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AD9789 -- Harmonic (Spurious) Signal present at 16.2MHz from Centre Frequency

Question asked by vinaygharat on Nov 2, 2011
Latest reply on Nov 10, 2011 by vinaygharat

     Dear All

 

I am using AD9789 interfaced with AD9516.

Schematic is almost similar to Evaluation Board AD9789-EBZ

 

We are using Single Channel, 32 bit Access, 16 Bit Data,  Complex mode ,

 

 

Fdac frequency is  2.340Ghz

Centre Frequency is 767.143Mhz

 

 

Calculated FTW is 0x3E7F4D

Calculated BPF centre Frequency (FC)  is 0x53E3

 

SUM SCALE is 0x1d

input Scalar is 0x40

Ch 0 Gain register  0xC5

 

 

Desired signal Amplitude is very high as we expected.

however, there are spurious signal comming at multiple of 16Mhz from  centre frequency,

We checked Parity and Satuaration counter but there was no issue there.

 

We are like stuck for 1 month .

 

Any ideas, suggestion are welcome.

 

Attached two files are

AD9789 parameter set

Spectral waveform

 

Thanks

Vinay

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