From: owner-ibis-users@eda.org (ibis-users) To: ibis-users-digest@eda.org Subject: ibis-users V1 #149 Reply-To: Sender: owner-ibis-users@eda.org Errors-To: owner-ibis-users@eda.org Precedence: bulk ibis-users Friday, October 8 2010 Volume 01 : Number 149 ---------------------------------------------------------------------- Date: Wed, 29 Sep 2010 06:48:52 -0700 From: "Muranyi, Arpad" Subject: RE: [IBIS-Users] RE: [IBIS] C_comp Max < C_comp Min Well, if we start talking on that level, I should mention that C_comp can be different for when the buffer is driving high, low, or receiving, and at various frequencies if you measure it with a frequency domain simulation (C vs. f). Arpad ================================================== - -----Original Message----- From: Haller, Robert [mailto:rhaller@enterasys.com] Sent: Wednesday, September 29, 2010 7:51 AM To: Bob Ross; Baker, Bonnie Cc: Walter Katz; 'Mirmak, Michael'; Muranyi, Arpad; 'ibis@server.eda.org'; 'ibis-users@server.eda.org' Subject: RE: [IBIS-Users] RE: [IBIS] C_comp Max < C_comp Min I always wanted to have separate values of C_COMP for Inputs and Outputs in IO cells because they tend to optimize to slightly different values. In general I found to split the difference or lean toward the input value, particularly on a Multi-load network. Bob - -----Original Message----- From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf Of Bob Ross Sent: Wednesday, September 29, 2010 1:33 AM To: Baker, Bonnie Cc: Walter Katz; 'Mirmak, Michael'; 'Muranyi, Arpad'; 'ibis@server.eda.org'; 'ibis-users@server.eda.org' Subject: Re: [IBIS-Users] RE: [IBIS] C_comp Max < C_comp Min All: Thanks Bonnie for your solution to the problem. You comply with IBIS, but provide a comment line for the value-to-corner mapping. That is the best we can do with IBIS today. For consistency for a particular PVT setting, all corner entries for a [Model] should have been for the same PVT conditions. [Model Spec] is already consistent in that respect. I have a number of objections to [Model Corner] proposal. One concern is that the C_comp parameters are related to actual silicon or Spice extraction values, and the other parameters are specification parmeters. overrides, spec. test setups, and limits. C_comp should remain separate. For better consistency, the IBIS committee should have defined a corner aligned C_comp by a keyword [C_comp] like [Pullup], etc. We did decide on a statistical range C_comp because in the early days, buffer to buffer differences due to metalization was a factor. We intend to let the user try different C_comp values to check design robustness. I now believe that was the wrong decision. Bob Baker, Bonnie wrote: > All, > > I had big concerns about this a few months ago. Originally, I was posting my IBIS models from my CMOS devices with the c_comp warnings from the parser. I then chose to list these values in numerical order to get away from those warnings because the IBIS standard and I felt the warnings were red flags to my customer. I have been reading the string over the last few days and I want to share our "solution" to this problem. Embedded in each buffer we have the following text: > > | typ min max > | (nom PVT) (Fast PVT) (slow PVT) > C_comp 9.298e-13 9.221e-13 9.527e-13 > | > | Where nom PVT is Nominal Process, 3.3V, 25C > | Fast PVT is Strong Process, 3.6V, -40C > | Slow PVT is Weak Process, 3.0V, 85C > > > Bonnie Baker > > -----Original Message----- > From: owner-ibis@eda.org [mailto:owner-ibis@eda.org] On Behalf Of > Walter Katz > Sent: Tuesday, September 28, 2010 8:22 AM > To: 'Bob Ross'; 'Mirmak, Michael'; 'Muranyi, Arpad'; 'ibis@server.eda.org' > Cc: 'ibis-users@server.eda.org' > Subject: RE: [IBIS-Users] RE: [IBIS] C_comp Max < C_comp Min > > All, > > What Bob is proposing will work for C_Comp, but will leave all the > other > 100 or so other parameters that have typ min max, that may need typ > slow fast, along with a number of other insonsistant methods of > defining corner conditions (e.g. Vinh_ac, Vinh_dc, Vinl_ac, Vinl_dc > are defined by corner in several JEDEC specs, while they are defined with sensitivity in IBIS 5.0. > > We have found that being able to specify parameters by Corner in > addition to Range is an important feature that is used very often in AMI modeling. > > Walter > > -----Original Message----- > From: Bob Ross [mailto:bob@teraspeed.com] > Sent: Monday, September 27, 2010 9:17 PM > To: Walter Katz; 'Mirmak, Michael'; 'Muranyi, Arpad'; 'ibis@server.eda.org' > Cc: 'ibis-users@server.eda.org' > Subject: Re: [IBIS-Users] RE: [IBIS] C_comp Max < C_comp Min > > All: > > The reasons for why we decided at that time to specify C_comp by > numerical value are well stated, and they are quite valid. But the > decision created a consistency mistake because we did not specify > buffer values completely for direct corner correlation. > > I would favor just addressing only the C_comp issue. A simpler > alternate proposal would be to introduce a new model sub-parameter > such as "C_comp_corner" that specifies the value to be used for the > corresponding corner. That would fit in with existing IBIS. > > We could establish rules such as > > C_comp is always required for full range > which could be outside the corner range for > buffer tolerance design and also to provide a > guarenteed support path for all existing tools. > > C_comp_corner is optional for picking a corner value > for direct corner correlation. > > Or we could require one or the other. > > Bob > > > > Walter Katz wrote: > >>All, >> >> >> >>There is a very simple solution to this issue, please review the >>enclosed draft {Model Corner] draft BIRD. >> >> >> >>Walter >> >> >> >>-----Original Message----- >>From: owner-ibis@eda.org [mailto:owner-ibis@eda.org] On Behalf Of >>Mirmak, Michael >>Sent: Monday, September 27, 2010 12:02 PM >>To: Muranyi, Arpad; ibis@server.eda.org; ibis-users@server.eda.org >>Subject: RE: [IBIS] C_comp Max < C_comp Min >> >> >> >>One other item to note: not all device technologies associate a >>numerically-smallest capacitance with the ?fast/strong? process. >> Assuming that CMOS rules universally apply would not have been >>appropriate, and IBIS does not include any notations as to which >>process technology is used in the design for the data presented. >>Without that information or some basic ordering assumption, parsers >>have no means to confirm that the C_comp data had been entered correctly. >> >> >> >>As Arpad states, the only way to have enforceable parsing rules was to >>order the C_comp from numerically-smallest to ?largest, with the >>assumption that the EDA tool would supply the missing information, >>likely from asking the user (for example, the tool might inquire about >>the process used for the IC in question). >> >> >> >>Michael Mirmak >> >>Intel Corp. >> >>Chair, IBIS Open Forum >> >> >> >>From: owner-ibis@eda.org [mailto:owner-ibis@eda.org] On Behalf Of >>Muranyi, Arpad >>Sent: Monday, September 27, 2010 7:35 AM >>To: ibis@server.eda.org; ibis-users@server.eda.org >>Subject: RE: [IBIS] C_comp Max < C_comp Min >> >> >> >>Fabio, >> >> >> >>The reason you are getting that message is because the die capacitance >> >>does not have a direct relationship with the fast/slow process corners >> >>and when we wrote the IBIS specification we decided that it was best >> >>to just put the small number into the min place and the big number >>into >> >>the max place. It was expected that an EDA tool would allow the user >> >>to try out all possible combinations between min/max curves and C_comp. >> >> >> >>Arpad >> >>====================================================================== >>== >> >> >> >>---------------------------------------------------------------------- >>-- >> >>From: owner-ibis@eda.org [mailto:owner-ibis@eda.org] On Behalf Of >>Fabio BRINA >>Sent: Monday, September 27, 2010 7:12 AM >>To: ibis@server.eda.org; ibis-users@server.eda.org >>Subject: [IBIS] C_comp Max < C_comp Min >> >>Hello Ibis experts, >> >> >> >> I'm working in CMOS tecnology; >> >> very often in the C_comp extraction I obtain the Min value bigger >>then Max value: >> >> the values come from ac simulations in these conditions: >> >> >> >> C_comp Min value consider: Vcc Min, Process Min, Temp Max >> >> C_comp Max value consider: Vcc Max, Process Max, Temp Min >> >> >> >> The Ibis Check output is: >> >> >> >>WARNING (line 76) - >> >> Model mod1: C_comp min value is not the smallest value listed >> >>WARNING (line 76) - >> >> Model mod1: C_comp max value is not the largest value listed >> >> >> >>Is that situation acceptable? >> >>or I have to switch the Min Value with Max Value? >> >> >> >>... suggestions are welcome ! >> >> >> >>Thank you, >> >>Fabio >> >> >> >> >>-- >>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. >> >> >>-- >>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. > > > - -- 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 - -- 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 | subscribe ibis-users | unsubscribe ibis | unsubscribe ibis-users | |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 | subscribe ibis-users | unsubscribe ibis | unsubscribe ibis-users | |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 ------------------------------ Date: Fri, 8 Oct 2010 18:53:53 +0530 From: Subject: [IBIS-Users]: DC voltage for C_comp Calculation This is a multi-part message in MIME format. - ------_=_NextPart_001_01CB66EC.10057C06 Content-Type: text/plain; charset="us-ascii" content-transfer-encoding: quoted-printable Hi, For the calculation of C_comp by AC sweep, we apply an AC signal along with some DC voltage. What should be the value of this DC voltage to get correct C_comp value? Thanks in advance. Regards Surendra Please do not print this email unless it is absolutely necessary.=20 The information contained in this electronic message and any attachments to= this message are intended for the exclusive use of the addressee(s) and ma= y contain proprietary, confidential or privileged information. If you are n= ot the intended recipient, you should not disseminate, distribute or copy t= his e-mail. Please notify the sender immediately and destroy all copies of = this message and any attachments.=20 WARNING: Computer viruses can be transmitted via email. The recipient shoul= d check this email and any attachments for the presence of viruses. 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Hi,

       For the calculation= of C_comp by AC sweep, we apply an AC signal along with some DC voltage. What should be the value of this DC voltage to get correct C_comp value?

 

Thanks in advance.

 

Regards

Surendra

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