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Unit 5 - Practice Quiz

ECE221

1 In an inverting summing amplifier with three input voltages applied through resistors respectively, and a feedback resistor , what is the output voltage ?

A.
B.
C.
D.

2 To configure an inverting summing amplifier as an averaging amplifier for inputs, which of the following conditions must be met?

A.
B. where all input resistors are equal
C. where all input resistors are equal
D.

3 What is the primary advantage of an Instrumentation Amplifier over a basic differential amplifier?

A. Higher bandwidth
B. Lower power consumption
C. High CMRR and high input impedance
D. Simpler circuit design

4 In a standard three-op-amp instrumentation amplifier, how many resistors are typically varied to adjust the gain?

A. One ()
B. Two
C. Three
D. All resistors

5 A voltage-to-current converter with a floating load is typically used in which application?

A. Driving a speaker
B. Low voltage signaling
C. Driving a grounded load
D. Testing diodes or driving panel meters

6 For a voltage-to-current converter with a floating load (load in feedback), the output current is given by:

A.
B.
C.
D.

7 Which circuit configuration is commonly used for a Voltage-to-Current converter with a grounded load?

A. Basic Inverting Amplifier
B. Voltage Follower
C. Howland Current Pump
D. Differentiator

8 A current-to-voltage converter is also known as a:

A. Transconductance amplifier
B. Transimpedance amplifier
C. Voltage follower
D. Difference amplifier

9 In an ideal basic integrator circuit using an op-amp, the feedback element is:

A. A Resistor
B. A Capacitor
C. An Inductor
D. A Diode

10 If a square wave is applied to the input of an ideal integrator, the output will be:

A. A Sine wave
B. A Triangular wave
C. A Square wave
D. A Spike

11 What is the primary problem with a basic ideal differentiator at high frequencies?

A. It stops working
B. The gain decreases
C. It becomes unstable and amplifies high-frequency noise
D. It turns into an integrator

12 To convert an ideal differentiator into a practical differentiator, what component is added?

A. A capacitor in parallel with the input resistor
B. A resistor in series with the input capacitor
C. A resistor in series with the feedback capacitor
D. An inductor in the feedback loop

13 A 'lossy integrator' or practical integrator includes a resistor in parallel with the feedback capacitor. What is the function of this resistor?

A. To increase the bandwidth
B. To limit the low-frequency gain and prevent saturation
C. To increase the slew rate
D. To convert it into a differentiator

14 The output of an op-amp differentiator is proportional to:

A. The integral of the input voltage
B. The rate of change of the input voltage
C. The amplitude of the input voltage
D. The square of the input voltage

15 Which of the following is an advantage of active filters over passive filters?

A. They require no power supply
B. They can provide gain and buffer the signal
C. They work at very high frequencies (GHz range)
D. They use inductors

16 What defines the 'order' of an active filter?

A. The number of op-amps used
B. The number of resistors used
C. The number of reactive elements (RC pairs) determining the roll-off
D. The value of the supply voltage

17 The roll-off rate of a first-order Butterworth filter is:

A. 20 dB/decade
B. 40 dB/decade
C. 6 dB/octave
D. Both A and C

18 In a First Order Low Pass Butterworth filter, the cut-off frequency is given by:

A.
B.
C.
D.

19 Which component configuration characterizes a First Order Active High Pass Filter?

A. Capacitor in the feedback loop
B. Capacitor in series with the input resistor at the non-inverting terminal
C. Capacitor in parallel with the input
D. Inductor in series with the input

20 What is the phase shift between input and output at the cut-off frequency for a first-order low-pass filter?

A. -90 degrees
B. -45 degrees
C. 0 degrees
D. -180 degrees

21 A Butterworth filter is characterized by:

A. Ripple in the passband
B. Ripple in the stopband
C. Maximally flat passband response
D. Fastest roll-off

22 A wide band-pass filter can be constructed by cascading:

A. A Low Pass Filter and a High Pass Filter where
B. A Low Pass Filter and a High Pass Filter where
C. Two Low Pass Filters
D. Two High Pass Filters

23 A Band Reject Filter is also commonly known as a:

A. Notch Filter
B. All-pass Filter
C. Delay Filter
D. Smoothing Filter

24 What is the primary function of an All-Pass Filter?

A. To attenuate all frequencies equally
B. To pass all frequencies with unity gain but change the phase
C. To block all frequencies
D. To remove noise

25 In a square wave generator using an op-amp (Astable Multivibrator), the feedback used is:

A. Only negative feedback
B. Only positive feedback
C. Both positive and negative feedback
D. No feedback

26 In an op-amp square wave generator, the frequency of oscillation depends on:

A. The supply voltage only
B. The RC time constant and the feedback fraction
C. The input offset voltage
D. The load resistor

27 A triangular wave generator is typically formed by connecting:

A. A differentiator to a square wave input
B. An integrator to a square wave generator
C. Two high pass filters in series
D. A voltage follower to a sine wave

28 In a triangular wave generator, what determines the slope of the ramp?

A. The amplitude of the square wave and the integrator RC time constant
B. The supply voltage of the integrator only
C. The feedback resistor of the comparator
D. The slew rate of the op-amp only

29 How is a sawtooth waveform different from a triangular waveform?

A. It has a constant frequency
B. It has equal rise and fall times
C. It has unequal rise and fall times
D. It is sinusoidal

30 A Voltage Controlled Oscillator (VCO) produces an output signal whose frequency is proportional to:

A. The input current
B. The input voltage
C. The supply current
D. The ambient temperature

31 Which logic creates a sawtooth wave generator from a triangular wave generator circuit?

A. Adding a diode in parallel with the integrator resistor
B. Using a larger capacitor
C. Removing the comparator
D. Using a dual supply

32 The Quality Factor (Q) of a Band Pass Filter determines:

A. The gain of the filter
B. The selectivity or sharpness of the passband
C. The input impedance
D. The DC offset

33 What is the gain of a voltage follower?

A. Infinity
B. Zero
C. Unity (1)
D. -1

34 In a first-order high pass filter, as frequency approaches infinity, the gain approaches:

A.
B. The passband gain defined by resistors ()
C. Infinity
D. -1

35 The phase shift of an All-Pass filter varies from:

A. 0 to 180 degrees
B. -90 to +90 degrees
C. 0 to 90 degrees
D. Fixed at 180 degrees

36 A scaling amplifier is essentially:

A. A summing amplifier where inputs have different weighting resistors
B. A unity gain buffer
C. A comparator
D. A differentiator

37 In a transconductance amplifier (Voltage-to-Current), if the load is grounded, the circuit relies on:

A. Positive feedback only
B. Matched resistors to balance the bridge (e.g., Howland)
C. A capacitor in the input
D. Open loop operation

38 The 'virtual ground' concept is most applicable to:

A. The non-inverting terminal in a non-inverting amplifier
B. The inverting terminal in an inverting amplifier with the non-inverting terminal grounded
C. The output terminal
D. The power supply pins

39 For a first-order low pass filter, if and , the cut-off frequency is approximately:

A. 159 Hz
B. 1.59 kHz
C. 15.9 kHz
D. 159 kHz

40 What happens to the output of an ideal integrator if the input is a constant positive DC voltage?

A. The output remains constant
B. The output ramps down linearly towards negative saturation
C. The output ramps up linearly towards positive saturation
D. The output oscillates

41 Which filter is used to remove mains hum (50Hz or 60Hz) from a signal?

A. Low Pass Filter
B. High Pass Filter
C. Narrow Band Reject (Notch) Filter
D. All-Pass Filter

42 In a Schmitt trigger (used in square wave generators), the hysteresis voltage is defined as:

A. The difference between the Upper Threshold Voltage () and Lower Threshold Voltage ()
B. The sum of the threshold voltages
C. The supply voltage
D. The offset voltage

43 To increase the period of oscillation in an op-amp square wave generator, one should:

A. Decrease the value of the capacitor C
B. Increase the value of the capacitor C
C. Remove the feedback resistor
D. Increase the supply voltage

44 The input impedance of an inverting summing amplifier is:

A. Infinite
B. Zero
C. Approximately equal to the corresponding input resistor for that channel
D. Equal to the feedback resistor

45 What is the effect of changing the duty cycle in a pulse generator?

A. It changes the frequency significantly
B. It changes the ratio of the ON time to the total period
C. It changes the amplitude
D. It converts the wave to a sine wave

46 Active filters are generally not suitable for:

A. Audio frequencies
B. Instrumentation signals
C. Very high voltage and high current applications
D. Biomedical signals

47 In a wide band-reject filter constructed by summing outputs, how are the filters arranged?

A. A Low Pass () and High Pass () in parallel, summed at output, with
B. Cascaded Low Pass and High Pass
C. Two All-Pass filters
D. Two Low Pass filters

48 Why is the Butterworth response often preferred for audio applications?

A. It has the steepest roll-off
B. It introduces the least phase distortion
C. It has no ripple in the passband (flat response)
D. It is the cheapest to build

49 The output of a differentiator for a sine wave input is:

A.
B.
C.
D.

50 A typical VCO IC used in analog electronics is:

A. IC 741
B. IC 555
C. IC 566
D. IC 7805