0Working with EMC Consultants

I plan to chair a technical session (theme 10, #38, "Signal Integrity Analysis and Design") at the IEEE International Symposium on EMC, to be held May 11- 16, 2003 in Istanbul, Turkey.

I know it's a long trip for many of you, but please consider joining me at this event. Precious few IEEE societies have expressed any interest in Signal Integrity, and I think we should do what we can to support their efforts.

My session will explore regions of common interest between the subjects of EMC and signal integrity.

Suggested topics include the control of ringing, crosstalk, ground bounce, power supply noise, signal rise time, stray returning signal currents, split ground planes, noise isolation barriers, and the propagation of extremely high-frequency waveforms.

The session chair has a special interest in digital systems operating at signaling frequencies in excess of 1 Gb/s.


Submission of abstracts & preliminary manuscripts: October 13, 2002

Notification of acceptance: November 15, 2002

Advanced program distribution: December 5, 2002

Camera Ready Manuscripts: March 15, 2003

*-------------*TECHNICAL TOPIC*----------------------*

Working with EMC Consultants

If you design very many digital products, at some point you'll probably have to hire an EMC consultant.

The biggest EMC mistake you can make is the failure to get your consultant involved at a sufficiently early stage. Getting early advice and guidance from someone who works on a daily basis with products just like yours is invaluable. Note that I said someone who works with products like yours. That's an important part of selecting a good EMC advisor-- you want someone who knows from direct experience what parts of your type of product will likely radiate the most.

Experience plays such a large role in EMC problems because EMC is an under-constrained optimization problem. In the theory of optimization, one worries about the number of constraints versus the number of variables in a problem. The world of EMC carries on the constraint side some radiated emission limits that you must not exceed, and a total product cost which should be minimized. That's about it.

On the variables side, there are zillions of ways to put together a product that could work. Every nut, bolt, panel, trace, wire, IC, and connector affects both emissions and cost. There are too many variables, and too few constraints. Working strictly from the constraints, there's no mathematical way to force out one perfect, optimum solution. Therefore, we fall back on experience.

Here's a checklist of design-experience issues you may want to take under consideration when evaluating an EMC person's background:

  • Clock speed, signal risetime, and RF carrier frequencies used
  • Total product power (relates to the complexity of the power delivery apparatus)
  • Physical size (wearable, desktop, rack-mount, or industrial plant)
  • Packaging complexity (custom or off-the-shelf IC packaging, flip-chip, MCM, etc.)
  • Use of removable or configurable components (this creates holes in the packaging)
  • External cabling (type and number of connections)
  • Manufacturing volume (at higher volumes more alternatives become available for cost reduction)
  • Sensitivity to cost (is it a military or consumer product)
  • Time-to-market (fast design cycles require immediate and unimpeded access to your advisor)

The second-biggest EMC mistake you can make is to hire more than one EMC advisor. That puts you into the same position as a man who owns two watches: he never knows which one is right.

It's not difficult to locate a good EMC consultant. One reasonable place to start is at your local IEEE EMC Society chapter meeting. The EMC society of the IEEE is particularly well organized. Most chapters hold regular meetings. At these meeting the members hear technical presentations, discuss the latest theories, eat some pizza, and talk about who's hiring whom. It's the perfect place to locate an advisor, check their references, and sign them up for work.

Or, if you want to meet a really large number of EMC professionals, and learn some neat stuff in the process, visit Turkey for the big international EMC symposium May 11-16, 2003. I'll be there.

Best Regards,
Dr. Howard Johnson