Question

Question 20 (1 point)

The ________ circuit overcomes the problem of false switching caused by noise on the input(s).

A) Schmitt trigger

B) input noise eliminator

C) differentiator

D) input buffer

Confused on this one, mainly the wording. Books states a Schimtt trigger is built in a comparator for hysteresis which helps with noise, but a schimitt triiger is not a "circuit" from what I gather in the text. Out of all the options there, the only one the book refers to as a "circuit" is a differentiator. But it states that is noisy which the question reads from what I gather stops/overcomes the noise.

The other two options are not noted anywhere in the chapter.

My reference material is from Electronic Devices by Floyd 10th Ed Chapter 13. Any help will be appreciated. Thank you.

Answer 1

The answer is undoubtedly Schimtt trigger as it provides noise immunity over  those input signals which causes  the problem of false switching .

Yes Schimtt trigger is built of comparator basically operational amplifier but there is little  difference between Schimtt trigger and comparator

Schimtt trigger uses  one part as comparator as for Schimtt trigger it is necessary to have both input signal as well as positive feedback (feedback at non inverting terminal ) .

But for comparator it is necessary to have input signal and it is not necessary to have feedback .Sometimes a comparator have feedback and sometimes it does not.

The confusion between differentiator and Schimtt trigger of one being circuit and other not being circuit.

Both are circuits having common thing as operational amplifier

Differentiator has capacitor and resistor at non inverting amplifier and hence act as negative feedback where as Schimtt trigger has resistor only but having positive feedback .

  

COMPARATOR CIRCUIT

DIFFERENTIATOR CIRCUIT

SCHMITT TRIGGER CIRCUIT

So answer is Schmitt Trigger .