Henry Ott Consultants

Electromagnetic Compatibility Consulting and Training

Mixed-Signal PCB Layout

Question: I attended your talk at the 2006 Audio Engineering Society convention in San Francisco and found your presentation on Partitioning and Layout of a Mixed-Signal PCB to be one of the most useful sessions that I have ever attended. I have been in the audio product design and manufacturing business since 1972 and currently lead a hardware design group, and can say that your presentation offered a real breakthrough in understanding for this engineer.

As I'm sure you know, its hard to retrain some engineers who follow old rules, often just because "that's the way we do it around here." In audio, the old analog star ground continues to be misapplied in today's DSP world. In many cases these designs have noise in the audio outputs and the products are susceptible to ESD and EMI.

In the two years since attending your talk, I have susccessfully applied your recommendations to probably thirty different designs.  When we began to employ your observations in our designs, we immediately saw success with the first boards. The young engineers in my group, suspecious and dubious at first, are comming around one by one as their projects are meeting audio performance requirements and passing EMC tests. Still there is more to learn and understand.

I make listning to your AES talk mandatory for our engineering team and have conducted several "design for audio and EMC" classes for my group. Still I think that we would benefit learning directly from you. Do you teach such classes? If that's not an option, mabe you can recommend some resources that we can access to continue to explore and learn in this area.

Answer: Following a new approach always produces much resistance, but I commend you on sticking to your guns and doing what you believe, and your results confirm, is the right approach.

In answer to your questions, yes I do offer in-plant as well as  public classes on "Partitioning and Layout of Mixed-Signal PCB." You can click here for an outline of the course.

Additional resources on the subject that I would recommend are:

1. My 2001 Printed Circuit Design magazine article on the subject.

2. My new book "Electromagnetic Compatibility Engineering," available in September 2009, has a whole chapter (Chapter 17) on the subject mixed signal PCB layout.

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Henry Ott Consultants
48 Baker Road Livingston, NJ 07039
Phone: 973-992-1793, FAX: 973-533-1442

May 21, 2009