Electronics > Metrology

Lowest drift, lowest noise voltage reference (ADR1000AHZ)

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kleiner Rainer:
I suspect that we have reached levels of sensitivity in our measuring equipment that we have to take events from background radiation and cosmic rays into account. Andreas, do you live in an area with granite rock, think "radon"?

The Wikipedia article about cosmic rays states:
"Cosmic rays have sufficient energy to alter the states of circuit components in electronic integrated circuits, causing transient errors to occur (such as corrupted data in electronic memory devices or incorrect performance of CPUs) often referred to as "soft errors". This has been a problem in electronics at extremely high-altitude, such as in satellites, but with transistors becoming smaller and smaller, this is becoming an increasing concern in ground-level electronics as well.[89] Studies by IBM in the 1990s suggest that computers typically experience about one cosmic-ray-induced error per 256 megabytes of RAM per month.[90] To alleviate this problem, the Intel Corporation has proposed a cosmic ray detector that could be integrated into future high-density microprocessors, allowing the processor to repeat the last command following a cosmic-ray event.[91] ECC memory is used to protect data against data corruption caused by cosmic rays."

If a cosmic ray event can flip a bit in dynamic memory - what could it do to the output signal of a precision reference?

Food for thought.

Greetings,

Rainer

Dr. Frank:
These spikes extend over longer period of time, instead of a few points only.
Therefore these are highly probable dips coming from the reference, not e.m.f.
2nd argument, other reference does not show such dips. I have observed similar effects on one of my 5 ADR1000 only, scroll upwards, please. These dips did not occur constantly, but there were quiet and noisy phases.
Cosmic rays should not play a role on bipolar, big area semiconductors as such

branadic:
Let me remind you of Eric's talk at MM2021 and his explaination of surface charges, so it isn't necessarily popcorn.

Also coupled interference can cause all sort of weird effects. For example I saw weird jumps that appeared to be popcorn noise on my ADR1399. They were invisible to me when I used a 7.5 digit meter because of it's larger noise, but came visible when I switched to an 8.5 digit meter. Both meters where running on the same integration time of 20 s though. It turned out that was some sort of common mode noise from my lab power supply powering the ADR when I switched to my ULNLPS (shielded transformer + LT3045) and these jumps immediately vanished. That effect stressed my head for the last days before I finally found the culprit.

So before drawing any conclusion it's good advice to check that this is not a human induced effect or error, like in 99.9% of the cases. :)

-branadic-

Andreas:

--- Quote from: branadic on May 28, 2022, 11:01:20 am ---Thanks Andreas, why are you convienced that what you are looking at is popcorn and not some weird emf event nearby?

--- End quote ---

Hello,

of course I am using a metal cookies box connected to the ground of the oscilloscope.
The reference itself and the 1/f amplifier are battery powered.
The scope is powered by a laptop which itself is normally mains powered.
(I have checked that this has only minor effect on the output).

The whole setup is placed in a "quiet" corner of my lab.
Hum is checked by FFT before start of the measurement.
The noise measurements are usually done "over night" where I have less influence from EMI sources.

The question is: how does EMI noise (usually influencing as common mode noise over small parasitic capacitances) look like in comparison to a popcorn noise which is a "rectangular jump in > 1 sec range" (in differential mode) at the output of the 0.1-10 Hz 1/f amplifier.

The simulation shows:
Popcorn noise shows up at each edge as "sawtooth" pulse with a time constant of ~1 sec at the output.

Measurement shows:
EMI-noise (e.g. fluorescent lamp switching) shows up as "short pulse" which is much less in duration in the us or ms range.

and also some weird noise (EMI-pulses from a accidently not disconnected USB-connector) showed up as short pulses with 16 sec regularly time interval.

with best regards

Andreas




Andreas:

--- Quote from: branadic on May 28, 2022, 01:24:59 pm ---For example I saw weird jumps that appeared to be popcorn noise on my ADR1399.

--- End quote ---

Is there any legend which colour is what?
I see Jumps on the blue line but no real difference between the upper and the lower chart.

with best regards

Andreas

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