It really depends on how complex your product is, and how good your PCB designer is. We are getting into some decently high-speed designs (LVDS/USB) and it is d

It really depends on how complex your product is, and how good your PCB designer is. We are getting into some decently high-speed designs (LVDS/USB) and it is definitely a learning process with every board... As far as pitfalls, they range from minor product alterations like requiring the addition of ferrite beads/elements on power lines/other wires inside the enclosure or altering component values on the board, to major alterations that require another board spin (adding extra passives like ferrites, decoupling caps, or just better PCB trace layouts), to very bad problems that require major redesign and rearchitecture of parts of the product. If you are still in the board design/prototype stage, try to add spots on data lines and high speed traces for: extra capacitors in parallel for decoupling and to target power supply ripples and harmonics, and 0 ohm resistors in series to later replace with ferrites to absorb EMI or low-value resistors to correct for trace impedance mismatches. You can always remove these when the design gets closer to production. Budget ~$1-2k extra as well if you want the testing house engineer to try various ferrites and shielding to get a design a few dB out of whack to pass while it is in their test environment. Of course, some of their recommendations may be too expensive/unworkable and some redesign is in order. Unfortunately, all of this costs time, money, and enormous amounts of energy cursing the gods of physics and RF when things go wrong... but that's part of the fun of designing new things, right? :) Great resource: http://www.murata.com/products/emicon_fun/index.html http://www.murata.com/products/emicon_fun/index.html