Including submodel selection keyword in IBIS model

Hi SI users,

We have been generating IBIS models for DDR2 memory and have always come across
a problem
Of including multiple ODT options for IOs. If we can include "submodel
selection" option in the IBIS model,
It would be possible to provide multiple ODT options in a single IO IBIS model
rather than creating the separate IO model to incorporate
Different ODTs.

Thanks and Regards,


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Brijesh.Shah 5 years 11 months 19 days

3 answers

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Answered bykeeyoung.kwon 5 years 11 months 19 days
Hi Brijesh,
I think you've been generating ODT models through power/ground clamp (V/I)
without submodel selection.
In this case, it will need different power/ground clamp curves for each ODT
As you mentioned, it looks nice to adopt single I/O model with simple submodels.

But, even if you select [add submodel] for an ODT, it will need separately
dynamic clamps in the end of IBIS for each ODT cases.
I don't know which one is simple to describe ODT. I think it depends on a work
process using spice2IBIS for the schematics.

Whatever you select, it will not matter to SI users if their simulator handles
model selector correctly.


Answered byBrijesh.Shah 5 years 11 months 19 days

It does, but when I have an IO pad with 5 ODT options. I have to make 5
different IO models, each with one ODT submodel.
If we have submodel selection, we can do it all in one IO model.


Answered bybuenoshun 5 years 11 months 19 days

Does the "model selector" that we select in the simulator not serve this
Normally we select the ODT option with that.

Istvan Nagy