Hi Bob, Thanks for subscribing me to the IBIS reflector. You are correct about the out of sync data in this mail and the IBIS model that I had sent across the first time. The IV table indicated as "ORIGINAL PULLUP TABLE" in my mail is different since it is generated with different GMIN across corners. The first IBIS model had IV table generated with a single GMIN value. I had indicated in my first mail that using different GMIN, I was able to reduce the number of mismatch errors/warnings. The remaining mismatch which could not be removed, was removed by correcting the IV data. The IV table under "CORRECTED PULLUP TABLE" is this latest one. I just realise that in my mail I have wrongly mentioned the IV table as Pullup table. It is actually the Pulldown table (as can be noticed in the tables definition) which I had modified. Your observation on the inconsistency between rising edge and falling edge is correct. I guess this inconsistency can be attributed to the buffer taking time to have all its internal nodes get to a stable condition. So the PAD voltage at T=0 is not the correct one. This forces me to capture the third rise / fall transition for the VT table. Now doing this makes the rise and fall consistent. However, the IV tables that get generated with DC simulations are consistent with buffer condition at T=0. As described in my previous mail, trying different GMIN, shifting to transient analysis and sweeping PAD with a slow PWL after ramping up supplies was looked into but with different level of success and failures. The method of varying GMIN across corners and correcting the Pulldown table does help in resolving the mismatch. The only concern after doing this is whether my IBIS model simulations will correlate with the Spectre netlist simulations? This might be the next problem to solve and take me back to where I started. Best regards, Birendra Rana -----Original Message----- From: Bob Ross [mailto:bob@teraspeed.com] Sent: Thursday, March 05, 2009 1:17 AM To: Birendra Rana (WT01 - Wipro NewLogic) Cc: bob@terasoeed; cin Subject: Re: Understanding IV-VT mismatch errors / warnings and their fix Hi Birendra: The last message went out on the IBIS Users reflector, but bounced on the IBIS reflector. I subscribed you to the IBIS reflector. I think we are out of sync. on the examples since the data (old) does not match the data I used. It is correct to get the proper I-V tables. If that solved the Error/Warning problems for V-T mismatches, then you did the correct thing. What I looked for in the data was possible double counting of the I-V data with the clamp data, but the clamps looked clean (negligible current) in the normal operation region. Internal weak on-die pullup terminators are often the source of V-T mismatch. My main concern in the model that I looked at was the the V-T data itself looked inconsistent. The rising edge for one of the test loads had different beginning/end points than the following edge. For the case I looked at, the typical falling edge had correct end points with 50 ohms to GND (.33 and 0) whareas the rising edge started at 0, but only went to .31. That was enough to produce a Warning. So I think you may have a better updated model than the one I was looking at. Best Regards, Bob birendra.rana@wipro.com wrote: > Hi Bob, > > Let me update you on what I did to get the mismatches removed. Instead > of scaling the VT tables, I updated the pullup IV table. This removed > all the mismatch warnings/errors. Found out that the pullup table > generated has deficiency of 1.2mA current for min corner and 0.2mA for > max corner. This "correction" changes the IV end points and brings > them closer to VT end points. > > I have one question on this method: is this a legal way to do it? > > FYI, I am yet to run a correlation check on the generated IBIS model > sim against the spectre netlist simulation. So verification is pending. > > Below are the IBIS pullup IV tables for your reference. The > corrections are done for voltages from 0.6V to 2.34V. > > Apologies for sending you a direct mail to you. I am not sure if my > mails have reached the group. Thanks once again for the previous > response. > > Best regards, > > Birendra Rana > > _________________________________________________________ > Wipro Technologies > Plot No 72, Keonics Electronics City, Hosur Main Road, Bangalore - > 560100 > Mob: +91 80 9880340060 | Tel: +91 80 30295448 > Email: birendra.rana@wipro.com | Website: www.wipro.com > > ORIGINAL PULLUP TABLE > -------------------------------- > [Temperature Range] 25.0000 0.1250k -40.0000 > [Voltage Range] 1.8000V 1.6500V 1.9500V > [Pulldown] > |Voltage I(typ) I(min) I(max) > | > -1.8000 -0.5584mA -0.3486mA -0.6344mA > -1.7400 -0.6003mA -0.3735mA -0.6834mA > -1.6800 -0.6489mA -0.4022mA -0.7406mA > -1.6200 -0.7059mA -0.4355mA -0.8081mA > -1.5600 -0.7735mA -0.4747mA -0.8887mA > -1.5000 -0.8551mA -0.5212mA -0.9869mA > -1.4400 -0.9554mA -0.5776mA -1.1088mA > -1.3800 -1.0812mA -0.6469mA -1.2641mA > -1.3200 -1.2437mA -0.7342mA -1.4681mA > -1.2600 -1.4606mA -0.8471mA -1.7473mA > -1.2000 -1.7632mA -0.9980mA -2.1501mA > -1.1400 -2.2106mA -1.2081mA -2.7758mA > -1.0800 -2.9258mA -1.5165mA -3.8553mA > -1.0200 -4.2139mA -1.9996mA -6.0823mA > -0.9600 -6.8113mA -2.8219mA -11.5493mA > -0.9000 -11.9362mA -4.2583mA -21.6409mA > -0.8400 -16.6401mA -6.3737mA -25.1748mA > -0.7800 -17.6857mA -8.0105mA -24.8418mA > -0.7200 -17.2472mA -8.5735mA -23.9135mA > -0.6600 -16.3772mA -8.7003mA -22.7636mA > -0.6000 -15.2791mA -8.3475mA -21.3760mA > -0.5400 -13.9840mA -7.6882mA -19.6898mA > -0.4800 -12.4838mA -6.8675mA -17.6476mA > -0.4200 -10.8035mA -5.9456mA -15.3009mA > -0.3600 -9.0504mA -4.9630mA -12.8798mA > -0.3000 -7.3321mA -3.9775mA -10.5093mA > -0.2400 -5.6846mA -3.0357mA -8.2118mA > -0.1800 -4.1192mA -2.1602mA -5.9989mA > -0.1200 -2.6443mA -1.3594mA -3.8830mA > -0.0600 -1.2683mA -0.6380mA -1.8782mA > 0.0000 13.4705fA 0.9549pA 8.7393pA > 0.0600 1.1519mA 0.5511mA 1.7338mA > 0.1200 2.1780mA 1.0120mA 3.3023mA > 0.1800 3.0687mA 1.3798mA 4.6793mA > 0.2400 3.8125mA 1.6513mA 5.8299mA > 0.3000 4.3968mA 1.8277mA 6.7118mA > 0.3600 4.8145mA 1.9249mA 7.2995mA > 0.4200 5.0789mA 1.9736mA 7.6319mA > 0.4800 5.2302mA 1.9987mA 7.8038mA > 0.5400 5.3145mA 2.0127mA 7.8958mA > 0.6000 5.3627mA 2.0211mA 7.9500mA > 0.6600 5.3914mA 2.0262mA 7.9851mA > 0.7200 5.4084mA 2.0289mA 8.0092mA > 0.7800 5.4178mA 2.0302mA 8.0259mA > 0.8400 5.4222mA 2.0310mA 8.0369mA > 0.9000 5.4256mA 2.0313mA 8.0434mA > 0.9600 5.4268mA 2.0315mA 8.0509mA > 1.0200 5.4275mA 2.0316mA 8.0526mA > 1.0800 5.4279mA 2.0316mA 8.0535mA > 1.1400 5.4282mA 2.0317mA 8.0540mA > 1.2000 5.4285mA 2.0318mA 8.0544mA > 1.2600 5.4287mA 2.0318mA 8.0546mA > 1.3200 5.4290mA 2.0319mA 8.0549mA > 1.3800 5.4291mA 2.0319mA 8.0551mA > 1.4400 5.4293mA 2.0319mA 8.0552mA > 1.5000 5.4295mA 2.0320mA 8.0554mA > 1.5600 5.4296mA 2.0320mA 8.0556mA > 1.6200 5.4298mA 2.0321mA 8.0557mA > 1.6800 5.4299mA 2.0321mA 8.0558mA > 1.7400 5.4300mA 2.0321mA 8.0560mA > 1.8000 5.4302mA 2.0323mA 8.0561mA > 1.8600 5.4303mA 2.0332mA 8.0562mA > 1.9200 5.4304mA 2.0377mA 8.0563mA > 1.9800 5.4305mA 2.0596mA 8.0565mA > 2.0400 5.4308mA 2.1260mA 8.0566mA > 2.1000 5.4319mA 2.2658mA 8.0567mA > 2.1600 5.4421mA 2.4934mA 8.0567mA > 2.2200 5.5048mA 2.8120mA 8.0569mA > 2.2800 5.6991mA 3.2150mA 8.0576mA > 2.3400 6.0690mA 3.6918mA 8.0673mA > 2.4000 6.6199mA 4.2243mA 8.1655mA > 2.4600 7.3386mA 4.7298mA 8.5126mA > 2.5200 8.2052mA 5.0516mA 9.1705mA > 2.5800 9.1922mA 5.3079mA 10.1258mA > 2.6400 10.1981mA 5.5241mA 11.3425mA > 2.7000 10.8061mA 5.7470mA 12.7798mA > 2.7600 11.1784mA 6.0130mA 14.3806mA > 2.8200 11.4924mA 6.3168mA 15.8396mA > 2.8800 11.7180mA 6.6517mA 16.4096mA > 2.9400 11.6296mA 7.0121mA 16.6678mA > 3.0000 11.5414mA 7.3945mA 16.7924mA > 3.0600 11.6634mA 7.7959mA 16.7979mA > 3.1200 11.8881mA 8.2132mA 16.6454mA > 3.1800 12.1672mA 8.6432mA 15.7287mA > 3.2400 12.4834mA 9.0822mA 13.8846mA > 3.3000 12.8266mA 9.5270mA 13.3560mA > 3.3600 13.1923mA 9.9746mA 13.0529mA > 3.4200 13.5774mA 10.4217mA 12.8283mA > 3.4800 13.9791mA 10.8657mA 12.6493mA > 3.5400 14.3931mA 11.3041mA 12.5008mA > 3.6000 14.8132mA 11.7350mA 12.3783mA > > CORRECTED PULLUP TABLE > ----------------------------------- > [Temperature Range] 25.0000 0.1250k -40.0000 > [Voltage Range] 1.8000V 1.6500V 1.9500V > [Pulldown] > |Voltage I(typ) I(min) I(max) > | > -1.8000 -0.5584mA -0.3486mA -0.6344mA > -1.7400 -0.6003mA -0.3735mA -0.6834mA > -1.6800 -0.6489mA -0.4022mA -0.7406mA > -1.6200 -0.7059mA -0.4355mA -0.8081mA > -1.5600 -0.7735mA -0.4747mA -0.8887mA > -1.5000 -0.8551mA -0.5212mA -0.9869mA > -1.4400 -0.9554mA -0.5776mA -1.1088mA > -1.3800 -1.0812mA -0.6469mA -1.2641mA > -1.3200 -1.2437mA -0.7342mA -1.4681mA > -1.2600 -1.4606mA -0.8471mA -1.7473mA > -1.2000 -1.7632mA -0.9980mA -2.1501mA > -1.1400 -2.2106mA -1.2081mA -2.7758mA > -1.0800 -2.9258mA -1.5165mA -3.8553mA > -1.0200 -4.2139mA -1.9996mA -6.0823mA > -0.9600 -6.8113mA -2.8219mA -11.5493mA > -0.9000 -11.9362mA -4.2583mA -21.6409mA > -0.8400 -16.6401mA -6.3737mA -25.1748mA > -0.7800 -17.6857mA -8.0105mA -24.8418mA > -0.7200 -17.2472mA -8.5735mA -23.9135mA > -0.6600 -16.3772mA -8.7003mA -22.7636mA > -0.6000 -15.2791mA -8.3475mA -21.3760mA > -0.5400 -13.9840mA -7.6882mA -19.6898mA > -0.4800 -12.4838mA -6.8675mA -17.6476mA > -0.4200 -10.8035mA -5.9456mA -15.3009mA > -0.3600 -9.0504mA -4.9630mA -12.8798mA > -0.3000 -7.3321mA -3.9775mA -10.5093mA > -0.2400 -5.6846mA -3.0357mA -8.2118mA > -0.1800 -4.1192mA -2.1602mA -5.9989mA > -0.1200 -2.6443mA -1.3594mA -3.8830mA > -0.0600 -1.2683mA -0.6380mA -1.8782mA > 0.0000 13.4705fA 0.9549pA 8.7393pA > 0.0600 1.1519mA 1.5511mA 1.7338mA > 0.1200 2.1780mA 2.0120mA 3.3023mA > 0.1800 3.0687mA 2.3798mA 4.6793mA > 0.2400 3.8125mA 2.6513mA 5.8299mA > 0.3000 4.3968mA 2.8277mA 6.7118mA > 0.3600 4.8145mA 2.9249mA 7.2995mA > 0.4200 5.0789mA 2.9736mA 7.6319mA > 0.4800 5.4302mA 2.9987mA 7.8038mA > 0.5400 5.5145mA 3.2827mA 7.8958mA > 0.6000 5.5627mA 3.2811mA 7.9500mA > 0.6600 5.5914mA 3.2862mA 7.9851mA > 0.7200 5.6084mA 3.2889mA 8.0092mA > 0.7800 5.6178mA 3.2802mA 8.0259mA > 0.8400 5.6222mA 3.2810mA 8.0369mA > 0.9000 5.6256mA 3.2813mA 8.0434mA > 0.9600 5.6268mA 3.2815mA 8.0509mA > 1.0200 5.6275mA 3.2816mA 8.0526mA > 1.0800 5.6279mA 3.2816mA 8.0535mA > 1.1400 5.6282mA 3.2817mA 8.0540mA > 1.2000 5.6285mA 3.2818mA 8.0544mA > 1.2600 5.6287mA 3.2818mA 8.0546mA > 1.3200 5.6290mA 3.2819mA 8.0549mA > 1.3800 5.6291mA 3.2819mA 8.0551mA > 1.4400 5.6293mA 3.2819mA 8.0552mA > 1.5000 5.6295mA 3.2820mA 8.0554mA > 1.5600 5.6296mA 3.2820mA 8.0556mA > 1.6200 5.6298mA 3.2821mA 8.0557mA > 1.6800 5.6299mA 3.2821mA 8.0558mA > 1.7400 5.6300mA 3.2821mA 8.0560mA > 1.8000 5.6302mA 3.2823mA 8.0561mA > 1.8600 5.6303mA 3.2832mA 8.0562mA > 1.9200 5.6304mA 3.2877mA 8.0563mA > 1.9800 5.6305mA 3.2896mA 8.0565mA > 2.0400 5.6308mA 3.2860mA 8.0566mA > 2.1000 5.6319mA 3.2858mA 8.0567mA > 2.1600 5.6421mA 3.4934mA 8.0567mA > 2.2200 5.6048mA 3.8120mA 8.0569mA > 2.2800 5.6991mA 3.8150mA 8.0576mA > 2.3400 6.0690mA 3.9918mA 8.0673mA > 2.4000 6.6199mA 4.2243mA 8.1655mA > 2.4600 7.3386mA 4.7298mA 8.5126mA > 2.5200 8.2052mA 5.0516mA 9.1705mA > 2.5800 9.1922mA 5.3079mA 10.1258mA > 2.6400 10.1981mA 5.5241mA 11.3425mA > 2.7000 10.8061mA 5.7470mA 12.7798mA > 2.7600 11.1784mA 6.0130mA 14.3806mA > 2.8200 11.4924mA 6.3168mA 15.8396mA > 2.8800 11.7180mA 6.6517mA 16.4096mA > 2.9400 11.6296mA 7.0121mA 16.6678mA > 3.0000 11.5414mA 7.3945mA 16.7924mA > 3.0600 11.6634mA 7.7959mA 16.7979mA > 3.1200 11.8881mA 8.2132mA 16.6454mA > 3.1800 12.1672mA 8.6432mA 15.7287mA > 3.2400 12.4834mA 9.0822mA 13.8846mA > 3.3000 12.8266mA 9.5270mA 13.3560mA > 3.3600 13.1923mA 9.9746mA 13.0529mA > 3.4200 13.5774mA 10.4217mA 12.8283mA > 3.4800 13.9791mA 10.8657mA 12.6493mA > 3.5400 14.3931mA 11.3041mA 12.5008mA > 3.6000 14.8132mA 11.7350mA 12.3783mA > > 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 > -- Bob Ross Teraspeed Consulting Group LLC Teraspeed Labs 121 North River Drive 13610 SW Harness Lane Narragansett, RI 02882 Beaverton, OR 97008 401-284-1827 503-430-1065 http://www.teraspeed.com 503-246-8048 Direct bob@teraspeed.com Teraspeed is a registered service mark of Teraspeed Consulting Group LLC 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 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 Wed Mar 4 21:16:24 2009
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