IV) COMPARATORS
Operational amplifiers are often used as comparators to compare the amplitude of one voltage with another.
In this application, the op-amp is used in the open-loop configuration (no feedback path), with the input voltage on one input and a reference voltage on the other.
Without a feedback path, the voltage gain of the circuit will be equal to the value of AOL for the op-amp.
The gain of a comparator is equal to AOL.
A comparator is a specialized op-amp circuit that compares two input voltages and produces an output that is always at either one of two states (high output or low output), indicating the greater or less than relationship between the inputs.
The comparator is a relatively simple circuit used to compare two voltages and provide an output indicating the relationship between those two voltages.
Level detector is a comparator used to compare an input voltage to a fixed dc reference voltage.