Hello Chetana... Just wanted to add that there is an excellent section in the "IBIS Modeling Cookbook" ver 4.0 that describes the relationship between the I-V and V-T curves (section 5.2.2) for the sake of data checking. The I-V curves can be used to predict the drive strength of your buffer when attached to a 50 Ohm Load and as Yasser mentioned below, Rfixture is used to determine the switching characteristics of your buffer. Just an additional note: The output impedance of your driver can be approximated by determining the slope of your tangent line to your I-V curve at your operating point. IBIS Modeling Cookbook ver 4.0 http://www.vhdl.org/pub/ibis/cookbook/cookbook-v4.pdf Mike C... Yasser Sabry <yasser_sabry@men tor.com> To Sent by: Chetana Raghuwanshi owner-ibis-users@ <chetana.raghuwanshi@nxp.com> eda.org cc ibis-users@eda.org, ibis@eda.org Subject 02/07/2008 06:59 [IBIS-Users] Re: [IBIS] IV curves AM w.r.t. Rfixture / Rload Hi Chetana, I think there is no relation between Pullup/Pulldown IV curves and Rfixture Rfixture is , generally, taken to be the transmission line characteristics impedance to which the buffer will be connected. It affects rising and falling waveforms The customer should be a ware of the mismatch between the buffer output impedance and the 50 Ohms line but this is not related to IBIS modeling Regards, Yasser Chetana Raghuwanshi wrote: Hello All, I am generating IBIS Models ( based on 2.0 Format) for a bidirectional IO cell with output impedence of 32 Ohms. Customer specification is to use Rfixture/Rload value of 50 Ohms for IBIS Models. But when I see my pullup and pulldown I-V curves, the loadline corresponds to the Resistive load of 32 Ohms which is nothing but the output impedence of driver in my Bidir cell. I think that the pullup and pulldown I-V curves should correspond to Resistive Load of 50 Ohms. Am I correct in assuming this ? Or is it expected that irrespective of the value of Rfixture / Rload pullup and pulldown curves should correspond to Zout of driver ? Thanks in Advance Best Regards Chetana -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. -- Thank you and Best Regards, Yasser Sabry ------------------------------------------- Yasser Mohammed Sabry Device Modeling Team Analog/Mixed Signal - DSM Division Mentor Graphics Egypt Tel: (+202) 416 3613 Mob: (+2010) 1834833 Fax: (+202) 418 6945 E-mail: yasser_sabry@mentor.com ------------------------------------------- -- This message has been scanned for viruses and dangerous content by 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 1993Received on Thu Feb 7 07:40:43 2008
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