For a ring osc. 3-stage is better than 4-stage in terms of jitter ? How to determine the stage number ?
I'm sorry to say you are wrong.
The more stage of ring-osc has better jitter performance due to their Q is better.
But the power consumption is high for the same frequency.
I usually simulate the phase noise to judge the number of stage and power.
Therefore, you need to know the phase noise spec. derived from jitter spec.
Of course, you need to prepare some margin.
Yibin.