Hi all I want to see the clock jitter in a ring oscillator output. I have tried but i cannot observe it. Anyone has any idea how to implement it........

Are you trying to simulate clock jitter? You would have to add noise sources. Otherwise you will get perfectly repeatable oscillations. If you simulate the digital locked loop circuit from caravel, that will show clock jitter (large cycle-to-cycle jitter) because the digital locking circuit generates the jitter by switching delay stages in and out. That's about the only way you can see jitter in simulation without manually injecting noise.