What is Barkhausen criteria for oscillation?

Answer 1

Looking at the expression, we note that when AB = -1, the gain is infinite this represents the condition for oscillation The requirements for oscillation are described by the Barkhausen criterion: The magnitude of the loop gain AB must be 1 The phase shift of the loop gain AB must be 180,or 180 plus an integer multiple of 360.

It should be mentioned that the criterion is necessary but not sufficient. The criterion is just an observation based on the assumption of a linear circuit.

Answer 2

Barkhausen Criteria: For sustained oscillations

1. The total phase shift around a loop is precisely 0 degree or 360 degree.

2. The magnitude of the product of open loop gain of the amplifier and the magnitude of the feedback factor is unity.

That is │Aβ│=1