SIMILAR QUESTION - Explain Barkhausen’s criteria for principles of oscillation.

An oscillation is basically an “amplifier” which does not have any ac i/p but it operates on the principle of +ve feedback to generate an or sig on its own at its o/p.

Thus it is clear that an amplifier can work as an oscillator if +ve feedback is made to exit. However +ve feedback not always guarantees oscillation.

An amp will work as an oscillation if and only if it satisfies a set of condition called “Barkhausen’s criteria”

Barkhausen’s Criteria:

It should be satisfied by an amp with +ve feedback to ensure the sustained oscillation.

For an oscillator circuit, there is no i/p sig $'V_s "$ , hence the feedback sig $V_f$, itself should be sufficient to maintain the oscillations.

Statement:

An oscillator will operate at the frequency for which the total phase shift introduced as measured from the i/p terminates, through the amp a feedback network and back again to the i/p is precisely equal to 0 degree or 360 degree or integral multiple of 360 degree.

At the oscillator frequency, the magnitude of the product of open loop gain of the amp A and feedback factor B is equal/ greater than unity. $|Aβ|≥1$ . The product Aβ is called loop gain.