インパルス性電磁雑音の自動測定に関する研究 : ディジタル基板からの放射雑音の測定

概要

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This paper reports on an automatic measurement of RF magnetic noise distribution radiated by PCB. Two-dimension distribution of RF magnetic noise was measured for a four-layer printed circuit board with a small loop antenna on a plane 20 mm distant from the board as well as a two-layer printed circuit board. As a result, a component perpendicular to the board is larger than a parallel component in the vicinity of PCBs. In an EMI aspect the perpendicular magnetic field is more hazardous than others because it causes larger induction on an adjacent PCB. In order to examine the induction noise on an actual PCB, an ad hoc induction-test board was prepared that comprises only a TTL NAND gate IC. RF voltage, which is caused by induction on a loop composed of the IC and a bypass capacitor, was measured at an output of a NAND through FET probe circuit. An induction noise was found large when the output level was H, whereas no significant noise was found at L level.
福山大学の論文