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Original question:

[FAQ] When implementing a USB 3.x signal redriver, what is the difference between pre-channel loss and post-channel loss...

TUSB211: pre-channel vs post channel and EQ setting

Ben Kuo
Expert 7560 points
Part Number: TUSB211

Dear team,

Since we want to check cable loss and where should we place our signal conditioner on PCB. I find a table from E2E as below.

And refer to below link for pre-channel and post-channel. 

https://e2e.ti.com/support/interface-group/interface/f/interface-forum/719929/faq-when-implementing-a-usb-3-x-signal-redriver-what-is-the-difference-between-pre-channel-loss-and-post-channel-loss

My question is, 

Since USB signal is bi-direction, the same trace will be either pre-channel or post channel, if so, how to refer to table 1 to set EQ and boost?

Regards,

Ben

  • 0
    TI__Mastermind 37500 points

    Hi Ben,

    Depending on how the two connected devices are communicating, there can be many different ways to setup a redriver taking trace length into consideration. If the communication will be primarily host to connector and you want to have an EQ setting of 3, going by the TUSB211 specs, you can have 6 inches between the host and redriver, and then 3 inches between the redriver and the connector, and you could flip these measurements for doing connector to host.

    If there is constantly going to be signals going to and from the host, then it may be best to go with the post-channel lengths on both sides of the redriver, that way the post-channel loss does not exceed the max amount.

    Please let me know if you have any other questions or need more clarification!

    Thanks,

    Ryan