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Visitor
Visitor
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Registered: ‎11-30-2017

Aurora 8B/10B throughput and User Clock

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Hi,

 

I have a design using an Artix-7 200T and I would like to use an Aurora 8B/10B link to transmit data to a second device in Simplex mode. The input to the link will be 4 bytes wide using 1 GT Lane. I want to achieve a data throughput of 2.56 Gbps. Reading PG046 (v11.1), page 10 suggests that the link has a 20% overhead. Therefore, the link throughput would need to be 3.2 Gbps to achieve my required data throughput. Please could someone confirm if this is correct?

 

Secondly, how do I calculate the user_clk_out frequency for the above configuration?

 

Thanks

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Moderator
Moderator
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Registered: ‎07-30-2007

You can use the GT transceiver wizard for this.  Adjust your line rate and protocol and then check the summary page (attached).  The TX and RX outclks are at 160 Mhz.  (line rate divided by the internal bus width).

 

 If you change from the normal 3.125 that aurora normally runs to 3.2 you will change the reference clock requirement from 125 to 128 Mhz so it might be better to bump it up to 3.75

 

The overhead is from the 8B10B.  You have to transmit 10 bits to get 8.   This is the majority of the overhead but there are also comma characters and clock correction so there is a little more overhead 20% is approximate.

 

 

 




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Moderator
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1,981 Views
Registered: ‎07-30-2007

You can use the GT transceiver wizard for this.  Adjust your line rate and protocol and then check the summary page (attached).  The TX and RX outclks are at 160 Mhz.  (line rate divided by the internal bus width).

 

 If you change from the normal 3.125 that aurora normally runs to 3.2 you will change the reference clock requirement from 125 to 128 Mhz so it might be better to bump it up to 3.75

 

The overhead is from the 8B10B.  You have to transmit 10 bits to get 8.   This is the majority of the overhead but there are also comma characters and clock correction so there is a little more overhead 20% is approximate.

 

 

 




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aurora.jpg