LMX2594EVM: LMX2594

Markus Reinhardt

Part Number: LMX2594EVM

Tool/software:

How is the phase noise power spectral density of VCO and OSC calculated from the given values for 1/f^3 noise and 1/f2 noise and noise floor of VCO and OSC
they are given as dBc/Hz values for 1/f^3 and 1/f^2 and the floor in PLLatinum Simulator.
Could someone tell me the formulas.

Thanks a lot

over 1 year ago

0 Noel Fung over 1 year ago

TI__Guru** 107300 points

Hi Markus,

I found some explanation from the user's guide (Help --> Users Guide).

0 Markus Reinhardt over 1 year ago in reply to Noel Fung

Prodigy 20 points

Hi Noel,

indeed I had read that sentence also before I asked my question. This section in the user guide refers to a system of three equations that I do not know but would like to know. I have a rough idea how they might be derived, but did not yet succeed in setting those up. If someone could help here, very much appreciated.

Markus

+1 Dean Banerjee over 1 year ago in reply to Markus Reinhardt

TI__Mastermind 28001 points

Markus,

The 1/f^3 noise changes 30 dB/decade, the 1/f^2 noise changes 20 dB/decade, and the floor is flat. So if you have 3 phase noise points at different offsets, you get 3 equations and 3 unkonwns.

My PLL book talks about this in chapter 22, page 185. Also see equation 22.13 in this same chapter.You can download it for free or order it for print at:

https://deanbanerjeepll.com/pll_book_page.html

Regards,

Dean

0 Markus Reinhardt over 1 year ago in reply to Dean Banerjee

Prodigy 20 points

Dean,

thanks a lot. That helps and by the way: your book is excellent! I recommend it to everybody interested in PLLs.

Regards,

Markus

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LMX2594EVM: LMX2594