Author Topic: Lowest drift, lowest noise voltage reference (ADR1000AHZ)  (Read 181845 times)

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Offline branadicTopic starter

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Re: Lowest drift, lowest noise voltage reference (ADR1000AHZ)
« Reply #475 on: November 16, 2024, 08:21:43 pm »
It's not just me, the temperature effect is real.
I used WebPlotDigitizer to get the samples from your plot and Plotter to remove drift by applying a hyperbolic fit, which worked better than the parabolic fit, though I know both aren't the right choice, but will do for the moment.
If I then replot the data with the drift removed from them we can clearly see a temperature influence. As it appears in similar amount on all three datasets, is it systematical and coming from your measurement device? If you would remove that temperature dependency from the data, how does the drift curve appear?

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« Last Edit: November 16, 2024, 08:31:20 pm by branadic »
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Offline Andreas

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Re: Lowest drift, lowest noise voltage reference (ADR1000AHZ)
« Reply #476 on: November 17, 2024, 06:36:29 pm »
Could you plz. plot drift (with the drift rate itself removed for sure) vs. ambient temperature? Is it just me or is there a small correlation?

I have drawn values over temperature from day 705 where the drift is rather stable.
I see no direct correlation drift over temperature on the ADR1000 measurements.
(the T.C. is adjusted to -6 ppb/K and -4.5 ppb/K on the 6.6V outputs and +20 ppb/K on the 10V output).
https://www.eevblog.com/forum/metrology/lowest-drift-lowest-noise-voltage-reference/msg5138967/#msg5138967

The ageing measurements on ADR1000A are always corrected by a LTZ#4  measurement.
(my most stable reference over time with -21 ppb/K)
So also the temperature coefficient of the 4 ADCs + both DMMs are corrected.

But I have to admit that this reference measurement on LTZ4 is the weak point.
If it fails, you have a common cause error which is also visible in LTZ#9 measurement.

When you look at the "dent" on day 726 it is not temperature related.
In the averaged measurements of the raw values on 15.03.2024 I can see that ADC#15 and ADC#17
measurement failed for some reason on LTZ#4 compared to 08.03.2024.
(not temperature related, probably bad contact or EMI related during measurement)
So normally I should exclude this measurement on day 726 from data.

with best regards

Andreas
 

Offline branadicTopic starter

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Re: Lowest drift, lowest noise voltage reference (ADR1000AHZ)
« Reply #477 on: November 17, 2024, 07:45:08 pm »
I think the temperature dependence is obvious in your previous post, at least to me.
I can see that temperature dependence subtracting different fit functions from your data, such as natural log y=A*ln(x/B) with:
A=-1.0447910452e+00 and B=5.2486706950e+00 for ADR#01 10V corr
A=-1.6667803966e+00 and B=1.0955854281e+01 for ADR#01 Vz corr
A=-1.7280758581e+00 and B=1.2283777186e+01 for ADR#02 corr

or cubic function y=ax³+bx²+cx+d. You can check that yourself using e.g. https://curve.fit/
What is left clearly correlates with your ambient temperature.

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Offline iMo

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Re: Lowest drift, lowest noise voltage reference (ADR1000AHZ)
« Reply #478 on: November 17, 2024, 09:33:56 pm »
@Andreas: when you look at the graph from a distance you may see - when the temperatures are typically "higher" the curve's downwards trend (the trend which may fit a function branadic has extracted) is slowing down a little bit, when the temperatures are typically "lower" the curve's downwards trend is speeding up a little bit..

« Last Edit: November 17, 2024, 09:43:45 pm by iMo »
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Offline aronake

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Re: Lowest drift, lowest noise voltage reference (ADR1000AHZ)
« Reply #479 on: November 27, 2024, 05:28:36 am »
Stock levels at analog.com of ADR1000 is gradually going upward. In July i saw 52, two weeks ago there was around 127, and now 444. So seems production is ramping up.

After some fiddling around I managed to order 5 last week. First I managed to get quotes but delivery was rejected. I though that could have to do with me living in Hong Kong. But contacted Analog customer support to ask the reason, and they told i had to order from a company e-mail. I have a company here in Hong Kong, so switched log-in to company e-mail and used company e-mail for order and then worked and i got a confirmed order. Two days later i got a tracking number, but items not sent yet. Seems sending date is scheduled for 29th now after two updates from analog. So looks like things are moving, but can not be sure until the ADR1000 are here....


2447041-0
 

Offline aronake

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Re: Lowest drift, lowest noise voltage reference (ADR1000AHZ)
« Reply #480 on: December 01, 2024, 08:43:33 am »
344 in stock now.

Who has ordered recently and how has it been going? Got delivery?

My status with the fedex trackning number is still Lable Created after a week, so seems Fedex has not received the package yet. Thats quite strange
 

Offline aronake

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Re: Lowest drift, lowest noise voltage reference (ADR1000AHZ)
« Reply #481 on: December 02, 2024, 05:44:06 pm »
344 in stock now.

Who has ordered recently and how has it been going? Got delivery?

My status with the fedex trackning number is still Lable Created after a week, so seems Fedex has not received the package yet. Thats quite strange

After a week with the fedex shipment in status "Label Created" I reached out to Analog customer support to be told first that the order was cancelled "due to trade compliance". When asking if they could give more details as I much rather buy from them than from unauthorized dealers as no authorized dealers have ADR1000 in stock I was told "ADI eshop cannot cooperate with your company".

In the meantime I managed to get a ADR1000 from an unauthorized dealer. But that one is very far out of specifications when it comes to stability. Either it was broken or some reject for quality issues or fake. If fake, someone has put lots of effort in making a fake. It has realistic characteristics on the current draw on the heater and from time to time, it can keep within 5 uV peak to peak for some hours. The board I am using it on is very close to reference design, instantly worked with LTZ1000 I tested it on. Some slight modifications made now to be closer to ADR1000 component values.

I can understand that Analog do not want to sell to everybody, but at the same time they are promoting the terrible business companies of selling fake and broken components.
 

Offline Andreas

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Re: Lowest drift, lowest noise voltage reference (ADR1000AHZ)
« Reply #482 on: December 23, 2024, 07:00:44 pm »
Hello,

I now passed 24 kHrs:

no clear direction of drift.

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
 

Offline Andreas

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Re: Lowest drift, lowest noise voltage reference (ADR1000AHZ)
« Reply #483 on: December 23, 2024, 07:27:55 pm »
Hello,

I did some interpolations to better approximate drift.

First: Error curve of coefficient for SQRT(Time)
After subtracting the (overall averaged) interpolation from the measured value the error curve shows different slopes before 7.5 kHrs and after 7.5 kHrs.

2nd: after leaving off the first 7.5 kHrs and calculating the error curve for the remaining part over time.
3rd: the same over temperature (with offsets of 0.5 ppm to better show the individual temperature slopes).
ADR#1 10V shows a significant slope whereas the other slopes are much lesser or hidden within measurement noise.

4th: simultaneous interpolation over SQRT(Time) and Temperature with time as X-AXIS.
5th: the same over temperature. (showing the measurement noise).

Results for Tempco of combined interpolation.
ADR1000#1 6V6: 18 ppb/K interpolated
ADR1000#1 10V: 39 ppb/K interpolated
ADR1000#2 6V6:  1 ppb/K interpolated

Each measurement is done relative to LTZ#4 which has -21 ppb/K (so this negative drift increases the result by +21 ppb)
The dertermined T.C. values for the used references and the expected T.C. for the ageing measurement is as follows.
ADR1000#1 6V6:    -6 ppb/K -(-21ppb/K) = +15 ppb/K expected
ADR1000#1 10V: +20 ppb/K -(-21ppb/K) = +41 ppb/K expected
ADR1000#2 6V6:    -5 ppb/K -(-21ppb/K) = +16 ppb/K expected

But of course there is a uncertainity of several ppb/K in the measured values..

with best regards

Andreas
 

Offline Andreas

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Re: Lowest drift, lowest noise voltage reference (ADR1000AHZ)
« Reply #484 on: December 23, 2024, 08:32:50 pm »
Hello,

I did some interpolations to better approximate drift.

First: Error curve of 3rd order (cubic) interpolation over time (kHrs)
After subtracting the (overall averaged) interpolation from the measured value the error curve shows outliers up to 1 kHrs so I left off the first kHr for the following interpolations.

2nd: after leaving off the first 1 kHr and calculating the error curve for the remaining part over time.
3rd: the same over temperature (with offsets of 0.5 ppm to better show the individual temperature slopes).
again ADR#1 10V shows a significant slope whereas the other slopes are much lesser or hidden within measurement noise
but seem to get a higher order tempco at the edges due to the 3rd order ageing coefficients.

4th: simultaneous interpolation over time (3rd order) and Temperature (linear) with time as X-AXIS.
5th: the same over temperature. (showing the measurement noise and the seemingly nonlinear T.C. behaviour at the lower edge).

Results for Tempco of combined interpolation.
ADR1000#1 6V6: 29 ppb/K interpolated
ADR1000#1 10V: 42 ppb/K interpolated
ADR1000#2 6V6: 12 ppb/K interpolated

The expected values are as above.

with best regards

Andreas
 

Offline Kleinstein

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Re: Lowest drift, lowest noise voltage reference (ADR1000AHZ)
« Reply #485 on: December 23, 2024, 08:46:10 pm »
The is quite some correlation between the ADR measurements. A correlation between the 10 V and 6.6 V from the same ref. is no surprize, but there is also quite some between the 2 references. The correlated part could be from the ADC, divider and it's reference or possible some common influence like EMI or pressure or humidity. With the rather sharp jumps humidity is not that likely.
 

Offline Andreas

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Re: Lowest drift, lowest noise voltage reference (ADR1000AHZ)
« Reply #486 on: December 24, 2024, 02:11:33 pm »
As already mentioned:

But I have to admit that this reference measurement on LTZ4 is the weak point.
If it fails, you have a common cause error which is also visible in LTZ#9 measurement.

When you look at the "dent" on day 726 it is not temperature related.
In the averaged measurements of the raw values on 15.03.2024 I can see that ADC#15 and ADC#17
measurement failed for some reason on LTZ#4 compared to 08.03.2024.
(not temperature related, probably bad contact or EMI related during measurement)
So normally I should exclude this measurement on day 726 from data.

with best regards

Andreas
 

Offline branadicTopic starter

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Re: Lowest drift, lowest noise voltage reference (ADR1000AHZ)
« Reply #487 on: January 20, 2025, 06:40:02 pm »
Here is an update of my ADR1000 reference against two Fluke 7000. The reference appears to be stable, but one of the F7000 drifts more than the other, still within spec though.

-branadic-
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Offline Andreas

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Re: Lowest drift, lowest noise voltage reference (ADR1000AHZ)
« Reply #488 on: Yesterday at 09:47:19 pm »
Hello,

I recently passed 25 kHrs:

There seems to be some common cause drift on all measurements
-> obviously my LTZ#4 (reference for relative drift in this case) drifted by 0.2 - 0.3 ppm during the last 1 kHr.

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
« Last Edit: Yesterday at 09:48:58 pm by Andreas »
 


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