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ADF4350 PLL Auxillary Output Power Incredibly Low

Question asked by Lee_RF on Dec 7, 2016
Latest reply on Dec 16, 2016 by Lee_RF

Greetings,

We recently designed a PCB with two of your ADF4350 PLL's. We're however having a problem with it. The auxiliary output (RF B) is about 25 dB less output power than the primary output (RF A). This is the case for both PLLs on the board and for two different PCBs, as in, 4 PLLs altogether.  

 

The datasheet is very clear that the primary and auxiliary output powers should be the same with the same settings. Something must be wrong because a PLL with -25 dBm output is completely worthless and can not be used for mixing.   I have added two pictures of the measured spectrum from a probe placed directly at the QFN package. I've also added a picture of the PCB and the schematic.  

 

Please answer us as soon as you possibly can so that we can continue our work. I am a big fan of your products and hope we can get this resolved.

 

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