We need reference voltage of 4,096V with the lowest noise.
We try ADR444 + output filter+pA low noise buffer amplifier.
Before we start counting and beating a dead path, you do not have a appnote or reference design with similar problem?
For specify. We need voltage reference with 0.1-10Hz output noise ~250nVp-p
Capacity how much can hang on output ADR4xx?
The ADR444 is a good choice in that, at 1.8uV, it has the lowest integrated noise from 0.1-10Hz of any of our references. It's rated load capacitance is 0.1uF.
You may also want to consider the new ADR4540. It has slightly higher 0.1-10Hz noise of 2.8uV but it has a max load capacitance of 100uF. So you should be able to hang much higher filter capacitance from it and still maintain stabillity of the reference's output.
A 100u, but make sure it is the lowest resistance polymer capacitor (not standard tantalum) you can find
I would use the ADR434. It's my favorite reference because it brings out an internal node, COMP,
allowing you to over compensate the loop and avoid noise peaking. See the "high frequency noise"
write up in the apps section of the data sheet.