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Does picking an amplifier with high amplifier open-loop gain guarantee an equivalent level of gain linearity?

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[edited by: Ryan_Curran at 9:36 PM (GMT -4) on 1 Sep 2021]
  • High amplifier open-loop gain is a good initial selection criterion for the highest accuracy circuits but isn’t enough by itself to guarantee the system will be linear to that extent.  Open-loop gain is specified via a two-point measurement and doesn’t consider the non-linear uncertainty in open-loop gain at other operating points.  MT-044 discusses open-loop gain uncertainty, how it translates into gain non-linearity and how it can be measured. 

    Other, possibly less obvious sources of amplifier non-linearity should also be considered.  For example, source impedances can interact with non-linear input currents and cause non-linearity totally independent of open-loop gain.  Also, uneven thermal heating of gain resistor networks can also cause significant non-linearity since the gain is changing as a function of the input and/or output signal levels.