Dear Syed et al, Your IBIS BIRD 95 proposal is one step forward towards a solution in which we can leverage IBIS in SSN and PI analyses. We appreciate the efforts of you and others who have contributed to this BIRD, and hope that we can all reap its benefits in the future. However, at this point in time, there are still some concerns/questions we have on the current proposal and would like to get these addressed before casting a supporting vote: 1. BIRD 95 focuses only on ONE pin at this time. We understand this is the "traditional" way IBIS looks at the problem. But, while we agree the BIRD appears to solve the challenge of modeling ONE buffer into ONE load, the degradation effects of MANY buffers switching is not accounted for (and may even be pre-empted by forcing the I/T characteristic of ONE buffer). 2. We also found that the "composite current" in BIRD 95 is likely under-specified right now (i.e., not enough data) to do the analysis accurately due to the strong dependency of the crowbar/pre-drive current on the specific load seen (Sam Chitwood had a presentation in DesignCon West 2005 mentioned this as well. Page 12, http://www.eda.org/pub/ibis/summits/jan05/chitwood.pdf). We do think this is an important piece that needs to be sorted out, especially if we intend to deal with SSN and PI at the system level, which we believe is the right approach. To take the next step forward, we ask you to give out your SPICE reference circuit to the public as Intel did when IBIS was originally proposed. Thus, the rest of us can better understand your perspective/assumptions. Donald Telian asked for this publicly at DesignCon West 2005. And we all happily heard Sergio's positive response. This is why I had suggested moving the Voting out for couple of weeks at least on this BIRD. Extending the vote out will allow us collectively to address the issues raised above by Cadence as well as others in the IBIS community. Should you decide to continue with the voting this Friday, Cadence will have to vote NO, since we think we can collectively come up with an improved proposal that addresses the goals and objectives for SSN and PI. We are working on extending this IBIS 95.5 proposal to address the issues I raised above. We will share our ideas, proposal and reference data/circuits when it is ready. Thank you, and let's take IBIS forward together! Lance Wang Cadence Design Systems, Inc. -----Original Message----- From: owner-ibis@eda.org [mailto:owner-ibis@eda.org] On Behalf Of Syed Huq Sent: Friday, April 29, 2005 8:38 PM To: ibis; ibis-users Subject: [IBIS] BIRD95.5: Power Integrity Analysis using IBIS To All: BIRD95.5 clarifies some node connections per some comments received at the IBIS meeting on April 22, 2005 and privately from John Angulo to add and clarify the "power reference terminal". Also some of the text is revised to focus on the internal terminals. Some change areas are noted by |***** lines and in the ANALYSIS ... section. BIRD95.5 will be up for vote in the Fri May 13 IBIS Teleconference. Syed Huq -- Cisco Systems, Inc Acting Chair - EIA IBIS Forum |------------------------------------------------------------------ |For help or to subscribe/unsubscribe, email majordomo@eda.org |with just 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 email a written request to ibis-request@eda.org. | |IBIS reflector archives exist under: | | http://www.eda.org/pub/ibis/email_archive/ Recent | http://www.eda.org/pub/ibis/users_archive/ Recent | http://www.eda.org/pub/ibis/email/ E-mail since 1993Received on Thu May 12 13:04:35 2005
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