The temperature-compensated film bulk acoustic resonator (FBAR) device
comprises an FBAR stack. The FBAR stack comprises an FBAR and a
temperature-compensating element. The FBAR is characterized by a resonant
frequency having a temperature coefficient, and comprises opposed planar
electrodes and a piezoelectric element between the electrodes. The
piezoelectric element has a temperature coefficient on which the
temperature coefficient of the resonant frequency depends at least in
part. The temperature-compensating element has a temperature coefficient
opposite in sign to the temperature coefficient of the piezoelectric
element.