I am currently trying to use a AD7322 but I have some problems with the accuracy and precision.
For exemple, I setup the input voltage at 3.76V (According my multimeter) and the range to ±10V as I use the internal reference (2.44mV is use to scale the data).
Fully diff: 6.314 / 6.256 / 6.353 / 6.273 / 6.2268 / 6.322
Pseudo diff: 2.796 / 2.681 / 2.527 / 2.544 / 2.427 / 2.615
Single Ended: 4.887 / 4.850 / 5.004 / 5.124 / 4.577 / 4.567 / 4.672
I attached the SPI command, it is the beginning of the configuration of the control register (0b10000010). The strange thing is that the input data is clocked on the fallaing edge of the SCK which is good but not the output data from the AD7322.
Please find also the schematic of the board.
I also have these components on another board where I use an external 3V reference but they also have this problems.
Forgot to precise for the scope image
Channel 1 (Blue): SCK
Channel 3 (Pink): MOSI
Channel 4 (Green): MISO
Channel 2 (Cyan): CS