Editor's Note: One of our bloggers, Chris Gammell, also cohosts a weekly podcast, The Amp Hour, with Dave Jones. On a recent program, they interviewed Henry Ott, who worked at Bell Labs for 30 years and then struck off on his own. For the last 30 years, he's been teaching classes on electromagnetic compatibility (EMC). Ott discussed his experiences and gave the guys some tips on dealing with EMC in everyday life. This is the first of two parts.
When asked what his class covers, Ott offered the following:
It's a three-day class. It's pretty much a general overview of EMC. We cover such things as grounding, cabling, shielding, digital layout and grounding, high-speed digital decoupling, big-signal PCB layouts, common mode filtering, conducted emission, RF, and transient immunity. We cover pretty much a gamut of different subjects, trying to make the broadest appeal. I also do a lot of one-day classes where we just spend all day on one subject. We might talk about shielding all day or mixing a layout all day, going into more depth. Usually, the public courses I do as a general class with a bunch of different subjects.
Many people may already know Henry Ott from the books they have on their desks. He wrote Noise Reduction Techniques in Electronic Systems in 1976; a revised edition came out in 1988. The timing of this book was interesting. The rise of the computer age seemed to coincide with the second version. And even though the modern-day techniques hold to many of the same principles, there wasn't treatment of the higher-speed signals we encounter in everyday electrical engineering these days.
The second edition had two chapters on digital, and now my present book is now half on digital, so [it's] interesting how times have changed there. But you know some very fundamental things like shielding and grounding are things that are the same for analog or digital — just the frequency components are different. One advantage I had is that a lot of the things in the book were very basic, and they last, even if technology changes, even if maybe some of the applications weren't very realistic at that point.
Since that time, Ott has continued his consulting career and advising people on the field of mixed-signal design. He has captured most of this knowledge in his more recent (2009) book with a different title, Electromagnetic Compatibility Engineering. (Bell Labs still owns the original copyright.) The new book is an ad hoc third edition of the book cited above, with six new chapters and much of the original material rewritten.
As for other books? Ott talks about “the three-book EMC library” (though many more exist in the marketplace).
There's a book called High Speed Digital Design by Johnson and Graham. I consider that a crossover book. It's kind of a lot of EMC issues and beginning to talk about some single-integrity issues. It's got a bunch of interesting measurements that are not in any other books, and it's also easy to read, so…
Of all the books I've got other than my own, I use that book the most. Then there's a third one if you are interested in the real high-frequency stuff signal integrity, as things are getting more and more today. It has almost the same title, High Speed Digital System Design. The word “system” is in there, and it's by three authors: Hall, Hall, and McCall. A lot of signal-integrity books are very theoretical, but this is a very readable book, and I loved the first sentence of the book, and I wished I'd thought of it. Out of a clear blue sky, the first sentence of the book says, “The speed of light is just too slow.”
Tomorrow, we present part 2 of the interview.