３８
Table 7
: PCI Express Insertion Loss Budget, 2.5 GHz with Carrier Board Slot Card
Segment
max. Length
[mm/inches]
Notes
L
A
127/5.0
Allowance for module trace. Coupling cap effects included within simulation.
L
B
COM Express™ connector simulated at 2.5 GHz.
L
C
113/4.45
Allowance for Carrier Board.
L
D
PCI Express Card slot connector simulated at 2.5 GHz.
L
E
80/3.15
Slot Card trace length from PCI Express Card Electromagnetical Spec.,
Rev. 1.1
Total
320/12.6
PCIe GEN2 Data clocked architecture
2.3.3.2 PCI Express Insertion Loss Budget with Carrier Board PCIE Device
The insertion losses previously allowed for the slot card and slot card connector are reallocated for use
on the Carrier Board, allowing longer Carrier Board trace lengths and more Carrier Board design
flexibility. The Module and COM Express connector loss budgets remain the same.
Figure 4
: PCI Express Insertion Loss Budget with Carrier Board PCIe Device
The module transmit and receive insertion loss budgets are different due to the presence of the coupling
caps in the module transmit path. The module transmit path insertion loss budget shall be 4.65 dB (3.46
dB + 1.19 dB). The module receive path insertion loss budget shall be 3.46 dB. COM ExpressTM
connector loss is accounted for separately.
The Carrier Board transmit and receive insertion loss budgets are different due to the presence of the
coupling caps in the Carrier Board transmit path. The Carrier Board transmit path insertion loss budget
shall be 9.49 dB (8.30 dB + 1.19 dB). The Carrier Board receive path insertion loss shall be 8.30 dB.
COM Express connector loss is accounted for separately.
