Re: [SI-LIST] : MECL System Design Handbook

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From: Ritchey Lee (leeritchey@earthlink.net)
Date: Tue Jun 05 2001 - 10:13:12 PDT


TOm,

I have such PCBs and have launched edges as fast as 60 pSEC into them
with no detectable perterbation. My objective is to see how PCB
features affect logic signals, none of which have edges faster than 60
pSEC by the time they reach the PCB. All of us who are looked to for
technical guidance should be doing the same.

It might be possible to "see" a 90 corner at some very high frequency,
some use numbers like 40 GHz, or at some bery large geometry, like 100
mil wide traces, but these cases aren't germain to what our community
works with day to day. The stuff of 10 mil traces ans thinner and edges
of 60 pSEC and slower are of interest. That's the reagon where we
should be sure our advice has meaning.

Lee

Dagostino, Tom wrote:

> I agree that this board is not the latest technology, that is why I
> qualified my offer, but it does have real square corners and the
> traces of interest are fairly isolated. If you can send me a test
> board that has good square corners that are isolated and that I can
> get a clean launch into I will measure that and publish those results
> too.I now have the GPIB system working on my scope again and will make
> some measurements on the test board I have. Tom Dagostino
> Modeling Manager
> Mentor Graphics Corp.
> SAE
> tom_dagostino@mentor.com
> 503-685-1613
>
> -----Original Message-----
> From: Ritchey Lee [mailto:leeritchey@earthlink.net]
> Sent: Friday, June 01, 2001 10:10 AM
> To: Dagostino, Tom
> Cc: 'Dr. Edward P. Sayre'; Rich Peyton; Roehrner Wolfgang;
> si-list@silab.eng.sun.com
> Subject: Re: [SI-LIST] : MECL System Design Handbook
> Wolfgang,
>
> The test board you cite doesn't relfect how real logic PCBs
> are built. No one uses 100 mil wide traces. Also, no one
> builds PCBs with such thick dielectrics. It would be
> misleading to suggest that what you measure with the
> structures you have apply to the structures that appear in
> logic PCBs, unless you show that the scaling is appropriate.
>
> Lee
>
> Dagostino, Tom wrote:
>
> >
> >
> > I have a board that demostrates this very nicely. As soon
> > as I get my scope/extraction system working again I will
> > publish some results. The board is two layers with ground
> > on one side and 50 Ohm traces on the other. Yes, these
> > traces are quite wide, on the order of 0.100". There are
> > several right angel bends with square corners. The
> > corners are quite visible.
> >
> > Tom Dagostino
> > Modeling Manger
> > Mentor Graphics Corp.
> > SAE
> > tom_dagostino@mentor.com
> > 503-685-1613
> >
> > -----Original Message-----
> > From: Dr. Edward P. Sayre [mailto:esayre@nesa.com]
> > Sent: Thursday, May 17, 2001 6:47 PM
> > To: Ritchey Lee; Rich Peyton
> > Cc: Roehrner Wolfgang; si-list@silab.eng.sun.com
> > Subject: Re: [SI-LIST] : MECL System Design Handbook
> >
> > Lee and others:
> >
> > I don't know what kind of TDR or fixturing you might have
> > used, but the
> > excess capacitance is very real and can be seen. It is
> > also illustrated in
> > a number of microwave books. If your fixturing caused a
> > significant loss (>
> > 100 ps) of risetime of the step out of the TDR, then the
> > capacitance effect
> > will be washed out.
> >
> > Sincerely,
> >
> > ed sayre
> > ==========================
> > At 08:36 AM 5/10/01 -0700, Ritchey Lee wrote:
> > >Any of you who want to know how the myth about right
> > angle bends got
> > >started, look
> > >at figure 7.17 on page 155. This alleges that right
> > angle bends can be
> > >seen by a
> > >TDR. I've done this measurement dozens of times and
> > coiuld never see a right
> > >angle bend.
> > >
> > >A few years ago, I called Mr. Blood the author of the
> > book and asked
> > >about the
> > >diagram. His reply was that he knew the diagram was
> > flawed, but there
> > >wasn't time
> > >to fix it before the book went to press.
> > >
> > >As a result, thousands of engineers have spend countless
> > time worrying
> > >about right
> > >angle bends.
> > >
> > >When we publish technical information such as this, it is
> > important to
> > >insure it
> > >is accurate.
> > >This applies especially to applications notes, whic often
> > contain entirely
> > >false
> > >data.
> > >
> > >Lee
> > >
> > >Rich Peyton wrote:
> > >
> > > > FYI,
> > > >
> > > > The hard copy can be ordered free of charge.
> > > >
> > > > Rich
> > > >
> > > > Roehrner Wolfgang wrote:
> > > >
> > > > > http://www.onsemi.com/home
> > <http://www.onsemi.com/home>
> > > > >
> > > > > In the Menu-tree go to:
> > > > >
> > > > > Technical Documents
> > > > > CD/Document Ordering
> > > > > General Search
> > > > >
> > > > > search for document number: hb205
> > > > > download it as pdf (or order!).
> > > > >
> > > > > regards,
> > > > > Wolfgang
> > > > >
> > > > > -----Original Message-----
> > > > > From: Ashok Babu K
> > [mailto:k.ashokbabu@gdatech.co.in]
> > > > > Sent: Tuesday, April 10, 2001 12:39 PM
> > > > > To: si-list@silab.eng.sun.com
> > > > > Subject: [SI-LIST] : MECL System Design Handbook
> > > > >
> > > > > Hi all,
> > > > > I see that a good resource for general high speed
> > termination design and
> > > > > especially ECL/PECL termination is Motorola's MECL
> > System Design
> > > Handbook by
> > > > > Blood Jr., and William R. Many articles and papers
> > specify the same as a
> > > > > good resource. Unfortunately I could not get the
> > soft copy of the MECL
> > > > > System Design Handbook. I could not get it from the
> > ON Semiconductor
> > > > > website. If any of you have the PDF file of the same
> > or know where it
> > > can be
> > > > > obtained, please inform me. Any suggestions of other
> > resources are highly
> > > > > welcome.
> > > > > Regards,
> > > > > Ashok.
> > > > >
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> > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~+
> > | NORTH EAST SYSTEMS ASSOCIATES, INC. |
> > | ------------------------------------- |
> > | "High Performance Engineering & Design" |
> > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~+
> > | Dr. Ed Sayre e-mail: esayre@nesa.com |
> > | NESA, Inc. http://www.nesa.com/ |
> > | Primrose Park Tel +1.978.392-8787 |
> > | 5 LAN Drive, Ste 200 Fax +1.978.392-8686 |
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