Elastic wave filter device and duplexer

Patent metadata

Field	Value
Publication number	US-9455682-B2
Application number	US-201514615503-A
Country	US
Kind code	B2
Filing date	Feb 6, 2015
Priority date	Aug 30, 2012
Publication date	Sep 27, 2016
Grant date	Sep 27, 2016

Abstract

In an elastic wave filter device, an elastic wave filter element chip is mounted on a board. In the elastic wave filter element chip, a ladder filter including a plurality of series arm resonators and a plurality of parallel arm resonators are provided. In/on the board, a first inductor connected in parallel to the series arm resonator and a second inductor connected between the parallel arm resonators P 1 -P 3 and a ground potential are provided. In/on the board, a shield electrode is located between the first inductor and the second inductor.

First claim

What is claimed is:

1. An elastic wave filter device comprising:
a board; and
an elastic wave element chip mounted on the board; wherein
the elastic wave element chip defines a ladder filter including a plurality of series arm resonators arranged on a series arm connecting an input terminal and an output terminal and a plurality of parallel arm resonators arranged on respective parallel arms connecting the series arm and a ground potential; and
a first inductor, a second inductor, and a shield electrode are provided in/on the board, the first inductor being connected in parallel to the at least one series arm resonator, the second inductor being connected between at least one of the parallel arm resonators and the ground potential, the shield electrode being located between the first inductor and the second inductor.

2. The elastic wave filter device according to claim 1 , wherein a ground terminal to be connected to the ground potential is located on the board, and the shield electrode is electrically connected to the ground terminal.

3. The elastic wave filter device according to claim 1 , wherein the shield electrode is electrically connected to an end portion of the parallel arm resonator that is to be connected to the ground potential.

4. The elastic wave filter device according to claim 1 , wherein the first inductor and the second inductor are separated in a lateral direction in/on the board, and the shield electrode is disposed between the first inductor and the second inductor that are separated in the lateral direction.

5. The elastic wave filter device according to claim 1 , wherein the first inductor and the second inductor are separated in a thickness direction of the board, and the shield electrode is disposed between the first inductor and the second inductor that are separated in the thickness direction.

6. The elastic wave filter device according to claim 1 , wherein
the first inductor is connected in parallel to the series arm resonator that is closest to one of the input terminal and the output terminal; and
the second inductor is connected to at least one of the plurality of parallel arm resonators that is closer to another one of the input terminal and the output terminal.

7. The elastic wave filter device according to claim 1 , wherein a common end portion configured to connect to the ground potential is shared by the parallel arm resonators that are respectively provided on at least two parallel arms, and the second inductor is connected between the common end portion and the ground potential.

8. A duplexer comprising:
a first filter including the elastic wave filter device according to claim 1 ; and
a second filter that has a passband different from that of the first filter.

9. The duplexer according to claim 8 , wherein a ground terminal to be connected to the ground potential is located on the board, and the shield electrode is electrically connected to the ground terminal.

10. The duplexer according to claim 8 , wherein the shield electrode is electrically connected to an end portion of the parallel arm resonator that is to be connected to the ground potential.

11. The duplexer according to claim 8 , wherein the first inductor and the second inductor are separated in a lateral direction in/on the board, and the shield electrode is disposed between the first inductor and the second inductor that are separated in the lateral direction.

12. The duplexer according to claim 8 , wherein the first inductor and the second inductor are separated in a thickness direction of the board, and the shield electrode is disposed between the first inductor and the second inductor that are separated in the thickness direction.

13. The duplexer according to claim 8 , wherein
the first inductor is connected in parallel to the series arm resonator that is closest to one of the input terminal and the output terminal; and
the second inductor is connected to at least one of the plurality of parallel arm resonators that is closer to another one of the input terminal and the output terminal.

14. The duplexer according to claim 8 , wherein a common end portion configured to connect to the ground potential is shared by the parallel arm resonators that are respectively provided on at least two parallel arms, and the second inductor is connected between the common end portion and the ground potential.

Assignees

• Murata Manufacturing Co

Inventors

• Kuzushita Takuma
• Taniguchi Yasumasa
• Miyake Takashi

Classifications

• H03H9/605

  consisting of a ladder configuration · CPC title

• H03H9/706

  Duplexers · CPC title

• H03H9/24

  Constructional features of resonators of material which is not piezoelectric, electrostrictive, or magnetostrictive · CPC title

• H03H9/0576 Primary

  including surface acoustic wave [SAW] devices · CPC title

• H03H2001/0085

  Multilayer, e.g. LTCC, HTCC, green sheets · CPC title