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ADF4350 issues

Question asked by starraytheon on May 15, 2014
Latest reply on Nov 5, 2014 by ryan-tsai

Hi Experts,


I am facing some issue in ADF4350, below is the question:


We have designed the PCB with 2 synthesizers ADF4350 on the PCB.

The digital and analogue VDD are fed from separate supplies at 3.3 VDC.


The current ADF4350 shows hunting around frequencies 452, 904 & 1808 MHz.  This can occur at ambient on some devices or as soon as we drop the temp down to 0 degrees.  The VCO unlocks and hunts in a bandwidth of approx. 12, 24, & 48 MHz respectively.

If the device is warmed up, it regains lock.

If the Analogue VDD is reduced by 0.3 VDC to 3.0 VDC, the device performs better but not as expected.


Pls kindly help to give some advice, it is effected by power supplies, or other issue? Thanks!



Yours Sincerely,

Tom Qi