How to suppress Ethernet communication interference in concentrators?

Concentrator Ethernet interfaces (such as 10/100M) operate at high frequencies, making them susceptible to interference and prone to radiation. Interference suppression requires addressing the transformer, common-mode choke, and PCB layout. An RJ45 connector with integrated common-mode choke and transformer (with filtering function) should be selected. A common-mode inductor CML3225A-510T should be connected in series on the differential signal lines of the PHY chip, ensuring that the differential pairs are strictly equal in length and spacing. Multi-stage decoupling (10μF + 0.1μF + 0.01μF) should be used on the PHY chip's power pins, and a PBZ1608E600Z0T ferrite bead should be added to isolate digital noise. On the PCB layout, the Ethernet area should be isolated from other circuits (especially power), maintaining a complete ground plane underneath. Shielded Cat5e cables should be used, with the shield grounded at the RJ45 metal casing. Through this design, the Ethernet interface can pass the IEC 61000-4-4 EFT 4kV test, and radiated emissions meet EN 55032 Class B.