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Reference effect on PLL PN (Read 111 times)
Farzaneh
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Reference effect on PLL PN
Nov 02nd, 2018, 7:51am
 
Hi,
I followed Ken's paper "Predicting the Phase Noise and Jitter of PLL-Based Frequency Synthesizer" to simulate the PN of PLL. I also imported my data to Matlab. The problem is that the PN that I got from Matlab is like my open loop VCO and when I remove or add reference jitter the PN is same. I also tried it for the example at the end of paper, in this case the PN is like PLL PN but when I remove reference jitter, again there is no difference. what the problem is?

Farzaneh
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Ken Kundert
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Re: Reference effect on PLL PN
Reply #1 - Nov 2nd, 2018, 9:57pm
 
Is it possible that the other sources of noise are dominating over the noise from the reference.

-Ken
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Farzaneh
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Re: Reference effect on PLL PN
Reply #2 - Nov 2nd, 2018, 10:05pm
 
No, because only VCO and reference have noise and my PFD/CP isn't noisy. My blocks are exactly same as example at the end of paper and I only change the values with my values.

Farzaneh
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Ken Kundert
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Re: Reference effect on PLL PN
Reply #3 - Nov 3rd, 2018, 11:38pm
 
Why didn't you also turn off the noise in the VCO as well?

-Ken
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