Surface acoustic wave filter configured to suppress spurious components caused by transverse mode

A surface acoustic wave filter configured to suppress spurious components caused by a transverse mode, the surface acoustic wave filter comprising:

• a substrate on which a support substrate, an energy confinement layer, and a piezoelectric layer are sequentially stacked;
• a first bus bar and a second bus bar each extending on the substrate in a first direction and spaced apart from each other in a second direction perpendicular to the first direction;
• a plurality of first interdigital transducer (IDT) electrodes and a plurality of second IDT electrodes alternately disposed to extend from the first and second bus bars in the second direction and spaced apart from each other in the first direction;
• a second dummy electrode extending from the second bus bar to face an end portion of each of the plurality of first IDT electrodes extending from the first bus bar;
• and
• a first dummy electrode extending from the first bus bar to face an end portion of each of the plurality of second IDT electrodes extending from the second bus bar,
• wherein spurious components are suppressed in a band of frequencies higher than an anti-resonance frequency;
• and
• wherein a width of each dummy electrode is between 55% and 70% of a width of a center portion (C1) of each IDT electrode, configured to simultaneously suppress the spurious components within both:
• a first frequency band between a resonance frequency and an anti-resonance frequency (Fr<f<Fa), and
• a second frequency band higher than the anti-resonance frequency (Fa<f).

A surface acoustic wave filter configured to suppress spurious components caused by a transverse mode, the surface acoustic wave filter comprising:

• a substrate on which a support substrate, an energy confinement layer, and a piezoelectric layer are sequentially stacked;
• a first bus bar and a second bus bar each extending on the substrate in a first direction and spaced apart from each other in a second direction perpendicular to the first direction;
• a plurality of first interdigital transducer (IDT) electrodes and a plurality of second IDT electrodes alternately disposed to extend from the first and second bus bars in the second direction and spaced apart from each other in the first direction;
• a second dummy electrode extending from the second bus bar to face an end portion of each of the plurality of first IDT electrodes extending from the first bus bar;
• and
• a first dummy electrode extending from the first bus bar to face an end portion of each of the plurality of second IDT electrodes extending from the second bus bar,
• wherein spurious components are suppressed in a band of frequencies higher than a resonance frequency;
• and
• wherein a width of each dummy electrode is between 55% and 70% of a width of a center portion (C1) of each IDT electrode, configured to simultaneously suppress the spurious components within both:
• a first frequency band between a resonance frequency and an anti-resonance frequency (Fr<f<Fa), and
• a second frequency band higher than the anti-resonance frequency (Fa<f).