Subject: RE: [IBIS-Users] [Fwd: Validation of IBIS model]
From: Ingraham, Andrew (Andrew.Ingraham@hp.com)
Date: Tue Dec 31 2002 - 10:53:06 PST
The "ringing" that I see with the SPICE model, looks more like some sort of numerical oscillation that you sometimes get in SPICE, and not real ringing. This numerical oscillation is an uncommon but occasional artifact of SPICE. If present, it can usually be eliminated by using .OPTION METHOD=GEAR rather than the default TRAPezoidal method.
You don't say how long the transmission line is, but it is probably not causing the sub-nanosecond wiggles that you are seeing on the SPICE model waveform.
If it isn't numerical oscillation, another place to look would be the package parasitic modeling. Either the IBIS model, or the simulator's use of it, might have simplified the circuit representation of the package, compared to the SPICE model.
Regards,
Andy
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