All, On die S-Parameter is just one part of the problem. Models requiring on die S-Parameter are incompatible with the rest of IBIS IV and VT data, including things liked Vdiff, Cdiff. The problem with [External Circuit] it that it is explicitly outside of a model definition and therefore not model based. So if a chip had 300 instances of the same SerDes differential model, then using [External Circuit] would require 300 instances of the same [External Circuit], this combined with IBIS inability to properly handle true differentials makes putting this capability in IBIS problematic. As soon as the current revision of the AMI specification is completed, SiSoft will be introducing new AMI parameters that satisfy the Analog modeling requirements to support the AMI algorithmic modeling. One additional compelling reason to put this into the .ami file is that we have found that configuring the ami algorithmic model also configures the analog parasitics. Walter Walter Katz 303.449-2308 Mobile 720.333-1107 wkatz@xxxxxxxxxx www.sisoft.com -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Muranyi, Arpad Sent: Tuesday, February 09, 2010 10:33 AM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: IBIS-AMI Vendor Support Help Ken, [External Model] may not work because it is specifically designed to replace the [Model] with a better modeling language content while preserving the same connectivity of the [Model] keyword. This means that the all of the nodes of [Model] or [External Model] are supposed to be connected the same exact way, which would prevent us to put die parasitics between the buffer model and the pads. However, [External Circuit] does not have this restriction, so we could potentially make use of that keyword for this purpose, perhaps referencing the new (proposed) IBIS-ISS capabilities which allow us to use S-parameters. If we went with this route, the question is, can we have a [Model] behind the [External Circuit], which is something I don't remember for sure now. I need to research the spec on that a little more... Arpad ======================================================================== -----Original Message----- From: Ken Willis [mailto:kwillis@xxxxxxxxxxx] Sent: Tuesday, February 09, 2010 9:19 AM To: 'Todd Westerhoff'; Muranyi, Arpad Cc: si-list@xxxxxxxxxxxxx Subject: RE: [SI-LIST] Re: IBIS-AMI Vendor Support Help Hi Todd, On #1, it makes sense to incorporate S-parameters into IO models, especially since some major IP suppliers have this data today. I think the item that brings some uncertainty is why this would be pushed into the algorithmic (AMI) portion of the model, especially if new syntax/API has to be invented and supported. The intent of AMI was to capture the adaptive filtering behavior of these advanced Serdes devices, which you couldn't really model well in a circuit model. If the S-parameters are largely parasitic data, it seems more straightforward to include them in the analog circuit part of the model. I understand that there is no standard "IBIS" syntax for S-params right now, but I would agree with Arpad that Touchstone is widely supported. Maybe we should be looking at [External Model] > Touchstone or something like that. But we can continue the discussion in the IBIS forum. Thanks, Ken Willis Sigrity, Inc. 860-871-7070 kwillis@xxxxxxxxxxx ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu