In my project I am using a CO2 sensor that output voltage in range 30mV ~ 50mV. The signal will then be amplified and filtered and be sent to a microcontroller for ADC.
My tutor suggested that I should get rid of the baseline (30mV) and only amplify the difference (50mV - 30mV = 20mV). But I can't think of a way to remove the baseline with electronic circuit.
Can anyone give me a hint or a reference to read so I can achieve this?
If you always want to subtract the same value just use an op-amp and 4 resistors as a difference amplifier. If you want more precision you can buy difference amplifier chips with well matched resistors inside it already. An instrumentation amplifier could also be a good choice here because it will have high input impedance.
Put your sensor on the non-inverting side of the instrumentation amplifier. Attach a 30mV reference to the inverting input of the instrumentation amplifier.
You will probably have to construct the 30mV reference from a 1.25V reference and a voltage divider. If you need to make the 30mV offset adjustable then use a potentiometer instead of a fixed divider.
