In this section of Electronic Devices and Circuits.It contain Feedback Amplifiers MCQs (Multiple Choice Questions Answers).All the MCQs (Multiple Choice Question Answers) requires in depth reading of Electronic Devices and Circuits Subject as the hardness level of MCQs have been kept to advance level.These Sets of Questions are very helpful in Preparing for various Competitive Exams and University level Exams.
This Section covers below lists of topics :
- Feedback Amplifiers MCQs.
- Negative Feedback in Amplifiers MCQs.
Practice it now to sharpen your concept.
PRACTICE IT NOW TO SHARPEN YOUR CONCEPT AND KNOWLEDGE
1. Open-loop gain of an amplifier is given by:
- A
- Aβ
- β
- None of the above
A. A
2. Loop gain is given by:
- A
- Aβ
- β
- None of the above
B. Aβ
3. In a feedback amplifier, sensitivity D is equal to:
- Aβ
- 1 – Aβ
- 1 + Aβ
- 1/(Aβ + 1)
C. 1 + Aβ
4. In a negative feedback amplifier, voltage sampling:
- Tends to decrease the output resistance
- Tends to increase to output resistance
- Does not alter the output resistance
- Produces the same effect on output resistance as current sampling
B. Tends to increase to output resistance
5. In a negative feedback amplifier, current sampling:
- Tends to increase the output resistance
- Tends to decrease the output resistance
- Does not alter the output resistance
- Produces the same effect on input resistance as voltage sampling
B. Tends to decrease the output resistance
6. In a negative feedback amplifier, series mixing:
- Tends to increase the input resistance
- Tends to decrease the input resistance
- Does not alter the input resistance
- Produces the same effect on input resistance as shunt mixing
A. Tends to increase the input resistance
7. In a negative feedback amplifier, shunt mixing:
- Tends to increase the input resistance
- Tends to decrease the input resistance
- Does not alter the input resistance
- Produces the same effect on input resistance as the series mixing
B. Tends to decrease the input resistance
8. Negative feed back in an amplifier improves:
- The signal to noise ratio at the output
- Reduces distortion
- Both (a) and (b)
- None of the above
C. Both (a) and (b)
9. For a shunt-shunt negative feedback amplifier
- Input impedance decreases but output impedance increases
- Both input impedance and output impedance increases
- Both input impedance and output impedance decreases
- None of the above
A. Input impedance decreases but output impedance increases
10. An amplifier with the negative feedback:
- Controls the gain
- Reduces the noise
- Reduces phase distortion
- All of the above
D. All of the above
11. An amplifier with resistive negative feedback has two left half plane poles in its open-loop transfer junction. The amplifier will be:
- Stable for all frequencies
- Unstable for all frequency
- Stable for a particular frequencies
- Unstable for a particular frequencies
A. Stable for all frequencies
12. Barkhusen criteria is:
- Positive feedback, Aβ = 1, θ = 0 or multiple 360
- Negative feedback, Aβ = 1, θ = 0 or multiple 360
- Positive feedback, Aβ = 0, θ = 0 or multiple 360
- Negative feedback, Aβ = 1, θ = 180
A. Positive feedback, Aβ = 1, θ = 0 or multiple 360
13. The negative feedback in an amplifier
- Increase the voltage gain
- Decrease the voltage gain
- Stabilize the voltage gain
- B and C both are correct
D. B and C both are correct
14. One of the effects of negative feedback in amplifier is to
- Increase the noise
- Decrease the harmonic distortion
- Increase the voltage gain
- Decrease the bandwidth
B. Decrease the harmonic distortion
15. An emitter follower circuit is widely used in electric instruments because
- Its voltage gain is very high
- Its voltage gain is less than 1
- Input impedance is high and output impedance is low
- It employees no bypass capacitor
C. Input impedance is high and output impedance is low
16. Negative feedback in amplifier
- Increase the gain stability
- Decrease distortion and noise level
- Increase input impedance and decreases output impedance
- All of these
D. All of these
17. The input impedance of an amplifier can be increased from 2 kilo ohm 250 Kohm by introducing
- Shunt current negative feedback
- Shunt voltage negative feedback
- Series current negative feedback
- None of these
C. Series current negative feedback
18. The what is gain of an amplifier is 100, when negative feedback with m=0.04 is introduced, it's been will be
- 20
- 25
- 4
- 0.4
A. 20
19. With negative feedback, the returning signal
- Aids the input signal
- Opposes the input signal
- Is proportional to output current
- Is proportional to differential voltage gain
B. Opposes the input signal
20. How many types of negative feedback are there?
- One
- Two
- Three
- Four
D. Four
21. A VCVS amplifier approximates an ideal
- Voltage amplifier
- Current-to-voltage converter
- Current-to-voltage converter
- Current amplifier
A. Voltage amplifier
22. The voltage between the input terminals of an ideal op amp is
- Zero
- Very small
- Very large
- Equal to the input voltage
A. Zero
23. When an op amp is not saturated, the voltages at the non-inverting and inverting inputs are
- Almost equal
- Much different
- Equal to the output voltage
- Equal to +15 V
A. Almost equal
24. The feedback fraction B
- Is always less than 1
- Is usually greater than 1
- May equal 1
- May not equal 1
C. May equal 1
25. An ICVS amplifier has no output voltage. A possible trouble is
- No negative supply voltage
- Shorted feedback resistor
- No feedback voltage
- Open load resistor
B. Shorted feedback resistor
26. In a VCVS amplifier, any decrease in open-loop voltage gain produces an increase in
- Output voltage
- Error voltage
- Feedback voltage
- Input voltage
B. Error voltage
27. The open-loop voltage gain equals the
- Gain with negative feedback
- Differential voltage gain of the op amp
- Gain when B is 1
- Gain at funity
B. Differential voltage gain of the op amp
28. The loop gain AOLB
- Is usually much smaller than 1
- Is usually much greater than 1
- May not equal 1
- Is between 0 and 1
B. Is usually much greater than 1
29. The closed-loop input impedance with an ICVS amplifier is
- Usually larger than the open-loop input impedance
- Equal to the open-loop input impedance
- Sometimes less than the open-loop impedance
- Ideally zero
D. Ideally zero
30. With an ICVS amplifier, the circuit approximates an ideal
- Voltage amplifier
- Current-to-voltage converter
- Voltage-to-current converter
- Current amplifier
B. Current-to-voltage converter
31. Negative feedback reduces the
- Feedback fraction
- Distortion
- Input offset voltage
- Loop gain
B. Distortion
32. A voltage follower has a voltage gain of
- Much less than 1
- 1
- More than 1
- A
B. 1
33. The voltage between the input terminals of a real op amp is
- Zero
- Very small
- Very large
- Equal to the input voltage
B. Very small
34. The transresistance of an amplifier is the ratio of its
- Output current to input voltage
- Input voltage to output current
- Output voltage to input voltage
- Output voltage to input current
D. Output voltage to input current
35. Current cannot flow to ground through
- A mechanical ground
- An ac ground
- A virtual ground
- An ordinary ground
C. A virtual ground
36. In a current-to-voltage converter, the input current flows
- Through the input impedance of the op amp
- Through the feedback resistor
- To ground
- Through the load resistor
D. Through the load resistor
37. The input impedance of a current-to-voltage converter is
- Small
- Large
- Ideally zero
- Ideally infinite
C. Ideally zero
38. The open-loop bandwidth equals
- funity
- f2(OL)
- funity/ACL
- fmax
B. f2(OL)
39. The closed-loop bandwidth equals
- funity
- f2(OL)
- funity/ACL
- fmax
C. funity/ACL
40. For a given op amp, which of these is constant?
- f2(CL)
- Feedback voltage
- ACL
- ACLf2(CL)
D. ACLf2(CL)
41. Negative feedback does not improve
- Stability of voltage gain
- Nonlinear distortion in later stages
- Output offset voltage
- Power bandwidth
D. Power bandwidth
42. An ICVS amplifier is saturated. A possible trouble is
- No supply voltages
- Open feedback resistor
- No input voltage
- Open load resistor
B. Open feedback resistor
43. A VCVS amplifier has no output voltage. A possible trouble is
- Shorted load resistor
- Open feedback resistor
- Excessive input voltage
- Open load resistor
A. Shorted load resistor
44. An ICIS amplifier is saturated. A possible trouble is
- Shorted load resistor
- R2 is open
- No input voltage
- Open load resistor
B. R2 is open
45. An ICVS amplifier has no output voltage. A possible trouble is
- No positive supply voltage
- Open feedback resistor
- No feedback voltage
- Shorted load resistor
D. Shorted load resistor
46. The closed-loop input impedance in a VCVS amplifier is
- Usually larger than the open-loop input impedance
- Equal to the open-loop input impedance
- Sometimes less than the open-loop input impedance
- Ideally zero
A. Usually larger than the open-loop input impedance
