I'm using a zener-diode temperature sensor, LM335, from sparkfun. It drops 10mV per degree K, so at 298K it drops 2.98V.
The trouble is when I read it with the Arduino analog pins, 1 notch on the ADC is nearly 1/2 degree C. For example, at room temperature I get 614 from analogRead() which my code spits out as 25.00C, but if it goes to 615, I get 25.49C. I'm usually only interested in temperatures from 0C to 100C at the very most, so this is a waste of my ADC's resolution.
I want to make a circuit so I can scale the output of the temperature sensor from 0 to 5V for any arbitrary temperature interval I'm interested in. I designed an op-amp circuit to do this, but I want to make sure it's valid before I build it.
I'm not sure about the feedback resistor...sometimes op-amp circuits use a simple inline feedback resistor like in my diagram, and sometimes they seem to require a voltage divider to ground, and I don't understand why. Also, I'm not sure if I can swing the output from 0 to 5V while operating the op-amp on 5v. Finally, what op-amp should I use?