[IBIS] RE: [ibis-macro] Re: IBIS-ISS Package Modeling Next Steps

Walter,

This is mostly a question about the supply voltages concept on
slides 8 and 9 of your presentation. I am not sure why this is
really necessary for several reasons.

The first is that a supply voltage model could be connected to
the power pin(s) of the package by the user of the EDA tool in
the design.

But if your argument is that the user would not know what the
voltages are supposed to be unless they are defined/documented in
the IBIS file somewhere, the other way of doing this would be in
an IBIS-ISS subcircuit. IBIS-ISS does have a DC voltage source,
and it has the rest of the elements to describe the parasitics
too. The model maker can put DC sources into their IBIS-ISS
package model or on-die interconnect model, or they can make a
specific IBIS-ISS power supply model and connect it to the
on-die pad/bump/node that it supposed to power up. This could
be done with the same mechanisms or syntax we would use for
instantiating on-die interconnects, or package "slice" models.

Voltage and parasitics variations could be parameterized and
associated with the simulation corner that way.

If there is a need for a self-powered and an unpowered model,
the model maker could use the [Alternate Package Model] keyword
and let the user select from two models, one that is powered
and another that is not powered. Or the powered model could
have a switch inside it in the form of a parameterized series
resistor that can have a very small or a very large value.

Do we really need this "special purpose" supply voltage syntax
(burden) in the specification?

Thanks,

Arpad
=================================================================

From: ibis-macro-bounce@freelists.org<mailto:ibis-macro-bounce@freelists.org> [mailto:ibis-macro-bounce@freelists.org]<mailto:[mailto:ibis-macro-bounce@freelists.org]> On Behalf Of Walter Katz
Sent: Tuesday, August 07, 2012 6:40 PM
To: IBIS-ATM
Subject: [ibis-macro] IBIS-ISS Package Modeling Next Steps

All,

At the next IBIS-ATM I would like to answer any questions about the presentation I gave today. Posted at:

http://tinyurl.com/cvykehz

or the full URL:

http://www.eda.org/pub/ibis/macromodel_wip/archive/20120806/walterkatz/IBIS-ISS%20Package%20Modeling/IBIS_ISS_Package_Modeling_120807.pdf

If you do have any questions, please either e-mail to this reflector or me directly.

More importantly, questions to the IC Vendor members:

1. Does the functionality described in this presentation satisfy your needs to generate package and on-die models using that your customers require?

2. If not, what additional functionality do you need?

3. Please e-mail answers to question 2 to this reflector or me directly in advance of the next IBIS-ATM meeting.

Finally, we need to decide whether to pursue this methodology, or use the methodology describes in BIRDs 125 and 145:

http://www.vhdl.org/pub/ibis/macromodel_wip/archive/20120724/arpadmuranyi/Package%20Modeling%20in%20IBIS/PackageModeling_with_BIRD125_145.pdf

Make IBIS-ISS Available for IBIS Package Modeling<http://www.eda.org/ibis/birds/bird125.1.txt>

Cascading IBIS I/O buffers with [External Circuit]s using the [Model Call] keyword<http://www.eda.org/ibis/birds/bird145.2.txt>

Walter

Walter Katz
wkatz@sisoft.com<mailto:wkatz@sisoft.com>
Phone 303.449-2308
Mobile 303.335-6156

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