GTS Transceiver PHY User Guide

ID 817660
Date 4/01/2024
Public

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2.5.1.2. PMA Primary PLL Configuration

The Primary PLL configuration can be used for OTN applications, in which you have a group of channels that are configured in fractional mode and you want to change the fractional value dynamically.

In the primary PLL configuration, the reference clock source for the local CDR and the TX PLL of other channels can be sourced from the PMA channel 0 TX PLL in the same GTS transceiver bank. The TX PLL of channel 0 must be in fractional mode and acts as the reference clock to the TX PLL of other channels. The clock source for the RX CDR of all channels is provided by the TX PLL of its own channel. Refer to the following figure for more information.

The Primary PLL configuration works only in a four channel configuration, where PMA channel 0 is always providing the reference clock to the TX PLL of the other three channels. The primary PLL configuration is limited within a GTS transceiver bank and cannot extend beyond the GTS transceiver bank.
Figure 24. Primary PLL Configuration

Refer to Primary PLL configuration in PMA Support for Fractional Mode table for more information about the implementation details.