This application note describes the background, technique and
results of EMI measurements on the PCK2001 (CKBF), showing
reduced EMI emissions over standard design techniques. Through
the use of circuit design, the high frequency EMI emissions from the
CKBF were reduced from a standard design approach. These
reduced emissions should help a board/systems manufacturer pass
FCC and CISPR EMI requirements.
BACKGROUND OF EMI, FCC AND CISPR
STANDARDS
EMI, Electro-Magnetic Interference, is any unwanted
electromagnetic signal which may degrade the performance of an
electronic device. It is generally thought of as one device creating
electromagnetic radiation that interferes with the operation or
performance of another device. PCs and PC motherboard designs
have to meet standards set by regulatory agencies. Two standards
are, FCC (Federal Communications Commission) regulations part
15B, and International Electrotechnical Commission’s International
Special Committee on Radio Interference (CISPR) 22B. These
regulations specify limits: