Lowest drift, lowest noise voltage reference (ADR1000AHZ)

[Noopy]

I didn't find the ADR1001 in myAnalog so I asked the customer service if it is possible to get a small quantity. The answer was promising but I didn't hear more since then... 

[Andreas]

Hello,

I now passed 17 kHrs:

the 10V/7V divider on ADR#01 drift has stabilized perhaps with a slight upward drift.

The 7V outputs of ADR#01 and ADR#02 trend to further settling.

Detailed explanation of the diagrams see post of 14 kHrs
https://www.eevblog.com/forum/metrology/lowest-drift-lowest-noise-voltage-reference/msg5138967/#msg5138967

with best regards

Andreas

[branadic]

Thanks Andreas. I haven't posted recent results for a while as we were waiting for our paper A 10 V Transfer Standard Based on Low-Noise Solid-State Zener Voltage Reference ADR1000 to be published.

Now that this is done I will post some new diagrams soon.

-branadic-

[branadic]

While the above mentioned paper covers an observation time of 850 days, I'm now approaching 1000 days.
For the paper noise measurements of the 10 V output (after 850 days) had to be performed and it was found that the output was slightly oscillating. A bit more capacitance between opamp output and inverting input was added, which resulted in a shift of the output voltage.

Furthermore, the output wasn't as stable as before, powering the reference from my Ultra Low Noise Lab Power Supply Extender for your existing lab supply. Hence why after 920 days I finally switched to a copycat of an LT1533 based power supply, from which it was running since then, but again slightly shifted the output. It will now be interesting to see, if things are stable. Attached is an updated diagram.

-branadic-

[ivo]

While the above mentioned paper covers an observation time of 850 days, I'm now approaching 1000 days.
For the paper noise measurements of the 10 V output (after 850 days) had to be performed and it was found that the output was slightly oscillating. A bit more capacitance between opamp output and inverting input was added, which resulted in a shift of the output voltage.

Furthermore, the output wasn't as stable as before, powering the reference from my Ultra Low Noise Lab Power Supply Extender for your existing lab supply. Hence why after 920 days I finally switched to a copycat of an LT1533 based power supply, from which it was running since then, but again slightly shifted the output. It will now be interesting to see, if things are stable. Attached is an updated diagram.

-branadic-

Is such a shift from change in PSU expected? It's within line voltage regulation? I agree with your paper's conclusion that you should have separated analysis of the standalone zener voltage from the amplification to 10V. As far as I can see - in the modern world although 10V is nice, the only true arbitrary number to choose, if implementing such a choice is not sacrificial to other parameters, is one that will be most easily used and useful to relevant ADCs (e.g near the top of their range[ s ]). I guess the only other competing factor is history - if other references are set to X, also aiming for X potentially allows an tighter comparison by using one as a null point (relative 0).

[dietert1]

If a setup has problems (in this case oscillation and power supply EMI) one needs to solve that. I think the apparent shifts of 3 and then 0.6 ppm are less remarkable than the fact that the first problem went unnoticed more than two years.
The first 920 days of the log may be or may not be typical for a ADR1000AHZ. That depends on whether that oscillation is typical..

Regards, Dieter

[iMo]

..A bit more capacitance between opamp output and inverting input was added, which resulted in a shift of the output voltage..
-branadic-

I reported here aprox +2ppm after adding the 4n7 foil into the feedback of the OPA189 in my myADR1001#1 (10V->10V buffer)..

[Andreas]

Hello,

I now passed 18 kHrs:

the 10V/7V divider on ADR#01 drift has stabilized but has still a slight upward drift.

The 7V outputs of ADR#01 and ADR#02 trend to further settling.

Detailed explanation of the diagrams see post of 14 kHrs
https://www.eevblog.com/forum/metrology/lowest-drift-lowest-noise-voltage-reference/msg5138967/#msg5138967

with best regards

Andreas