A Novel Decoupling Method to Reduce Radio Frequency Interference (RFI) Noise From High-Speed Connector

This article proposes an innovative method to effectively suppress radio frequency interference (RFI) noise from a high-speed differential channel passing through connectors. The proposed method uses a decoupling network (DN) to eliminate common-mode (CM) radiation generated from a high-speed connector to a nearby antenna. The DN comprises a six-port coupler on the connector side, a four-port coupler on the antenna side, and a phase delay line. This article presents the design concept, detailed signal flow graph analysis, and a step-by-step design procedure for implementing the DN. To demonstrate the effectiveness of the approach, a DN was designed and implemented for a universal serial bus (USB) 3.0 connector and a planar inverted-F antenna operating at 2.475 GHz. Both simulation and measurement results are presented, showing good agreement. The implemented DN achieved about 25-dB reduction in CM noise coupling at the target frequency and at least 10-dB reduction over a wide frequency range from 2.43 to 2.55 GHz. This validates the outstanding performance of the proposed method in mitigating RFI issues in compact electronic devices with high-speed interfaces. Furthermore, the proposed DN does not affect the normal operation of both the antenna and the high-speed differential signals.