[SI-LIST] Re: We ought to address mutual SI-EMI issues in this forum
- From: "istvan novak" <istvan.novak@xxxxxxxxxxxxxxxx>
- To: <Roy.Leventhal@xxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Mon, 2 Sep 2002 21:15:45 -0400
Roy,
Thanks for bringing up the topic. I personally feel that your charter and
mission
is very important for both the SI and EMI/EMC communities. In those years
when the term 'signal-integrity' was not yet commonly used, reflections,
crosstalk and impedance-matching was mostly done by people with EMI/EMC
background. Gradually signal integrity grew into an independent discipline,
but
it is time again to combine efforts.
Regarding item 1 on your list, before this year's EPEP conference, at the
Future
Directions of IC Packaging workshop, we will have an invited talk just with
this
goal in mind. Check out the program at http://www.epep.org/courses.html
Todd Hubing "The Impact of Chip and Package Design on Radiated EMI"
Regards
Istvan Novak
SUN Microsystems
----- Original Message -----
From: "Roy Leventhal" <Roy.Leventhal@xxxxxxxx>
To: <si-list@xxxxxxxxxxxxx>
Sent: Monday, August 26, 2002 1:49 PM
Subject: [SI-LIST] We ought to address mutual SI-EMI issues in this forum
>
> All,
>
> I'm sending you this message because I believe we need to begin much
better
> communications with our co-workers who concentrate on EMI/EMC issues. You
> can help by sharing your views. These can be on any subject of mutual
> interest between the EMI community and the SI community. But, to start the
> ball rolling, please share any of your thoughts on:
>
> 1. Productive ways to communicate between the two communities both at work
> and in outside venues such as symposiums and publications.
>
> 2. Modeling and simulation in SI and EMI and how this facilitates
> understanding.
>
> 3. Measurements and terminology and how this must relate the models and
> simulation used across different technical disciplines.
>
> 4. How best to draw into this communication other technical areas that
will
> have to be involved in order for any of us to succeed.
>
> 5. The role of standards.
>
> I agreed to be a point of contact between TC10 and SI-LIST. It is my aim
to
> facilitate communication between the EMI community and the SI community.
>
> For item 4 above I'm thinking of component package design and modeling for
> circuits AND EMI effects. Plus, the same issues for the IC chips
themselves.
> Plus the participation of the PWB and standards communities.
>
> Recently, I attended EMC 2002 in Minneapolis. I sat in on the meeting of
> IEEE EMCS Technical Committee 10 (TC10) "Signal Integrity and
> Microelectronic Technology." It was well attended by your peers with
> outstanding reputations in EMI who know about SI-LIST, but don't have the
> bandwidth to be very active in it. The attendees felt that the two
> communities are being driven together by the press and progress of
> technology. They also felt the impossibility of succeeding in isolation
from
> each other. There is a long tradition of interest in EMI in the IEEE.
While
> their evident interest in SI is very recent, I believe it is genuine. I
> noted at least 15 papers presented at the seminar that touched on some
> aspect of EMI from chips and packages. The IEEE press bookselling booth
also
> had a brand new text:
>
> "Signal Integrity Effects in Custom IC and ASIC Designs"
> Raminderpal Singh
> IEEE Press & John Wiley & Sons, Inc., c2002
> ISBN 0-471-15042-8
>
> I'll share some of my perceptions and opinions (based on my experiences)
> below to start this discussion going. Your experience, therefore opinions,
> can be different. So much the better for the sake of the discussion.
>
> I believe the relations between the SI community and the product/logic
> design community plus the PCB design community already have a good
teamwork
> paradigm that allows them to meld together their separate talents and
skills
> in a highly effective way. This work involves a lot of modeling and
> simulation at the front end, a (virtual) verification of layout and
routing
> and as a diagnostic tool of physical board problems. A lot of
communication
> goes on between this team to meet their mutual and sometimes conflicting
> goals. To simplify a lot:
>
> The logic engineer would be happy with logic that is hooked up correctly
and
> has good timing (ideal ones and zeros with infinitely fast edges).
>
> The SI engineer wants good clean switching waveforms without noise,
ringing,
> etc., for reliable switching. Fast edges often cause problems.
>
> The board engineer wants to achieve the above seemingly unreasonable
demands
> at minimum cost and maximum producability.
>
> Driver strength and speed, physical structures that radiate, support EM
> fields, have losses and influence feedback effects insure that what
> engineers and designers do at every physical scale impacts every other
> physical scale. Particularly at today's speeds and complexity.
>
> As an SI engineer I've noted that after the product engineer, the PCB
> designer and I complete our concurrent tasks the design process enters a
new
> (often excruciatingly painful) phase called "trying to pass regulatory."
In
> this endeavor there doesn't seem to be a lot of modeling, simulation and
> communication that goes on between the SI engineer and the EMI engineer.
The
> EMI engineer might be happiest with no fast edges at all and lots of
> shielding. There also seems to be many iterations of build-test-find/fix
> problems-retry. During this phase, if successful, there is a lot of stress
> on everyone.
>
> I know that EMI engineers are often every bit {and often more) technically
> sophisticated as I am. I presume that they would like to see simulations
at
> the system level with multiple boards, different data patterns,
enclosures,
> attached cables, etc., that would match their test bench data.
>
> For starters there is an extremely important missing area of models and
data
> that prevents this match up between system simulation and test stand
> measurements. That missing link is the EMI modeling of the chips and
> components on a board. Without it there is virtually no chance that
> simulation and measurement will ever match. Package modeling information
is
> often considered competitive and proprietary. However, in the IBIS
spec/data
> exchange approach we have the possibility of rendering the information
> behavioral and non-process specific as we go up from
> chip-package-board-system scale.
>
> Also, the above complex system level simulation might be impractical
without
> a lot more computing power than we have today.
>
> Lastly, such a system level simulation involves many different software
> capabilities. For example chip, board and system level components and
> structures probably involves several different modeling techniques. For
> example: SPICE, IBIS, S-parameter models plus different methods to handle
> radiation, (TLM, FDTD, MOM, PEEC?) non-ideal grounds, etc.
>
> What this really implies is cooperation between several competing software
> companies. Because, a company that attempted all this at once would lack
> focus and technical excellence. I see a number of such partnerships being
> discussed. But, potentially competing companies are just beginning such
> discussions.
>
> However, we are all missing an opportunity here if we wait for the system
> solution.
>
> That is an opportunity to inject increased modeling, simulation, design
> intelligence and communication into the step between SI and passing
> regulatory. We need to take the software tools as they are (or soon will
be)
> and use them apriori and diagnostically to knock down EMI risks and
problems
> on an individual net level. Then, proceed to feed the behavioral
information
> up/down to/from the next level of scale: chip-package-board-system.
>
> Simulation is critical in addition to a rules-based approach because you
> must get down to predicting/diagnosing what is actually going on amongst
> many possible physical mechanisms. The discussions on this list often
> involve heated advancement of different theories (rules) unaided by data.
> Models used in the simulation must be based on reality and then be
verified
> by measurement. Or, the models can be recognized as speculation when that
is
> an appropriate initial problem solving strategy.
>
> Design rules and standards have their place in this discussion. We would
> like to avoid paralysis by analysis.
>
> That which is considered physical is considered behavioral at the next
> physical level down. Ohms law (V, I, and R) involves electrons and
material
> properties at a more fundamental physical level and is considered
behavioral
> down at that level. I believe we need to investigate using voltage,
current
> and voltage-time curves plus auxiliary information as the data exchange
> format between the different physical scales.
>
> I recently participated in an exercise using modeling and simulation
apriori
> and diagnostically to knock down EMI risks with a client and their team.
It
> was very successful in terms of time, cost and performance vs. the
> traditional pass regulatory paradigm. They doubled their clock speed and
> were cleaner on EMI emissions than the older product on a much more
> compressed schedule. They didn't have to add an expensive shielding box.
>
> Simulation and modeling tools do not have to be perfect and complete to be
> of great benefit. You do need to know their limitations. All they have to
do
> is to assist you in the steady application of good design principles,
> problem solving and the implementation of design intent.
>
> The above experience also reinforced my belief that the best engineers use
a
> combination of simulation and measurement to meet their design challenges.
>
> Best Regards to All,
>
>
> Roy Leventhal
>
>
>
>
>
>
>
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