RE: [IBIS-Users] IBIS model check

From: Tom Dagostino <tom_at_.....> Date: Wed Aug 17 2005 - 12:22:02 PDT · This archive was generated by hypermail 2.1.8 : Wed Aug 17 2005 - 12:22:31 PDT

In any engineering situation to verify something, to ensure it is correct,
you need a standard to verify against. In this case you need either the
original SPICE or measurements of an actual device.  Without either of these
how can you verify?

You can always use some engineering judgment to see if the curves look
reasonable.  I would look at the datasheet for the buffer as a place to
start to base reasonableness on.

Tom Dagostino
Teraspeed(R) Labs
13610 SW Harness Lane
Beaverton, OR 97008
503-430-1065
tom@teraspeed.com
www.teraspeed.com

Teraspeed Consulting Group LLC
121 North River Drive
Narragansett, RI 02882
401-284-1827

-----Original Message-----
From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org]On
Behalf Of Indira Gazula
Sent: Wednesday, August 17, 2005 11:52 AM
To: Dekker Graden
Cc: ibis-users@eda.org
Subject: RE: [IBIS-Users] IBIS model check

So effectively, in the absence of either spice curves or measurement data,
I'm stuck with no way of verifying the IBIS model?

Indira.

-----Original Message-----
From: Dekker Graden [mailto:dekker@teraspeed.com]
Sent: Wednesday, August 17, 2005 11:27 AM
To: Indira Gazula
Subject: Re: [IBIS-Users] IBIS model check

There are a couple of methods for checking.

One is using the spice for the same part and seeing if the IV and VT
curves match up.

The other way is to take a real part and perform some measurements on
it. Then conpair the measurement results to the IBIS file to see how
closely they match up.

Dekker

Indira Gazula wrote:

>Hi All,
>
>I have a general question: How does one check if the IBIS model provided
has
>correctly generated data. I ask this because, I was recently working on a
>model which I thought was generationg unneccesarily high voltage levels
>(point-to-point). To test I had just connected the IO model I had to
itself,
>without any interconnects in-between and found the voltages to be beyond
the
>spec levels. I understand that the model impedance might not be matched to
>the load value the data was generated for, but was just wondering how one
>could make sure.
>
>Regards,
>Indira.
>
>-----Original Message-----
>From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org]On
>Behalf Of Muranyi, Arpad
>Sent: Wednesday, August 17, 2005 9:43 AM
>To: ibis-users@eda.org
>Subject: RE: [IBIS-Users] Mixed-Signal Analog IO ?
>
>
>If that's what you need to model a band gap device,
>you can also consider a pair of IV curves in the
>clamp tables.  Those are always on, whether the
>model drives or receives, and you can make a
>voltage divider with two appropriately shaped and
>sized IV curves.
>
>Arpad
>===================================================
>
>-----Original Message-----
>From: Tom Dagostino [mailto:tom@teraspeed.com]
>Sent: Wednesday, August 17, 2005 9:34 AM
>To: Lars Snith; Muranyi, Arpad
>Cc: ibis-users@eda.org
>Subject: RE: [IBIS-Users] Mixed-Signal Analog IO ?
>
>...
>...
>...
>For a voltage output like the output of a band gap reference make a voltage
>divider using a terminator model whose values give you the Thevenin
>equivalent for the output impedance of the part you are trying to model.
>
>|------------------------------------------------------------------
>|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
>
>|------------------------------------------------------------------
>|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
>
>
>

|------------------------------------------------------------------
|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