[SI-LIST] Re: Package Model in IBIS
- From: "Muranyi, Arpad" <Arpad_Muranyi@xxxxxxxxxx>
- To: "si-list@xxxxxxxxxxxxx" <si-list@xxxxxxxxxxxxx>
- Date: Mon, 27 Jun 2011 16:35:24 +0000
Thanks Weston for filling in the gaps that I forgot to
address in my previous response. With that and another
private response I got, I would like to add that my hope
is that we will have a much more elegant solution for
IBIS package modeling very soon.
We are in the finishing stages of the new IBIS-ISS
specification (Interconnect Subcircuit Specification),
which basically standardizes the passive (and LTI) subset
of HSPICE with the permission of Synopsys, and will
include S-parameter support among many other useful
features:
http://www.eda.org/ibis/ibis-iss_wip/IBIS_ISS_review_draft_13.pdf
I have also submitted BIRD 125, which describes a
proposal for making use of IBIS-ISS for IBIS package
modeling:
http://www.eda.org/pub/ibis/birds/bird125.txt
This proposal is being discussed in the various IBIS
meetings, and my hope is that it will be accepted soon.
With these capabilities we could have a much improved
package modeling capability in IBIS. I can just see the
questions flooding in "when will all this be available"?
Unfortunately I do not know the exact dates, and I really
don't want to step out of my bounds here and say things
which are better said by our IBIS Chairman (Mike Mirmak),
but we are indeed in the finishing phase on IBIS-ISS now,
which could mean approval or official ratification around
the end of the summer. Regarding the upcoming versions
of IBIS, the plan is to have an "intermediate" version
with a bunch of IBIS-AMI corrections, and shortly thereafter
release another IBIS version with some additional new
features (for AMI and regular IBIS) which will address
the package modeling needs among others as well. My
guess and hope is that at least one of these should
possibly happen before this year is over...
Arpad
=========================================================
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Beal, Weston
Sent: Monday, June 27, 2011 11:05 AM
To: Newbie Pugal; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Package Model in IBIS
Pugal,
If the package pin length is much shorter than the signal rise/fall time then a
lumped RLC model is adequate to model the effect that the package has on the
signal. Also, the lumped L and C values can be used to calculate the effective
impedance (sqrt(L/C)) and delay (sqrt(LC)) of the pin. This assumption is good
as long as the delay is much shorter than the signal rise/fall time. As the
rise/fall time approaches the delay calculated from the lumped pin model, the
model becomes gradually less accurate. Depending on your accuracy needs, you
need to use a correct distributed package model when the delay through the
package is 1/10 to 1/6 the rise/fall time.
Regards,
Weston
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Newbie Pugal
Sent: Monday, June 27, 2011 7:38 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Package Model in IBIS
Hi All,
I'm Little confused with the package model definition in IBIS.
As far as I understand we can add Package model command and provide the package
model details like RLC and length details.
My doubt is if we do not have the package Model definition in the IBIS file
will the RLC values given for each pin consider as a package model? If so the
Length details are ignored?
What is the use of the lumped RLC values provided in the IBIS file?
Since I'm new to SI Please provide some basic information about Package Model
in IBIS.
Thanks
Pugal
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