phase noise calculation using MATLAB [hlp]

[april1975]

Hello
I have analysed a CMOS PLL with HSPICE. I have tried transient analysis and printed the output data in a txt file.
Then I have used MATLAB for fft analysis of this txt file. Now, I want to calculate phase noise of the PLL. How I can do this? Is there any MATLAB function or SIMULINK block to do this?
Tnx

 

[april1975]

Hello
I have used MATLAB to get fft, log10 and then plot the output. But the output is:

I see that phase noise is about -10dBc/Hz for 100kHz and about -27dBc/Hz for 1MHz. Is it true?
About the PLL: an improved ring oscillator is used as VCO. pls hlp.