Alright, I cannot let
zlymex get all the glory, so let get some more nanovolts flying.
How about we build few known LNA designs to test in practical environments?
Two with quarupled opamps. LNA1 with Analog instrumentation amp, AD8428.
Paper about it here. Second is discrete one, using ADA4522-4, copycat of
zlymex's design.
And third one is classic from Jim with few changes, based off Linear AN124.
I do realize gain of these amps are different, so perhaps option to set equal gain should be considered, or just leave them as is, using "black box" test approach, to see which one has less noise.