Filter device, multiplexer, radio frequency front-end circuit, and communication device
AssigneeMurata Manufacturing Co., Ltd.
InventorKoji Nosaka
Life of this patent
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Abstract
A filter device includes a first input/output terminal and a second input/output terminal, as well as a series-arm circuit disposed on a path that connects the first input/output terminal and the second input/output terminal, and a parallel-arm circuit connected to a node on the path and a ground. At least one of the series-arm circuit or the parallel-arm circuit includes a resonance circuit, and the resonance circuit includes a first acoustic wave resonator, and a first capacitor connected in parallel to the first acoustic wave resonator, and having a greater electrostatic capacitance per unit area than that for the first acoustic wave resonator.
Claims19
A filter device that includes a first input/output terminal and a second input/output terminal, the filter device comprising:
- a series-arm circuit disposed on a path that connects the first input/output terminal and the second input/output terminal;
- and
- a parallel-arm circuit connected to a node on the path and a ground,
- wherein at least one of the series-arm circuit or the parallel-arm circuit includes a resonance circuit, and
- the resonance circuit includes:
- a first acoustic wave resonator;
- and
- a first capacitor connected in parallel to the first acoustic wave resonator, and having a greater electrostatic capacitance per unit area than that for the first acoustic wave resonator, wherein the first acoustic wave resonator is a surface acoustic wave resonator that includes:
- a piezoelectric substrate;
- and
- an interdigital transducer (IDT) electrode that is formed on the piezoelectric substrate and includes electrode fingers,
- the first capacitor includes a comb-shaped capacitor that is formed on the piezoelectric substrate and includes electrode fingers, and
- a gap between adjacent electrode fingers out of the electrode fingers included in the comb-shaped capacitor is narrower than a gap between adjacent electrode fingers out of the electrode fingers included in the IDT electrode.
A filter device that includes a first input/output terminal and a second input/output terminal, the filter device comprising:
- a series-arm circuit disposed on a path that connects the first input/output terminal and the second input/output terminal;
- and
- a parallel-arm circuit connected to a node on the path and a ground,
- wherein at least one of the series-arm circuit or the parallel-arm circuit includes a resonance circuit, and
- the resonance circuit includes:
- a first acoustic wave resonator;
- and
- a first capacitor connected in parallel to the first acoustic wave resonator, and having a greater electrostatic capacitance per unit area than that for the first acoustic wave resonator
- wherein the first capacitor includes:
- a first electrode;
- a second electrode facing the first electrode;
- and
- an insulating component disposed between the first electrode and the second electrode,
- the first acoustic wave resonator includes:
- a third electrode;
- a fourth electrode facing the third electrode;
- and
- a piezoelectric component disposed between the third electrode and the fourth electrode, and
- the insulating component has a permittivity higher than a permittivity of the piezoelectric component.
A filter device that includes a first input/output terminal and a second input/output terminal, the filter device comprising:
- a series-arm circuit disposed on a path that connects the first input/output terminal and the second input/output terminal;
- and
- a parallel-arm circuit connected to a node on the path and a ground,
- wherein at least one of the series-arm circuit or the parallel-arm circuit includes a resonance circuit, and
- the resonance circuit includes:
- a first acoustic wave resonator;
- and
- a first capacitor connected in parallel to the first acoustic wave resonator, and having a greater electrostatic capacitance per unit area than that for the first acoustic wave resonator
- wherein the first capacitor includes:
- a first electrode;
- a second electrode facing the first electrode;
- and
- an insulating component disposed between the first electrode and the second electrode,
- the first acoustic wave resonator includes:
- a third electrode;
- a fourth electrode facing the third electrode;
- and
- a piezoelectric component disposed between the third electrode and the fourth electrode, and
- the insulating component is thinner than the piezoelectric component.
Dependencies are inferred from the claim text.