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amplifier (AMP)

An amplifier (AMP) is an active quadripole with inputs and outputs. The input variable fed to it, which can be an input voltage, is increased by the amplifier by a certain gain factor and made available as an output variable. In all amplifiers, the gain is frequency dependent and causes a frequency response.

Generally, amplifiers use active electronic components, electron tubes, transistors, MOSFETs or other active components. Since they are used in different applications, their circuit design is adapted to the corresponding requirements. In this context, one speaks of amplifier classes, which are marked with letters. In addition to the generally comparable amplifier classes, there are also manufacturer-specific amplifier classes.


circuit symbols

circuit symbols

Amplifiers are used wherever an attenuated signal level has to be adapted, for example in transmission lines, receiving equipment, radios, mobile phones, audio equipment, etc. Depending on the application, amplifiers are divided into RF amplifiers, preamplifiers, IF amplifiers and power amplifiers. According to the circuit principle, a distinction is made between operational amplifiers, chopper amplifiers and differential amplifiers, and in terms of characteristics between linear amplifiers, logarithmic amplifiers, parametric amplifiers and summing amplifiers.

Important parameters of amplifiers include gain and frequency response, power output, efficiency, input and output impedance, linearity, and phase and group delay. In LANs, amplifiers are generally referred to as repeaters because they usually also perform regeneration functions.

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Englisch: amplifier - AMP
Updated at: 29.08.2018
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