| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a piezoelectric filter wherein productivity is high, electrical characteristic is superior and filter characteristic to temperature change is stable, and to provide a communication apparatus and a method for manufacturing the piezoelectric filter. <P>SOLUTION: A piezoelectric resonator part is constituted of an SiO<SB>2</SB>thin film 2 on a substrate surface, a piezoelectric thin film 3, a lower electrode 4 and an upper electrode 5. From among a plurality of the piezoelectric resonator parts, the lower electrodes 4 in the piezoelectric resonator parts, where a resonance frequency is set to be comparatively low are made thick, as compared with the lower electrodes in the other piezoelectric resonator parts. For example, the piezoelectric resonators of low resonance frequency are made parallel resonators, and the piezoelectric resonators of high resonance frequency are made series resonators, thereby constituting a ladder-type filter. <P>COPYRIGHT: (C)2003,JPO |
