Subject: [IBIS-Users] RE: model issue for input receiver
From: Tom Dagostino (tom@teraspeed.com)
Date: Wed Apr 30 2003 - 16:55:23 PDT
Jeff
An input has several characteristics. One is input C or C_comp, another is
the input thresholds such as Vinh and Vinl. A third characteristic are the
clamp characteristics. Another is the DC input resistance. For most CMOS
inputs this input resistance is very high, so high that we can neglect it
(OK, it shows up as nAmps or pAmps). But for the case where the input
resistance of the receiver is finite, like a 50 Ohm termination, we need to
model it. We place that model in one of the clamp tables.
A terminator has input C and input R but has no ability to differentiate
between a logic low and a logic high. Thus a terminator model cannot be
used for an input which has thresholds it needs to let the simulator
understand.
So, input and terminator models are not interchangeable. They have
different applications. But inside the input model we can describe a
termination.
Tom Dagostino
Teraspeed Consulting Group LLC Teraspeed Consulting Group LLC
2926 SE Yamhill St. Device Modeling Division
Portland, OR 97214 13610 SW Harness Lane
Beaverton, OR 97008
http://www.teraspeed.com 503-430-1065
tom@teraspeed.com
-----Original Message-----
From: Eric Hsu [mailto:ehsu@netlogicmicro.com]
Sent: Wednesday, April 30, 2003 4:11 PM
To: tom@teraspeed.com; Muranyi, Arpad
Cc: Ibis-Users (E-mail)
Subject: RE: model issue for input receiver
Hi Tom and Muranyi,
Do you mean there is no difference for input receiver when generating ibis
model? No matter it has or not terminator resistor on chip, I always can use
the same model type like input?
Thanks for your guidance!
Best Regards,
Eric Hsu
Interface Technologies
NetLogic Microsystems, Inc.
450 National Ave.
Mountain View, CA 94043
650-961-6676 x198
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> -----Original Message-----
> From: Tom Dagostino [mailto:tom@teraspeed.com]
> Sent: Wednesday, April 30, 2003 3:54 PM
> To: Eric Hsu
> Subject: RE: model issue for input receiver
>
> If you use terminator you do not have an input model but a model of a
resistor. An input model is what you want with the characteristic of the on
die resistor embedded in one of the clamp curves.
>
> Tom Dagostino
>
> Teraspeed Consulting Group LLC Teraspeed Consulting Group LLC
>
> 2926 SE Yamhill St. Device Modeling Division
>
> Portland, OR 97214 13610 SW Harness Lane
>
> Beaverton, OR 97008
>
> http://www.teraspeed.com 503-430-1065
>
> tom@teraspeed.com
>
> -----Original Message-----
> From: Eric Hsu [mailto:owner-ibis-users@server.eda.org] On Behalf
Of Eric Hsu
> Sent: Wednesday, April 30, 2003 3:33 PM
> To: Ibis-Users (E-mail)
> Cc: Frank Dunlap
> Subject: model issue for input receiver
>
> Hi
>
> Can I choose "terminator" as my [model type] if I have an input
receiver with on die terminator? If true, can I also use subparameters
[Vinh] and [Vinl] to define input threshold voltage? If true, then what is
the meaning of "...but has no digital logic thresholds..." for terminator
model in IBIS spec. 3.2 version, page20?
>
> Best Regards,
>
> Eric Hsu
> Interface Technologies
> NetLogic Microsystems, Inc.
> 450 National Ave.
> Mountain View, CA 94043
> 650-961-6676 x198
>
> CONFIDENTIALITY NOTICE
> This message is intended only for the individual or entity to which
it is
> addressed and may contain information that is privileged,
confidential and
> exempt from disclosure under applicable law or contract. If you are
not
> the intended recipient, or the employee or agent responsible for
> delivering the message to the intended recipient, you are hereby
notified
> that any dissemination, distribution or copying of this
communication is
> strictly prohibited, and we ask that you delete this message and
notify us
> by return email. Thank you for your cooperation.
> This e-mail contains NetLogic Microsystems, Inc. Confidential
information
>
>
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