AnsweredAssumed Answered

ADF4350 low spur mode vs low noise mode

Question asked by MikeV on Feb 9, 2012
Latest reply on Mar 1, 2012 by rbrennan

I'm evaluating the ADF4350 and comparing it to the datasheet figures.  I'm seeing some strange results that don't seem to match for Figure 11 and 12.  I am using the ADF4350 Evaluation Board.

 

For Figure 11 conditions, I'm seeing many spurious tones compared to the datasheet, and for Figure 12 conditions, I see spurs well above the phase noise level.  I should also say that for Figure 11, I see intermittent spurs, but I assume those are environmental.  Can you review my settings and let me know what I could be doing wrong?

 

I have the E5052A in Trace->Spurious->dBc mode, so the spurs are in dBc, not dBc/Hz.  fREF=50MHz, fPFD=25MHz, fVCO=4227MHz, fRFOUTA=2113.5MHz, loop band width = ~40kHz.

 

Figure 11 register settings:

00580005

009C82FC

0000000B

00009E42

000083E9

00548050

 

Figure 12 register settings:

00580005

009C82FC

0000000B

60009E42

000083E9

00548050

 

Thank you !

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