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Registered: ‎06-28-2019

The unexpected phase difference change of the Clock after TX Phase Interpolator in Kintex Ultrascale Plus

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Hello everyone,

I encountered a problem when using the GTY TX PI which running in its PI Code Stepping Mode (Page.161 ug576).

According to my configuration, the clock phase difference between the TXOUTCLKPCS (after PI) and the GTREFCLK0 should increase with a step of 22ps. But actually, I got no increase within the first about 20 times configuration and got an abrupt phase increase (△phase = 1000/3.5Ghz = +286ps) in the next configuration. And in the following about 20 times configuration, the phase difference would stay still again. AND AGAIN, the next configuration would get an abrupt phase change: either +286ps(high chance) or -286ps(low chance).

The FPGA is XCKU13P-2i.My line rate is 3.5Ghz and the reference clk to CPLL is 175MHz. I have tried this experiment on the evaluation board KCU116 (XCKU5P FPGA) and got the same results. But on the evaluation board KCU105 (XCKU040) the result was just as expected.

I am very confusing about that, does anyone have any ideas or suggestions?

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Xilinx Employee
Xilinx Employee
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Registered: ‎10-19-2011

Hi wubo123@mail.ustc.edu.cn ,

from the page number you tell I guess you are looking at an older version of ug576. Current version is v1.6 and here the sequence for US+ GTH is given on page 165.

For an updated version of the sequence to use for US GTH please check with AR73258.

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Xilinx Employee
Xilinx Employee
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Registered: ‎10-19-2011

Hi wubo123@mail.ustc.edu.cn ,

from the page number you tell I guess you are looking at an older version of ug576. Current version is v1.6 and here the sequence for US+ GTH is given on page 165.

For an updated version of the sequence to use for US GTH please check with AR73258.

------------------------------------------------------------------------------
Don't forget to reply, give kudo and accept as solution
------------------------------------------------------------------------------

View solution in original post

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