Surface acoustic wave resonator, its manufacturing method, and radio circuit
AssigneeThe Japan Steel Works, Ltd.
InventorsKazuhito KISHIDA, Shoji KAKIO, Kengo OGAWA, Hiroaki YOKOTA
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Abstract
In a surface acoustic wave resonator according to an embodiment, a quartz-crystal substrate includes an AT-cut 0° X-propagation first quartz-crystal substrate and a Z-cut second quartz-crystal substrate bonded over the first quartz-crystal substrate. A propagation direction of a surface acoustic wave in the second quartz-crystal substrate is inclined from an X-axis of a crystal by 27 to 33°, 87 to 93°, or 147 to 153°, and a thickness of the second quartz-crystal substrate is 0.2 to 1.0 times a wavelength of the surface acoustic wave.
Claims13
A surface acoustic wave resonator comprising
- a quartz-crystal substrate;
- and
- an IDT (Interdigital Transducer) electrode formed over the quartz-crystal substrate, wherein
- the quartz-crystal substrate comprises:
- an AT-cut 0° X-propagation first quartz-crystal substrate;
- and
- a Z-cut second quartz-crystal substrate bonded over the first quartz-crystal substrate,
- a propagation direction of a surface acoustic wave in the second quartz-crystal substrate is inclined from an X-axis of a crystal by 27 to 33°, 87 to 93°, or 147 to 153°, and
- a thickness of the second quartz-crystal substrate is 0.2 to 1.0 times a wavelength of the surface acoustic wave.
A method for manufacturing a surface acoustic wave resonator, comprising the steps of:
- (a) bonding a Z-cut second quartz-crystal substrate over an AT-cut 0° X-propagation first quartz-crystal substrate;
- and
- (b) forming an IDT (Interdigital Transducer) electrode over the second quartz-crystal substrate, wherein
- a propagation direction of a surface acoustic wave in the second quartz-crystal substrate is inclined from an X-axis of a crystal by 27 to 33°, 87 to 93°, or 147 to 153°, and
- a thickness of the second quartz-crystal substrate is 0.2 to 1.0 times a wavelength of the surface acoustic wave.
A radio circuit comprising:
- a first amplifier configured to amplify a reception radio-frequency signal wirelessly received by an antenna;
- a second amplifier configured to amplify a transmission radio-frequency signal to be wirelessly transmitted from the antenna;
- a reception radio-frequency filter through which the reception radio-frequency signal amplified by the first amplifier passes;
- and
- a transmission radio-frequency filter through which the transmission radio-frequency signal to be input to the second amplifier passes, wherein
- at least one of the reception radio-frequency filter and the transmission radio-frequency filter includes a surface acoustic wave resonator,
- the surface acoustic wave resonator comprises:
- a quartz-crystal substrate;
- and
- an IDT (Interdigital Transducer) electrode formed over the quartz-crystal substrate,
- the quartz-crystal substrate comprises:
- an AT-cut 0° X-propagation first quartz-crystal substrate;
- and
- a Z-cut second quartz-crystal substrate bonded over the first quartz-crystal substrate,
- a propagation direction of a surface acoustic wave in the second quartz-crystal substrate is inclined from an X-axis of a crystal by 27 to 33°, 87 to 93°, or 147 to 153°, and
- a thickness of the second quartz-crystal substrate is 0.2 to 1.0 times a wavelength of the surface acoustic wave.
Dependencies are inferred from the claim text.