The AD7710 works well in the precense of external vibrations, but when I use
the AD7798 the performance falls to unacceptable level in the precense of the
same vibrations...can you explain ?
The AD7710 uses a free-running filter with no chopping so the roll off is
quicker than with the AD7798 filter. The AD7798 was designed to use chopping
resulting in low offset/low offset drift. However, the roll-off is slower for a
given update rate. An external R-C filter is used for anti-aliasing but this
filter is required to removed images at multiples of the master clock. To
include a filter for vibrations would require a filter with very low bandwidth.
The AD7190/2 again uses a free-running filter. So, the filter response will be
comparable with the AD7710 response.