Using transformer at DDS output can help to depress spurs?

[tony_lth]

In DDS AD9858 datasheet, it is possible to use a transformer at the DDS output pins, i.e. Iout and --Iout.
1. What is the benefits using a transformer at the DDS output?
2. I want to convert diff output to single end output, so I think to using Configuration A transformer, using secondary linking to the DDS diff output, and using primary for single end output. Is it right?
3. My single end output impedance is 50R, so the impedance ratio of the transformer should be "1:1", right?
Thank you very much.

 

[tony_lth]

Is there any goodway to depress the spurs?

 

[FvM]

Depends on what kind of spurs you are referring to. Spurs generated due to DAC nonlinearity, e.g fudamental harmonics and intermodulation products can be possibly reduced by a transformer or differential amplifier. Spurs generated by the DDS algorithm, that are already present in the digital data, can't be reduced.