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COM Express Carrier Type 2
Design
Guide
3.4.2
PCIE Signals AC Couple
Figure 3 PCIe Rx Coupling Capacitors
Device Down refers to a PCIe target device implemented down on the carrier board. Device Up refers
to a PCIe target device implemented on a slot card (or mini PCIe card, ExpressCard, AMC card).
There are several distinctions between a PCIe Device Down and Device Up implementation.
Device Down:
Coupling caps for the target device PCIe TX lines (COM Express module PCIe RX lines) are down on
the carrier board, close to the target device TX pins;
Trace length allowed for PCIe signals on the carrier board is longer for the Device Down case than for
Device Up.
Device Up:
Coupling caps for the target device PCIe TX lines (COM Express module PCIe RX lines) are up on the
slot card.
Trace length allowed for PCIe signals on the carrier board is shorter than for the Device Down case,
to allow for slot card trace length.
The coupling caps for the COM Express module PCIe TX lines are defined by the COM Express
Specification to be on the module.
Summary of Contents for COM Express Carrier
Page 1: ...COM Express Carrier Type 2 Design Guide October 2009 Confidential and Proprietary ...
Page 17: ...COM Express Carrier Type 2 Page 17 of 103 Design Guide Figure 1 COM Express Type 2 Connector ...
Page 36: ...Page 36 of 103 COM Express Carrier Type 2 Design Guide Table 5 SDVO Layout Requirement ...