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differential amplifier

Differential amplifiers are completely balanced amplifiers of high sensitivity with two inputs and outputs. In a differential amplifier, the input signals of inputs 1 and 2 are ideally amplified with identical gain factors and the same frequency response

and are available at outputs 1 and 2. If the input levels are identical, then the output levels are also identical, so there is no voltage between output 1 and 2, the differential voltage is zero

. Only if there are deviations between the input levels will a differential voltage build up between the outputs. The output amplitude is therefore always equal to the amplified difference between the input levels.

Block diagrams for differential amplifiers

Block diagrams for differential amplifiers

Identical input signals are suppressed, which is expressed in a high common-mode rejection. This property is also used for interference voltage suppression. If interference signals with the same polarity reach the two inputs, they are compensated by the common-mode suppression. This applies equally to hum signals as well as to interspersed RF signals.

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Englisch: differential amplifier
Updated at: 24.04.2010
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