Hi All,
I am simulating phase noise of a ring oscillator from 100Hz to 500MHz (pss +pnoise)
I am simulating phase noise of a free running oscillator ( Just a ring oscillator and no stimulus to ring oscillator ). The ring oscillator is parasitic extracted.
I am getting a phase noise profile which looks close to ideal specially beyond 100MHz (please see attached image). It is hitting close to spectre noise floor . I have two doubts :
1) Is my simulation correct ? During the course of measurement, the free running oscilator will show a phase noise profile which doesn't look anything like that shown by simulation ( Oscillator will drift and hence carrier will drift and hence phase noise measurement will be kind of wrong . Oscillator needs to be stabilized for measurement of phase noise)
2) Is there a way to make this good looking phase noise bad in simulation with free running ring oscillator. ( When I am using injection locked oscillator with injection source having the phase noise profile of a real source (agilent VSG) , I am getting almost correct phase noise profile)
Please advise
Thanks,
Vishal
