I am learning about how to use Operational Amplifiers as comparators. I understand that comparators are used to compare an input signal to a reference voltage. However, I am having a hard time visualizing this.

Say that I wanted a comparator with a reference voltage of 0 V (therefore, the output will be either positive or negative depending on whether the input signal is positive or negative, respectively). How could I draw a circuit like this?

I hope my question is clear.


1 Answer 1


Electronics Tutorials actually has a very good diagram of this.

enter image description here

Henceforth, when you're talking about reference voltages, it can depend on the structure of the reference voltage itself and it can be determined by Kirchhoff's Laws, i.e. Kirchhoff's Current Law.

enter image description here

If you have any more questions, I invite you to check out that hyperlink I put at the beginning of my answer.

  • 1
    \$\begingroup\$ Thank you. I've actually already read this tutorial, but I think my main point of confusion is: is there no feedback top in a comparator? Because they never draw it out... \$\endgroup\$
    – Bee
    Commented Sep 5, 2018 at 23:58
  • 2
    \$\begingroup\$ @Bee You're welcome :) and that's correct. There aren't any feedback networks in these diagrams I have above. If there was any feedback, you would have your typical \$\displaystyle H=\frac{A}{1+A\beta}\$ transfer function.... Here, it's only \$H=A\$ so it's all feedforward. \$\endgroup\$
    – user103380
    Commented Sep 6, 2018 at 0:05

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