| 摘要 |
<P>PROBLEM TO BE SOLVED: To enhance a Q value and to allow a surface acoustic wave resonator to be reduced in size. <P>SOLUTION: In a surface acoustic wave resonator in which an IDT having electrode fingers exciting surface acoustic waves is provided on a crystal substrate, the IDT comprises: a first region disposed at a central portion; and a second region and a third region disposed at both sides of the first region. In the first region, a frequency is constant. The second region and the third region include portions where frequencies are sequentially decreased as the electrode fingers of the second and third regions get close to end portions of the IDT. Where the frequency in the first region is defined as Fa, a frequency at an end portion in the second region is defined as Fb<SB POS="POST">M</SB>and a frequency at an end portion in the third region is defined as Fc<SB POS="POST">N</SB>, Fa, Fb<SB POS="POST">M</SB>and Fc<SB POS="POST">N</SB>satisfy expressions of: 0.9815<Fb<SB POS="POST">M</SB>/Fa<0.9953; and 0.9815<Fc<SB POS="POST">N</SB>/Fa<0.9953. <P>COPYRIGHT: (C)2013,JPO&INPIT |
