My inquiry is about getting nearer to 24bits of resolution when the inputs of the front end of the AD7195 are shorted (AIN1 and AIN2). The device is in a default state as none of the registers have been written to, but they have all been read: Status:0x0, Mode:0x80060, Configuration: 0x117, Data: 0x7ffbda, ID: 0xa6, GPOCON: 0x2, Offset: 0x800000, FullScale: 553a40. The front end consists of a differential pair, with adjustable collector current, driving an AD8475. With a little effort I am unable to measure a differential voltage at the input into the AD7195. The differential pair is sourced by the same voltage regulators as the AD7195.
Attached is a image of the schematic, AFE.png.
Any help to increase the SNR would be appreciated!