Printed Circuit Board Design and Layout Questions

3. What is expert system software "looking for" when it examines a board layout?

Expert system tools examine boards in much the same manner as a professional EMC engineer. They evaluate possible EMI sources, coupling paths and antennas, then identify and rank potential EMC problems. Expert system algorithms to evaluate and identify EMC problems with printed circuit board (PCB) designs have been developed and are described in the literature [1-4]. These algorithms analyze printed circuit board sources and structures to estimate the maximum likely radiated emissions due to particular coupling mechanisms. Algorithms developed so far look for many types of potential problems with a circuit board layout, including:

• Structures that may induce voltages that drive a heatsink or cable relative to the board
• Structures that may induce currents on cables
• Structures that may drive resonances in a shielded enclosure
• Radiation directly from the power bus structure
• Potentially disruptive ESD current paths
• Circuits potentially vulnerable to magnetic field coupling

References

[1] T. Hubing, J. Drewniak, T. Van Doren and N. Kashyap, “An expert system approach to EMC modeling,” Proc. 1996 IEEE Int. Symp. Electromag. Compat., Santa Clara, CA, Aug. 1996, pp. 200-203.

[2] N. Kashyap, T. Hubing, J. Drewniak and T. Van Doren, “An expert system for predicting radiated EMI from PCB’s,” Proc. 1997 IEEE Int. Symp. Electromag. Compat., Aug. 1997, pp. 444-449.

[3] H. Shim, T. Hubing, T. Van Doren, R. DuBroff, J. Drewniak, D. Pommerenke and R. Kaires, “Expert system algorithms for identifying radiated emission problems in printed circuit boards,” Proc. 2004 IEEE Int. Symp. Electromag. Compat., Santa Clara, CA, Aug. 2004, pp. 57-62.

[4] Y. Fu and T. Hubing, "Analysis Of Radiated Emissions From A Printed Circuit Board Using Expert System Algorithms," IEEE Trans. on Electromagnetic Compatibility, vol. 49, no. 1, Feb. 2007, pp. 68-75