Amplifier
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 Amplifier facts

• An amplifier functions by taking power from a power supply and controlling the output to match the input signal shape but with a larger amplitude
• In this sense, an amplifier modulates the output of the power supply based upon the properties of the input 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 discrete 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