Elastic wave resonators and filters

An elastic wave filter comprising:

• a piezoelectric substrate;
• and
• a plurality elastic wave resonators disposed on a surface of the piezoelectric substrate, each elastic wave resonator including a pair of comb-shaped electrodes having first and second overlapping regions in which electrode fingers of the comb-shaped electrodes interdigitate, the second overlapping region being provided on both outside edges of the first overlapping region in an overlapping width direction, an overlapping width of the first overlapping region being greater than an overlapping width of the second overlapping region, an electrode finger pitch in the second overlapping region being greater than an electrode finger pitch in the first overlapping region, and the pair of comb-shaped electrodes being configured to excite a first elastic wave in the first overlapping region and to excite a second elastic wave in the second overlapping region, a frequency of the first elastic wave being higher than a frequency of the second elastic wave.

An elastic wave resonator comprising:

• a piezoelectric substrate;
• and
• a pair of comb-shaped electrodes provided on a surface of the piezoelectric substrate, the pair of comb-shaped electrodes including first and second overlapping regions in which electrode fingers of the comb-shaped electrodes interdigitate, the second overlapping region being provided on both outside edges of the first overlapping region in an overlapping width direction, an overlapping width of the first overlapping region being greater than an overlapping width of the second overlapping region, the pair of comb-shaped electrodes being configured to excite a first elastic wave in the first overlapping region and to excite a second elastic wave in the second overlapping region, a frequency of the first elastic wave being higher than a frequency of the second elastic wave, the first overlapping region including a first number of electrode fingers, and the second overlapping region including a second number of electrode fingers fewer than the first number of electrode fingers, and the second overlapping region including a first phase region and a second phase region, a phase of the second elastic wave generated by the electrode fingers in the first phase region being different from a phase of the second elastic wave generated by the electrode fingers in the second phase region.