What would be the expected thermal stability/drift of the Gain value when external resistors are added at the inputs of these amplifiers for filtering? (For example, two 10-Ohm resistors, per datasheet example at 9.1.3 Signal Filtering).
It is understood that in this configuration the Gain will have an additional initial error of about -0.83 %, this is not critical in our application, as it will be calibrated out.
However, we are interested in the magnitude of the thermal drift for the Gain in the above configuration; there are no indications in the datasheet for that parameter.
Clearly, the excellent datasheet value for the "Gain error vs temperature" (1.5 ppm/°C typical, 20 ppm/°C maximum) can not be maintained.
From various AppNotes and Reports, it seems that the internal resistors are optimized for incredibly tight thermal tracking, but the absolute value of the on-board resistors can vary as much as +/- 30 % or more.
Furthermore, the influence on the Gain is manly from the Bias network at the Inputs (with equivalent resistance of 1250 Ohms ?) What would be the TCR value of that Bias network?