RE: [IBIS-Users] Correct use of [Temperature Range]

From: Lynne D. Green <lgreen22_at_.....>
Date: Mon Mar 23 2009 - 11:30:24 PDT
An additional note: one of the most common model problems seen by the IBIS
Model Review Committee is a Typ [Temperature] of 25.

According to the IBIS spec, [Temperature] is on-die (roughly 25 above
ambient).  If the model maker forgot to account for on-die temperature rise,
Typ and <Hot> data will not be accurate.

Best regards,
Lynne Green
Chair, IBIS Model Review Committee


"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-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf
Of Vuletic Radovan (QAG PX D PDE)
Sent: Monday, March 23, 2009 6:15 AM
To: Lars Snith; ibis-users@server.eda.org
Subject: RE: [IBIS-Users] Correct use of [Temperature Range]

Hi Lars,

usually in IBIS modeling I refer to the typ, min and max PVT cases as to the
nominal, slow and fast PVT cases.

In max (fast) PVT cases usually one should have the best transistor device
parameters ("fastest" transistors), highest voltage and - now comes the
trick (if there is one at all) - lowest temperature for CMOS circuits (since
CMOS transistors usually have negative temperature coefficient - meaning
lower temperature yields in higher current --> faster switching) or highest
temperature for bipolar transistors (devices) since usually they have
positive temperature coefficient and therefore at higher temperatures they
deliver higher current (in some cases some smoke as well :-))

Similar (but opposite) in slow PVT case: put there slowest device models,
lowest voltage and highest temperature for CMOS or lowest temperature for
bipolar devices.

Of course,  I can imagine that in some very special cases some deviations
from above rules could happened.

So, if you are having IBIS models of some vendor that uses both CMOS and
bipolar technologies having different temperatures for the same PVT case I
would say that it makes sense - if that is not the case, I would than
directly clarify with the model provider if there is a bug in the model or
not.

I hope this helps.


Best regards / Mit freundlichen Grüßen / S po¹tovanjem Radovan Vuletiæ Staff
Engineer Product Development

Qimonda AG
QAG PX D PDE
MUC/10.2.236 AP 3
Am Campeon 1-12
D-85579 Neuebiberg
Germany

Phone:		+49 (0)89 60088 1233
Fax (PC):	+49 (0)89 60088 45 5305
Mobile:              +49 (0)160 7476262

E-mail: radovan.vuletic@qimonda.com
Web:  http://www.qimonda.com/


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-----Original Message-----
From: owner-ibis-users@server.eda.org
[mailto:owner-ibis-users@server.eda.org] On Behalf Of Lars Snith
Sent: Monday, March 23, 2009 1:27 PM
To: ibis-users@server.eda.org
Subject: [IBIS-Users] Correct use of [Temperature Range]

Hello Friends,

Let me once and for all try to nail down an issue that seem to be a constant
source of confusion.

The IBIS model syntax defines the triplet order [typ] [min] [max].
But this relates to the overall case, not the individual parameter, right?
So to make things match the real operational case the [min] of [Temperature
Range] would really need to be the maximum temperature, right?

Looking at what others do is not much help here, I see examples of both
variants, frequently from the same vendor(!). So an authorative answer would
be appreciated.


Best regards,  Lars Snith
--
Those who can, Do
Those who can't, Simulate

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Received on Mon Mar 23 11:33:20 2009

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