negative feedback: Circuit principle of an amplifier. A defined part of the amplified signal (see Signal) returns to the input (input) phase-inverted. Through the counter-coupling. the amplification factor can be set precisely and distortion components are reduced, but runtime and timing problems arise. This is why negative feedback is rarely used today.
If it is used anyway, then mainly four reasons:
- to stabilize the gain factor
- to increase the bandwidth
- can output impedance to reduce
- and finally also to minimize the non-linear distortions.
The aspect of distortion reduction seems to stir the spirits the most. Negative feedback is a very effective measure to keep distortions, as measured by a corresponding measuring device, small.
Not to forget: Negative feedback reduces the overall level of distortion but adds new distortion products in the process – tempting the designer to use multiple cascaded gain stages to improve the readings (apart from the greater amplifier stability that this brings).