Acoustic wave filter and acoustic wave duplexer
AssigneesFujitsu Media Devices Limited, Fujitsu Limited
InventorsSatoru Matsuda, Shogo Inoue, Takashi Matsuda, Masanori Ueda
Life of this patent
Estimating the term…
Abstract
An acoustic wave filter includes: a ladder filter that has acoustic wave resonators connected in series and parallel arms; an inductor that is provided between a ground and at least one of the parallel-arm resonators in the ladder filter; and a resonance circuit that is provided in parallel with the inductor, and is located between the ground and the parallel-arm resonators in the ladder filter. In this acoustic wave filter, the resonance frequency of the resonance circuit is expressed as: 2f0−150 MHz<fr<2f0+150 MHz or 3f0−150 MHz<fr<3f0+150 MHz, where fr represents the resonance frequency, and f0 represents the passband frequency of the ladder filter.
Claims10
An acoustic wave filter comprising:
- a ladder filter that has acoustic wave resonators connected in series and parallel arms;
- an inductor that is provided between a ground and at least one of the parallel-arm resonators in the ladder filter;
- and
- a resonance circuit that is provided in parallel with the inductor, and is located between the ground and the parallel-arm resonators in the ladder filter,
- a resonance frequency of the resonance circuit being expressed as:
- 2f0−150 MHz<fr<2f0+150 MHz
- or
- 3f0−150 MHz<fr<3f0+150 MHz
- where fr represents the resonance frequency, and f0 represents the passband frequency of the ladder filter.
An acoustic wave duplexer comprising:
- a transmission filter that is formed with an acoustic wave filter and is connected to an antenna terminal and a transmission terminal;
- a reception filter that is connected to the antenna terminal and a reception terminal;
- and
- a matching circuit that is provided between the antenna terminal and the transmission filter, between the antenna terminal and the reception filter, or between the antenna terminal and both the transmission filter and the reception filter,
- the acoustic wave filter including:
- a ladder filter that has acoustic wave resonators connected in series and parallel arms;
- an inductor that is provided between a ground and at least one of the parallel-arm resonators in the ladder filter;
- and
- a resonance circuit that is provided in parallel with the inductor, and is located between the ground and the parallel-arm resonators in the ladder filter,
- a resonance frequency of the resonance circuit being expressed as:
- 2f0−150 MHz<fr<2f0+150 MHz
- or
- 3f0−150 MHz<fr<3f0+150 MHz
- where fr represents the resonance frequency, and f0 represents the passband frequency of the ladder filter.
Dependencies are inferred from the claim text.