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Selecting RX adaptation mode for L-tile Transceiver

New Contributor II


I am using S-10 SoC Dev kit (L-tile).

I am targeting 20Gbps line rate for my end application.

Initially I sent a incremental pattern and trying to get back the same pattern using FMC loopback card. During this exercise, I observed that loopback test is failing when I keep RX adaptation mode to "Manual CTLE,Manual VGA, DFE Off". When I set RX Adaptation mode to "Adaptive CTLE,Adaptive VGA, All-Tap Adaptive DFE" I observed BER is 0.

There are 4 settings allowed for RX adaptation mode in Native PHY for L-tile Transceiver, namely

Manual CTLE,Manual VGA, DFE Off

Adaptive CTLE,Adaptive VGA,DFE Off

Adaptive CTLE,Adaptive VGA, All-Tap Adaptive DFE

Adaptive CTLE,Adaptive VGA, 1-Tap Adaptive DFE.


My question is, what are the criteria to select one among these different modes ?


With regards,



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As I understand it, you have some inquiries related to the RX adaptation mode selection. For your information, generally the selection would be dependent on your system requirement. For example, in some cases, user would prefer to manually manually tune the XCVR channels, then he would select the manual mode. In other cases where you want things to be automated, you may select the adaptive modes. The mode selection would depend on your system loss characteristics. Note that the lesser blocks enabled, indirectly you would have lesser power consumption.


In your case, I would recommend that you start with Adaptive CTLE,Adaptive VGA,DFE Off mode to see if it helps. If not, then you can proceed to next modes ie with 1-Tap Adaptive DFE to see if it works. 


Please let me know if there is any concern. Thank you.


Best regards,

Chee Pin


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