Surface acoustic wave resonator
AssigneeOki Electric Industry Co., Ltd.
InventorsKenichi Anasako, Yoshiaki Fujita, Hisanori Ehara, Tomokazu Komazaki
Life of this patent
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Abstract
A surface acoustic wave filter includes an antenna terminal, a transmitting filter and a variable branching line both of which are coupled to the antenna terminal and a receiving filter coupled to the variable branching line. The transmitting filter has a first end series-arm SAW resonator, a second end series-arm SAW resonator, a middle series-arm SAW resonator coupled between the first and second end series-arm SAW resonators and parallel-arm SAW resonators. Each of the first and second end series-arm SAW resonator has a first resonance frequency. The middle series-arm SAW resonator has a second resonance frequency that is higher than the first resonance frequency.
Claims20
A surface acoustic wave filter comprising:
- an antenna terminal;
- a transmitting filter coupled to the antenna terminal, the transmitting filter including,
- a first end series-arm SAW resonator and a second end series-arm SAW resonator both of which have a first resonance frequency,
- a middle series-arm SAW resonator coupled between the first and second end series-arm SAW resonators, the middle series-arm SAW resonator having a second resonance frequency that is higher than the first resonance frequency, and
- a plurality of parallel-arm SAW resonators;
- a variable branching line coupled to the antenna terminal;
- and
- a receiving filter coupled to the variable branching line.
A surface acoustic wave filter comprising:
- an antenna terminal;
- a transmitting filter coupled to the antenna terminal, the transmitting filter including,
- a first end series-arm SAW resonator having a first resistance value,
- a second end series-arm SAW resonator having the first resistance value,
- a middle series-arm SAW resonator coupled between the first and second end series-arm SAW resonators having the first resistance value,
- a first parallel-arm SAW resonator coupled to the first end series-arm SAW resonator and the middle series-arm SAW resonator having a second resistance value that is lower than the first resistance value,
- a second parallel-arm SAW resonator coupled to the second end series-arm SAW resonator and the middle series-arm SAW resonator having the second resistance value;
- a variable branching line coupled to the antenna terminal;
- and
- a receiving filter coupled to the variable branching line.
A surface acoustic wave filter comprising:
- an antenna terminal;
- a transmitting filter coupled to the antenna terminal, the transmitting filter including,
- a first end series-arm SAW resonator and a second end series-arm SAW resonator both of which have a first resistance value,
- a middle series-arm SAW resonator coupled between the first and second end series-arm SAW resonators, the middle series-arm SAW resonator having a second resistance value that is lower than the first resistance value, and
- a plurality of parallel-arm SAW resonators;
- a variable branching line coupled to the antenna terminal;
- and
- a receiving filter coupled to the variable branching line.
Dependencies are inferred from the claim text.