Temperature dependence of the quality factor in LC-type passive wireless temperature sensors

In this paper, a LC tank circuit has been designed, fabricated and tested, to study the temperature dependence of the quality factor in the LC-type passive wireless temperature sensors. The performance of the wireless signal transmission is studied by a group of inductances and by studying the impedance characterization of the LC tank. A theoretical model of temperature dependence of quality factor is established, and is found to be in good agreement with the experiment results. The quality factor Q as a function of temperature, expressed in Q-factor shift per temperature difference, is 0.0246/ °C, which compares well to the theoretically determined slope of 0.0275/ C. Up to 2.5% change in quality factor per C change of temperature is demonstrated. Both the resonance frequency and the quality factor Q of the LC sensor are strongly dependent on temperature.