Acoustic wave filter device and composite filter device
AssigneeMurata Manufacturing Co., Ltd.
InventorJunpei YASUDA
Life of this patent
Estimating the term…
Abstract
An acoustic wave filter device includes a second filter section connected to a first filter section. The second filter section includes acoustic wave resonators in a ladder circuit configuration. Of the acoustic wave resonators in the first and second filter sections, the acoustic wave resonator having the smallest fractional bandwidth is included in the second filter section. In the second filter section, inductors are respectively connected between parallel arm resonators and a reference potential. Attenuation near a pass band in the second filter section is larger than attenuation near a pass band in the first filter section.
Claims26
An acoustic wave filter device comprising:
- a first filter section including a ladder circuit including at least one first serial arm resonator and at least one first parallel arm resonator, the at least one first serial arm resonator and the at least one second parallel arm resonator each being defined by an acoustic wave resonator;
- and
- a second filter section connected to the first filter section and including a ladder circuit including at least one second serial arm resonator and at least one second parallel arm resonator, the at least one second serial arm resonator and the at least one second parallel arm resonator each being defined by an acoustic wave resonator;
- wherein
- a fractional bandwidth of the second filter section is smaller than a fractional bandwidth of the first filter section;
- the first filter section includes or does not include at least one first inductor connected between the at least one first parallel arm resonator and a reference potential;
- the second filter section includes at least one inductor connected between at least the one second parallel arm resonator and the reference potential;
- and
- an inductor having a largest inductance value among the at least one first inductor and the at least one second inductor each connected between the at least one first parallel arm resonator or the least one second parallel arm resonator and the reference potential is included in the second filter section.
An acoustic wave filter device comprising:
- a first filter section including an LC filter including at least one first inductor and at least one first capacitor;
- and
- a second filter section connected to the first filter section and including a ladder circuit including at least one second serial arm resonator and at least one second parallel arm resonator, the at least one second serial arm resonator and the at least one second parallel arm resonator each being defined by an acoustic wave resonator;
- wherein
- a fractional bandwidth of the second filter section is smaller than a fractional bandwidth of the first filter section.
An acoustic wave filter device comprising:
- a first filter section including a first ladder circuit;
- and
- a second filter section connected to the first filter section and including a second ladder circuit including at least one serial arm resonator and at least one parallel arm resonator, the at least one serial arm resonator and the at least one parallel arm resonator each being defined by an acoustic wave resonator;
- wherein
- an inductor connected between a serial arm and a reference potential is provided in the second filter section.
Dependencies are inferred from the claim text.