Schmitt Trigger Using Op-Amp MCQ [Free PDF] – Objective Question Answer for Schmitt Trigger Using Op-Amp Quiz

11. The voltage level at which the comparator is saturated by a differential input equal to greater than a specified voltage is called

A. Zero output level
B. Positive output level
C. Negative output level
D. All of the mentioned

Answer: C

The negative output level or output low voltage is the negative dc output voltage with a comparator saturated by a differential input equal to or greater than the specified voltage.

 

12. When the logic level of strobe output is at zero, then the output current is called

A. Strobe terminal current
B. Strobe current
C. Strobe threshold current
D. Strobe’s bias current

Answer: B

The strobe current is the current out of the strobe terminal when it is of the zero logic current.

 

13. The strobe release time is defined as

A. Time required for output to rise to logic threshold
B. Time required for input to rise to logic threshold
C. Time required for output to rise to zero logic
D. Time required for output to rise to one logic

Answer: D

The strobe release time is the time required for the output to rise to the logic threshold voltage after the strobe terminal has been driven from zero to the one logic level.

 

14. Which of the following comparator can operate from ±15 to down to +5v supply in op-amp?

A. µA741
B. µA311
C. µA351
D. All of the mentioned

Answer: B

µA311 precision comparator is designed for low-level signal detection and high-level output drive capability. So, it can operate from ±15v op-amp supplies down to the logic +5v supply used for IC logic.

 

15. Find the comparator that has a slow response time

A. LM1414
B. µF311
C. ICL8001
D. None of the mentioned

Answer: A

LM1414 has a slow response time typically of 30ns, whereas µAF311 & ICL800 have a response time of 200ns and 250ns.

 

16. Why ICL8001 op-amp comparator is preferred for most applications?

A. Low power consumption
B. High response time
C. High input current
D. Balanced input offset voltage

Answer: A

The important feature of ICL8001 is low power consumption. It consumes power in the range of 30mw.

 

17. Which op-amp is preferred for applications like high-speed A-D converter and zero-crossing detector.

A. ICL8001
B. LM1414
C. µA311
D. µA670

Answer: D

µA670 is a high-speed differential voltage comparator with complementary TTL output. It has a typical response time of 16ns and operates from supplies of ±4.5v – ± 6.5v.

 

18. What is Barkhausen criterion for oscillation?

A. Aß > 1
B. Aß < 1
C. Aß = 1
D. Aß ≠ 1

Answer: C

The Barkhausen criterion for oscillation is Aß = 1.
Where A-> gain of amplifier and ß-> transfer ratio.

 

19. At what condition the output signal can be continuously obtained from the input signal?

A. When the product of input voltage and the feedback voltage is equal to 1
B. When the product of amplifier gain and transfer ratio is equal to 1
C. When the product of feedback voltage and transfer ratio is equal to 1
D. When the product of amplifier gain and the input voltage is equal to 1

Answer: B

When Aß=1, the feedback signal will be equal to the input signal. At this condition, the circuit will continue to provide output, even if the external signal is disconnected. This is because the amplifier cannot distinguish between external signal and signal from the feedback circuit. Thus, the output signal is continuously obtained.

 

20. An oscillator is a type of

A. Feedforward amplifier
B. Feedback amplifier
C. Waveform amplifier
D. RC amplifier

Answer: B

An oscillation is a type of feedback amplifier in which a part of the output is fed back to the input via a feedback circuit.

 

21. What is the condition to achieve oscillations?

A. |Aß|=1
B. ∠Aß=0o
C. ∠Aß=multiples of 2π
D. All the mentioned

Answer: D

All the conditions should be simultaneously satisfied to achieve oscillations.

 

22. What happens if |Aß|<1

A. Oscillation will die down
B. Oscillation will keep on increasing
C. Oscillation remains constant
D. Oscillation fluctuates

Answer: A

If |Aß| becomes less than unity, the feedback signal goes on reducing in each feedback cycle and oscillation will die down eventually.

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