An operational amplifier (op-amp) is an integrated circuit (IC) that amplifies the difference in voltage between two inputs.
In the most basic circuit, an op-amp acts as a voltage amplifier or a comparator. It can also be configured as a filter, phase shifter, buffer (voltage follower), etc.
Op-amps are widely used for various applications in almost all electrical appliances. For example, op-amps amplify analog signals from various sensors in IoT-connected home appliances and measuring instruments. A dual-supply op-amp has five pins: positive power supply, negative power supply, noninverting input, inverting input, and output. Generally, these pins are named as shown below. (The simboles of positive and negative power supply pins may be omitted in single-supply op-amps.) Since an op-amp is a differential amplifier, it amplifies a difference in voltage between the noninverting and inverting inputs and produces a single output voltage.
The polarity of the output signal is the same as that of the noninverting input and opposite to that of the inverting input.