Subject: Re: [IBIS-Users] RE: model issue for input receiver
From: Bob Ross (bob@teraspeed.com)
Date: Wed Apr 30 2003 - 19:05:54 PDT
Eric:
I agree with Tom's and Scott's responses to your question. Everything
is included for C_comp.
The C_comp should be extracted, if possible, in a high-Z or Input mode
for 3-state and I/O buffers. The Terminator model type is analogous
to the high-Z mode of a 3-state buffer where the Vinl and Vinh are
not specified or used.
However, several additional keyword are available only for Terminator
models in IBIS that were intended for actual terminator components:
[Rpower], [Rgnd], [Rac], and [Cac].
Best Regards,
Bob
Eric,
In order to characterize C-comp, it is necessary to measure everything, all die
capacitance of I/O cell, clamping and ESD structures, along with all other
parasitic capacitance in the redistribution layer, if that is not included in
the package model.
regards,
scott
Tom Dagostino wrote:
> Yes, C_comp includes all the capacitance associated with the I/O cell. If
> it has a powerclamp or a termination resistor then the capacitance of those
> should be included in C_comp. Also see IBIS 4 that has many different
> C_comp values, each associated with different structures in the cell.
>
> 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 5:33 PM
> To: tom@teraspeed.com; Muranyi, Arpad
> Cc: Ibis-Users (E-mail); Ross, Bob
> Subject: RE: model issue for input receiver
>
>
> Hi Tom, Muranyi, and Bob,
>
> Thanks for your clear answer. It's really helpful for me.
> There is the other related question. When characterizing C_comp, should
> spice netlist consider every thing on die, including clamping diode (or
> transistor) and terminator resistor?
> Bob, do you mind also providing your professional comment for that? (I still
> remember you had a very good and practical presentation mention about C_comp
> characterization in designcon2003, such as "Frequency domain" or "Time
> domain" Techniques.)
>
> 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 4:55 PM
> To: Eric Hsu; 'Muranyi, Arpad'
> Cc: 'Ibis-Users (E-mail)'
> Subject: RE: model issue for input receiver
>
>
> 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
>
> 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
>
>
>
>> -----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
>
>>
-- Bob Ross Teraspeed Consulting Group LLC Teraspeed Consulting Group LLC 2926 SE Yamhill St. Device Modeling Division Portland, OR 97214 13610 SW Harness Lane 503-239-5536 Beaverton, OR 97008 http://www.teraspeed.com 503-430-1065 bob@teraspeed.com 503-246-8048 Direct|------------------------------------------------------------------ |For help or to subscribe/unsubscribe, email majordomo@eda.org |with just the appropriate command message(s) in the body: | | help | subscribe ibis <optional e-mail address, if different> | subscribe ibis-users <optional e-mail address, if different> | unsubscribe ibis <optional e-mail address, if different> | unsubscribe ibis-users <optional e-mail address, if different> | |or email a written request to ibis-request@eda.org. | |IBIS reflector archives exist under: | | http://www.eda.org/pub/ibis/email_archive/ Recent | http://www.eda.org/pub/ibis/users_archive/ Recent | http://www.eda.org/pub/ibis/email/ E-mail since 1993
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