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How to sense mV range signal with ADC with Vref+=3.3V?

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mav1234

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The analog output of a sensor that I want to digitize is in the 0-150mV range. The lowest Vref to the ADC of my Microcontroller I can supply is 3.3V.

Looking for some circuit recommendations to amplify the 0-150mV signal to get it to 0-3.3V range to utilize the full accuracy of the ADC.

Any recommendations / ideas?
 

If your ADC was 10 bit resolution then u can sense a change of 3.3/(2^10) \[\approx\] 3.2 mv so u can represent your signal in 150/3.2 \[\approx\] 47 steps, u can use ADC directly if this step is fine by you, or u can amplify the signal to span the full possible 1024 steps, u can do this by a simple amplifier circuit using op-amps, the one i prefer is the non-inverting op-amp, It uses two resistors and an op-amp.

gain = 1+(R2/R1)

**broken link removed**

you will need to amplify the input by 1024/47 = 22 times

So just pick your resistor values.

Use an op-amp that works on 0-5v rails, i prefer the LM358.
 

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