[SI-LIST] Re: Issues with Midpoint Crossing of DifferentialIBIS Buffer

Hi Adam,
Thanks for the tip, but I was already aware of that.

Regards,
Tim





Adam.Tambone@xxxxxxxxxxxxxxxxx
07/31/2002 01:40 PM

 
        To:     Timothy Coyle/Americas/NSC@NSC
        cc:     si-list@xxxxxxxxxxxxx@Internet
        Subject:        Re: [SI-LIST] Issues with Midpoint Crossing of 
Differential IBIS Buffer


Hello Tim,

Here is a small tip that you might not have tried yet.  The 'ramp' keyword
associated with B-Elements in HSPICE specifies what V-t data to use.
ramp=0 uses ramp data, ramp=1 uses the first set of V-t data for rising 
and
falling waveforms, and ramp=2 uses two sets each of V-t data for rising 
and
falling waveforms.  Perhaps this will help.

Rgds,
Adam




|---------+---------------------------->
|         |           "Timothy Coyle"  |
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>-------------------------------------------------------------------------------------------------------------------------------|
  |                                                        |
  |        To:      si-list@xxxxxxxxxxxxx                        |
  |        cc:                                                        |
  |        Subject: [SI-LIST] Issues with Midpoint Crossing of 
Differential IBIS Buffer                                           |
 
>-------------------------------------------------------------------------------------------------------------------------------|




Hi,
I am having issues with a differential IBIS buffer. When I run the file in
XTK, it works fine. When I run the file in HSPICE, the midpoint crossing
is not correct. The transition
rate and waveshape of an individual driver are good, but the midpoint
crossing is towards Vcc.  I checked the V-T data to see if the
rising/falling data crossed at the
midpoint, and it does. I'm wondering if this is a problem with the I-V or
V-T data, or both? Or is this a simulator issue? Instead of using a
differential load resistor, I tied
the outputs to a load resistor to a reference voltage (Vos), and then the
midpoint crossing was accurate.
Any suggestions/comments?

Regards,
Tim


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