However, the outputs signal produced with negative feedback has less distortion, given that the produced distortion itself has been subtracted and attenuated through the feedback loop.įigure 31 shows the basic schema of a global negative feedback loop.
Given that the distortion depends on the output level, in both cases, the distortion internally introduced is the same. Suppose we compare two output signals having the same level: one produced with global negative feedback and the other without. To better understand this, first note that distortion level produced by an amplifier stage depends on the output level and does not depend on its input level. Similarly, when a distorted output signal is fed back, and subtracted from the input signal, distortion is also attenuated. If the input and the output signals have identical shapes, the subtraction has the only effect of attenuating the input signal and consequently the produced output signal. Global negative feedback consists in using a negative feedback loop, which subtracts the output signal, appropriately attenuated, from the input signal. The effect of the global negative feedback can be explained intuitively as follows. If the distorted pre-amplified signal is given to a push-pull stage, its distortions are amplified as well.Ī technique to reduce distortions, across all amplifier stages, is the global negative feedback. When an input stage has a single-ended configuration and operates in non-linear areas, it produces distortions.
Push-pull stages are able to reduce harmonic distortions, specifically second order distortions, produced in the stage itself.
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