Comparative Study of Three SAW Configurations for Temperature Sensing

Abstract

This paper demonstrates three SAW configurations' electrical and mechanical behaviors: a one-port resonator, a two-port resonator, and a delay line that works as temperature sensors of around 440 MHz characteristic frequencies. We investigate the sensitivity of the sensors for temperatures up to 200 °C. A linear behavior of the frequency shift versus temperature is observed; the resulting sensitivity of the sensors is evaluated at 22.74 ppm/°C for the one-port resonator, 23.17 for the two-port resonator, and 3.83 ns/°C for the delay line structure. The electromechanical coupling coefficient (k2) is 0.492 % for the delay line, 0.489 % for the one-port resonator, and 0.55% for the two-port resonator. The quality factor QFactor calculated from Y11 electrical input admittance is 2858 for the one-port resonator, 2977 for the delay line, and 2903 for the two-port resonator. The optimized piezoelectric layer thickness value, for the one port resonator, is hAlN=1.5µm.