RE: ibis VT curves

Hi,

With regards to:

1) Actually, with the question I had earlier, i found that after restarting
my computer, I did see the ramp data affect my simulation in HyperLynx, as
expected. Sorry about the confusion.

3) To my understanding, VI curves describe DC behaviour, and VT curves
describe transient behaviour.

Regards,
Betty Luk

> -----Original Message-----
> From: Simon Schaeffer [mailto:simon.schaeffer@cern.ch]
> Sent: Thursday, November 16, 2000 8:13 AM
> To: ibis
> Subject: ibis VT curves
>
>
> Hi,
>
> I'm working on ibis models and I met the same problem as
> Betty Luk, it's
> to say that in playing around with my IBIS model (changing
> the ramp data
> manually), I didn't see any changes with Sigxplorer (Specctraquest
> signal explorer expert). However, in making the same changes
> in the ibis
> model used in pspice I saw differences.
> I have done this with an ibis model with and without the VT curves.
> I have used "ibis2spice" from Intusoft but this program
> doesn't convert the VT curves, it just uses the [Ramp] parameters.
> So, I am trying to build a new ibis2spice program using the VT curves.
>
> My questions are:
>
> 1) Why doesn't the [Ramp] modifications influence the results (Betty
> Luk's question)
>
> 2) Why use the VT curves instead of the [Ramp] parameters?
> Is it "only"
> to get a more accurate curve?
>
> 3) I am puzzled by the apparent contradiction that might arise if both
> the
> VT and VI curves are available. For example, a VT curve has been
> specified with the following load:
>
>
> out -----/\/\/\/\/-----|
> 50 |
> + ___|___ 1.25V
> ---
> |
> |
> |
> GND
>
> Going from low to high, the VT curve switches from 400mV to 2V.
>
> How can I use this information for other loads?
> For example:
>
> - 50 Ohm load only
> (i.e. the dc offset has been removed. My simulated output
> will now want
> to be something defined by the VI curve. How do I sensibly use the VT
> curve in this case?)
>
> - 100 Ohm load only
>
> 4) Do I have to take into account the Rfixture and Vfixture
> values used
> while specifying the VT curves?
>
>
>
> Thanks for your feedback
> Simon Schaeffer
>
 
Received on Thu Nov 16 06:38:18 2000