An amplifier, electronic amplifier or (informally) amp is a digital gadget that can boost the power of a signal (a time-varying voltage or current). An amplifier makes use of electric power from a power supply to increase the amplitude of a signal. The quantity of boosting offered by an amplifier is determined by its gain: the ratio of result to input. An amplifier is a circuit that could offer a power gain above one.

An amplifier could either be a different piece of equipment or an electrical circuit had within another gadget. Amplification is basic to contemporary electronics, and also amplifiers are widely used in mostly all digital devices. Amplifiers can be categorized in various methods. One is by the regularity of the digital signal being amplified; audio amplifiers magnify signals in the audio (noise) series of less than 20 kHz, RF amplifiers amplify frequencies in the superhigh frequency array in between 20 kHz as well as 300 GHz, and servo amplifiers and instrumentation amplifiers might work with very low frequencies to guide existing. A further difference is whether the result is a linear or nonlinear depiction of the input. Amplifiers can additionally be classified by their physical positioning in the signal chain; a preamplifier might come before various other signal processing stages, for example.

The initial useful tool that can intensify was the triode vacuum tube, designed in 1906 by Lee De Woodland, which caused the first amplifiers around 1912. Vacuum tubes were made use of in mostly all amplifiers till the 1960s– 1970s when the transistor, invented in 1947, replaced them. Today, many amplifiers use transistors, however vacuum tubes continue to be made use of in some applications.

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