RE: [IBIS-Users] Non-existence of C_load in [Ramp] keyword

The RAMP key word only allows a purely resistive load which is the load that
should be used for extraction of VT curves and thus ramps. My experience
with models that have had non zero C_fixture is not good. The simulators
that I used with these models did not produce acceptable results showing
incredible amounts of waveform distortion. It is my recommendation (and
from members of the IBIS committee that I have discussed this with) not to
use C_fixture when extracting the VT curves. If you are making a model from
SPICE there is no need to have any capacitance in the load when doing the
simulations. If you are making the model from measurements you should be
able to design the test fixture to minimize any stray parasitic. BUT IN
ANY CASE DO NOT INCLUDE CREF IN THE MODEL UNDER C_FIXTURE!!!

Regards,

Tom Dagostino

Teraspeed 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

www.teraspeed.com

From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf
Of surendra.deshmukh@wipro.com
Sent: Thursday, September 16, 2010 4:56 AM
To: ibis-users@eda.org
Subject: [IBIS-Users] Non-existence of C_load in [Ramp] keyword

Hi,

    The [Ramp] keyword used in IBIS initial version is still there in new
versions along with VT tables. This Ramp keyword also gives Rload value.

 My question is as far as these VT tables are calculated only for Rixture
(or Rload), simulator has a choice to take value from [Ramp] keyword without
any problem but if these tables are generated for Rfixture and C_fixture
values (non-zero C_fixture value) then there is no any keyword C_load inside
the [Ramp] section.

        How the simulator handles this case where [Ramp] is calculated for
Rfixture and C_fixture but there is no any C_load keyword in ramp section?
Does [Ramp] require any C_load keyword?

Regards

Surendra

Please do not print this email unless it is absolutely necessary.

The information contained in this electronic message and any attachments to
this message are intended for the exclusive use of the addressee(s) and may
contain proprietary, confidential or privileged information. If you are not
the intended recipient, you should not disseminate, distribute or copy this
e-mail. Please notify the sender immediately and destroy all copies of this
message and any attachments.

WARNING: Computer viruses can be transmitted via email. The recipient should
check this email and any attachments for the presence of viruses. The
company accepts no liability for any damage caused by any virus transmitted
by this email.

www.wipro.com

-- 
This message has been scanned for viruses and 
dangerous content by  <http://www.mailscanner.info/> MailScanner, and is 
believed to be clean. 
-- 
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.
--------------------------------------------------------------------
|For help or to subscribe/unsubscribe, e-mail majordomo@eda-stds.org
|with 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 e-mail a request to ibis-request@eda-stds.org.
|
|IBIS reflector archives exist under:
|
|  http://www.eda-stds.org/pub/ibis/email_archive/ Recent
|  http://www.eda-stds.org/pub/ibis/users_archive/ Recent
|  http://www.eda-stds.org/pub/ibis/email/         E-mail since 1993