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Adventurer
Adventurer
5,584 Views
Registered: ‎05-27-2008

Eye scan - GTX RX Margin Analysis : Vertical offset parameter

Hello,

We are currently working on implementing the eye scan feature with a Kintex 7 (xc7k325tffg900-2).

 

I have seen that the vertical offset parameter (ES_VERT_OFFSET) can range from -127 to 127 (8-bit binary in LPM mode).

Can someone give me the value in voltage of this parameter (differential voltage threshold)? What is the maximum voltage value? Is it function of the amplitude of our input signal or is it fixed?

Thank you very much for your answer,

Hermine Feron.

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Moderator
Moderator
5,482 Views
Registered: ‎02-16-2010

Re: Eye scan - GTX RX Margin Analysis : Vertical offset parameter

ES_VERT_OFFSET as 8 bits which includes the values from -127 to 128 i.e., 256 codes and I think one code is 2 mv. So I expect that ES_VERT_OFFSET is covering 256*2=512mV
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Observer
Observer
4,804 Views
Registered: ‎04-02-2011

Re: Eye scan - GTX RX Margin Analysis : Vertical offset parameter

I'm wondering if there is any more discussion on this topic.

 

From looking through the DC and AC switching characteristics for the Kintex7 (DS183) you can see that the differential peak-to-peak voltage is 1.25V for speeds 6.6Gb/s and up (it's 2V peak to peak below 6.6Gb). If the peak to peak voltage is 1.25, would it make sense that the 256 steps (codes) of threshold would apply to the entire range? Meaning, each step would be about 4mV (or even greater in the 2V peak to peak case).

 

I'm trying to work this out myself, so please let me know if this isn't the case.

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