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DS160PR410: DS160PR410 AC-coupling capcitors

Asaf Abraham
Prodigy 150 points
Part Number: DS160PR410

Hello,

At page 20 at the datasheet of DS160PR410 there is a note regarding the AC-coupling capcitors of the DS160PR410:

          * Place AC-coupling capacitors near to the receiver end of each channel segment to minimize reflections.

As I understand, that means that the AC-coupling capacitors should be placed near the receiver input.

This demand collides with the demand of the transmitter to put AC-coupling capacitors at the output of the transmitter.

1) Should I place AC- coupling capacitors at the output of the trasmitter and at the input of the receiver?

2) If not, where should I place the AC-coupling capacitors? At the input of the receiver or at the output of the transmitter?

Best regards,

Asaf Abraham

  • 0
    TI__Guru* 93670 points

    Hi Asaf,

    PCIe designs normally have AC coupling Cap on TX side. If there is a chip to chip PCIe connection, then we should place the AC coupling Cap on the receiving end.

    When PCIe high speed signals go to PCIe connectors it is recommended to place these within 400mils of the connector pins. Further these Caps pcb layout should be staggered so they will not create a big cut in the pcb layout.

    Regards,, Nasser 

  • 0 in reply to Nasser Mohammadi
    Prodigy 150 points

    Hi Nasser,

    Thanks for your reply.

    My design includes a FPGA1 device, DS160PR410 and FPGA2 device.

    I undestand from your answer that at the input of DS160PR410 I should put a coupling cap (near the DS160PR410 and not near FPGA1), and a coupling cap at the input of FPGA2 (near FPGA2 and not near the output of DS160PR410). Am I right?

    Also I didnt understand the issue of the cut. Should I make a cut at the PCB under the coupling caps?

    Best regards,

    Asaf