Re: [IBIS] IBIS Open Forum teleconference minutes (June 1, 2007)

From: Zhiping Yang <zhiping_yang_at_.....>
Date: Tue Jun 19 2007 - 14:57:41 PDT
Hi Michael,

Thanks for your comments. I will be more than happy to participate the ad-hoc meetings on touchstone format discussion in the future.  Here is the issue I had with Mix-mode S-parameter based on an example of 2 pair differential line:

2 pair differential transmission line can be represented in 4 port single-ended S-parameter file without any confusion.  It can also be easily translated to 4 port mix-mode S-parameter file without any problem ( the port impedance has to change, but new proposal covers that very well).  The problem I had is the reverse translation from 4 port mix-mode s-parameter file to 4 port single-ended s-parameter file because there is no sufficient info in the mix-mode s-parameter file itself.  To be more clear, let's assume single-ended terminal #1 and #2 are on one side and terminal #3 and #4 are on the other side of the transmission line.  For mix-mode s-parameter, I could assume port #1 and port #2 are differential mode and port #3 and #4 are common mode.  The mix-mode port #1 and #3 are from single-ended terminal #1 and #2.   Do you think the above information is sufficient to make translation from mix-mode s-parameter to single-ended s-parameter?  I think it is not.  The reason
 is that the user still don't know how the differential port was originally defined.  It could be terminal #1 - #2 or #2 - #1.  By considering both ends of transmission line, there could be 4 potential transformation matrices.   If the new touchstone format could include the definition of the mixed port in s-parameter file itself, the translation between the single-ended and mix-mode s-parameter will be no issue.  This is just my personal understanding.  I am looking forward to hearing feedback from others.

Another proposal I had is about the definition of infinite big number (1 over zero).  It might be worth to officially define it in touchstone format.   The infinite number could be very useful for Z and Y parameter files.  For example, it is impossible to define a simple series resistor in 2-port Z-parameter file without infinite number, and same true for a shut resistor in 2-port Y-parameter file.  This infinite number may not helpful in modeling the real circuit in Z or Y parameter file since any matrix with infinite number can not be effectively used in circuit simulators, but it does offer an easy way to warn the end user that something is wrong with the input data.

Thank and best regards,

Zhiping




----- Original Message ----
From: "Mirmak, Michael" <michael.mirmak@intel.com>
To: Zhiping Yang <zhiping_yang@yahoo.com>; rrwolff@micron.com; ibis@server.eda-stds.org
Sent: Thursday, June 14, 2007 10:19:42 AM
Subject: RE: [IBIS] IBIS Open Forum teleconference minutes (June 1, 2007)

Zhiping,

To answer your concerns, the Ad Hoc Interconnect team considered two
significant upgrades to the format but declined both:
1) Direct entry of mixed-mode S-parameter data
2) Complex reference impedances

In our discussions, we found that both these issues could be handled
through mathematical manipulation of data already available under the
existing format or through other, less drastic, proposed changes. 

You are certainly welcome to participate in our Ad Hoc Interconnect
meetings to continue the discussion.  Thanks!

- Michael Mirmak
  Intel Corp.
  Chair, EIA IBIS Open Forum

-----Original Message-----
From: owner-ibis@server.eda.org [mailto:owner-ibis@server.eda.org] On
Behalf Of Zhiping Yang
Sent: Thursday, June 07, 2007 10:55 PM
To: rrwolff@micron.com; ibis@server.eda-stds.org
Subject: Re: [IBIS] IBIS Open Forum teleconference minutes (June 1,
2007)

Hi Randy,

Thanks for generating the meeting minutes.

I briefly looked at the proposed Touchstone format proposal, but I
didn't see the mix-mode S-parameter is mentioned in the proposal.  There
are some unique properties associated with mix-mode S-parameter.  It is
nice if they are additional info can be included as optional parameters
for mix-mode S-parameter file.  This topic might already be discussed.
If so, I am very sorry that I missed it.  

Thanks a lot!

Zhiping

----- Original Message ----
From: "rrwolff@micron.com" <rrwolff@micron.com>
To: ibis@server.eda-stds.org
Sent: Thursday, June 7, 2007 9:16:17 AM
Subject: [IBIS] IBIS Open Forum teleconference minutes (June 1, 2007)

The minutes of the June 1, 2007 IBIS Open Forum teleconference can be
accessed at the following link:

http://www.eda-stds.org/ibis/minutes/min2007/m060107.pdf


Randy Wolff
Micron Technology
Secretary, IBIS Open Forum



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Received on Tue Jun 19 14:58:08 2007

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