I have a question regarding the linearity of the AD9252. I am using a system that contains 32 ADC channels using the 4 off AD9252 devices. I find that I obtain the data sheet figures for INL if I drive only a single input channel of the AD9252. However if I drive all eight channels concurrently from the same source I obtain INL figures 2.5x worse than the data sheet worst case. I am wondering if anyone has come across this or if you have any good advice for me?
Does anybody know if this is a 'feature' of the part and would recommend changing the part for the AD9257-65 (I believe I can accommodate the small changes in device pin out)
The attachment has a couple of linearity plots and some circuit fragments that may be helpful.