Give a reliable ION circuit for REF+?

Question

Circuit design

If I'm right, then it's enough just to put the roll on 5 volts, stir up its regulation, and put normal LC filters at the roll input.
>>> And I turned out to be wrong, but the question remained open, what inexpensive and good enough ION for ADC measurements would you advise (but better than in the STM32 microcontroller).