Re: 8b/10b and EMI packaging
But what you are all missing in your comments is what Tom Truman pointed out in
Albuquerque - that the choice of coding is an NRE within an asic, but the EMI
performance, either designed in or designed after the fact, is NOT an NRE but in
fact, a re-occuring charge each time a product is sold. At what time period
within a project we apply EMI design methods, the size of the project, and who
implements those methods, directly relates to the re-occuring costs.
At the last few meetings, everyone had cost as something they want to keep low,
and about every fourth person presenting indicated 'we all want to make money'.
So, wether we have EMI problems or not, anti-EMI costs money - period. So, if
we can stick some of it back into NRE and out of product cost, we all make more
The last point Dan Dove already made and that was based on Jonathan's remarks:
"This might have been said about 10 or 100 or 1000. We will see. Rather
than choose a "spikey" code and roll the dice, I would recommend
using careful consideration for the code.. then roll the dice. :)"
Just my thoughts
Edward Chang wrote:
> You are right, no question about it. As long as it is cost-effective, all
> parts including component package, board layout, circuit design, cable
> dressing ... should use the good common practice to avoid the unnecessary
> EMI headache.
> Edward S. Chang
> Comment from a reflector-lurker:
> Regarding EMI design, I should point out that the most
> cost-effective system designs take EMI characteristics
> into the basic board designs to such a degree that EMI
> is reduced at the source as much as possible. This
> not only improves the stability and manufacture of the
> designs, but also allows for cheaper packaging materials
> for the enclosures (which can really affect today's
> competitive edge on appearances and cost - use of
> plastics and the like).
> Just my two-cents worth!
> Best to you,
> Wayne Belshaw
> Amdahl Corporation
Member of Technical Staff
High Speed Communications VLSI Research
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