EMI Radiation Suppression of Cables and Connectors for 5G Mobile Devices

Electromagnetic interference (EMI) radiation of the Sub-Miniature-A (SMA) and board-to-board (BTB) connectors for flexible stripline cables in 5G mobile devices is investigated in this paper. It is found that contact uncertainty and gaps between the SMA connector and flexible printed circuits board (PCB) provide a leakage path for the commonmode current. Introducing more grounding points or filling gaps with conductive adhesive is effective to suppress the leakage from the SMA connector. Besides, the surface current distribution and radiation patterns show that the common-mode radiation from a BTB connector is much stronger, which is mainly caused by its unshielded grounding transition. By replacing the grounding pins with shielded walls, the leakage will be dramatically reduced and the EMI radiation is suppressed.