Electronics > Metrology

ADR1001 - Ovenized Voltage Reference System

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iMo:
An update..
Note:
34401A, 100NPLC, 10M input
7.1.23 powered off for 10minutes
24.1.23 powered off for 20minutes
18.2.23 powered off for 16 hours
5.3.23 powered off for 20minutes
17.3.23 - the first "metro-LAB measurement" Vref = 9.999.895Volt, powered off for 3 hours

Andreas:

--- Quote from: iMo on March 27, 2023, 07:42:25 am ---17.3.23 - the first "metro-LAB measurement" Vref = 9.999.895Volt, powered off for 3 hours

--- End quote ---
with the same uncertainity as the other measurements?

branadic:
I expect these uncertainties of ±0.7 ppm to be a bit too overoptimistic, not sure where these are coming from.  :-//

-branadic-

iMo:

--- Quote from: Andreas on March 27, 2023, 06:55:31 pm ---
--- Quote from: iMo on March 27, 2023, 07:42:25 am ---17.3.23 - the first "metro-LAB measurement" Vref = 9.999.895Volt, powered off for 3 hours

--- End quote ---
with the same uncertainity as the other measurements?

--- End quote ---
After several measurements in two labs I will evaluate.. A long way to go..

magic:

--- Quote from: Noopy on March 21, 2023, 04:52:38 am ---I now assume in the ADR1001 it looks like this. The emitter is missing and the contact in the middle changed to a Anode Sense.
If you look closely and compare it with the ADR1000 structure you can see that there is a ring missing. That is the emitter area.



--- End quote ---
I'm now quite confident that this is correct indeed.

There are no meaningful connections to D1 anode-sense and Q2+Q3 base, only a reverse-biased PNP which activates under some abnormal conditions.
Q2+Q3 collector is loaded by R1 (the long resistor north-west of the reference cell) to REF6P6_S, as in usual ADR1000 applications.
There is no opamp; Q2+Q3 collector drives a sequence of two NPN inverting gain stages south of the reference cell, also resistively loaded.
The final gain stage drives a PNP emitter follower and then the NPN emitter followers at REF6P6_F output.
All other PNPs near the gain stages are reverse biased and irrelevant in normal operation.
The circuit immediately west of the reference cell looks like a bias generator.

Everything checks out. Q2+Q3 replaces the Q1 of ADR1000.

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