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US 2012/0068790 A1Published application
Elastic wave device
AssigneeNihon Dempa Kogyo Co., Ltd.
InventorSusumu Yoshimoto
Life of this patent
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Abstract
There is provided an elastic wave device that is capable of suppressing deterioration in flatness of a frequency characteristic in a pass frequency band yet has excellent ESD resistance. At positions apart from a crossing area of electrode fingers 12, 12 toward a bulbar 11, first float dummy electrodes 16, 16 and a second float dummy electrode 18 are provided between adjacent IDT electrodes 1, 1 and between the IDT electrode 1 and a grating reflector 2 which are adjacent to each other. These float dummy electrodes 16, 18 are in a state of electrically floating from other regions, and these float dummy electrodes 16, 18 are formed so as to correspond to an arrangement pattern of the electrode fingers 12 in the IDT electrode 1.
Claims11
An elastic wave device comprising:
- a plurality of IDT electrodes arranged apart from each other along a propagation direction of an elastic wave;
- and grating reflectors sandwiching the plural IDT electrodes from both sides in terms of the propagation direction of the elastic wave, the IDT electrodes and the grating reflectors being formed on a common piezoelectric substrate,
- wherein the plural IDT electrodes each comprise:
- a pair of busbars connected to one and the other of a signal port and a ground port respectively;
- and electrode fingers extending in a comb shape from each of the busbars toward the opposite busbar, and an arrangement pattern of the electrode fingers in each of the IDT electrodes and a separation size between the adjacent IDT electrodes are set in order for an arrangement pattern of the electrode fingers in the IDT electrodes to be continuously formed along the propagation direction of the elastic wave,
- wherein the grating reflectors each comprise:
- a plurality of grating electrode fingers extending along a length direction of the electrode fingers and disposed apart from each other in the propagation direction of the elastic wave;
- and grating busbars connecting one-side tips and the other-side tips of the grating electrode fingers respectively, and an arrangement of the grating electrode fingers and a separation size of each of the grating reflectors from the adjacent IDT electrode correspond to the arrangement pattern,
- wherein, assuming that in one IDT electrode out of the two adjacent IDT electrodes, the electrode finger adjacent to the other IDT electrode is called a first end electrode finger, an end portion closer to the other IDT electrode in the busbar opposite the busbar connected to the first end electrode finger, out of the pair of the busbars of the one IDT electrode, is apart from an extension area of a tip of the first end electrode finger toward the one IDT electrode side,
- wherein a first float dummy electrode extending in a direction perpendicular to the propagation direction of the elastic wave is formed in the extension area to prevent an electrostatic discharge damage between regions different in potential between the one IDT electrode and the other IDT electrode, and
- wherein a width size of the first float dummy electrode and separation sizes of the first float dummy electrode from the IDT electrodes on both sides of the first float dummy electrode correspond to the arrangement pattern, and the first float dummy electrode is in a state of electrically floating from the plural IDT electrodes, the signal port, the ground port, and the grating reflectors.
8 more elements
An elastic wave device comprising:
- an IDT electrode formed on a piezoelectric substrate and including:
- a pair of busbars each connected to a signal port or a ground port;
- and electrode fingers extending in a comb shape from each of the busbars toward the opposite busbar;
- and
- a grating reflector formed on the piezoelectric substrate to be apart from the IDT electrode in a propagation direction of an elastic wave, and including:
- a plurality of grating electrode fingers extending along a length direction of the electrode fingers and disposed apart from each other in the propagation direction of the elastic wave;
- and grating busbars connecting one-side tips and the other-side tips of the grating electrode fingers,
- wherein, in the IDT electrode and the grating reflector, an arrangement pattern of the electrode fingers, an arrangement pattern of the grating electrode fingers, and a separation size between the IDT electrode and the grating reflector are set in order for an arrangement pattern of the electrode fingers in the IDT electrode to be continuously formed along the propagation direction of the elastic wave,
- wherein, assuming that the electrode finger adjacent to the grating reflector is called a second end electrode finger, an end portion closer to the grating reflector in the busbar opposite the busbar connected to the second end electrode finger, out of the pair of busbars of the IDT electrode, is apart from an extension area of the second end electrode finger toward the IDT electrode,
- wherein a second float dummy electrode extending in a direction perpendicular to the propagation direction of the elastic wave is formed in the extension area to prevent an electrostatic discharge damage between the grating reflector and the IDT electrode, and
- wherein a width size of the second float dummy electrode and separation sizes of the second float dummy electrode from the IDT electrode and from the grating reflector correspond to the arrangement pattern, and the second float dummy electrode is in a state of electrically floating from the IDT electrode, the signal port, the ground port, and the grating reflector.
8 more elements
An elastic wave device comprising:
- an IDT electrode formed on a piezoelectric substrate and including:
- a pair of busbars each connected to a signal port or a ground port;
- and electrode fingers extending in a comb shape from each of the busbars toward the opposite busbar;
- and
- a grating reflector formed on the piezoelectric substrate to be apart from the IDT electrode in a propagation direction of an elastic wave, and including:
- a plurality of grating electrode fingers extending along a length direction of the electrode fingers and disposed apart from each other in the propagation direction of the elastic wave;
- and grating busbars connecting one-side tips and the other-side tips of at least the grating electrode finger located second from an IDT electrode-side end up to the grating electrode finger at an end portion opposite the IDT electrode,
- wherein, in the IDT electrode and the grating reflector, an arrangement pattern of the electrode fingers, an arrangement pattern of the grating electrode fingers, and a separation size between the IDT electrode and the grating reflector are set in order for an arrangement pattern of the electrode fingers in the IDT electrode to be continuously formed along the propagation direction of the elastic wave, and
- wherein the grating electrode finger disposed apart from the grating busbar is in a state of electrically floating from the IDT electrode, the signal port, the ground port, and other regions of the grating reflector.
6 more elements
Dependencies are inferred from the claim text.