I have a sensor which is connected to +12V and it shows some small variations at the output.
I have an opamp which I have configured in AC input, inverting amplifier. therefore I should supply it with the load voltage and then find the best value for + rail (by default the half of the VCC which is 6), something like the figure below, but the opamp maximum supply is 3.3V. I am bounded to use this opamp and I can not change the sensor voltage.
Need some kind of voltage regulator for the 3.3V OP. If the load impedance isn't low, a zener diode circuit might be sufficient. Or use a 12V capable OP.