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 :

1. Feedback Amplifiers MCQs.
2. 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
• β
• None of the above

#### 2. Loop gain is given by:

• A
• β
• None of the above

• 1 – Aβ
• 1 + Aβ
• 1/(Aβ + 1)

#### 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

#### 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

#### 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

#### 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

#### 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

#### 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

#### 10. An amplifier with the negative feedback:

• Controls the gain
• Reduces the noise
• Reduces phase distortion
• 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

#### 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

#### 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

#### 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

#### 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

#### 16. Negative feedback in amplifier

• Increase the gain stability
• Decrease distortion and noise level
• Increase input impedance and decreases output impedance
• 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

• 20
• 25
• 4
• 0.4

#### 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

• One
• Two
• Three
• Four

#### 21. A VCVS amplifier approximates an ideal

• Voltage amplifier
• Current-to-voltage converter
• Current-to-voltage converter
• Current amplifier

#### 22. The voltage between the input terminals of an ideal op amp is

• Zero
• Very small
• Very large
• Equal to the input voltage

#### 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

#### 24. The feedback fraction B

• Is always less than 1
• Is usually greater than 1
• May equal 1
• May not equal 1

#### 25. An ICVS amplifier has no output voltage. A possible trouble is

• No negative supply voltage
• Shorted feedback resistor
• No feedback voltage

#### 26. In a VCVS amplifier, any decrease in open-loop voltage gain produces an increase in

• Output voltage
• Error voltage
• Feedback voltage
• Input 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

#### 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

#### 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

#### 30. With an ICVS amplifier, the circuit approximates an ideal

• Voltage amplifier
• Current-to-voltage converter
• Voltage-to-current converter
• Current amplifier

#### 31. Negative feedback reduces the

• Feedback fraction
• Distortion
• Input offset voltage
• Loop gain

#### 32. A voltage follower has a voltage gain of

• Much less than 1
• 1
• More than 1
• A

#### 33. The voltage between the input terminals of a real op amp is

• Zero
• Very small
• Very large
• Equal to the input voltage

#### 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

#### 35. Current cannot flow to ground through

• A mechanical ground
• An ac ground
• A virtual ground
• An ordinary 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

#### 37. The input impedance of a current-to-voltage converter is

• Small
• Large
• Ideally zero
• Ideally infinite

• funity
• f2(OL)
• funity/ACL
• fmax

• funity
• f2(OL)
• funity/ACL
• fmax

#### 40. For a given op amp, which of these is constant?

• f2(CL)
• Feedback voltage
• ACL
• ACLf2(CL)

#### 41. Negative feedback does not improve

• Stability of voltage gain
• Nonlinear distortion in later stages
• Output offset voltage
• Power bandwidth

#### 42. An ICVS amplifier is saturated. A possible trouble is

• No supply voltages
• Open feedback resistor
• No input voltage

#### 43. A VCVS amplifier has no output voltage. A possible trouble is

• Open feedback resistor
• Excessive input voltage

#### 44. An ICIS amplifier is saturated. A possible trouble is

• R2 is open
• No input voltage

#### 45. An ICVS amplifier has no output voltage. A possible trouble is

• No positive supply voltage
• Open feedback resistor
• No feedback voltage