[SI-LIST] IBIS I/O model in HSPICE question

  • From: Ed Sayre III <esayre3@xxxxxxxx>
  • To: <si-list@xxxxxxxxxxxxx>
  • Date: Wed, 12 Feb 2003 18:15:52 -0500

Hi All,
    I am running an IBIS I/O model in HSPICE and have see some very strange 
results dependant on the input voltage swing.  I am using the Ibis I/O in 
the driver mode, driving a simple resistor load and another sim driving a 
match terminated 25 Ohm tline and resistor load.  According to Page 18-43 
of the 2000.2 manual either a 0-1V swing can be used for the input or a 
typical 0-3.3V input swing can be used.  When I compare the outputs of the 
I/O the two input level I find they are significantly different in wave 
shape and peak overshoot. The 3.3V swing gives significant overshoot spikes 
on the output node of the I/O model. When I look at the output current 
(very clean and controlled, it would seem that ohms law is not observed, 
this doesn't make sense.
     Does anyone have an idea of why this is occurring, and is it typical 
of Ibis model outputs run in HSPICE  to behave differently dependant on 
what voltage swing is applied to the input node of the driver??? BTW, I am 
in direct contact with the vendor so I am interested in seeing if people 
have seen this and if it is a model or an IBIS/HSPICE issue.

         Thanks in advance,


                         "High Performance Engineering & Design"
  Dr. Edward Sayre 3rd            e-mail: esayre3@xxxxxxxx
  NESA, Inc.                              http://www.nesa.com/
  5 Lan Drive, Suite 200          Tel  +1.978.392-8787 x 218
  Westford, MA 01886 USA       Fax +1.978.392-8686

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