Don't attach pictures of PSS/Pnoise setting GUI.
It is very difficult to see necessary information from those.
Always you attach many useless pictures.
Show me netlists regarding analysis statements, option statements and signal source definitions.
I wrote this repeatedly in this thread.
I checked the time period of all nodes and found 10n,20n,60n,120n.
There are many nodes in your circuit.
They are not only four nodes.
Surely confirm all nodes.
The Designer's Guide Community Forum - Beat frequency for a dual modulus divider
Then I tried setting "beat period=240n",to my surprise,it converged finally.
But I don't think the result is correct.
Rather my surprise is that you can't understand a working mechanism of your frequency divider at all.
Obviously your "relharmnum" is wrong in your Pnoise setting.
Show me time domain waveforms as results of PSS.
1.The "Conv norm" is 76.5e-03,is it right?
Right.
And it takes only 6 iterations to converge in Shooting-Newton-PSS.
So your circuit is very easy for Shooting-Newton-PSS.
2.When PSS converges,the freq=4.16667MHz+(10KHz->100MHz) in PNoise.
Again your "relharmnum" is improper in your Pnoise setting.
The 4.16667MHz is just 240n which is beat period.
Again don't use a term of "beat" !!
I think it is wrong doing PNoise like this, am I right?
Needless to say, wrong.
And the phase noise is also awful.
Again your "relharmnum" is improper in your Pnoise setting.
Again show me netlists regarding analysis statements, option statements and signal source definitions.
It seems a fundamental frequency of your circuit is "200MHz/48".
If you want to observe noise around "200MHz/4", you have to set "relharmnum" as "12" in Pnoise setting.
Your "maxsideband=7" is too small in Pnoise setting.
And you have to include "12" as "Output Harmonics" in PSS setting.
Surely read my appends in this thread.
pss pss fund=200M/48 harmsvec=[48 24 12 6 3 0] maxacfreq=10*200M
+ maxperiods=200 maxiters=15
+ tstab=1.2u // 5*fund_period=5*(48/200MHz)
+ outputtype=all
+ errpreset=moderate annotate=status
pnoise ( fout 0 ) pnoise sweeptype=relative relharmnum=12
+ start=10k stop=100M dec=11 maxsideband=10*48 annotate=status
As I've thought, your problem is very easy.
Surely understand a working mechanism of your frequency divider correctly before EDA Tool Play.
I also wrote this very early in this thread.
and somebody has the same issue as mine.
I don't think so.
I think simply fundamental frequency is not correct.
At least, frequency at "P4" can be never 200MHz/4.
Again surely confirm time period of all nodes.
How are they different ?
I don't think your problem can be resolved even if you use Cadence Spectre instead of Synopsys HSPICE.
Methodolgies of simulation are completely same even if you use any vendor's simulator.
I think you need a study of basic theory of PLL before EDA-Tool-Play.
All problem is simply that you can't understand a working mechanism of your frequency divider at all.