Thanks guys for the technical advices.

The 2.5V reference comes from National Semiconductor's LM385-2.5. My input signal is from National's LM50 - a centrigrade temperature sensor that gives me 100mV to 1.75V for a -40C to +125C temperature range (10mV/C). The design only calls for -30C to 60C or 200mV to 1.1V in this case. The 10-bit ADC is inside Infineon C515C micro and is set to read a range between 0 - 5V based upon the existing circuit.

I am using LM324 for the design. The initial calculation puts me on a 92mV reference. I was wondering if the noise might throw this reference out of the window if I use a simple voltage divider. So far the SPICE simulation has given me the expected result. I'll build the real circuit and see how it goes.

Thanks again!