A simple and practical digital thermometer with an accuracy better than 0.1
degreesC over a near-room-temperature (from - 10 degreesC to 50 degreesC)
measurement range has been developed. The instrument is compact and battery
operated and provides for both digital and analog outputs. A four-lead pla
tinum thermal sensor, driven by a constant current loop, allows fur accurat
e temperature readings with high immunity to the contact resistances and to
their variations. A low-noise electronics allows for temperature measureme
nts with a 1 mK resolution. By experimentally characterizing the non-linear
ity of the adopted Pt-100 sensor, a suitable readout correction table has b
een calculated in order to compensate for the sensor non-linear behavior. T
his compensating procedure allows for a wider (from - 50 degreesC to + 200
degreesC) and higher accuracy (similar to 0.05 degreesC) measurement range.
The ultimate accuracy was essentially limited by the accuracy of the tempe
rature standard used for calibration. (C) 2001 Published by Elsevier Scienc
e Ltd.