AnsweredAssumed Answered

AD9739A-FMC-EBZ rev C vs. rev B changes

Question asked by JFERNAN3 Employee on Jun 26, 2014
Latest reply on Aug 14, 2014 by danf

Hi EZ team,


I have a customer that is experiencing some problems with the AD9739A-FMC-EBZ(rev C)


They need to use AD9739A with an external clock signal (2.4GHz), which is generated with a Signal Generator.


To make this possible, they need to change two capacitors, which are located in the rear of the board and select the ADCLK914 clock source in the switch.


This is not new for them because it is essentially the same operation they have done with our previous revB board. According to the schematics available online at, aparently there is no other noticeable change  (revB uses an jumper to select clock source and revC uses one switch - but they need always to change the two capacitors, which is somewhat annoying and strange...).


With our previous AD9739A-FMC-EBZ (revB), they were able to do this change, without any problems.

But this revC is unable to lock the clock signal when they try to use the external clock.

When they revert the capacitors to their original position, they are able to lock the clock signal generated by ADF4350 synthesizer without any problems.


As mentioned previously, they checked schematics of the two revisions of this board several times and we didn't find any noticeable change that could be related with this problem.


And according to their tests (in which, we are able to use the original synthesizer), this doesn't seem to be an hardware problem.


Could you please check if they are missing something or doing something wrong


Thanks in advance for a prompt replay


Best Regards