How important is it that the VDRIVE pin of the AD7606 be low noise? I am designing it to interface to an ADSP-BF547. Its 3.3V supply will be identical to the Buck Switcher in the schematic for the ADSP-BF548 EZ-KIT Lite:
on the lower right portion of page 126.
My concern is the switch mode power supply ripple coupling noise into the A to D conversions, and whether I should source the 3.3V from a linear regulator for VDRIVE.