[SI-LIST] Re: Draft Touchstone 2.0 document available

Patrick:

Here are my personal views and thought-process favoring NOT
changing:

First it is a CLEARLY a no-brainer - clean up this legacy "mistake"
where it was correct in the 1980's for unknown reasons that
are totally irrelevant now and forever.

Except ...

What is the impact on industry?

Touchstone is well entrenched and the IBIS Committee is in no way
positioned or even interested in creating a disruption that would
force anyone to change what they are doing.

The primary reason for keeping as much old legacy stuff is to
MAXIMIZE both UPWARD and DOWNWARD transformation between
existing Touchstone format usage and the the new Version 2.0
format usuage.

Specificially if a tool produces a Version 2.0 file for two-port
S-parameters and wants to process it in any tool that does
NOT accept the format, all the user has to do is remove ONLY three
text lines CLEARLY POSITIONED at the TOP of the FILE with
this text:  [Version], [Number of Ports], and [Number of Frequencies].

Adding the TRIVIAL step of interchanging two text-fomatted
column-pairs becomes the first step that has a high
probabilty of occationally hurting you (forgot).

... And visa versa.

So I apply counter-intuitive logic:

The primary reason for minimizing legacy garbage change
on one side (format) is to maximize the acceptance of
the format and its additional features.

Bob

Mirmak, Michael wrote:
> Patrick,
> 
> Thank you for the kind comments and suggestions!
> 
> The specification is now being considered by the IBIS Open Forum for
> standardization and your request was discussed at our most recent
> meeting, this past Friday.  We can certainly consider making this change
> in version 2.0 files.  It would not be a difficult adjustment to make to
> the draft and would make the format more consistent.
> 
> One concern is simply whether changing the order for version 2.0 files
> would increase confusion in switching to the new format, particularly
> when converting existing files to 2.0 would be convenient.  We tried to
> navigate a middle path between making radical improvements in 2.0 and
> keeping existing Touchstone files, tools and methods almost unchanged.
> In addition to maintaining backward compatibility, we elected to
> maintain most of the existing network data format, in order to make the
> 2.0 transition reasonably easy.  The exception is the removal of
> normalization, which was required to support per-port impedances.
> 
> So, in your opinion (and in that of the SI-List readers) would
> correcting the ordering of S12, S21 in 2.0 files outweigh the resulting
> inconsistency with the previous ordering and existing files, tools,
> etc.?
> 
> Thanks again for your comments, and also thanks to those who provided
> comments off-line.  Anyone interested in the topic is certainly welcome
> to attend our Open Forum teleconferences and participate in the
> Touchstone 2.0 discussions.
> 
> - Michael Mirmak
>   Intel Corp.
>   Chair, IBIS Open Forum
> 
>   http://www.eigroup.org/ibis/
>   http://www.eda.org/ibis/
> 
> -----Original Message-----
> From: Zabinski, Patrick [mailto:zabinski.patrick@xxxxxxxx]=20
> Sent: Sunday, December 16, 2007 7:33 AM
> To: Mirmak, Michael; si-list@xxxxxxxxxxxxx
> Subject: RE: [SI-LIST] Re: Draft Touchstone 2.0 document available
> 
> Michael,
> 
> Thank you and the IBIS Open Forum for supporting and updating
> the Touchstone Spec.  The spec has become a de facto industry
> standard, and it is in much need of updating.
> 
> Overall, I really like the improvements suggested in Draft Version 2.
> They should enhance the utility of the file format and ease
> tool development that supports the format.
> 
> I spoke with a few folks about the draft, and we would appreciate
> consideration of one change.  Under Network Parameter Data, the
> ordering of the S-parameter matrix elements are consistent for
> most - but not all - matrix sizes.
> 
> More specifically, the 1-, 3-, 4-, 5-, ... port matrices are
> presented in Ascending-Row then Ascending-Column order, which
> matches most (all?) common matrix representations.
> 
> In contrast, the 2-port matrix breaks this order, in that S21
> (Row 2) is listed before S12 (Row 1). =20
> 
> Although we can generally adapt to the 2-port matrices having their
> own unique element ordering, it has historically caused many
> issues for several of us.  Several analysis and measurement tools
> do not follow this ordering, and many engineers are unaware of
> the uncommon ordering.
> 
> If at all possible, we would much appreciate the 2-port matrix
> element ordering to comply with the rest of the spec.  By doing so,
> it would make Touchstone format consistent with many
> commercially-available
> tools and make it easier (i.e., less error prone) for folks to
> develop tools around it.
> 
> Much appreciate your consideration.
> 
> Pat
> 
> 
>>=20
>>=20
>>-----Original Message-----
>>From: Mirmak, Michael=3D20
>>Sent: Wednesday, December 12, 2007 5:26 PM
>>To: si-list@xxxxxxxxxxxxx
>>Subject: Draft Touchstone 2.0 document available
>>=20
>>=20
>>The IBIS Open Forum has completed a draft of an improved Touchstone
>>specification, entitled Touchstone 2.0, to expand the capabilities of
>>the original format and eventually release it as an industry standard.
>>Some of the changes in the new version include:
>>=20
>>- support for independent per-port reference impedances
>>- the number of ports that may be represented is unlimited
>>- support for lower- or upper-half matrix representations, to reduce
>>file size
>>- the version number, the number of ports and the number of=20
>>frequencies
>>in any file have all been made explicit
>>=20
>>Backward compatibility with 1.0 models has been preserved.
>>=20
>>Touchstone 2.0 will be formally introduced at this week's IBIS Open
>>Forum teleconference, for review and comment in preparation for
>>standardization.
>>=20
>>The latest review draft may be obtained at the URL below.  =20
>>Comments are
>>welcome.
>>=20
>>http://www.eda.org/ibis/docs/touchstone2_review_draft.pdf=3D20
>>=20
>>- Michael Mirmak
>>  Intel Corp.=3D20
>>  Chair, IBIS Open Forum
>>=20
>>  http://www.eigroup.org/ibis/
>>  http://www.eda.org/ibis/
>>=20
> 
> ------------------------------------------------------------------
> 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:
> http://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:     
>               http://www.freelists.org/archives/si-list
> or at our remote archives:
>               http://groups.yahoo.com/group/si-list/messages
> Old (prior to June 6, 2001) list archives are viewable at:
>               http://www.qsl.net/wb6tpu
>   
> 
> 


-- 
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@xxxxxxxxxxxxx

Teraspeed is a registered service mark of Teraspeed Consulting Group LLC

------------------------------------------------------------------
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:
http://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:     
                http://www.freelists.org/archives/si-list
or at our remote archives:
                http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
                http://www.qsl.net/wb6tpu

Other related posts: