Hello Akhilesh, There are two basic kinds of mismatch that you can have between spice and IBIS simulation. 1) Waveforms are shifted in time, but shape of rising/falling edges match. In this case, the IBIS simulator is probably doing the right thing -- it is not the job of the IBIS model to model this "startup time". 2) Mismatch between the rising/falling edges in Spice as compared to the IBIS simulator. You need to be careful when removing lead time in VT curves. In many IBIS models, the relative delay between different VT curves is very important. The safest thing to do is to remove the SAME lead time from all curves for a particular driver model. This is the safest thing to do. Optionally, there is a refinement to this, which is: a) For single ended models -- Remove the same lead time from all RISING waveforms. Remove the same lead time for all FALLING waveforms; b) For differential models -- The relative timing between RISING and FALLING waveforms is important, so you should remove the same lead time for all the RISING and FALLING waveforms. Cary Mandel Applications Engineer Mentor Graphics -----Original Message----- From: owner-ibis@server.eda.org [mailto:owner-ibis@server.eda.org] On Behalf Of Akhilesh CHANDRA Sent: 14 May 2007 11:42 To: 'Itzhak Peleg'; ibis@server.eda-stds.org Cc: Akhilesh CHANDRA Subject: RE: [IBIS] How we can model startup time in IBIS. Hello Itzik, If I remove it from my VT table then I can run the design at 800MHZ but then I have mismatch in IBIS and spice results. In this case my spice have 3ns startup time but it's missing in IBIS models. Regards Akhilesh -----Original Message----- From: Itzhak Peleg [mailto:itzikpe@marvell.com] Sent: Monday, May 14, 2007 3:44 PM To: Akhilesh CHANDRA; ibis@eda-stds.org Subject: RE: [IBIS] How we can model startup time in IBIS. Hi Akhliesh You can you remove the same lead time in all curves. For example removing 3ns from each curve subtracting the new 1st time point from each time point (so the curve will start at 0ns time). Then write the curves to the IBIS model. -- Regards Itzik Peleg Board Technology Group Marvell Semiconductor Israel Ltd 6 Hamada Street Mordot HaCarmel Industrial Park Yokneam 20692, ISRAEL Email - itzikpe@marvell.com Tel - +972 4 9091192 Cell - +972 54 4452482 Fax - +972 4 9091501 WWW Page: http://www.marvell.com ======================================================================== This message may contain confidential, proprietary or legally privileged information. The information is intended only for the use of the individual or entity named above. If the reader of this message is not the intended recipient, you are hereby notified that any dissemination, distribution or copying of this communication is strictly prohibited. If you have received this communication in error, please notify us immediately by telephone, or by e-mail and delete the message from your computer. Thank you! ======================================================================== -----Original Message----- From: owner-ibis@server.eda.org [mailto:owner-ibis@server.eda.org] On Behalf Of Akhilesh CHANDRA Sent: Monday, May 14, 2007 12:18 PM To: ibis@server.eda-stds.org Cc: Akhilesh CHANDRA Subject: [IBIS] How we can model startup time in IBIS. Hello Experts, I am doing IBIS model of an IO operating at 800MHZ frequency. It have startup time of 3nsec. After 3ns design gives output of 800mhz frequency. If I model this time in waveform database of IBIS models the I have over clocking issue and design is not work at this high frequency. Can you help me to model this startup time. Is anyone make IBIS model of such designs. Regards Akhilesh -- 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 -- 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 -- 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 Mon May 14 04:38:11 2007
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