Temperature Sensing by Using Film Bulk Acoustic Resonator at 2.4 GHz Band

Abstract

A four-layered film bulk acoustic resonator (FBAR) with an Al/AlN/SiN/Au composite structure was fabricated The FBAR is composed of a surface micromachined cantilever whose copper scarification layer is released by wet etching. A temperature coefficient (TC) of resonant frequency of -34 5 ppm/degrees C in the temperature range from 10 to 80 degrees C at 2 4 GHz is obtained. Using this resonator, an oscillator for temperature sensing was constructed, in which temperature can be detected easily by measuring the shift in oscillation frequency The TC of the oscillator is almost the same as that of the resonator. (C) 2009 The Japan Society of Applied Physics