Band elimination filter, filter device, antenna duplexer and communication apparatus
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsHiroyuki Nakamura, Shun-Ichi Seki, Keiji Onishi
Life of this patent
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Abstract
A band elimination filter includes an input terminal and an output terminal. A capacitor is coupled between a first terminal connected to the input terminal and a second terminal connected to the output terminal. The first terminal is grounded only via a first grounding point. The second terminal is grounded only via a second grounding point. A first acoustic resonator is connected between the first terminal and the first grounding point and a second acoustic resonator is connected between the second terminal and the second grounding point.
Claims37
A band elimination filter, comprising:
- an input terminal and an output terminal;
- one capacitor between a first terminal connected to said input terminal and a second terminal connected to said output terminal;
- wherein
- said first terminal is grounded via only a first grounding point;
- said second terminal is grounded via only a second grounding point,
- a first acoustic resonator is connected between said first terminal and said first grounding point,
- a second acoustic resonator is connected between said second terminal and said second grounding point, and
- a normalized impedance, which is obtained by normalizing a characteristic impedance of said input terminal or said output terminal, is smaller than 1.5.
A band elimination filter, comprising:
- an input terminal and an output terminal;
- a first inductor between a first terminal connected directly to said input terminal and a second terminal connected to said output terminal;
- wherein
- said first terminal is grounded via only a first grounding point;
- said second terminal is grounded via only a second grounding point,
- a first acoustic resonator is connected between said first terminal and said first grounding point, and
- a second acoustic resonator is connected between said second terminal and said second grounding point,
- wherein a normalized impedance, which is obtained by normalizing a characteristic impedance of said input terminal or said output terminal, is smaller than 1.5.
Dependencies are inferred from the claim text.