Hi all!
I was recently doing some experiments with voltage references and found a resolution limit to test it in my instruments.
My initial goal was investigate how far I could go with "simple" voltage references.
So, I used a REF5030, a integrated resistor network to divide it by 3 and a very low drift op. amp. (OPA4192) to bufferize the output. I added some extra circutry at output to make it more rugged, too. I also used the trimming scheme suggested in the REF datasheet (and trimed it to 1.0000V at output).
To provide thermal stability, I physically attached a small aluminum block to the main active components and controlled heated it to 40C (the famous LTZ1000 have this arrangement).
As result, I obtained a 1.0000V in my Fluke 8050A. There is a 200uV fluctuation that disappears as the Al block heats.
And here my doubts begins.
The voltage output stabilizes in the resolution limit of my instruments. Now I dont know what happens beyond it.
It will take a while until I get a voltmeter with more resolution, so I ask to more experimented colleagues: how far you reached doing this kind of arrangement?
I know I can reach very good resolutions with a LTZ1000, but my intention with this experiment was to know how far I can go WITHOUT a LTZ1000.
Any thoughts?