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Opamp overview

An opamp amplifies the voltage difference between the two input pins. Ideally the gain is infinite, the offset voltage is zero, the inputs draw no current and introduce no noise. Circuit behaviour is defined by passive components which are used to set feedback from the output to the input.  One of the simplest circuits is the non-inverting amplifier where the gain is set by the passive components, ZF and ZG.
Schematic for non-inverting amplifier
The simplest analysis, assuming an ideal opamp, will yield the result that Vout = Vin * (ZF + ZG) / ZG.


The ideal valid range of common mode signals has no limits, and the device tolerates infinite differential voltages.  Input characteristics can be grouped into voltage and current specifications.


The output needs to be able to drive the feedback network and the load without difficulty.