Efficient Electronic Digitizer for Linearizing Remotely Located Thermistors

This letter introduces an efficient linearizing digital interface designed for remote thermistors. The proposed approach utilizes an enhanced relaxation-oscillator topology to render a direct-digital output that is directly proportional to the sensed temperature. Furthermore, the system compensates for cable resistance and maintains constant-current excitation for the sensor. The digitizer design is both simple and innovative, avoiding the need for matched references and minimizing the impact of various circuit nonidealities. The working principle of the interfacing system is established in this letter, followed by simulation studies. A thorough hardware evaluation of the developed digitizer reveals promising results, including low nonlinearity (0.41%), a high signal-to-noise ratio (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$&gt;$</tex-math></inline-formula>67 dB), and a measurement span of 120 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula>C, all while remaining unaffected by cable resistance. This system is well-suited for aerospace applications and other scenarios, requiring accurate thermistor-based temperature measurements.