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Noise filter solutions for WIFI/USB3.x RFI interference

QTC proposed a CMC-RFI filter for high CM noise rejection at WiFi band of 2.4~2.5GHz, which CM attenuation more than 30dB typ., (refer to NB RFI test spec.)

In addition, for more solid & exact contribution on WIFI RFI noise rejection, QTC also provided an alternative RFI filter reference design guide with external LC tunable resonate circuit to extend more wider rejection band specified (example: 2.4~2.5GHz Wifi band)

As shown testing result with QTC evaluation kits, we succeeded the proposal in reference circuit we proposed.

For compact size trend of portable devices such as S/P and NB, currently USB2.0 port CMC size tend to be 0806 size down lower from 1210; Meanwhile, per RFI suppression concern on USB3.1-gen1/gen2 bus, we recommend more smaller size, such as 0806 size to replace 1210 size currently used in USB2.0. QTC PN#QTC14CZ series are recommended, there’re three Zcm impedance (04/07/12) of ES sample available for different RFI noise band suppression (i.e., WIFI/LTE/…).
•This case: use QTC14CZ12 type for 2.4GHz RFI interference in NB design.