[muRata] EMC Solutions: Noise Suppression Examples

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Noise conducted from the motherboard or stemming from the graphic board is conducted to the video signal lines. Noise is then emitted by using the display cable as an antenna. Special care must be taken when selecting a filter for the RGB video signal lines. Using an incorrectly selected EMI filter will deteriorate picture quality. The NFW31S Series (Chip EMIFIL® for signal lines), featuring high separation between signal and noise, as well as great noise suppression, is installed to suppress the noise.

Noise Emission Status
Noise Suppression Model

Improving the Case Connection
Improving the GND on Extension Boards
Installing EMI filters on the Clock Line
Installing EMI filters on Bus Lines
Installing EMI filters on Interface Cable Ports
Installing EMI filters on Video Signal Lines on Graphic Board

Noise suppression effects produced when installing
the NFW31SP107X1E4 (cut-off frequency: 100MHz) on the RGB lines

Installing Chip "EMIFIL" for signal lines on RGB lines

Before installing the EMI filter			Noise generated from the ICs on the graphic board or conducted from the motherboard is emitted by using the display cable as an antenna. When the NFW31SP107X1E4 (Chip EMIFIL® for signal lines, cut-off frequency: 100 MHz) is installed on the video signal lines (RGB lines), the noise level is suppressed by 10 to 12 dB. Using a filter with a high constant may distort the video signal waveform, deteriorating the picture quality. Attention must be paid for correct filter selection.
After installing the EMI filter