Measuring microAmps

Discussion in 'General Electronics Chat' started by gregj64, Mar 14, 2012.

  1. gregj64

    Thread Starter New Member

    Mar 14, 2012
    3
    0
    Hi all,

    I'm looking to develop/source a datalogger that can measure in the single microamp range. It would be an inline current probe that would sit between an energy harvesting source and a battery and could detect with an accuracy of +/-100nA if at all possible!

    Perhaps I'm looking for 2 things:
    - The data logger would be relatively straight forward.
    - The current sensor is where I'm running into difficulty, if there was an IC part someone had come across or an amplifier circuit with reasonably low levels of noise that someone could recommend.

    What I would like is something I can leave to make automated sensor readings over time at set intervals. I'd prefer not to have to go down the labview Keithley metering route for cost reasons!

    Any advice would be appreciated,
    Greg.
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    What are your minimum and maximum current readings?
    What is the voltage at the hot side?
     
  3. gregj64

    Thread Starter New Member

    Mar 14, 2012
    3
    0
    The voltage on the Energy harvester side will vary from 0.5 to 3.3. Id be happy with just a 3.3V system however!

    The minimum and max current readings would be 1µA to 100mA ideally.
    The max range could be dialled down to 10mA if it made the resolution more achievable.

    Thanks for the reply!
     
  4. MrChips

    Moderator

    Oct 2, 2009
    12,449
    3,363
    So you are looking at a dynamic range from 100nA to 100mA, 1:1000000.
    You will need a 20-bit ADC.

    There are 24-bit delta-sigma ADC which would provide 20 NOEB.
     
  5. gotumal

    Active Member

    Mar 24, 2008
    99
    0
    This seems have a huge dynamic range. Instead of using higher resolution ADC, you could probably use gain controlled amplifier with some 12 bit resolution ADC. What is the sampling rate you are looking for?
     
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