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I made a DC measurement board based on ADC and ARM. Now I want to add 'self-calibration in filed' function to it. I think I need a voltage reference and a voltage divider. And I don't want to calibrate my calibrator. I just need the voltage output error from the setting value (calculated from reference voltage and divide ratio) don't exceed 0.1% (because the voltage reference I used only has a initial accuracy 0.05%, so I don't expect the whole system can achieve the same accuracy with it). Now I have two ideas:

  1. Use a resistor voltage divider network. If can't buy one, I need make it myself, using 0.1% metal film resistors. And I may need an analogue switch such as ADG seris, and precision OPs, etc.
  2. Use a MDAC. The DAC may expensive, but it may need less parts than the method 1.

Any suggesions? Which one is better?

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Your voltage divider idea only works if you have a voltage source of the requisite accuracy to be the power source for the divider. 0.1% resistors in a divider circuit do not magically make an accurate voltage if the supply to the divider has lots of noise and/or ripple on it or the absolute voltage level is not known to the desired accuracy level.

Instead you should consider the use of an accurate shunt voltage reference. You can get these as accurate as you wish to pay for. They act as an almost perfect zener diode.

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  • \$\begingroup\$ Why a shunt voltage reference? May I use a series voltage reference? I only need a voltage maximum 2V, so I choosing ADI's ADR42x series. \$\endgroup\$
    – diverger
    Jun 15 '16 at 6:05
  • \$\begingroup\$ Parts like the ADR42x will also work. Shunt references may be more common is all. \$\endgroup\$ Jun 15 '16 at 6:54

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