Current-feedback linearization technique for RTDs

A very simple yet accurate linearization technique for RTDs is described. Correction of the intrinsic parabolic curvature of this type of temperature transducer is performed by changing the amplitude of the excitation current as the temperature varies. Instead of keeping the excitation current constant, independent of the sensor temperature, as usual, a feedback component is added in order to establish an excitation current that is linearly related to the sensor temperature. Measurements of a miniature in-head transmitter, which incorporates the technique, have shown that an accuracy of 0.1% can be easily achieved in production. The simplicity and efficiency of the technique make it suitable for low-cost implementations.