====================================================================== IBIS INTERCONNECT TASK GROUP http://www.ibis.org/interconnect_wip/ Mailing list: ibis-interconnect@freelists.org Archives at http://www.freelists.org/archive/ibis-interconn/ ====================================================================== Attendees from August 9 Meeting (* means attended at least using audio) ANSYS Curtis Clark Cadence Design Systems Bradley Brim Cisco David Siadat Intel Corp. Michael Mirmak* Keysight Technologies Radek Biernacki, Ming Yan Mentor, A Siemens Business Arpad Muranyi* Micron Technology Justin Butterfield*, Randy Wolff* SAE ITC Maureen Lemankiewicz, Logen Johnson Signal Integrity Software Walter Katz*, Mike LaBonte* Teraspeed Labs Bob Ross* University of Aveiro in Portugal Wael Dghais Michael Mirmak convened the meeting. No patents were declared. Justin Butterfield took minutes. Review of Minutes: - Michael called for review of the minutes from the August 2 meeting. Randy Wolff moved to approve the minutes. Mike LaBonte seconded. The minutes were approved without objection. Review of ARs: - Mike to update the BIRD189.5 draft 5 and send it out to mailing list. - He reported that it was sent out but not yet posted. Opens: - Arpad Muranyi would like to get some answers about what to do when one of the Interconnect Models in the path is missing. BIRD189.5 does not say that both models of pins to pads and pads to buffers are required. - Bob Ross sent out two presentations on referencing to cover if there is time. Mike added that the referencing is an important issue that needs to be discussed. - Mike commented that when terminals are connected by signal_name, a policy of which nodes are connected needs to be chosen. BIRD189.5 draft 5: Mike stated that it is difficult to determine exactly how to connect the Unused_port_termination. Walter Katz stated an unused port means the model maker is saying to ignore it, and the way to ignore it is to terminate it. Arpad asked about Touchstone 2, if reference impedance of the terminal should be used. Walter stated he agrees with using the reference impedance for Touchstone. Walter thought for ISS, the default termination is the Unused_port_termination value. If it is not specified, the EDA tool has to decide. Michael asked what happens if you have large numbers of models and the Unused_port_termination value is different for these models. Walter stated in that case, the EDA tool or user can make the decision. Bob stated his concern is that the Unused_port_termination is adding something to the simulation that does not exist. He favors allowing the EDA tool to make the decision. Arpad said that Ken Willis of Cadence mentioned that EDA tools have already been doing this for connector models. Walter commented the Unused_port_termination is a recommendation from model maker. Mike suggested to call it Default_unused_port_termination. Bob commented the port termination should be by terminal. Arpad thought Unused_port_termination parameter is still useful for ISS where the impedance is not known. Michael asked if the current BIRD189.5 text allows the EDA tool to make the decision. Arpad replied that the way it is written that is not the case. Walter mentioned he objects to the 3rd paragraph in the Unused_port_termination rules section. Unused ports for Touchstone should be terminated. Arpad thought that this parameter should only be used for ISS. Walter said that the way the text is written if the parameter is not stated, then the port is terminated. Arpad added that there needs to be a way to specify an actual open. Michael asked what changes should be made to BIRD189.5. Walter commented that the EDA tool can choose to terminate these unused terminals as it sees fit, and the Unused_port_termination parameter gives the default value. Mike suggested to make the first sentence in the Unused_port_termination rules section less definitive. Bob stated he sees two choices. The first option is to remove the Unused_port_termination parameter and make the EDA tool responsible for selecting per port termination. The second option is to keep the parameter and allow the EDA tool to override it. Michael stated the Unused_port_termination value gives useful data. If there is some preference from the model maker it is communicated to the EDA tool even though it can be overridden. The model maker may not know the final system impedance. Mike will take an AR to rewrite this section, then we can discuss the issue further. Michael stated the next issue in BIRD189.5 is when terminals are connected with signal_name. Walter stated if signal_name is used, then all the terminals are shorted together for pin, pad or buffer as the case may be. Michael asked what change is needed to BIRD189.5 to resolve this issue. Bob commented that there is still a question of how the references are connected. The referencing can be ambiguous. Walter disagreed that it is ambiguous. Bob said that [Pin Mapping] is already defined for Example 4, but the referencing also goes through the [Interconnect Model] in this example. Michael asked about Arpad's question in regards to the missing connections in the path. He asked Arpad to propose some options. Arpad mentioned he was looking for confirmation that BIRD189.5 does not define what to do in these cases. Walter commented that shorting is recommended when you only have a model for pin to pad. However, when you have a die only interconnect model, the EDA tool can make a decision to use a legacy package model format. Mike moved to adjourn. Walter seconded. The meeting adjourned without objection.