Fully differential operational amplifiers (FDAs) can easily be used to attenuate and level-shift high-voltage input signals to match the input requirements of lower-voltage ADCs. This article is Part 3 of a three-part series. This paper will show how to adapt the circuits presented in Parts 1 and 2 to the more complex case where the input signal is a high-voltage, SE unipolar input with arbitrary common mode voltage.