Issue 146 September 2002
Killing the EMI Demon

The Struggle With EMI

When Rabbit Semiconductor introduced its first microprocessor, the Rabbit 2000, the company thought that the customers wouldn’t have too much trouble with EMI. The maximum clock speed was fairly low at 30 MHz, and Rabbit gave suggestions in the design manual on how to avoid EMI problems. But, it turned out that the customers were mostly smaller companies with limited expertise in this fairly exotic area. They were focused on the innovative products that they were designing, not gobbledygook government regulations.

Many of the customers took their product along with $5000 to a test lab, but they subsequently found themselves going back to the drawing board. Executives at Rabbit decided to do everything they could to make it impossible for the next-generation processor, the Rabbit 3000, to flunk the radiated emission tests. In the process, they even found some solutions that could be compatibly retrofitted to the first-generation microprocessor to make that device much better from the EMI perspective. The cumulative effect of the improvements turned out to be so effective that Rabbit met the goal to make it nearly impossible to flunk the government EMI tests with a Rabbit 3000-based product, even at 50-MHz clock speeds.