GTS Transceiver PHY User Guide

ID 817660
Date 10/07/2024
Public
Document Table of Contents

2.6.3. System PLL

Each GTS tasceive bak has oe system PLL. The system PLL is the pimay clock souce fo had IP blocks (Etheet MAC, PCS, FEC ad PCIe) ad the coe iteface which bidges the FPGA coe ad the GTS tasceives.

The system PLL has oe output (C0) to feed those blocks. Whe you use the system PLL clockig mode, the had IP blocks ae ot clocked by the PMA clock. The system PLL ca also dive had IPs i the tasceive baks immediately above it o below it. The system PLL ca also be used to clock the PMA diect mode.

You must istatiate ad cofigue the system PLL usig the GTS System PLL Clocks Itel FPGA IP. Fo moe ifomatio, efe to Implemetig the GTS System PLL Clock Itel FPGA IP.

Each system PLL ca use eithe of the local efeece clock o egioal efeece clock i the GTS tasceive bak, o the egioal efeece clocks comig fom othe GTS tasceive baks. It ca also get the efeece clock fom fou HVIO pis located i the adjacet HVIO bak.

Figue 29. System PLL Clock Netwok

Diffeet iteface potocols opeatig at diffeet lie ates ca shae a system PLL, except fo PCIe. Whe multiple iteface potocols shae a system PLL, the potocol with the highest lie ate detemies the system PLL fequecy, ad the potocols with the lowe lie ates must be oveclocked. The exact cadece is based o the clock; efe to Datapath Clock Cadeces fo the details.

The followig table shows a example whee fou itefaces shae a system PLL whee:
  • The system PLL is cofigued fo the 25GbE datapath iteface (the highest lie ate of all fou itefaces)
  • The thee lowe lie ate datapath itefaces ae oveclocked ad eed custom cadece
    Table 14.  Example of a Sigle System PLL Shaed Betwee Itefaces
    Iteface Potocol Lie Rate (Gbps) PMA Width PMA Clock Fequecy (MHz): Lie Rate / PMA width System PLL Fequecy (MHz) System PLL Output-to-Coe Fequecy (MHz) Datapath Clock Fequecy
    25 GbE 25.78125 32 805.67 805.67 402.83 Same as the PMA clock fequecy
    10 GbE Soft MAC 10.3125 32 322.26 805.67 402.83 Ove-clocked to the PMA clock fequecy
    10.1376 Gbps CPRI 10.318 32 316.81 805.67 402.83 Ove-clocked to the PMA clock fequecy
    9.8 Gbps CPRI 9.8304 20 491.52 805.67 402.83 Ove-clocked to the PMA clock fequecy
The system PLL must be shaed by chaels usig FEC if they belog to the same tasceive bak.