[muRata] EMC Solutions: Noise Suppression Examples

Noise Emission Status
Noise Suppression Model

Improving the GND
Installing EMI filters on the Parallel Interface
Installing EMI filters on the DC Power Supply Input and Lines
Installing EMI filters on Motor Control Lines
Installing EMI filters on the Clock Line
Installing EMI filters on Bus Lines
Installing EMI filters on the IC Power Supply Line

Examples of Noise Suppression for USBs

Noise suppression effects produced when
installing the BLM21PG221SN1 (Chip Ferrite Bead,
220 ohms at 100 MHz) on the IC power supply line

Before installing the EMI filter			Because of high-speed signal switching inside the IC, high frequency noise is also generated on the line that supplies power to the IC. High frequency noise is conducted to the AC power supply cable through the power supply line on the board. Noise is then emitted by using the power supply cable as an antenna. When the BLM21PG221SN1 (Chip Ferrite Bead, 220 ohms at 100 MHz) is installed on the IC power supply line, the noise level is suppressed by approximately 2 dB. Since a filter with low DC resistance is required for power supply lines to prevent voltage drops, the BLMxxP Series (Chip Ferrite Bead For Large Current) that features low DC resistance is suitable.
After installing the EMI filter