Intel Pentium 4 Processor in the 423-pin package EMI Guideline

Intel® Pentium® 4 Processor in the 423-pin package EMI Guideline
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Figure 4 Prototype Ground Frame
2.6 EMI Test Capabilities
FCC regulations in the United States specify the maximum test frequency for products with clocks in
excess of 1GHz is 5 times the highest clock frequency or 40 GHz, which ever is lower. Pentium® 4
processors are expected to initially be available at 1.4 GHz and 1.5 GHz, which means the maximum
frequency which must be scanned is 7.5 GHz. OEMs are advised to enquire into the capabilities of
their preferred EMC test lab to ensure they are able to scan up to 7.5 GHz.
History indicates that processor performance and frequency double approximately every 2 years. With
this in mind, it would be advisable to be prepared for the frequencies that will need to be scanned in
the next few years.
Since the FCC Rules ultimately require testing to 40 GHz, commercial test equipment has been
developed which is capable of making measurements to that frequency. Although it will be some time
before processors require testing at this frequency, it may be cheaper to upgrade to 40 GHz now rather
than making several intermediate steps.
It is also possible to upgrade various parts at different times. The spectrum analyzer may be upgraded
to 40GHz today while only obtaining the necessary antennas to support the initial processor
frequencies. As processor speed increases, the necessary antennas and cables could be purchased
which would support testing to the higher levels. Cost flexibility in antenna selection is probably the
greatest, as different antenna designs are necessary for different frequency ranges.
3.0 Summary
High speed clock frequencies within the Pentium® 4 processor will make EMI compliance more
challenging. In order to facilitate successful chassis and motherboard designs, Intel has developed a
number of components and techniques to reduce or contain EMI emissions. OEMs are advised to
verify that their preferred EMC test facility is capable of measuring the required frequencies.