TEMPERATURE EFFECT COMPENSATION IN AVIATION PIEZORESISTIVE PRESSURE SENSORS

Abstract

Currently, piezoresistive pressure sensors (PDS) find expanded applications in various microelectronic devices used in aviation technology. The behavior of the electrical signal of such PDS mainly depends on the ambient temperature. It is known that the temperature drift of the PDS output signal is influenced by various factors: the temperature effect, the dependence of the resistance of the sensitive element on the concentration of impurities, the dependence of the Young's modulus of the sensor membrane and substrate materials on temperature, etc. It was found that the previously developed analytical calibration model of the sensor output signal, which takes into account the models describing individual temperature effects, does not allow the pressure to be measured with the required accuracy in the temperature range characteristic of aviation equipment from –60 C to 140 C. Therefore, conventional polynomial mathematical models are used to describe the dependence of the PDS output signal on the measured pressure and temperature. The work uses a traditional approach, when the dependence of the output voltage on pressure is represented using a polynomial of relatively low order, and the dependences of the coefficients of this polynomial on temperature are also specified by the corresponding polynomials. Unfortunately, the temperature dependences of the coefficients are adequately described only by high-order polynomials (at least 7), which complicates the model identification procedure and leads to computation errors. Therefore, the authors proposed to look for the dependence of the coefficients on temperature in the form of cubic splines. The paper describes in detail the identification technique of the polynomial model under consideration and obtains expressions for correcting the PDS readings when measuring pressure in wide temperature ranges. In order to experimentally confirm the efficiency of the proposed method, an intelligent industrial automated system for the calibration of traffic rules, described in the work, was used. It is shown how it can be used to take experimental data to calibrate the sensor readings over a wide temperature range, and the procedure for identifying the mathematical model of the pressure sensor required to minimize the cost of its certification is described. The results of experimental studies of specific pressure sensors used in aviation technology are presented.