PURPOSE: To control the frequency accurately by adhering another piezoelectric element to a surface acoustic wave element such as a resonator with a reflector or a surface acoustic wave filter and working the surface acoustic wave element by varying an applied voltage to the piezoelectric element.
CONSTITUTION: A piezoelectric element 20 is adhered to the entire back surface of a surface acoustic wave element 10 so that its lengthwise direction is mad coincident with a propagation direction of a surface acoustic wave of the element 10. A back surface of the element 10 is adhered to a ground side electrode of the element 20 by an adhesive on a piezoelectric ceramic substrate subject to polarization processing made of a zircon titanate group. While no voltage is applied to the element 20, a signal whose frequency is 85-86MHz is applied from an analyzer 32 to interdigital electrodes 11, 12 as sweeping the signal and a resonance frequency of nearly 85.51MHz is obtained. Moreover, an increased voltage of 50V is applied to the element 20 and a resonance frequency of nearly 85.50MHz is obtained and an increased voltage of 100V is applied to the element 20 and a resonance frequency of nearly 85.495MHz is obtained. The resonance frequency is decreased almost linearly as the applied voltage to the element 20 is increased.
HIKITA KAZUYASU
SUETSUGU TAKUZO
IIZUKA HIROYUKI
NAKAMURA KENZO
