I have two questions regarding the phase noise simulation results (PSS + Pnoise) for ring oscillators:
(1) How much the precision of the initial oscillation frequency is important in estimating phase noise ?
(2) The results that I get for the phase noise seems a bit high. I feel there is a shift up in all the frequencies. In very low frequencies (close to carrier) the phase noise is largely positive. Comparing with the analysis presented in [Abidi, JSSC 2006] the phase noise sounds very high. Does someone has any idea that what could be wrong?
The ring oscillator designed to oscillate at 2.4 GHz using CML gates with a tail bias current of about 200 uA.
Thanks in advance for your help.
Still not enough info to go on. Can you contact customer support instead so you can provide all the necessary information to understand what you're doing? Did you use a more recent version of the simulator? (I'm a bit surprised lorenzian wasn't there with MMSIM72, so something sounds a bit strange in your setup; maybe it was a very early MMSIM72 version - I can't quite remember when it was introduced).
Either way, I'm not sure if that's what your problem is.