Risks of EMI on differential links

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Risks of EMI on differential links

Flex connectors, like processors or camera, are quite used. Figure 2 presents an extreme

case.

Figure 2. Example of skew between interior and exterior traces on a flex

Flex connector is shielded and the link radiates and generates a large amount of noise,

which causes antenna desense on the mobile handset limiting drastically the receiver

sensitivity (Figure 3).

Figure 3. Radiations induced by skew on a differential link

The most efficient way to cancel this noise is to insert a filter to suppress it. This filter is

called: common mode filter (Figure 4).