Electronics > Projects, Designs, and Technical Stuff

Uber low noise current source suggestions

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1audio:
Would this work?

Use a transformer with the primary designed to not saturate at 650 mA with a 10:1 or 100:1 (1000:1 may not have the bandwidth needed) turns ratio. Sense the DC current on the primary and use the secondary for sensing the current noise and feedback a correction for the current noise. Similar to this: http://www.wenzel.com/documents/finesse.html

You would also need to sense the temperature of the primary to correct for the change in DCR of the copper in the primary.

awallin:
here's some noise-analysis found by google: http://atomoptics-nas.uoregon.edu/odom_current/libbrecht-hall-noiseanalysis.pdf

it would be good if someone could make an effort and plot the different specs in the same figure!!?


* Steck's Libbrecht-Hall design simple opamp/MOSFET designs
* Sisyph link above http://www.sisyph.com/smc11-puy-mary-ultra-low-noise-current-source
* Erickson's Libbrecht-Hall design https://arxiv.org/abs/0805.0015
* the Vescent product https://www.vescent.com/products/electronics/d2-105-laser-controller/

grouchobyte:
Some good suggestions and ideas here. Thank you. I am now reviewing the prelim docs of the laser to try and understand the sensitivity to noise and the various mechanisms that need be  considered in the overall operational transfer function.

My original guesstimate was mostly theoretical based on some matlab sims, but I might need to get the noise initially as low as I can and then either ease up on the noise requirement or find find some way to mitigate any unwanted noise-induced behavior.

At this point I think I can get away with about 10nA p-p of noise in a 50khz BW and many of your suggestions are a step in that direction.

Again, thanks to all the regular folks, some of whom I easily recognize, like Marco,  Blueskull and David Hess, etc.

BTW: The Government of Canada thanks you for your help.  :)

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