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288 Views
Registered: ‎11-08-2018

IBERT on VCU108

Hello,

I am trying to evaluate GTY transceivers between 2 VCU108 boards with the IBERT IP (I am using the QUAD126 with a Bullseye connector on both sides).

When I am working in differential, everything is OK.

 But when I use them in single-ended-like scheme (only “_P” are connected), I have 2 kinds of figure:

  1. When the “_N” are left floating, everything is OK.
  2. When a 50 Ohm adaptation is placed on each “_N”, it is NOK (channels are not even locking)

 I tried 2 IBERT configurations and they are both giving these same results mentioned above. These configurations are:

  1. Link Coupling : AC + programmable termination = 800 mV
  2. Link coupling : DC + floating termination

 

Correct me if I am wrong but there is no AC coupling on the VCU108 board right?

 To be clear, my final goal is to make these links work with only the positive parts (“_P”). How could that be done?

Thank you for your guidance

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Xilinx Employee
Xilinx Employee
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Registered: ‎03-30-2016

Re: IBERT on VCU108

Hello @ultrascaleaddict

XF_VCU108.png

 

>Correct me if I am wrong but there is no AC coupling on the VCU108 board right?

Your understanding is correct.

>To be clear, my final goal is to make these links work with only the positive parts (“_P”). How could that be done?

Xilinx Transceivers (including GTY) are designed and tested to work with differential connectivity configuration. There is no guarantee that GTY will work with single-ended configuration, channels will have less margin. I am wondering how the IBERT EyeScan diagram looks like on your board.

Please consider to use HP I/O bank instead for single-ended.

 

Thanks & regards
Leo

 

 

 

 

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