1. alat elektronik yang digunakan untuk meningkatkan kekuatan sinyal masukan.
  2. komponen yang digunakan untuk meningkatkan pembesaran suatu mikroskop.
Merriam-Webster Online Dictionary
amplifier (noun)
one that - amplifies , specifically an electronic device (as in a stereo system) for voltage, current, or power - amplifying
amplifier (Wikipedia)
This article is about electronic amplifiers. For other uses, see Amplifier (disambiguation).
A 100 watt stereo audio amplifier used in home component audio systems in the 1970s.
Graph of the input (blue) and output voltage (red) of an ideal linear amplifier with an arbitrary signal applied as input. Amplification means increasing the amplitude (voltage or current) of a time-varying signal by a given factor, as shown here. In this example the amplifier has a voltage gain of 3; that is at any instant

An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the power of a signal (a time-varying voltage or current). An amplifier functions by using electric power from a power supply to increase the amplitude of the voltage or current signal. An amplifier is effectively the opposite of an attenuator: while an amplifier provides gain, an attenuator provides loss.

An amplifier can either be a separate piece of equipment or an electrical circuit contained within another device. Amplification is fundamental to modern electronics, and amplifiers are widely used in almost all electronic equipment. Amplifiers can be categorized in different ways. One is by the frequency of the electronic signal being amplified; audio amplifiers amplify signals in the audio (sound) range of less than 20 kHz, RF amplifiers amplify frequencies in the radio frequency range between 20 kHz and 300 GHz. Another is which quantity, voltage or current is being amplified; amplifiers can be divided into voltage amplifiers, current amplifiers, transconductance amplifiers, and transresistance amplifiers. A further distinction is whether the output is a linear or nonlinear representation of the input. Amplifiers can also be categorized by their physical placement in the signal chain.

The first practical electronic device that could amplify was the triode vacuum tube, invented in 1906 by Lee De Forest, which led to the first amplifiers around 1912. Vacuum tubes were used in almost all amplifiers until the 1960s–1970s when the transistor, invented in 1947, replaced them. Today most amplifiers use transistors, but vacuum tubes continue to be used in some applications.