Henry Ott EMC seminar, San Francisco, Oct 15-17, 2008

I just got a flyer from Henry Ott about a 3-day seminar on electromagnetic compatibility engineering. Cost is $1375. Henry is a former Bell Labs researcher that really understands signal integrity, EMC and RFI issues in your design. He has done great work in figuring out layout issues on PC boards. I have blogged about Henry’s assertion that you should not cut up ground planes. I wholeheartedly agree, it usually causes more problems than it solves. The whole cutting-up-the-plane suggestion came from application engineers working at semiconductor companies that never had to get a whole system working. The A to D converter guys would plop an ADC on an evaluation board and warn you to separate the analog and digital grounds. Easy to say, but what do you do if you have multiple converters? How do you handle multiple power supplies? Henry says that you should keep one plane, and he prefers to call it a reference plane rather than a ground plane since most designs have a chassis common, not an earth ground. Then he says you should use component placement and routing discipline in order to keep the digital signals out of the analog circuits. He presented some great work on how far away traces have to be for them to not interfere. It makes me love stripline buried between planes, rather than microstrip that can radiate out 12 times its width. Here is the course content:

Cabling

Electric and magnetic field coupling, crosstalk. Cable types: coax, twisted pair and ribbon cables. Cable shielding. Cable terminations.

Grounding principles

Why do we ground? Ground systems: single point, multipoint, hybrid. Ground loops. Return current paths, split planes.   EMC grounding philosophy. AC power grounds.

Digital layout and grounding

Noise Sources, PCB layout, power distribution, ground grids, characteristics of ground planes. Decoupling capacitors; value, placement, resonance and limitations.

High-speed digital decoupling

Alternative decoupling methods, use of distributed decoupling capacitance, power supply isolation, effect of paralleling capacitors. Embedded PCB capacitance.

D-M emission modeling

Radiated emission mechanisms. Fourier spectrum. Differential-mode emission modeling. Methods of controlling differential-mode emission. Clock dithering. Cancellation techniques.

Common-mode filtering

Basic C-M filter theory. Filter source and load impedances. Single-stage filters. Multi-stage filters. Ferrite chokes versus shunt capacitors. Effectiveness of different C-M filter configurations. C-M filter mounting and layout

Transmission lines

Transmission line effects, transmission line radiation, and matching. How current flows on transmission lines.

Mixed signal PCBs

Defining the Problem. A/D converter requirements, return current paths, split ground planes. PCB partitioning, bridges and moats, routing discipline.

RF & transient immunity

RF immunity; circuits affected, PCB layout, audio rectification, RFI filters. Transient immunity; circuits affected, the three-prong approach, keeping transient energy out, protecting the sensitive devices, designing software/firmware for transient immunity.

Conducted emission

AC power line conducted emission models, switching power supplies, parasitic capacitance, layout. Common-mode and differential-mode conducted emission, common-mode chokes, saturation. Power line filters.

Shielding

Absorption and reflection loss. Seams, joints, gaskets, slot antennas, and multiple apertures. Waveguides below cutoff, conductive coatings. Cabinet and enclosure design.