Operational amplifier
The μA741, a popular early integrated op amp | |
| Component type | Discrete circuit Integrated circuit |
|---|---|
| Inventor | Karl D. Swartzel Jr. |
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| Electronic symbol | |
Circuit diagram symbol for a representative op amp. Pins are labeled as listed above. | |
An operational amplifier (often op amp, op-amp, or opamp) is a DC-coupled electronic amplifier with a differential input, a (usually) single-ended output voltage, and an extremely high gain. Its name comes from its original use of performing mathematical operations in analog computers. The voltage-feedback opamp (VFOA or VFA, the focus of this article) amplifies the voltage difference between its two inputs, while the less common current-feedback op amp (CFOA) amplifies the current between its two inputs.
By using negative feedback, the characteristics of an op amp application circuit (e.g., its gain, input and output impedance, bandwidth, and functionality) 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 (an op amp with a differential rather than single-ended output), the instrumentation amplifier (usually built from three op amps), the isolation amplifier (with galvanic isolation between input and output), and negative-feedback amplifier (usually built from one or more op amps and a resistive feedback network).