Comparator

Op-amp comparator. The operational amplifier has a very high open-loop gain, so even slight differences between the positive and negative inputs cause the output to reach the supply rail voltages. When the non-inverting (positive) input is greater than the inverting (negative) input, the output is the positive supply rail voltage; when the non-inverting (positive) input is less than the inverting (negative) input, the output is the negative supply rail voltage.