*Feedback:-

feedback is simply refers to mixing a part of the output signal of amplifier with applied input.

• Feedback signal is basically inproportion to output signal, X ∝Y,

where, X- feedback siganl, Y-output siganl

X=KY, K- feedback factor/Reverse transmission factor

*Feedback is basically either positive feedback or negative feedback.

• Positive feedback:- If feedback signal ‘X’ is added to the applied input then it is called as ‘ positive feedback’

Z=W+X, where, W- Applied input

X- feedback, Z- net input.

Where, (X,Y,W,Z)– voltage/current

*In electronics and control systems positive feedback can increase the systems gain far too much which would give rise to oscillatory circuit responses as it increases the magnitude of the effective input signal.

*So simply positive feedback in electronics is used to boost gain and phase margin, that’s why it is preferred in oscillator.

*One of the most general applications of positive feedback in electronics are linear (harmonic) oscillators, which require an overall real loop gain of “+1”, which can be established using positive feedback only.

thanks &Regards

Rahul Mishra