I am simulating both the OP484 and the ADA4084 in the attached LTspice schematic. The circuit provides a linear output voltage as a function of the input voltage. The input voltage also biases the amplifier. I originally assumed I should only specify that this circuit will work with input voltages down to the 3.0V minimum supply voltage for single-supply operation. The model suggests the amplifiers may continue to work well below 3.0V. The OP484 output is linear down to 1.8V and the ADA4084 down to just under 1.5V. I am curious how much I should trust these results, and how they might vary over life with temperature/radiation exposure.