Troubleshooting Guide
1000BASE-T/100BASE-TX/10BASE-T Physical Layer Compliance Tests Manual
130 Intel Confidential
•
Each trace is the same length.
•
Each trace is the same impedance.
•
One trace should mirror the other within the maximum suggested separation of one-tenth of an
inch.
•
Each trace needs to encounter common (or shared) components at the same distance from the
PHY as the other trace in the same differential pair.
Good power to ground decoupling is important around the PHY and out to the RJ-45 connector.
There are two types of decoupling capacitors, high frequency and bulk. The high frequency
decoupling capacitors usually have a value of 0.1 µF and are placed throughout the board,
especially close to power, ground, and fast switching signals. The bulk capacitors are used to keep
the V
CC
and ground from bouncing. These are typically 22 µF tantalum capacitors on
motherboards. However, for the family of Intel
®
EtherExpress
™
PRO/100 adapters 4.7 µF ceramic
capacitors are used.
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