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Altera_Forum's avatar
Altera_Forum
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16 years ago

Arria II GX SerDes - lowest data rate

We are designing a modular interface to an Arria II GX SerDes which will usually be running at approx 1 Gbps. We also need to support legacy modules which are running at 125 Mbps.

Can the SerDes be configured to run at 125 Mbps?

Related question: The documentation lists OC-3 as a supported speed in the Introduction paragraph but not in the section on SONET. Do the SerDes support OC-3?

Thanks in advance,

StevenB

4 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    16 years ago

    Thanks for the link, the pancake.

    The problem is the documentation is inconsistent ... there are other locations which imply the part can run at OC-3 rates (155 Mbps). I also believe the minimum rate is 600 Mbps as you pointed out - an FAE indicated it is the lower limit of the CDR PLL - but there is an FPGA designer here who believes ha can recover a 125 Mbps stream in the SerDes as long as the FPGA also gets the clock (on separate pins) along with the data.

    I'm looking to see if anyone else has experience doing this.
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    i would say the OC-3 is probably done with LVDS rather than a GX. ASI is on that same protocol list but it uses LVDS.

    i think the give away is that there is no functional mode listed for OC-3, but there is for OC-12 and OC-48.

    you might file an SR and have it clarified in the document that OC-3 uses LVDS.