Best out-of-the-box 10V reference?

[Andreas]

Hello,

for measuring 1/f (0.1 .. 10 Hz) noise on references you will need typically a bandwidth limited low noise amplifier with 10000 fold amplification.
(3uVpp give 30 mV on your scope).

I have bought 2 VRE3050AS from DigiKey in 2011. (So short after Thaler was bought by APEX).

One of the main issues that I had was the high noise (3 uVpp typical in data sheet) and 9uVpp in average on measurements.
(Screen shot with 2uV/Div + 1s/Div)

with best regards

Andreas

[Insatman]

Hello,

for measuring 1/f (0.1 .. 10 Hz) noise on references you will need typically a bandwidth limited low noise amplifier with 10000 fold amplification.
(3uVpp give 30 mV on your scope).

I have bought 2 VRE3050AS from DigiKey in 2011. (So short after Thaler was bought by APEX).

One of the main issues that I had was the high noise (3 uVpp typical in data sheet) and 9uVpp in average on measurements.
(Screen shot with 2uV/Div + 1s/Div)

with best regards

Andreas

Andreas,   Any chance you could share the circuit for that 10,000x Amplifier?   I would like to build one.

[cellularmitosis]

@Instaman, there are some good designs in this thread: https://www.eevblog.com/forum/metrology/diy-low-frenquency-noise-meter/

If you are going to DIY, you need an input capacitor with very low leakage.  pmcouto found some rubycons which will work well: https://www.eevblog.com/forum/metrology/diy-low-frenquency-noise-meter/msg1214172/#msg1214172

You can also purchase an LNA from user Pipelie on this forum, if he still has some in stock.

[Andreas]

Andreas,   Any chance you could share the circuit for that 10,000x Amplifier?   I would like to build one.

already did this in one of the LNA threads:
e.g. starting from here
https://www.eevblog.com/forum/metrology/diy-low-frenquency-noise-meter/msg1148974/#msg1148974
https://www.eevblog.com/forum/projects/low-frequency-very-low-level-dc-biased-noise-measurements/msg658078/#msg658078
one user here (mimmus78 ?) has built a more professional PCB from the full cirquit diagram (PDF) than my hand etched single layer design.

with best regards

Andreas

[Insatman]

Andreas,   Any chance you could share the circuit for that 10,000x Amplifier?   I would like to build one.

already did this in one of the LNA threads:
e.g. starting from here
https://www.eevblog.com/forum/metrology/diy-low-frenquency-noise-meter/msg1148974/#msg1148974
https://www.eevblog.com/forum/projects/low-frequency-very-low-level-dc-biased-noise-measurements/msg658078/#msg658078
one user here (mimmus78 ?) has built a more professional PCB from the full cirquit diagram (PDF) than my hand etched single layer design.

with best regards

Andreas

I followed that thread and it contains several spice simulations and a few schematics,  but I never found the schematic or PDF of your amplifier.   I was also not able to find mimmus78.   Lots of discussion of building out of discrete components but the photo shows two LT op amps.   Am I right in that the 10K:1 gain is done in a single stage followed by a buffer amplifier?    I would have guessed multiple stages but I'm not an analog expert.   Any help would be appreciated.

Thanks....Insatman

[cellularmitosis]

It is attached as FILT1105w.pdf here: https://www.eevblog.com/forum/metrology/ultra-precision-reference-ltz1000/msg834013/#msg834013

Google translate actually does a pretty good job with mikrocontroller.net now!

https://www.mikrocontroller.net/topic/250656#2679335

https://www.mikrocontroller.net/topic/207061?goto=2060389#2060389

https://www.mikrocontroller.net/topic/207061?goto=2060260#2060260

[mimmus78]

Hello,

for measuring 1/f (0.1 .. 10 Hz) noise on references you will need typically a bandwidth limited low noise amplifier with 10000 fold amplification.
(3uVpp give 30 mV on your scope).

I have bought 2 VRE3050AS from DigiKey in 2011. (So short after Thaler was bought by APEX).

One of the main issues that I had was the high noise (3 uVpp typical in data sheet) and 9uVpp in average on measurements.
(Screen shot with 2uV/Div + 1s/Div)

with best regards

Andreas

Andreas,   Any chance you could share the circuit for that 10,000x Amplifier?   I would like to build one.

I have few more unpopulated PCB ... If you want one, just pm me.

Inviato dal mio ONEPLUS A5010 utilizzando Tapatalk

[3roomlab]

i had a little play time with the original spice model, and tried some numbers on it. it seems to work (the original file parameter TC = 20e-6)
but does anyone actually use it to determine compensation values?

but realistically speaking, if the VREF does have the TC on the edge of 20ppm/C, and the simulation seem to come up with a compensation for a certain range, would you still do it? (@ about 9th iteration, i found some values which give a "flat-ish" plateau even for a 20 ppm? how real can this be?  ) ** just to be sure, for the plot with the "flat", i added extra 2 points, the curve now appears to be a "S". a very interesting "compensation"