(Solved): 7.31 SAW resonator temperature sensor. The SAW resonator can be used to sense any quantity that wi ...

7.31 SAW resonator temperature sensor. The SAW resonator can be used to sense any quantity that will affect its resonant frequency, including tem- perature. The sound velocity of quartz is 5,900 m/s at 20 °C. The speed of sound is temperature dependent and increases by 0.32 mm/s/°C, and the coefficient of thermal expansion is 0.557 µm/m/°C. (a) Sketch a compensated sensor that will measure temperature but not be affected by other quantities such as ambient pressure. Can this be done in practice? (b) Calculate the sensitivity to temperature for a SAW sensor operating at 400 MHz. Comment on the practicality of this sensor.