I have a similar circuit like
Wheatstone bridge: 2x 350 ohm strain gauge (GF 2, 0.3%, 6-12 ppm) 2x 350 ohm resistor (0.1% 25 ppm)
I measure 40 ppm, so the resistance change is only 0.028 ohm.
How could I nullify the error that comes from the tolerance of the resistors the offset of the in-amp and temperature change?
For the first part of the question I found that simple voltage divider at the reference is an okay solution and the temp change doesn't have such a great effect.
The task is to drive a JFET if I measure more than 40 ppm, so I'd put the JFET to the output of the in-amp and set the REF voltage so if I get say 41 ppm the few uV difference with the amplifier is enough for the JFET to open. Is there a better, easier solution for this problem? Is "my" solution okay?
In another question Spehro Pefhany suggested AD8237 instead ina-128.