information:classification, structural:expansion
An operational amplifier is a DC-coupled electronic voltage amplifier with a differential input, a (usually) single-ended output, and an extremely high gain. Its name comes from its original use of performing mathematical operations in analog computers. By using negative feedback, an op amp circuit's characteristics can be determined by external components and have little dependence on temperature coefficients or engineering tolerance in the op amp itself. This flexibility has made the op amp a popular building block in analog circuits. Today, op amps are used widely in consumer, industrial, and scientific electronics. Many standard integrated circuit op amps cost only a few cents; however, some integrated or hybrid operational amplifiers with special performance specifications may cost over US$100. Op amps may be packaged as components or used as elements of more complex integrated circuits. The op amp is one type of differential amplifier. Other differential amplifier types include the fully differential amplifier, the instrumentation amplifier, the isolation amplifier, and negative-feedback amplifier.