I would take the smallest number from the fast corner for the C_comp-min value and the largest number from the slow corner for the C_comp-max value, and average these two for the typical C_comp value. You might wonder why do it this way. Usually the capacitance on the die is somewhat independent from the transistor process corners, because a lot of it is a factor of the metallization process on the die. These may vary independently from the transistor (silicon) process variations, so it is possible to have combinations which are not described in your min or max corner transistor models. But if you know these relationships better and don't think that having such combinations will ever happen, you can pick the fast min value for C_comp-min and slow-max value for C_comp-max. I hope this helps, even if I didn't give you a direct answer. Arpad ==================================================================================== From: Amitava Banerjee [mailto:tava@cypress.com] Sent: Thursday, July 04, 2013 3:35 AM To: Muranyi, Arpad; ibis-users@eda.org Subject: RE: Query on Ccomp parameter for IBIS model Thanks Arpad for this explanation. Actually we have run for all the corners. The data has been given below. Please let us know if our assumptions are ok. Do we need to take the worst case number across process corners for C_comp_max. And similarly the lowest 'estcap' value for C_comp_min. Simulation type := Corner :- typ-typ ; Temp :- 27 ; Vcc=1.8V outdcbias estcap 0.0000 2.706e-12 0.2000 2.752e-12 (max) 0.4000 2.706e-12 0.6000 2.673e-12 0.8000 2.626e-12 1.0000 2.436e-12 1.2000 1.934e-12 1.4000 1.809e-12 (min) 1.6000 1.825e-12 1.8000 1.851e-12 C_comp (typ) = ( 2.76 + 1.809 ) / 2 pF = 2.2805 pF Simulation type := Corner : slow-slow ; Temp : 125 ; Vcc=1.7V outdcbias estcap 0.0000 2.877e-12 0.2000 2.939e-12 (max) 0.4000 2.877e-12 0.6000 2.814e-12 0.8000 2.680e-12 1.0000 2.482e-12 1.2000 1.939e-12 1.4000 1.923e-12 1.6000 1.955e-12 1.7000 1.979e-12 C_comp (max) = 2.939 pF Simulation type := Corner : fast-fast ; Temp : -40 ; Vcc=1.9V outdcbias estcap 0.0000 2.532e-12 0.2000 2.569e-12 0.4000 2.532e-12 0.6000 2.511e-12 0.8000 2.510e-12 1.0000 2.415e-12 1.2000 2.073e-12 1.4000 1.714e-12 (min) 1.6000 1.724e-12 1.8000 1.740e-12 1.9000 1.751e-12 C_comp (min) = 1.714 pF Regards, Amitava From: owner-ibis-users@eda.org<mailto:owner-ibis-users@eda.org> [mailto:owner-ibis-users@eda.org] On Behalf Of Muranyi, Arpad Sent: Wednesday, July 03, 2013 8:26 PM To: ibis-users@eda.org<mailto:ibis-users@eda.org> Subject: [IBIS-Users] RE: Query on Ccomp parameter for IBIS model Girija/Amitava, Attachments are usually not allowed on these email discussion forums, because they would overload the servers too much... From within the voltage range of your signal swing, pick the smallest value of those capacitances for C_comp-min and the highest value for C_comp-max and put the average of those two in C_comp-typ. I hope this helps, Arpad =============================================================== From: owner-ibis-users@eda.org<mailto:owner-ibis-users@eda.org> [mailto:owner-ibis-users@eda.org] On Behalf Of Girija V Chougala Sent: Wednesday, July 03, 2013 5:39 AM To: ibis-users@eda.org<mailto:ibis-users@eda.org> Cc: Amitava Banerjee Subject: [IBIS-Users] RE: Query on Ccomp parameter for IBIS model Hi All, As attachment is huge, sending data again which I have simulated for bias voltage versus capacitance. param_dcbias C_comp temperature 0. 2.880e-12 85.0000 0.2000 2.937e-12 85.0000 0.4000 2.880e-12 85.0000 0.6000 2.837e-12 85.0000 0.8000 2.768e-12 85.0000 1.0000 2.600e-12 85.0000 1.2000 2.343e-12 85.0000 1.4000 1.902e-12 85.0000 1.6000 1.922e-12 85.0000 1.8000 1.960e-12 85.0000 Please let me know which value I should use in my IBIS model. Regards, Girija/Amitava From: Girija V Chougala Sent: Wednesday, June 26, 2013 2:15 PM To: ibis-users@eda.org<mailto:ibis-users@eda.org> Cc: Amitava Banerjee Subject: Query on Ccomp parameter for IBIS model Hi, I have worked on deriving C_comp value for an I/O buffer (used the same technique given in IBIS cookbook - http://www.vhdl.org/ibis/cookbook/cookbook-v4.pdf ). The Vcc of the device is 1.8V. I have simulated C_comp for different bias voltages (VDC) - 0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8. The different C_comp values obtained are given in the attached bmp file. Please let me know which value should I use in my IBIS model. Thanks & Regards, Amitava This message and any attachments may contain Cypress (or its subsidiaries) confidential information. 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If it has been received in error, please advise the sender and immediately delete this message. -- 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 mikelabonte@eda-stds.org |or ibis-request@eda-stds.org | |IBIS reflector archives exist under: | | http://www.eda-stds.org/ibis/email_archive/ Recent | http://www.eda-stds.org/ibis/users_archive/ Recent | http://www.eda-stds.org/ibis/email/ E-mail since 1993Received on Thu Jul 4 09:04:33 2013
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