Electronics > Projects, Designs, and Technical Stuff
Current measurement from 0.1uA to 1A
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BrianHG:

--- Quote from: IanB on December 03, 2018, 09:46:41 pm ---
--- Quote from: BrianHG on December 03, 2018, 09:33:38 pm ---
--- Quote from: Gyro on December 03, 2018, 11:54:53 am ---
--- Quote from: IanB on December 03, 2018, 07:45:17 am ---... is a range of 107 orders of magnitude.

--- End quote ---

Thats a lot of orders of magnitude.  ;D

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Yes, that numbers of orders of magnitude actually exceeds the capability of all the matter in our solar system by a long shot, even going from a fentoamp through all the current produced if all our sun's energy output was turned into electrical current all at once.

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Damn, such literal minded people around here   ::)

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Come on, were having fun with a little at the 'expanse' of your little scale.
What you have actually really done is gone from the fento-amp to the same amount of current produced by around 1000 class 1-a supernovas all going off all simultaneously at once...  :scared:
coppercone2:
I think thermals will destroy your calculations. Find how many PPM sstability you need first and then look at how the resistor is going to react to cooling and heating to those ranges.
splin:
A few questions:
1) What is the maximum voltage drop you can tolerate at 1A?

2) Is .1uA the minimum resolution you need? If not what resolution do you need when measuring a .1uA current?

3) What accuracy do you hope to achieve on the 1A and .1uA ranges?

4) What bandwidth do you need? Are you measuring DC, steady AC or dynamic signals such as the current draw of a microcontroller system switching from full power to sleep mode? If the latter, how fast does it need to track the signal?
sandy.holmarc:

--- Quote from: splin on December 03, 2018, 10:53:34 pm ---A few questions:
1) What is the maximum voltage drop you can tolerate at 1A?

2) Is .1uA the minimum resolution you need? If not what resolution do you need when measuring a .1uA current?

3) What accuracy do you hope to achieve on the 1A and .1uA ranges?

4) What bandwidth do you need? Are you measuring DC, steady AC or dynamic signals such as the current draw of a microcontroller system switching from full power to sleep mode? If the latter, how fast does it need to track the signal?

--- End quote ---
Hi splin,
Thank you very much for the assistance.
1.  maximum voltage drop  at 1A is 1V(my application needs 1V to -1V voltage range)
2.  0.1uA  is the minimum range ,i need 10nA resolution if possible
3   I can tolerate up to 10nA error current
4   I am measuring a DC voltage ,output range of -1V to 1V.
any help would be greatly appreciated.


 
mvs:

--- Quote from: sandy.holmarc on December 04, 2018, 04:33:44 am ---1.  maximum voltage drop  at 1A is 1V(my application needs 1V to -1V voltage range)
2.  0.1uA  is the minimum range ,i need 10nA resolution if possible
3   I can tolerate up to 10nA error current
4   I am measuring a DC voltage ,output range of -1V to 1V.
--- End quote ---
It is getting better and better... 1 Ohm shunt, 10nV max error.
Best opamps available on the market have offset error of about 1-10µV. Thermoelectric effect may add also some µV to error.
You do not get away with single shunt, you need to switch ranges.
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