I use a AD9117 with IQ modulator ADRF6755. I have used 50 Ohm 1% at the output of the DAC, balanced filter for limit bandwidth, 100 Ohm 1% to close filter at the input of ADRF6755. AD9117 generate 0.5V of pedestal and signal go from -0.45 to +0.45 V (0.90 Vpp). In this configuration, with my surprise, I have a "amplitude imbalance" of 2 % ... ... with change of Gain on "I path" I managed to get "amplitude imbalance" of 0.05 % ... ...
The DAC AD9117 have two pin for adjust current generator of DAC : FSADJI and FSADJQ with the respective resistance of 1.6K 1%.
For decrease the phenomenon I can connect FSADJI with FSADJQ together with a single resistor ?
What other measures can I use ?
Thanks very much.