RE: [IBIS] About Fork in The Package Model

From: Muranyi, Arpad <Arpad_Muranyi@mentor.com>
Date: Wed May 25 2011 - 15:26:06 PDT

Johann,

Unfortunately the IBIS package model cannot do any
forks or joins. The assumption in IBIS currently is
that there is a 1 to 1 mapping between pins and pads.

This is not going to help you in the short run, but
it is kind of funny that we just talked about this
in the IBIS Interconnect Task Group meeting today...

We are aware of the problem and we are trying to come
up with a solution, hopefully for the next major IBIS
spec.

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

-----Original Message-----
From: owner-ibis@eda.org [mailto:owner-ibis@eda.org] On Behalf Of
Nittmann, Johann
Sent: Wednesday, May 25, 2011 3:14 PM
To: ibis@server.eda-stds.org
Subject: RE: [IBIS] About Fork in The Package Model

Hi,

A particular signal in one of our packages is using a fan out (fork) to
4 locations on the die. Hence I am considering of defining a [Package
Model] for this single signal using fork etc. For all other signals I am
planning of just providing RLC models as part of the [Pin] definition.

Following your discussion below from 2007 on this topic - the end points
or die pads are not defined in the [Package Model] section - hence how
can EDA tool vendors connect the package to receiver ibis models? I am
trying to figure out how useful this forked [Package Model] will be to
our customers? From the discussion below this point was not clear.

Thanks,

Johann

Johann Nittmann
Principal Engineer
Cavium Networks
100 Nickerson Road
Marlborough, MA 01752
Tel: 508 683 8869

 

-----Original Message-----
From: owner-ibis@server.eda.org [mailto:owner-ibis@server.eda.org] On
Behalf Of Beal, Weston
Sent: Monday, May 07, 2007 2:13 PM
To: Lynne D. Green; Yasser Sabry; ibis@server.eda-stds.org
Subject: RE: [IBIS] About Fork in The Package Model

According to the IBIS 4.2 specification FORK and ENDFORK are allowed in
package models. I haven't seen them used in package models in a long
time. The only use I saw for FORK in a package model was to represent
the plating traces in ceramic PGA packages. That's been a few years ago.
So the answer to the original question is that the branch didn't go
anywhere. In the actual finished package the plating traces were just
stubs off the signal trace. They needed to be modeled correctly because
of the impedance discontinuity that they created.

Regards,
Weston

-----Original Message-----
From: owner-ibis@server.eda.org [mailto:owner-ibis@server.eda.org] On
Behalf Of Lynne D. Green
Sent: Monday, May 07, 2007 9:42 AM
To: 'Yasser Sabry'; ibis@server.eda-stds.org
Subject: RE: [IBIS] About Fork in The Package Model

Hello, Yasser,

FORK and ENDFORK not allowed in PKG models.
FORK and ENDFORK are allowed in EBD and ICM models.

- Lynne

"IBIS training when you need it, where you need it."

Dr. Lynne Green
Green Streak Programs
http://www.greenstreakprograms.com
425-788-0412
lgreen22@mindspring.com

-----Original Message-----
From: owner-ibis@eda.org [mailto:owner-ibis@eda.org] On Behalf Of Yasser
Sabry
Sent: Sunday, May 06, 2007 9:11 AM
To: ibis@eda-stds.org
Subject: [IBIS] About Fork in The Package Model

Hi all,

Fork is used to make branches. In EBD, it is clear where these branches
go
to as the destination node or pin is specified. However, in package
model
the destination is not clear for me. Where do the branches go to?

Thanks for your help,
Yasser Sabry

-------------------------------------------
Yasser Mohammed Sabry
Device Modeling Team
Analog/Mixed Signal - DSM Division
Mentor Graphics Egypt
Tel: (+202) 416 3613
Mob: (+2010) 1834833
Fax: (+202) 418 6945
E-mail: yasser_sabry@mentor.com
-------------------------------------------

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Received on Wed May 25 15:26:32 2011

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