How to know the noise floor level or the corner frequency in PSS?

[Beardolphinaries]

Hi, I am doing ring oscillator
When I use PSS and Pnoise, I can see the 1/f^3 and 1/f^2 in the phase noise curve, but this curve go further down as frequency offset increase. It doesn't calculate the noise floor, does it? If so, how I can know the noise floor level or the corner frequency?

Thansk a lot.

 

[lijianheng]

Re: Phase noise in PSS

What is the minimum value of phase noise and the offset frequency value?

 

[Beardolphinaries]

Re: Phase noise in PSS

The ring oscillator works at several GHz, and the phase noise is about
-65dBc/Hz @ 200kHz
-83dBc/Hz @ 1MHz.
the 1/f^3 and 1/f^2 corner is at less than hundreds of kHz, after that, the phase noise reduce at 20dB/dec at the theory. But there should be a corner of noise floor, isn't there? So, I doubt Spectre doesn't calculate this? or I need to something?
Thanks a lot.

 

[lijianheng]

Re: Phase noise in PSS

-83dBc@1MHz should be far from the noise floor, you may need to enlarge the offset range to see it.

 

[mooner]

Phase noise in PSS

the corner of noise floor is about 30M in my ring vco