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Balun for DS90UB925Q and DS90UB926Q

R. Scalick
Prodigy 160 points

Hallo,

could you give me a recommendation for a Balun for DS90UB925Q and DS90UB926Q ? What are the requirements for this Balun. (Datarate max. 1,485GBit/s)

I tried to find at Toko and Murata. My reqirements are impedance transormation from 100Ohm (balanced) to 50Ohm unbalanced and back. I think that this could be the same componet.  

regards

Rudi

  • 0
    TI__Expert 4210 points

    Hi Rudi,

    Sorry, these parts were only design to be AC coupled and have been characterized accordingly.

    We did not do any testing with a balun so I don't have a recommendation at this time.

    Regards,

    Darryl

  • 0 in reply to Darryl Jeong
    Prodigy 160 points

    Hi Darryl,

    many thanks for your info.

    Maybe it is possible for you to give me an advice  how to specify a balun for above mentioned devices.

    - Necessary frequ range ?

    - I think the insertion loss is not so critical, because the required cable lenght is only 2 to 5m.

    . Flatness of insertion loss ?

    - and so on

    kind regards

    Rudi

  • 0 in reply to R. Scalick
    TI__Genius 13475 points

    Rudi

    The biggest issue with AC coupling the link between the DS90UB925 and '926 is the fact that since the back-channel is implemented with the low end of the frequency spectrum, the Balun would need to have a very wide frequency response - from a few kHz up to several GHz, and I don't believe that such a component is available.

    As Darryl points out, our characterization is all done with DC coupled, twisted pair cable, and it is only with this medium that we can guarantee the operation of the devices.

    Mark

     

  • 0 in reply to Mark Sauerwald88474
    Prodigy 160 points

    Hi Mark,

    at first many thanks for your quick response.

    If I don`t use the back channel (only the hi speed "forward" - stream), do you see then a possibility ?

    By the way the coupling between serializer and deserializer is ac coupled !

    regards

    Rudi

     

  • 0 in reply to R. Scalick
    TI__Genius 13475 points

    Rudi

    Your chances of getting the system working with only the forward channel are much better - my suggestion would be to contact your local TI representative, and get an evaluation kit to try out the link with various different Baluns and media between the Serializer and Deserializer.

    And yes - you are correct, we normally AC couple the link with series capacitors - my mistake.

    Mark