Low Latency 40G for ASIC Proto Ethernet Intel® FPGA IP User Guide

ID 683221
Date 11/10/2022
Public
Document Table of Contents

3.5.2. Adding the Transceiver PLL

Low Latency 40G for ASIC Proto Ethernet IP cores require an external PLL to drive the TX transceiver serial clock, in order to compile and to function correctly in hardware. In many cases, the same PLL can be shared with other transceivers in your design.

Figure 4. PLL Configuration Example for MAC+PCS variantThe TX transceiver PLL is instantiated with an Intel® FPGA ATX PLL IP core. The TX transceiver PLL must always be instantiated outside the Low Latency 40G for ASIC Proto Ethernet IP core.
Figure 5. PLL Configuration for PCS only variant

You can use the IP Catalog to create a transceiver PLL.

  • Select Stratix 10 Transceiver ATX PLL.
  • In the parameter editor, set the following parameter values:
    • PLL output frequency to 5156.25 MHz. The transceiver performs dual edge clocking, using both the rising and falling edges of the input clock from the PLL. Therefore, this PLL output frequency setting supports a 10.3125 Gbps data rate through the transceiver.
    • PLL integer reference clock frequency to 644.53125 MHz.

You must connect the tx_serial_clk input pin of the Low Latency 40G for ASIC Proto Ethernet IP core PHY link to the output port of the ATX PLL.