Compact and accurate digital thermometer based on Anderson's loop and Pt-100 sensor

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.