Arria V Avalon-ST Interface for PCIe Solutions User Guide

ID 683733
Date 1/04/2023
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The Hard IP contains a clock domain crossing (CDC) synchronizer at the interface between the PHY/MAC and the DLL layers. The synchronizer allows the Data Link and Transaction Layers to run at frequencies independent of the PHY/MAC. The CDC synchronizer provides more flexibility for the user clock interface. Depending on parameters you specify, the core selects the appropriate coreclkout_hip. You can use these parameters to enhance performance by running at a higher frequency for latency optimization or at a lower frequency to save power.

In accordance with the PCI Express Base Specification, you must provide a 100 MHz reference clock that is connected directly to the transceiver.

As a convenience, you may also use a 125 MHz input reference clock as input to the TX PLL.