319282-007 Datasheet, PDF (556/586 Pages) Intel Corporation – 10 GbE Controller

Intel^® 82598 10 GbE Controller
8.3.2.5 Reference Planes
Do not cross plane splits with the MAUI high-speed differential signals. This causes impedance
mismatches and negatively affects the return current paths for the board design and layout. Refer to
Figure 8-5.
Traces should not cross POWER or GND plane splits if at all possible. Traces should stay 6x the dielectric
height away from plane splits or voids. If traces must cross splits, capacitive coupling should be added.
Figure 8-5. Do Not Cross Plane Splits
Figure 8-6. Traces 6x Dielectric Splits
Keep Rx and Tx separate. This helps to minimize crosstalk effects since the TX and RX signals are NOT
synchronous. This is the more "natural" routing method and will occur without much user interference.
It is also recommended that the MAUI signals stay at least 6x dielectric height away from any POWER
or GND plane split. This improves impedance balance and return current paths.
If a high-speed signal needs to reference a power plane, then ensure that the height of the secondary
(power) reference plane is at least 3 x h (height) of the primary (ground) reference plane.
Intel^® 82598 10 GbE Controller
Datasheet
556
Reference Number: 319282-007
Revision Number: 3.2
October 2010