**Barkhausen’s criteria: **

1. Loop gain (β.Av) should be ≥ 1.

2. Phase shift between the input and output signal must be equal to 360^{0} or 0^{0}

Barkhausen's Criteria - To obtain sustain oscillation the loop gain AB = 1 and phase shift of feedback signal should be 0^{0} or 360^{0} of an amplifier. it is called as barkshausen's criteria.

Types -

RC oscillator

RC-Phase shift oscillator

Wien bridge oscillator

LC Oscillator

Hartley oscilator

Colpitts oscillator

Crystal oscillator