The following guidelines should be
followed when designing the layout:
- Decoupling capacitors should
be placed as close to the VCC pins as possible. Placing the decoupling
capacitors directly underneath the device is recommended if the board design
permits.
- High-speed differential
signals TXnP/TXnN and RXnP/RXnN should be tightly coupled, skew matched, and
impedance controlled.
- Vias should be avoided when
possible on the high-speed differential signals. When vias must be used,
take care to minimize the via stub, either by transitioning through most or
all layers or by back drilling.
- GND relief can be used (but
is not required) beneath the high-speed differential signal pads to improve
signal integrity by counteracting the pad capacitance.
- GND vias should be placed
directly beneath the device connecting the GND plane attached to the device
to the GND planes on other layers. This has the added benefit of improving
thermal conductivity from the device to the board.