６４
2.6.3 Gb Ethernet Routing Guidelines
10/100/1000 Ethernet Insertion Loss Budget
Figure 16
: 10/100/1000 Ethernet Insertion Loss Budget
COM Express Ethernet implementations should conform to insertion loss values less than or equal to
those shown in the table above. The insertion loss values shown account for frequency dependent
material losses only. Cross talk losses are separate from material losses in the Gb Ethernet
specification.
“Device Down” implementations, in which the Ethernet target device is implemented on the Carrier
Board (for instance, an Ethernet switch), may add the insertion loss for the RJ45 Ethernet jack and
integrated magnetics to the Carrier Board budget. This insertion loss value is typically 1 dB. The Carrier
Board insertion loss budget then becomes LC + 1 dB, or 1.15 dB.
Table 19
: 10/100/1000 Ethernet Insertion Loss Budget, 100 MHz
Segment
Loss (dB) Notes
L
A
0.08
Up to 3 inches of module trace @ 0.28 dB / GHz / inch
L
B
0.02
COM Express
TM
connector at 100 MHz measured value
L
C
0.15
Up to 5 inches of Carrier Board trace @ 0.28 dB / GHz / inch
L
D
24.00
Cable and cable connectors, integrated magnetics, per source spec.
Total
24.25
