• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Answers 2 answers
  • Subscribers 32 subscribers
  • Views 206 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DS100BR410: AC coupling capacitor

K.Shidara
Expert 3225 points
Part Number: DS100BR410

Hi Team

Would you advise below questions?

My customer uses this IC for transfer 6Gbps CML differential signal from FPGA to another

FPGA on different board.

Q1 . Is both output and input cap needed like attached application Diagram?

Q2. Would you advise recommend cap value?

Thanks

Best regards,

Shidara

  • 0
    TI__Guru* 88835 points

    Hi Shidara-San,

    1). Yes we need to AC couple on both inputs and outputs as you have shown in Typical Application Diagram.

    2). This depends on the application. PCIe specification recommends 220nF AC coupling cap values. DS100BR410 EVM uses 0.1uF AC coupling caps.

    Regards,, Nasser

  • 0 in reply to Nasser Mohammadi
    TI__Expert 3225 points

    Hi Nasser-san

    Would you let me know the question to your answer more?

    1, Understood both cap are needed but I'd like to know the further meaning of both cap existing.

        My understanding is that Even put output cap, there is a possibility to be induced DC imbalance 

        on its cable which should be removed by input cap, right?

    2, OK, Because of EVM is 0.1uF, let me recommend 0.1uF first with depends on the signal comment.

    Thanks

    Best regards,

    Shidara

  • 0 in reply to K.Shidara
    TI__Guru* 88835 points

    Hi Shidara-San,

    Inputs and outputs are isolated from one another. There is a limiting function between input and output signal path. Input cap takes care of the induced DC imbalance - due to the data pattern - on input - before the limiting amp - and output AC coupling cap takes care of the induced DC imbalance generated on the output.

    Regards,, Nasser

  • 0 in reply to Nasser Mohammadi
    TI__Expert 3225 points

    Hi Nasser-san

    Thank you very much for your explanation.

    I understood.

    Best regards

    Shidara