Tech Papers
How Spread Spectrum Clock Generators Accelerate FCC Certification of System Designs
Fujitsu Semiconductor America (FSA)
White Paper
November 2009
This paper will explain Electro-Magnetic Interference (EMI) and its effect on FCC certification. Alternative approaches to mitigating EMI will be mentioned, and the benefits of using Spread Spectrum Clock Generators (SSCG) explained. Finally the paper will describe the Fujitsu SSCG family, which is designed to reduce the overall bill of materials (BOM) cost, shorten the design cycle time, and enable first-pass FCC certification success without compromising system performance.
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GREAT-Terry
2/15/2011 11:25 AM EST
Good article. Spread spectrum added to clock and power supply is an interesting topic but it indeed add jitter to clocks so will it affect some precision measurement for some particular portion of the system? Anyway, using spread spectrum for switching mode power supply is already a known practice to get around switching noise.
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zeeglen
2/23/2011 6:15 PM EST
Spreading it around does not make it go away. It might look like the level is reduced to a narrow-band victim, but makes no difference to a wide-band victim.
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Arfer
3/9/2011 6:26 AM EST
This is the second article in as many weeks on the use of spread spectrum clocking to cheat EMC testing, hopefully the FCC will read them, and change their testing accordingly such that these methods of "hiding" noise no longer work. Then enginneers can concentrate on other design methods, which are listed in this article, such as good board design and screening etc.
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