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charlescanaff
Visitor
Visitor
5,452 Views
Registered: ‎06-04-2016

ML605 Virtex-6 GTX no buffer differential

Hi !

I generate differential signals out of a ML605 board from  Virtex-6 GTX TX through FMC (got a little expansion board

to get SMA connectors).

Signal are ok on the scope.

I would like to feed a 50 ohms single-ended board with this differential signal.

 

Can you tell me if the following is ok and without "problems like getting the port toasted" :

 

I planned to

    - first put "DC blocks" (capacitances) on-cable on both side of the differential

    - then connect one side to the 50-ohms destination board input

    - connect the other side to the ground of the destination board using a passthrough 50ohm SMA with a ground

                            output ( via a little chain).

 

I know that I may lose power but I can live with this ( signal will be amplify on the next stage ).

 

Thanks for your help.

 

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athandr
Xilinx Employee
Xilinx Employee
5,442 Views
Registered: ‎07-31-2012

Can't you use differential to single ended converters?
Thanks,
Anirudh

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charlescanaff
Visitor
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Registered: ‎06-04-2016

This is for a kind of fast prototyping. If possible, I need to get a quick solution "pluggable" on SMA without

going in board design and fabrication ( these steps may be part of a future evolution of the project ).

 

The GTX produce 2Gbps signal.

I saw that there are some baluns  that seems to support that speed with enough bandwidth to not distort

too much the signal. But they are quite expensive just for a prototype...

 

I also tried a little demo board for a differential ampli in  single-ended on output , but the design of the board was

not appropriate for our needs.

 

Do you think that the solution I proposed with "DC blocks" and 50 ohms impedance on the "unused" side of

the differential output may damage the FPGA GTX port ?

 

Thanks again for your help.

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charlescanaff
Visitor
Visitor
5,256 Views
Registered: ‎06-04-2016

Yes, that's the idea...

 

which single ended converters will work and how ?

 

I have a 2Gbps signal getting out through SMA ( got a FMC expansion card with SMA connectors for this purpose).

It work when I look at the scope.

 

What config will be the best to get high output directly in single-mode (if possible)  and to adapt the output impedance ?

or if I get it differential (as I actually do ) how can I adapt it? Which single ended converters will fit well

this speedy signal?

 

Are there some design samples of outputs from Virtex-6 GTX that goes to something else than same or similar serdes ?

 

Thanks,

 

Charles

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