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Large Spurs of ADF4356

Question asked by Coney on Apr 21, 2017
Latest reply on May 22, 2017 by Brigid.Duggan


   We are seeing a lot of large PFD harmonic spurs at the output of ADF4356.

   When the output comes from the VCO directly (f > 3400MHz) , the harmonic spurs appear such as the picture 1. It is much larger than the datasheet.

   On my eval board,  f_refin = 140M, R = 2, PFD  frequency is 70MHz.Fout = 6.5 GHz and 5.4GHz


   Looking forward to your reply.

   Best regards.