After clearing the DMM buffer, short term instability is less than 1uV.
My house is running no HVAC for the last three weeks. I am enjoying the short period where no air conditioning is required and no furnace is required. So, the temperature inside swings+/- 5 deg F
This is how my LTZ looks like on the DMM7510 after almost 130000 readings
But I had to move it away from any kind of disturbances like WiFi or DECT phones and so on.
And where these measurements are taking it was till not perfect.
Finally I can post, phew.
VintageNut
You can use A9 PCBA with anything from 10VDC to 20VDC. I usually test all LTZ modules with +15, just easy to get by with 7815.
No need for negative voltage either.
The negative supply serves as a sort of passive current compensation..
You'll see that, if you sum up all different currents, like through the zener, and both transistors, and compare that value to the current through that strange dummy resistor to negative supply.
Anyhow, this is not needed, and gives no big advantage, as the circuit is an exact copy of the datasheet.
Therefore, you can run it from any single positive supply, like TiN already wrote.
Again, before attempting to make precision measurements, proper thermal and electromagnetic shielding is required.. this board is sitting inside a double shield in the 3458A..
And your measurements already showed many spikes from external sources (SMPSU?, AC mains line switching?) and maybe popcorn noise or influence from air draught (these longer fluctuations).
Frank
Ah yes, another hint from the "Super LTZ .." thread.
These short spikes were always visible, in mostly all stand alone / DIY solutions, because the original circuit is extremely sensitive to external noise.
Especially both BE diodes like to pick up and rectify any external noise, causing these spikes and in turn, shifts of the reference voltage.
Andreas has made big improvement on this sensitivity, by adding a bunch of blocking capacitors on these crucial points..
Both of my own DIY LTZ1000 references still showed some spikes, despite a proper shield and grounding, but simply adding two capacitors even improved that behaviour.. please search on the latest pages of this blog, I think I have indicated, what to do very easily.. also going for your reference..
The fully equipped circuit of Andreas is even more immune, and has even less disturbances left.
Frank
I will have to get my LNA amplifier assembled and tested first to do this test.
My only scope have too high noisefloor to do this kind of measurements without preamp.