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Contributor
Contributor
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Registered: ‎09-06-2018

GTH reference clock phase noise mask band of integration

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Hello,

I am trying to understand if my clock reference is matching GTH phase noise mask specification of the ds892-kintex-ultrascale-data-sheet. Table 54.

What is the max band of integration to consider if I am sourcing a 200 MHz clock frequency to a MGT reference clock input ? 

Also should I keep -130 dBc/Hz value for integration above1 MHz to the max band of integration when using a QPLL ?

Thank you for your help.

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Xilinx Employee
Xilinx Employee
273 Views
Registered: ‎03-30-2016

Hello @sby38 


>What is the max band of integration to consider if I am sourcing a 200 MHz clock frequency to a MGT reference clock input ?

Please use the following values for 200MHz :
Phase_noise_us.png


>Also should I keep -130 dBc/Hz value for integration above1 MHz to the max band of integration when using a QPLL ?

Yes. (but it should be -133.87 dBc/Hz instead)


BTW, There are many factors that have impact on your Transceiver signal quality transceiver other than REFCLK phase noise ( for example : power-rail noise, channel characteristic , input signal-integrity etc)
So, It is a good thing ensure your REFCLK phase noise is within the value mentioned in Table 54, but please confirm if your IBERT eye-scan result has a wide open eye that satisfy the following eye-mask.
EyeScan_Mask.png


Regards
Leo

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Xilinx Employee
Xilinx Employee
274 Views
Registered: ‎03-30-2016

Hello @sby38 


>What is the max band of integration to consider if I am sourcing a 200 MHz clock frequency to a MGT reference clock input ?

Please use the following values for 200MHz :
Phase_noise_us.png


>Also should I keep -130 dBc/Hz value for integration above1 MHz to the max band of integration when using a QPLL ?

Yes. (but it should be -133.87 dBc/Hz instead)


BTW, There are many factors that have impact on your Transceiver signal quality transceiver other than REFCLK phase noise ( for example : power-rail noise, channel characteristic , input signal-integrity etc)
So, It is a good thing ensure your REFCLK phase noise is within the value mentioned in Table 54, but please confirm if your IBERT eye-scan result has a wide open eye that satisfy the following eye-mask.
EyeScan_Mask.png


Regards
Leo

View solution in original post

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Contributor
Contributor
255 Views
Registered: ‎09-06-2018
Thank you for your quick answer.
Regards
Stéphane