Non-inverting operational amplifier ($K=1+R_f/R_g$)

An operational-amplifier configuration applying the signal to the non-inverting input and returning a fraction of output to the inverting input. In stable unsaturated ideal operation, zero input current and equal input voltages give the displayed voltage gain. The feedback resistor $R_f$ connects output to the inverting input and $R_g$ connects that input to the reference wavefunction node.