Introduction:
The goal of this Confluence page is to explain an application of operational amplifiers, specifically Comparators, in addition to explaining the fundamentals of an Operational Amplifier. This also serves as an explanation to our HW onboarding activities, where we ask people to design a simple comparator circuit. There is an extension question that asks people : What if the values being compared are the same? The solution will be explained in this article. It’s worth noting that Comparators are an application of an Operational Amplifier, however this doesn’t mean you should go buy an off-the-shelf Operational Amplifier to use as a Comparator. There are some reasons for this, but that is beyond the scope of this article.
What is an Operational Amplifier?
An operational amplifier, as the name suggests , amplifies signals. More specifically, it is an voltage amplifier with differential inputs, and usually a single-ended output(there is one output). In the diagram below, Vs+ and Vs- are the supply rails for the amplifier, so usually Vs+ = Supply Voltage and Vs- = Ground.
If it wasn’t clear already, op-amps operate on analog inputs, and can be used to amplify/attenuate these inputs and carry out mathematical operation(addition, subtraction, differentiation and integration, yes it can do calculus). Because of this, you’ll see opamps encountered in many circuits and ICs.