How to determine the type of feedback in the ciruit?

crutschow

Joined Mar 14, 2008
30,805
If the feedback back to the input is in-phase with the input, the feedback is positive, and if it's out-of-phase, the feedback is negative.
 

#12

Joined Nov 30, 2010
18,223
Feedback is the title of the last Forum on the Forums page.:D

But seriously, most circuits with feedback use negative feedback. It controls gain, and controls gain across frequency ranges. Negative feedback diminishes distortion (if you do it right). The usual way to design is with more than enough gain and then control how much gain with negative feedback. In the other direction is oscillators. They use positive feedback. I've built a few unintentional oscillators myself.:p Another place for positive feedback is called hysteresis. You can change the switching point voltage of a comparator with positive feedback, but not turn it into an oscillator.
 

ScottWang

Joined Aug 23, 2012
7,295
If you try to ask a EE question, please name a practical circuit or attach a circuit, it is more easy to discuss, otherwise that is just like using your hand to catch the wind.
 
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