GTP transceiver buffer bypass problem

[maxinquaye]

Hello, I am using an Artix7 on the AC701 evaluation board and I have the following problem with the GTP transceiver buffer bypass or phase alignment:

When I enable buffer bypass in the transceiver wizard there is a periodic jitter on the recovered clock with 1,5MHz and its harmonics (see attached image). When I disable buffer bypass this problem does not occur.

I use just one receiver channel connected to the SFP transceiver of the AC701 board without decoding and comma alignment. The frequency of reference and recovered clock is 155,52MHz. There is no periodic jitter on the reference clock.

Does anyone have an idea how to fix that?

[mcgett]

The recovered clock output is not a very clean source due to the CDR function.  What is your concern?

[maxinquaye]

I need the recovered clock to drive another transmitter's reference clock and for that it needs to have very low jitter. I also need fixed latency on the data thats why I use the buffer bypass.

[maxinquaye]

I need the recovered clock to drive another transmitter's reference clock and for that it needs to have very low jitter. I also need fixed latency on the data thats why I use the buffer bypass.

[venkata]

You will need to use an external synthesizer to clean the jitter in RXRECCLK.