[SI-LIST] Correlation to lab measurement
- From: "Santangelo, Steven" <SSantangelo@xxxxxxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>
- Date: Tue, 8 Jun 2010 10:22:50 -0400
Hi All,
I'm trying to correlate some lab measurements to my simulations in
Cadence PCB SI (SpectraQuest). I have a 400MHz unidirectional LVDS
interface between two Xilinx devices that is terminated in 100ohms
inside one of the devices. My lab measurements show a pretty good
reflection occurring on the rising and falling edges of the waveform.
I'm trying to determine if this is being caused by the ball to I/O pad
trace length in the package (plus my BGA breakout). My simulation only
shows a slight bend in the waveform rather than the non monotonic ring
that I see in the lab. The bend does correlate well time wise (location
on the edge) with the lab measurement. I don't really know much about
the limitations of IBIS models so I'm wondering if some of the
discrepancy could be due to that.
FYI: I'm using the models that Xilinx "ibiswriter" puts out. The
rise/fall times of the waveforms are in the neighborhood of 300pS.
Thanks
Steve
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