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adf5355

Question asked by yckim on Aug 7, 2016
Latest reply on Aug 15, 2016 by yckim

Hello,

 

I have tried to use ADF5355 as RF PLL integrated VCO chip.

 

When I test chip with board, The output has some spur...

 

There is my PLL setting

 

I didn't use REF EVAL board. so I used USB to serial Port and ARM chip (coretex M4)

 

 

First, I set chip upper setting value for initialization. After picture is output on spectrum.

It seems to be FM modulation..... So I changed loop filters on datasheet and ADsimPLL, or REF source 100MHz to 122.88MHz. But this spur is always displayed on spectrum... I think it not integer boundry spur,cuz spur is on display with integer setting as 4GHz or 5GHz. I don't know how to solve....  Plase help me!!

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