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I have a sensor that produces an analog voltage on output that can vary between 1,2 V and 1,4 V. As soon as my A/D converter on my Arduino would be not so effective with only 0,2V of variations, I would like to expand this range.

If I'm not wrong, there should be a way to subtract 1,2 V from my analog signal, so I will have a range between 0 and 0,2 V and amplify the signal, let's say, 10 times so, the new range will be 0 - 2 V, way better for reading from a microcontroller.

Now, I don't know what's the name of this type of circuit and, most import, how much they consume because my system is a very low powered circuit (400mA).

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    \$\begingroup\$ Op-Amp adder, Op-Amp amplifier. \$\endgroup\$ – Janka Sep 4 '19 at 12:49
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    \$\begingroup\$ 1) if you use the Arduino's ADC with a 1.5 V reference voltage you get LSB steps of ~1.5 mA, that still gives 133 steps. That may not sound like much but if the sensor has a noise level of for example 3 mV then it it enough. 2) If you don't need fast measurements you can do multiple measurements and then use the average value, that will act like the ADC has more bits. 3) My point: you assume that you need to shift and amplify the voltage but you show no proof that it is actually needed 4) 400 mA isn't really low power. \$\endgroup\$ – Bimpelrekkie Sep 4 '19 at 12:53
  • \$\begingroup\$ Considering I have an IR emitter, 6 gas sensors, a humidity sensor, an ozone sensor, and a temperature sensor, everything with its control circuit and that the uC must read all the sensor and send data via wireless I think it's pretty low power... AnywayI didn't know about the Arduino's ADC Ref. going to check \$\endgroup\$ – NicoCaldo Sep 4 '19 at 12:56
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I recommend reading TI AN-31 appnote. You are probably looking for one of these enter image description here

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