[SI-LIST] Free Margin

From: Scott McMorrow <scott@xxxxxxxxxxxxx>
To: "si-list@xxxxxxxxxxxxx" <si-list@xxxxxxxxxxxxx>
Date: Thu, 21 Nov 2013 12:12:27 -0500
I've been pondering a few past and recent discussions about particular SI
design techniques.  I know I can be a "correct by design" Nazi, advocating
very strict adherence to advanced modeling, simulation, and measurement
technologies on pretty much every aspect of a design.  There is a reason
for this.
In the course of having looked at somewhere north of 50 designs per year
for the past 20 years, I've seen many good things, some bad things, and a
few surprises.  The surprises that Mr. Murphy throws at us concern me most.
There are things we cannot fully know about the design of some
semiconductor circuits, the materials in our boards, or the complex
electromagnetic behavior of thousands of circuits operating simultaneously.
 It is my experience that those things I don't know have the tendency of
coming back and biting me.

As a result, I advocate such things as the utilization of advanced
measurement and de-embedding of as-built material properties,  the
optimization of via transitions, not crossing split planes of any kind, and
optimization of pretty much every dc blocking capacitor.  I like ground
planes and vias, hate power planes for carrying signal energy, and greatly
concern myself with what happens inside of cavities.

Why?  Because in electronics we don't normally apply a safety margin to our
designs, like say a an engineer working on a design where life is at risk,
such as a building or bridge.  Each generation we push to the absolute
limit of specifications.

So why do all this in-depth measurement and analysis?

Because it's free margin ...

      ... and much less expensive than the time and cost of product failure.


regards,

Scott
-- 

Scott McMorrow
Teraspeed Consulting Group LLC
16 Stormy Brook Rd
Falmouth, ME 04105

(401) 284-1827 Business

http://www.teraspeed.com

Teraspeed® is the registered service mark of
Teraspeed Consulting Group LLC

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[SI-LIST] Free Margin

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