VCO phase noise simulation

[molotov]

vco phase noise simulation

Hello,

I'm using a tool to design and simulate different properties and C/C's of VCO.
When i try to simulate the phase noise on ELDO-RF with UMC 0.18u Design Kit, i get strange results:

1) The value of phase noise at 1Hz is over 0dB (actually it reaches 60dB or so)

2) The phase noise shape is somehow strange with the -30 and -20 dB/dec. slopes changed in some points....it became -20 then -40 then -20 !!!
i realized that its due to the varactor but i want to know if there is a soln. here as the phase noise is degraded so much.

Please if anyone faced any of this reply.

Thanks in advance,
Aboel3la

 

[AdvaRes]

Could you please tell me how did you plot it ?
Why your Y axis is in DB. Phase noise is in dBc, you know ?

You should obtain figures like this one: