Problem with DA and a transformer

[EricGuo]

DA help

Hi,all
I used AD9702 from AD to translate the digital singal to differential ouput and a RF transformer to translate the differential ouput to a single output. if i do not connect the transformer, the differentail analog ouput is linear with the digital input, but if i connect the transformer, the single ouput is nonlinear with the digital input. It looks like the transitory respone for charging a capacitor .
anyone has experience ,please help to solve the problem. thanks!

 

[bunalmis]

Re: DA help

DC bias and set points changed If you use single output.
This is normal.


Why yo dont use two differantial outputs?

 

[ddt694]

you can use a op amp to convert differential ouput to a single output,
it is easy.
see your ad9702 datasheet.

 

[EricGuo]

noise

thank you for your info.
I have another problem. Since I directly connect FPGA output to the DA digital input, it seems that the switch noise of Data/clock/control signal
transition greatly degrade the system performance. I test the noise on DA analog ground, it's about 200mv/pp. Oh my god, the analog output is only about 1V/pp. ask for Help!