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AD9913 Evaluation Board Variable Output Voltage

Question asked by on Jul 2, 2018
Latest reply on Jul 11, 2018 by KennyG

I am having trouble with the AD9913 Evaluation Board. I cannot seem to get a consistent output voltage over the range of 1MHz - 100MHz. This is what I am seeing:



I setup the software like this: 



I am seeing similar results using either a 25MHz sine wave generator input into the REFCLK input or installing a 25MHz crystal. I am measuring the DUT FILTER OUT using a LeCroy WaveRunner 610zi with a 1 foot BNC cable.


Any idea why this is the case? Is this due to the AD9913, the output transformer, or the 100MHz LPF? I've attached the AD9913 evaluation board schematic. 


Thanks for your help.