the circuit, which determines the exact threshold voltage for switching the output state
D. Which input voltage is larger

21 A passive RC low-pass filter has and . What is its cutoff frequency?

low-pass filter Medium
A.
B.
C.
D.

22 In a passive RC high-pass filter, how does the output behave as the input frequency approaches zero (DC)?

high-pass filter Medium
A. Output approaches zero
B. Output doubles the input
C. Output equals the input
D. Output becomes infinite

23 A band-pass filter has a lower cutoff of and an upper cutoff of . What is its bandwidth?

band-pass filter Medium
A.
B.
C.
D.

24 An inverting amplifier uses and . What is its voltage gain?

inverting and non-inverting op-amp Medium
A.
B.
C.
D.

25 A non-inverting amplifier has and . What is its voltage gain?

inverting and non-inverting op-amp Medium
A.
B.
C.
D.

26 In an inverting op-amp circuit, why is the inverting input terminal called a virtual ground?

simple op amp circuits â virtual ground concept Medium
A. It floats at the supply voltage
B. It is held at nearly by feedback without a physical ground connection
C. It carries large current to ground
D. It is directly wired to the ground rail

27 For an ideal operational amplifier, what are the input impedance and output impedance respectively?

properties of operational amplifier Medium
A. Infinite and zero
B. Infinite and infinite
C. Zero and infinite
D. Zero and zero

28 An op-amp has an open-loop gain of and a maximum output of . What differential input voltage drives the output to saturation?

device properties of the operational amplifier Medium
A.
B.
C.
D.

29 A summing amplifier has inputs and through equal input resistors , with feedback resistor also . What is the output voltage?

op-amp as an adder and subtractor Medium
A.
B.
C.
D.

30 In a basic difference amplifier with all four resistors equal, if (non-inverting path) and (inverting path), what is the output?

op-amp as an adder and subtractor Medium
A.
B.
C.
D.

31 An op-amp integrator is given a constant positive DC input voltage. What is the resulting output waveform?

op-amp RC circuits â op-amp integrator Medium
A. A square wave
B. A linearly decreasing (negative-going) ramp
C. A constant positive level
D. A rising exponential

32 An op-amp differentiator receives a linear ramp input. What is the output?

op-amp differentiator Medium
A. A constant DC level
B. A linear ramp
C. A sine wave
D. An exponential decay

33 An active high-pass filter uses and in its frequency-selective network. What is the cutoff frequency?

active high pass filter Medium
A.
B.
C.
D.

34 A first-order active band-pass filter is commonly formed by cascading which two stages?

active band pass filter Medium
A. Two identical low-pass stages
B. A low-pass stage and a high-pass stage
C. A comparator and an integrator
D. Two identical high-pass stages

35 What is the primary function of an active band-stop (notch) filter?

active band stop filter Medium
A. Attenuate all frequencies equally
B. Attenuate a specific band while passing frequencies above and below it
C. Pass only a narrow band of frequencies
D. Pass all frequencies above a cutoff

36 What is a key advantage of an active filter over an equivalent passive RC filter?

active filter Medium
A. It consumes no power
B. It only uses inductors and capacitors
C. It works without any power supply
D. It can provide gain and avoids bulky inductors

37 When an op-amp is used as a comparator with slightly greater than the reference voltage , what is the output?

op-amp as a comparator and its application in anti-lock braking systems Medium
A. Zero volts
B. Negative saturation voltage
C. Positive saturation voltage
D. Exactly

38 In an anti-lock braking system (ABS), how is an op-amp comparator typically used?

op-amp as a comparator and its application in anti-lock braking systems Medium
A. To amplify the brake pedal force linearly
B. To integrate the vehicle's acceleration over time
C. To compare a wheel's speed signal against a reference and detect impending lock-up
D. To filter out engine noise from the audio system

39 In a practical op-amp integrator, a large feedback resistor is placed across the capacitor mainly to:

op-amp RC circuits â op-amp integrator Medium
A. Reduce the input impedance to zero
B. Increase the integration speed
C. Convert it into a differentiator
D. Prevent output drift and saturation from DC offset

40 An op-amp has a slew rate of . What is the minimum time required for its output to swing from to ?

device properties of the operational amplifier Medium
A.
B.
C.
D.

41 A passive first-order RC low-pass filter has and . At what frequency does the output power drop to half of the maximum, and what is the phase shift there?

low-pass filter Hard
A. , phase
B. , phase
C. , phase
D. , phase

42 A first-order passive RC high-pass filter is cascaded (unbuffered) with an identical stage. Compared to a single stage, how does the overall −3 dB cutoff frequency behave?

high-pass filter Hard
A. It shifts lower than the single-stage
B. It stays exactly at the single-stage
C. It becomes independent of R and C
D. It shifts higher than the single-stage due to loading interaction

43 A band-pass filter has a center frequency and a quality factor . What is its bandwidth and the approximate lower cutoff frequency?

band-pass filter Hard
A. ,
B. ,
C. ,
D. ,

44 In an inverting amplifier with an ideal op-amp, the inverting input is called a virtual ground. If a real op-amp has finite open-loop gain and the closed-loop gain magnitude is 100, what is the approximate voltage at the inverting node when ?

simple op amp circuits – virtual ground concept Hard
A.
B.
C. exactly
D.

45 An inverting amplifier uses and . A non-inverting amplifier is built to give the same gain magnitude. What feedback and input resistor ratio must the non-inverting stage use?

inverting and non-inverting op-amp Hard
A.
B.
C.
D.

46 A summing amplifier has inputs through and through , with . What is ?

op-amp as an adder and subtractor Hard
A.
B.
C.
D.

47 An ideal op-amp integrator has and . A constant input of is applied starting at with zero initial capacitor charge. What is at ?

op-amp RC circuits – op-amp integrator Hard
A.
B.
C.
D.

48 A practical op-amp differentiator adds a series input resistor to the capacitor to limit high-frequency gain. If , and , above what frequency does the circuit stop differentiating?

op-amp differentiator Hard
A.
B.
C.
D.

49 A first-order active high-pass filter (non-inverting) uses , , and sets a passband gain of 11. What are its cutoff frequency and passband gain in dB?

active high pass filter Hard
A. ,
B. ,
C. ,
D. ,

50 An active band-pass filter is formed by cascading a low-pass stage with and a high-pass stage with . What is the approximate center frequency (geometric mean) and bandwidth?

active band pass filter Hard
A. ,
B. ,
C. ,
D. ,

51 A band-stop (notch) filter is required to reject mains interference with a quality factor . What is the rejection bandwidth?

active band stop filter Hard
A.
B.
C.
D.

52 In an ABS system, a comparator compares a wheel-speed voltage against a reference proportional to vehicle speed. Hysteresis is added using positive feedback. What is the primary benefit of this hysteresis?

op-amp as a comparator and its application in anti-lock braking systems Hard
A. It prevents rapid chattering of the output near the threshold due to noise
B. It increases the comparator's open-loop gain
C. It converts the comparator into a linear amplifier
D. It eliminates the need for a reference voltage

53 An op-amp has a gain-bandwidth product (GBW) of . It is configured as a non-inverting amplifier with a gain of 50. What is the approximate closed-loop bandwidth?

properties of operational amplifier Hard
A.
B.
C.
D.

54 An op-amp has a slew rate of . What is the maximum frequency of a sine wave with peak amplitude that can be reproduced without slew-rate distortion?

operational amplifier abstraction- device properties of the operational amplifier Hard
A.
B.
C.
D.

55 A difference amplifier has all four resistors equal to . If is applied to the non-inverting path and to the inverting path, what is , and what is the ideal common-mode gain?

op-amp as an adder and subtractor Hard
A. , common-mode gain
B. , common-mode gain
C. , common-mode gain
D. , common-mode gain

56 A practical op-amp integrator places a resistor in parallel with the feedback capacitor , with input resistor . What is the DC gain and why is needed?

op-amp RC circuits – op-amp integrator Hard
A. DC gain ; increases integration accuracy at high frequency
B. DC gain ; limits DC gain to prevent output saturation from offset/bias
C. DC gain ; sets the unity-gain frequency
D. DC gain ; provides AC coupling only

57 A Sallen-Key second-order low-pass filter is designed for a Butterworth response. What damping/quality factor and cutoff behavior characterize this maximally flat response?

active filter Hard
A. , critically damped with 20 dB/decade rolloff
B. , with ripple in the passband and 40 dB/decade rolloff
C. , maximally flat passband with 40 dB/decade rolloff
D. , with a peaking passband and 20 dB/decade rolloff

58 An ideal op-amp differentiator with and receives a triangular input that ramps linearly from to over . What is the output voltage magnitude during this ramp?

op-amp differentiator Hard
A.
B.
C.
D.

59 An inverting amplifier is designed for a gain of −20 with . The op-amp has an input bias current. To minimize DC output error from bias currents, what resistor should be placed at the non-inverting input?

inverting and non-inverting op-amp Hard
A. (direct ground connection)
B. equal to
C. equal to
D. (parallel combination of and )

60 A comparator-based ABS controller detects impending wheel lock when wheel deceleration exceeds a threshold. If the wheel-speed sensor outputs a voltage proportional to speed and the circuit differentiates then compares it, what condition triggers the brake-release signal?

op-amp as a comparator and its application in anti-lock braking systems Hard
A. When the raw wheel-speed voltage equals the supply voltage
B. When the comparator operates in its linear region
C. When the differentiated signal (deceleration) crosses the negative reference threshold
D. When the integrated speed signal reaches zero
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