Filter device

• US 10,447,232 B2
• Filed: 11/16/2018
• Issued: 10/15/2019
• Est. Priority Date: 05/19/2016
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Konaka, Yohei
• Primary Examiner(s): Takaoka, Dean O
• Application Number:
  US16/193,153
• Publication Number:
  US 20190089329A1
• Time in Patent Office: 333 Days
• Field of Search: 333133, 333187, 333193
• CPC Class Codes: H01Q 1/526 Electromagnetic shields
• CPC Class Codes: H01Q 5/328 between a radiating element and ground
• CPC Class Codes: H03H 9/0009 using surface acoustic wave devices
• CPC Class Codes: H03H 9/0014 using bulk acoustic wave devices
• CPC Class Codes: H03H 9/02086 Means for compensation or elimination of undesirable effects
• CPC Class Codes: H03H 9/02913 Measures for shielding against electromagnetic fields shielding of electrical components in general H05K9/00
• CPC Class Codes: H03H 9/542 including passive elements H03H9/545 takes precedence
• CPC Class Codes: H03H 9/568 consisting of a ladder configuration
• CPC Class Codes: H03H 9/6483 Ladder SAW filters
• CPC Class Codes: H03H 9/706 Duplexers
• CPC Class Codes: H03H 9/725 Duplexers

Abstract

A filter device includes an antenna terminal to be connected to an antenna, first inductors connected between the antenna terminal and a ground potential and defined by parallel divided inductors, and first and second acoustic wave filters commonly connected to the antenna terminal and including second inductors, respectively. The first inductors and the second inductors are electromagnetically coupled to each other mainly in a one-to-one relationship.

Claims

1. A filter device comprising:

an antenna terminal to be connected to an antenna;

a plurality of first inductors connected between the antenna terminal and a ground potential and defined by a plurality of parallel divided inductors; and

a plurality of band-pass filters commonly connected to the antenna terminal and including respective second inductors;

wherein

the plurality of first inductors and the second inductors are electromagnetically coupled to each other mainly in a one-to-one relationship.

2. The filter device according to claim 1, wherein the plurality of first inductors are electromagnetically shielded from each other.

3. The filter device according to claim 1, wherein at least one of the second inductors is connected to the ground potential.

4. The filter device according to claim 1, wherein the second inductors include at least one inductor not connected to the ground potential.

5. The filter device according to claim 1, wherein at least one of the plurality of band-pass filters is a ladder filter.

6. The filter device according to claim 1, wherein at least one of the plurality of band-pass filters is a longitudinally coupled resonator acoustic wave filter.

7. The filter device according to claim 1, wherein the plurality of band-pass filters include three or more band-pass filters commonly connected to the antenna terminal.

8. The filter device according to claim 1, wherein the plurality of band-pass filters include first, second, third, and fourth acoustic wave filters commonly connected to the antenna terminal.

9. The filter device according to claim 8, wherein the first and third acoustic wave filters are transmission filters, and the second and fourth acoustic wave filters are reception filters.

10. The filter device according to claim 8, wherein

the first acoustic wave filter is a transmission filter having a pass band in a range from about 1710 MHz to about 1785 MHz;

the second acoustic wave filter is a reception filter having a pass band in a range from about 2110 MHz to about 2170 MHz;

the third acoustic wave filter is a transmission filter having a pass band in a range from about 1920 MHz to about 1980 MHz; and

the fourth acoustic wave filter is a reception filter having a pass band in a range from about 1805 MHz to about 1880 MHz.

11. The filter device according to claim 8, wherein the first and second acoustic wave filters are ladder filters.

12. The filter device according to claim 8, wherein

at least one of the first and second acoustic wave filters includes:

an input terminal;

series arm resonators connected in series to each other between the input terminal and the antenna terminal; and

parallel arm resonators connected to the ground potential;

wherein

one of the second inductors is connected between one of the parallel arm resonators and the ground potential.

13. The filter device according to claim 12, wherein at least one third inductor is connected between another one of the parallel arm resonators and the ground potential.

14. The filter device according to claim 1, wherein a coefficient of coupling between one of the plurality of first inductors and a corresponding one of the second inductors is about −

0.0017.

15. The filter device according to claim 14, wherein a coefficient of coupling between another one of the plurality of first inductors and a corresponding another one of the second inductors is about −

0.0037.