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Parallel DigiPot (AD8304) as gain setting resistor for Instrumentation Amp (AD8422)

Question asked by nicko on Oct 27, 2016

Hi All...........


Just wondering if you can you parallel up the 4 stages inside the AD8403 to make nom 250R and use them as Rg for In-Amp ?


schematic idea


This is mainly for calibration of the front end and not dynamic gain changing. Once set for a particular input condition the wiper values (all the same) will not be changed.


Points I'm considering are what effects there might there be on -

Overall TCR ?

Noise ?


Has anyone tried this, will it work or are there any other thoughts or ideas ?


Many thanks..............