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SI simulation differs with real measurement a lot

Question asked by nate.wang on Jun 22, 2015
Latest reply on Jul 20, 2015 by matthias.cosaert

Hi Sir,

 

I am a beginner of Hyperlynx, try to do SI simulation as a reference for my next version of PCB design.

 

On my current PCB, there are 64 LVDS interfaces, all running at maximum 960Mbps, from eight ADC (ADI AD9279) to a FPGA (Xilinx Virtex-6).

 

Below is real measurement of one of the LVDS interface ( at 250Mbps, at FPGA side ) :

250Mbps.png

 

And below is SI simulation result from Hyperlynx,

as you can see, simulation result is totally different from the real measurement.

s1.png

stimulus setting as below :

s2.png

simulation trace :

board.png

 

On the other hand, we had previously assign a 3rd party company to perform SI simulation on these LVDS traces, below are two of the results :

 

at 480Mbps :

si-480Mbps.png

 

at 960Mbps :

si-960Mbps.png

 

They use exactly the same IBIS models of mine in Hyperlynx(also attached in this post), so I do think my problem is related to parameter setting in Hyperlynx (?).

 

Any comment is appreciated, thanks in advance.

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