I used a precision thermistor, a precision resistor and (as I recall) a 20 bit delta sigma ADC in this thermometer: http://www.gla-ag.com/ . Since the supply to the top of the resistor was also the ADC reference, a precision reference was not required. Linearization is done with a table and linear interpolation. Harold --=20 FCC Rules Updated Daily at http://www.hallikainen.com - Advertising opportunities available! Not sent from an iPhone. --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .