Hi KmB,
A common method to estimate the DC accuracy or total un-calibrated DC error of the instrumentation amplifier is to add the uncorrelated errors using the root-sum-of -squares.
Below is an excerpt of an Application Brief for a similar device providing examples of DC error analysis: "Optimizing Strain Gauge Accuracy With INA851 vs Discrete Design". The INA851 is a fully differential output amplifier similar to the PGA855 where the gain is fixed/set using a single external resistor. The error analysis is based on offset, gain error, CMRR, and temperature drift specifications. The application brief provides an estimate of DC error based on typical and max datasheet specifications.
One great feature of the programmable gain amplifiers (PGAs) such as the PGA855: the gain is set using all internal resistors that are ratiometrically matched providing outstanding low gain error ( ±0.02% typical, ±0.07% max), and very low gain error drift.
An error analysis for the PGA855 will be similar as the one featured on the application brief document (see INA851 table/example below), but based on the PGA855 specifications/equations. I can work in a calculation example specific to the PGA855 including offset, gain, CMRR, non-linearity, and provide an update. What is the min/max differential input voltage range, and input common-mode voltage range? Which gains will be used in this system and/or What is the required output voltage range? Is there a temperature range requirement?
Thank you and Regards,
Luis
