Does Oscillator Need Feedback? If yes, Positive Or Negative?

yes, a positive feedback is required. As oscillator does not use any input ideally so it uses positive feedback. When output is applied to the input , it is called positive feedback. This is also due to the Bakhausen criterion.

Osillator which means producing output without input, it means we give feedback as input.The input must be positive-directly taken from output,so it is called as positive feedback.If the feedback was negative, it would serve to damp the oscillation and to "kill" the oscillator.

B. R. Sainyes, a positive feedback is required. As oscillator does not use any input ideally so it uses positive feedback. When output is applied to the input , it is called positive feedback. This is also due to the Bakhausen criterion.

thanks @ #-Link-Snipped-#.
what is Bakhausen criterion

^^ Barkhausen criterion is a set of conditions under which a linear electronic circuit will oscillate.

<a href="https://en.wikipedia.org/wiki/Barkhausen_stability_criterion" target="_blank" rel="nofollow noopener noreferrer">Barkhausen Stability Criterion</a>

Actally, the 2 condtions are, simply,

1) The loop gain should be 1 and
2) The phase shift around the lop should be zero or a multiple of 2*pi

If these conditions are satisfied, then that circuit will oscillate.

Why - ve feed not produce oscillations