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964 Views
Registered: ‎11-14-2019

AC coupling for Aurora

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Hi, We are trying to comunicate between two FPGAs using Aurora and Interlaken Protocol(Zync and Virtex). 

1. Is it necessory to use AC coupling for the lines?

2. If we want use same protocol to communicate between same FPGAs(Zync and Zync), then also is AC coupling necessory?

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drjohnsmith
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Registered: ‎07-09-2009
AC coupling is normally done at the Tx end , near the FPGA.

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drjohnsmith
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Registered: ‎07-09-2009
does it NEED to be AC coupled, no.
Is it much much easier if it is AC coupled , YES
AC coupling the signal takes away all the worries about power supplies being different at each end, one fpga being powered configured the other not, et all

Aurira has coding so that the AC coupling works,

Aurora is a generic protocol, that just pumps parallel data from one chip to another over serial lines.
What parallel data you want to send , is up to you

This might be of interest if you want to join two chips
https://www.xilinx.com/products/intellectual-property/axi-chip2chip.html
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934 Views
Registered: ‎11-14-2019

Hi Jhon smith,

Thanks for the prompt reply,

We are designing a networking board that has multiple FPGA's interconnected in a single PCB( 4 ZU21DR & 1 VU13P).

We will be utilizing all 16 GTY's available in ZU21DR and 104 GTY's available in VU13P.

As there are multiple high-speed signals it would be difficult to add AC-Coupling capacitors to all of them.

Can you please let me know the precautions that need to take care when a the board is designed without AC-coupling capacitor between GTY's.

Regards,
Chandra

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drjohnsmith
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Registered: ‎07-09-2009
all you need is 0201 capacitors,
or if you can fit 01005 beasts,
A network of connections is a double reason to use AC coupling, it will remove a lot of problems,

If you have identical FPGAs, on the same board, that are all powered up at the same time and always configured together, then the links just connect, DC.
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drjohnsmith
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Registered: ‎07-09-2009
Knew Id seen this somewhere
https://www.xilinx.com/support/documentation/application_notes/xapp1096-dc-coupling-gtx-transceivers.pdf
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839 Views
Registered: ‎11-14-2019

Hi Jhon,

Thanks for the quick reply.

I have one more query regarding the placement of AC-Coupling capacitors.

The coupling capacitor should be placed "very near to the corresponding pin in the FPGA" or "Anywhere in the path" ?

 

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drjohnsmith
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Registered: ‎07-09-2009
AC coupling is normally done at the Tx end , near the FPGA.

<== If this was helpful, please feel free to give Kudos, and close if it answers your question ==>

View solution in original post

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