I am trying to design an interface for a PT100 temperature sensor (2-wire variant) with an output range of 0-1V. I currently have the sensor driven by a 1mA constant current source and a 100Ω resistor driven by an identical current source as a reference. These two signals are then connected to a 2 op amp differential amplifier constructed of one AD822 IC. In Proteous this circuit works fine but when it is constructed the op amps never fully go to ground, they sit at about 0.08V which corresponds to around 8degC, not great.
Now one solution I could think of would be to generate a negative supply of the op-amp so the voltage could swing around 0V but and negative supply generator would have to be cheap and relatively small.
I really am starting to chase my tail on this one. If anyone has any suggestions I would be very grateful.
Thanks,
Now one solution I could think of would be to generate a negative supply of the op-amp so the voltage could swing around 0V but and negative supply generator would have to be cheap and relatively small.
I really am starting to chase my tail on this one. If anyone has any suggestions I would be very grateful.
Thanks,