Date: Tue Dec 20 2005 - 04:02:49 PST
Itzik Peleg and all, Thank you very much for your help. Please see my answers in line with your comments. 1. This buffer operation is intended for a load resistance of more than 5k ohm. 2. Yes, you are right. I should allow more transient simulation time for min corner. However, reported behavior (correlation of hspice vs IBIS) is for typ corner. Even I have tried with 50, 100, 500 & 5k ohm terminations for capturing V-t waveforms. But I could not see any improvement in the correlation. I am still investigating this issue. Thanks & Best Regards, Venu -----Original Message----- From: Itzik Peleg [mailto:itzikpe@marvell.com] Sent: Thursday, December 15, 2005 7:09 PM To: Ummalaneni, Venu Babu (Venu); ibis-users@eda.org; ibis@eda.org Subject: RE: [IBIS] RE: [IBIS-Users] hspice vs IBIS model correlation at different capacitive loads Hello Venu Here are my comments reviewing your model: 1. The loading condition is 1k ohm !? isn't this buffer should be used in 50 ohm environment? If the answer is yes then you should use 50 ohm. 2. It seems like the slow didn't finish the complete transition. You should allow more time for the V(t) simulation in order that the response get to steady state (like the maximum case in red). This also causing the warning that you have when using IBIS check: ************************************************************** WARNING - Model ATA4N1K000: The [Rising Waveform] with [R_fixture]=1000 Ohms and [V_fixture_min]=0V has MIN column DC endpoints of 0.00V and 2.78v, but an equivalent load applied to the model's I-V tables yields different voltages (-0.00V and 2.92V), a difference of 0.00% and 4.69%, respectively. WARNING - Model ATA4N1K000: The [Falling Waveform] with [R_fixture]=1000 Ohms and [V_fixture_min]=3V has MIN column DC endpoints of 0.21V and 3.00v, but an equivalent load applied to the model's I-V tables yields different voltages ( 0.05V and 3.00V), a difference of 5.54% and 0.00%, respectively. **************************************************************** 3. Based on the 2 previous points I can think of a buffer for slow interface that should be used in 50 ohm environment. If this is the case you should allow the transient simulation more time on 50 ohm. Hope this will halp. -- 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 <BLOCKED::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! ======================================================================== _____ From: Ummalaneni, Venu Babu (Venu) [mailto:venubabu@agere.com] Sent: Thursday, December 15, 2005 1:07 PM To: Itzik Peleg; Todd Westerhoff (twesterh); ibis-users@eda.org; ibis@eda.org Subject: RE: [IBIS] RE: [IBIS-Users] hspice vs IBIS model correlation at different capacitive loads Itzik Peleg, Thanks for your concern. I think there is no such feedback. Here, I am attaching the IBIS model. Thanks & Regards, Venu -----Original Message----- From: Itzik Peleg [mailto:itzikpe@marvell.com] Sent: Wednesday, December 14, 2005 12:50 PM To: Ummalaneni, Venu Babu (Venu); Todd Westerhoff (twesterh); ibis-users@eda.org; ibis@eda.org Subject: RE: [IBIS] RE: [IBIS-Users] hspice vs IBIS model correlation at different capacitive loads Hello Venu Just to add one more possibility doe's your buffer has a feedback? Could you attached the IBIS model, or show the I(V) and V(t) curves? -- 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 <BLOCKED::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! ======================================================================== _____ From: owner-ibis@eda.org [mailto:owner-ibis@eda.org] On Behalf Of Ummalaneni, Venu Babu (Venu) Sent: Tuesday, December 13, 2005 2:49 PM To: Todd Westerhoff (twesterh); ibis-users@eda.org; ibis@eda.org Subject: [IBIS] RE: [IBIS-Users] hspice vs IBIS model correlation at different capacitive loads Todd, Thanks for your inputs. I have verified the programming options of driver and it's fine. Here, I am attaching the correlation waveforms of the simulations by using a 0.1 ohm resistor instead of transmission line in both load (5pF & 30pF) cases. Still, I am seeing a bad correlation in 30pF case. Please ignore my previously attached *.PDF. Once again thanks for your response. Best Reagrds, Venu -----Original Message----- From: Todd Westerhoff (twesterh) [mailto:twesterh@cisco.com] Sent: Tuesday, December 13, 2005 5:43 PM To: Ummalaneni, Venu Babu (Venu); ibis-users@eda.org; ibis@eda.org Subject: RE: [IBIS-Users] hspice vs IBIS model correlation at different capacitive loads Venu, How long is the transmission line you're using ... about 1ns? Your IBIS driver in the 30pf case seems to be taking several round-trips to charge the load where the HSpice driver doesn't - if this is a programmable driver, is it possible the driver settings for the two plots are different? In the top plot for the 30pf case, the IBIS driver looks like a much weaker output with a faster slew rate to me ... Todd. Todd Westerhoff High Speed Design Group Manager Cisco Systems 1414 Massachusetts Ave Boxboro, MA 01719 email:twesterh@cisco.com ph: 978-936-2149 ____________________________________________ "Always do right. This will gratify some people and astonish the rest." - Mark Twain _____ From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf Of Ummalaneni, Venu Babu (Venu) Sent: Tuesday, December 13, 2005 5:38 AM To: ibis-users@eda.org; ibis@eda.org Subject: [IBIS-Users] hspice vs IBIS model correlation at different capacitive loads Hi Gurus, I have an ATA* IBIS model and it is correlating well with hspice model when I am using a 5pF load followed by a transmission line. If I replace the 5pF load with 30pF correlation is bad (particularly in 2nd page waveform of attached PDF). Could some one comment on this, where it is going wrong? Your comments/inputs are highly appreciated. Attachments: ata4nik_5pf.pdf - hspice and IBIS model waveforms captured using 5pF load ata4nik_30pf.pdf - hspice and IBIS model waveforms captured using 30pF load Thanks & Best Regards, Venu <<ata4n1k_30pf.pdf>> <<ata4n1k_5pf.pdf>> |------------------------------------------------------------------ |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
