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PLL BW measurement (Read 4865 times)
raja.cedt
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PLL BW measurement
Nov 08th, 2010, 5:16am
 
hi, can any please tell me how to find BW in silicon
I know that Intersecting point of VCO phase noise and pll phase noise point is almost BW. Is this exact method or can any one please explain often how people measures?


Thanks.
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Mayank
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Re: PLL BW measurement
Reply #1 - Nov 19th, 2010, 5:22am
 
Quote:
Intersecting point of VCO phase noise and pll phase noise point is almost BW
approximately, yes.
You could tell by pll phase noise graph itself in most of the cases.
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raja.cedt
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Re: PLL BW measurement
Reply #2 - Nov 19th, 2010, 6:22am
 
hi mayank,
how can you say from overal PLL phase noise. I htink from where phase noise start falling (means the boundary between inband and outoff band noise), do you have any document for this

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love_analog
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Re: PLL BW measurement
Reply #3 - Mar 3rd, 2011, 2:04pm
 
To measure PLL BW, you put a refclock with a modulated sinewave input. So you are modulating the phase of the input refclock. Then you look at the output on the spectrum analyzer. You should see a spur at the same frequency as the phase modulation. The measure of the spur compared to the input refclock spur gives you a value for the attenuation. At att=-3db is where PLL BW is.
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