Does RJ45 need to be grounded?
The general advice of wire manufacturers, and the general configuration of pre-manufactured cables, is for both ends to be grounded. This is contrary to common knowledge in electrical engineering regarding ground loops and the potential for lightning-induced current.
Does Ethernet cable need grounding?
It is worth noting that all the shielded Ethernet cables should have a ground connection for their shields. In case your cable has an incorrect ground connection, the chances are there will be ground loop currents and also the associated interference to the Ethernet signal.
How does the RJ45 connector work above the ground plane?
Visualizing Option 1 is rather simple: just run the system ground plane throughout the 2nd layer. The system ground will run beneath the magnetics and extend up to the RJ45 connector. A shielded connector will sit against the chassis and enclosure, so its internal shielding will be referenced back to the system ground.
Do you need a shielded RJ45 Ethernet connector?
If I am going to use a PCB mount RJ45 connector for 100mbps Ethernet, does it need to be a shielded connector, or can I get away with using an unshielded one? Is there some standard which deals with this, or is it just my responsibility to get the thing EMC tested.
Can a STP cable be used with an unshielded RJ45?
If we have an unshielded RJ45, there is no chassis ground connection from the connector shroud. Note that STP cable needs to be used with a shielded RJ45 connector, but UTP cable could be used with either shielded or unshielded RJ45 connectors.
How are MAC / PHY and RJ45 connectors routed?
Traces between the MAC/PHY, magnetics circuit, and the RJ45 connector are routed as differential pairs with defined impedance. Note that this includes traces within a discrete magnetics circuit. The differential impedance is set to 100 Ohms to provide matching to the cable’s differential impedance.