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Transceiver reference lock issue

New Contributor I

Hi Experts,

I use Arria 10 GX device for my designed board and use transceiver phy for interface.


I have built many production boards and some of them, approximately 10 to 15%, interface don't work.


I have done many analysis, then I found a symptom on the failed board, that rx_is_lockedtoref is always low from completion of configuration. Of course, rx_set_locktoref goes to High.


Regarding the fine boards, after completion of configuration, rx_set_locktoref goes to High immediately, and rx_is_lockedtoref goes to high immediately also.

And consequent process is different between the fine board and failed board. On the both of boards, rx_set_locketodata goes to High after detect Rx signal, after rx_std_signaldet goes to High, then fine board receives data correctly, but failed board get random variant data only.


I guess that rx_is_lockedtoref (CDR reference lock) failure causes such symptom, then I have been inquiring the transceiver phy user guide for Arria 10, but I still have not gotten enough information.


So I would like to ask some questions.

(1) When lock-to-reference works, which settings are necessary for lock? Reset? Reconfiguration? proper frequency value, i.e. using prescaler?


(2) For lock-to-ref, is it used clkusr?


(3) I think lock-to-ref uses PLL, is it correct? And if so, what is a PLL-source clock, two clock should be there, one of them is reference clock and what is another one? If no, what is lock-to-ref?


I have other observation also, then I write it to my response for avoiding confusion.




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New Contributor I


I describe another observation of this issue.


Some of the failed boards fail at High temperature only, I think it means High temperature of Arria 10.

At the cool duration, such boards work fine, rx_is_lockedtoref goes to High and it receives rx data correctly. And after heat up, sustaining supplying power to the board, the interface is continuing fine work. It would mean all clocks and connections are fine even at the high temperature.

However, after power off and on once, rx_is_lockedtoref does not go to High after configuration.


It looks, capability for lock-to-ref.


How about that? And does anyone have any idea?




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