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DS320PR1601: REDRIVER

SHEKHA SHOUKATH
Intellectual 510 points
Part Number: DS320PR1601

Tool/software:

Hi,

Is there a limit in number of vias in a diiferential signal?

can we use 5 via in transceiver signals?

Thanks and Regards,

Shekha Shoukath

  • 0
    TI__Mastermind 20901 points

    Hi Shekha,

    Generally speaking, the fewer the vias in the high speed path, the better. Vias can act introduce unwanted inductance or capacitance to a high speed channel, which is very sensitive to signal integrity disturbances.

    Please note our PCIe Gen5 layout guidelines here, which I believe will be a helpful reference for you: https://www.ti.com/lit/an/snla426/snla426.pdf 

    Best,
    David

  • 0 in reply to David Waier
    Intellectual 510 points

    Hi,

    In that document, it is specified only to minimize the number of vias.

    Can I know the exact number of vias to be used especially in transceiver lanes. 

    Thanks and Regards,
    Shekha Shoukath

  • 0 in reply to SHEKHA SHOUKATH
    TI__Mastermind 20901 points

    Hi Shekha,

    It is difficult to state exactly how many vias could be used, as the design of the vias (stub length, back drill, shape, ground stitching) is very critical and can impact the channel frequency response, making it complex.

    My overall suggestions would be:

    1. Minimize the number of vias on PCIe channels connected to the redriver
    2. Simulate the layout to ensure that PCIe channels meet expected signal integrity or layout requirements.

    Best,
    David