Characteristics of Operational Amplifier MCQ - Objective Question Answer for Operational Amplifier Characteristics Quiz

51. Open-loop op-amp configuration has

A. Direct network between output and input terminals
B. No connection between output and feedback network
C. No connection between input and feedback network
D. All of the mentioned

Answer: A

In an open-loop configuration, the output signal is not fed back in any form as part of the input signal and the loop that would have been formed with feedback is open.

52. In which configuration does the op-amp function as a high gain amplifier?

A. Differential amplifier
B. Inverting amplifier
C. Non-inverting amplifier
D. All of the mentioned

Answer: D

An op-amp functions as a high gain amplifier when connected in an open-loop configuration. These three are the open-loop configuration of an op-amp.

Differential amplifier
Inverting amplifier
Non-inverting amplifier

53. How does the open-loop op-amp configuration classified?

A. Based on the output obtained
B. Based on the input applied
C. Based on the amplification
D. Based on the feedback network

Answer: B

Open-loop configurations are classified according to the number of inputs used and the terminal to which the input is applied when a single input is used.

54. What will be the voltage drop across the source resistance of the differential amplifier when connected in an open-loop configuration?

A. Zero
B. Infinity
C. One
D. Greater than one

Answer: A

The source resistances are normally negligible compared to the input resistance. Therefore, the voltage drop across input resistors can be assumed to be zero.

55. The output voltage of an open-loop differential amplifier is equal to

A. Double the difference between the two input voltages
B. Product of voltage gain and individual input voltages
C. Product of voltage gain and the difference between the two input voltages
D. Double the voltage gain and the difference between two input voltages

Answer: C

The output voltage of an open-loop differential amplifier is equal to the product of voltage gain and the difference between the two input voltages.

56. Calculate the output voltage for the given circuit.

A. V_o = 7v
B. V_o = 5.9v
C. V_o = 12v
D. V_o = 11.4v

Answer: C

The output voltage, V_o = A*(V_in1-V_in2)

(Since R_in1 and R_in2 are negligible compared to input resistance in an open-loop differential amplifier).

= > V_o = 4*(12v-9v) = 12v.

57. Find the output of inverting amplifier?

A. V_o = AV_in
B. V_o = -AV_in
C. V_o = -A(V_in1– V_in2)
D. None of the mentioned

Answer: B

In an inverting amplifier, the input signal is amplified by gain A and is also inverted at the output. The negative sign indicates that the output voltage is of opposite polarity.

V_o = -AV_in

58. Determine the output voltage for the non-inverting amplifier input voltage 37µVpp sinewave. Assume that the output is a 741.

A. -7.44 Vpp sinewave
B. 74 Vpp sinewave
C. 7.4Vpp sinewave
D. 0.7 Vpp sinewave

Answer: C

The output voltage for non-inverting amplifier

V_o = A*V_in

= 200000 * 37µ = 7.4 Vpp sinewave.

59. What happens if any positive input signal is applied to an open-loop configuration?

A. Output reaches saturation level
B. Output voltage swing’s peak to peak
C. Output will be a sine waveform
D. Output will be a non-sinusoidal waveform

Answer: A

In open-loop configuration, due to the very high gain of the op-amp, any input signal slightly greater than zero drives the output to saturation level.

60. Why open-loop op-amp configurations are not used in linear applications?

A. Output reaches positive saturation
B. Output reaches negative saturation
C. Output switches between positive and negative saturation
D. Output reaches both positive and negative saturation

Answer: C

When operated in an open loop, the output switches between positive and negative saturation levels. For this reason, open-loop op-amp configurations are not used in linear applications.

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