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Phase Noise obtained from different methods (Read 203 times)
subtr
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Phase Noise obtained from different methods
Dec 12th, 2016, 12:15am
 
Hi,

I'm relatively new to design of PLL's/DLL's . I have constructed a delay line who's accumulated jitter is to be measured. I measured using :
1. Noise type = "time average" and plotted the PM and integrated it to get the jitter.

2. Noise type = "jitter" option and punched out Jc value.

3. Tran Noise : took each crossing of threshold and calculated the mean, std deviation of Period.

I don't see the results matching. I see there is always a factor of ~2 between 1) and 2). Are these methods consistent with each other? If not what do you suggest to be the right way of measurement of accumulated jitter in the output of a delay line? Embarrassed

Please Help.
Thank you.
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Re: Phase Noise obtained from different methods
Reply #1 - Dec 14th, 2016, 10:26am
 
Hi

The jitter you calculated from the "time average", by integrating the phase noise is the absolute jitter. The Jc value is the cycle jitter. Jc jitter is first difference of the absolute jitter. Thus, Jc is ~2x the absolute jitter.
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Re: Phase Noise obtained from different methods
Reply #2 - Dec 19th, 2016, 1:17am
 
Deba,

Thank you for the response. But I would also like to know why Tran Noise way of calculating accumulated jitter using matlab is not matching with the jitter Jc number. The matlab code has been tested and verified with many chip results is what I understand.


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