LOW PASS FILTER

• US 20170170798A1
• Filed: 02/27/2017
• Published: 06/15/2017
• Est. Priority Date: 03/24/2015
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: MASUDA, Hiroshi
• Granted Patent: US 10,110,193 B2
• Time in Patent Office: Days
• CPC Class Codes: H01F 17/0013 with stacked layers
• CPC Class Codes: H01F 2017/0026 Multilayer LC-filter
• CPC Class Codes: H01F 2017/004 with the coil helically wound around an axis without a core
• CPC Class Codes: H03H 2001/0085 Multilayer, e.g. LTCC, HTCC, green sheets
• CPC Class Codes: H03H 7/0115 comprising only inductors and capacitors H03H7/075, H03H7/09, H03H7/12, H03H7/13 take precedence
• CPC Class Codes: H03H 7/09 Filters comprising mutual inductance
• CPC Class Codes: H03H 7/1708 Comprising bridging elements, i.e. elements in a series path without own reference to ground and spanning branching nodes of another series path H03H7/07 takes precedence
• CPC Class Codes: H03H 7/1725 Element to ground being common to different shunt paths, i.e. Y-structure
• CPC Class Codes: H03H 7/1733 Element between different shunt or branch paths H03H7/425 takes precedence
• CPC Class Codes: H03H 7/1766 Parallel LC in series path H03H7/1783 takes precedence

Abstract

A low pass filter includes a first via-hole conductor connected to a first end portion of a first inductor and a third end portion of a second inductor and extending to another side in a lamination direction with respect to a second end portion of the first inductor and a fourth end portion of the second inductor, and a first capacitor electrically connected in parallel with at least a portion of the first inductor and a portion of the second inductor and defined by a first capacitor conductor layer. The low pass filter allows the interval between attenuation poles to be easily adjusted.

Claims

1. A low pass filter comprising:

a multilayer body including a plurality of insulator layers laminated in a lamination direction;

a first LC parallel resonator including a first inductor including a first end portion at a first side in the lamination direction and a second end portion at a second side in the lamination direction, the first inductor having a helical shape turning around while extending in the lamination direction;

a second LC parallel resonator including a second inductor including a third end portion at the first side in the lamination direction and a fourth end portion at the second side in the lamination direction, the second inductor including a helical shape turning around while extending in the lamination direction, the second LC parallel resonator being electrically connected in series with the first LC parallel resonator;

a first via-hole conductor connected to the first end portion of the first inductor and the third end portion of the second inductor and extending to the second side in the lamination direction with respect to the second end portion of the first inductor and the fourth end portion of the second inductor; and

a first capacitor electrically connected in parallel with at least a portion of the first inductor and a portion of the second inductor and defined by a first capacitor conductor layer.

2. The low pass filter according to claim 1, further comprising a second capacitor provided at the second side in the lamination direction with respect to the first inductor and the second inductor and including a second capacitor conductor layer and a first ground conductor layer opposing each other;

wherein

the first via-hole conductor is connected to the second capacitor conductor layer.

3. The low pass filter according to claim 2, further comprising an outer electrode provided on a surface of the multilayer body at the second side in the lamination direction;

wherein

the outer electrode and the first ground conductor layer are electrically connected to each other.

4. The low pass filter according to claim 1, wherein

the first LC parallel resonator further includes a third capacitor electrically connected in parallel with the first inductor;

and

the first capacitor conductor layer is electrically connected (i) between the second end portion of the first inductor and the third capacitor or (ii) only to the first inductor, and overlaps the second inductor when seen in plan view from the lamination direction.

5. The low pass filter according to claim 1, wherein the first capacitor conductor layer overlaps the first inductor and the second inductor when seen in plan view from the lamination direction.

6. The low pass filter according to claim 2, wherein the first ground conductor layer includes a rectangular or substantially rectangular main body provided at a center of one of the plurality of insulator layers and band-shaped projection portions projecting from the main body.

7. The low pass filter according to claim 1, further comprising a third inductor electrically connected between the first LC parallel resonator and the second LC parallel resonator.

8. The low pass filter according to claim 1, further comprising a plurality of outer electrodes electrically connected to the first LC parallel resonator and the second LC parallel resonator.

9. The low pass filter according to claim 8, further comprising a fourth inductor electrically connected between the first ground conductor layer and one of the plurality of outer electrodes.

10. The low pass filter according to claim 8, wherein the plurality of outer electrodes are provided on a lowermost layer of the multilayer body.

11. The low pass filter according to claim 8, wherein the first LC parallel resonator and the second LC parallel resonator are electrically connected in series between two of the plurality of outer electrodes, and a third one of the plurality of outer electrodes is connected to ground.

12. The low pass filter according to claim 1, wherein inductor conductor layers which define the first inductor have point symmetry with inductor conductor layers which define the second inductor, about centers of the plurality of insulator layers.

13. The low pass filter according to claim 2, wherein

the first LC parallel resonator further includes a third capacitor electrically connected in parallel with the first inductor;

the first capacitor conductor layer is electrically connected between the second end portion of the first inductor and the third capacitor, and overlaps the second inductor when seen in plan view from the lamination direction; and

the first ground conductor layer includes a rectangular or substantially rectangular main body provided at a center of one of the plurality of insulator layers and band-shaped projection portions projecting from the main body.

14. The low pass filter according to claim 2, wherein

the first LC parallel resonator further includes a third capacitor electrically connected in parallel with the first inductor;

the first capacitor conductor layer is electrically connected only to the first inductor, and overlaps the second inductor when seen in plan view from the lamination direction; and

the first ground conductor layer includes a rectangular or substantially rectangular main body provided at a center of one of the plurality of insulator layers and band-shaped projection portions projecting from the main body.

15. The low pass filter according to claim 1, wherein

the first LC parallel resonator further includes a third capacitor electrically connected in parallel with the first inductor;

the first capacitor conductor layer is electrically connected between the second end portion of the first inductor and the third capacitor, and overlaps the second inductor when seen in plan view from the lamination direction; and

the low pass filter further includes a third inductor electrically connected between the first LC parallel resonator and the second LC parallel resonator.

16. The low pass filter according to claim 1, wherein

the first LC parallel resonator further includes a third capacitor electrically connected in parallel with the first inductor;

the first capacitor conductor layer is electrically connected only to the first inductor, and overlaps the second inductor when seen in plan view from the lamination direction; and

the low pass filter further includes a third inductor electrically connected between the first LC parallel resonator and the second LC parallel resonator.

17. The low pass filter according to claim 1, wherein

the first LC parallel resonator further includes a third capacitor electrically connected in parallel with the first inductor;

the first capacitor conductor layer is electrically connected between the second end portion of the first inductor and the third capacitor, and overlaps the second inductor when seen in plan view from the lamination direction;

the low pass filter further includes a plurality of outer electrodes electrically connected to the first LC parallel resonator and the second LC parallel resonator; and

the low pass filter further includes a fourth inductor electrically connected between the first ground conductor layer and one of the plurality of outer electrodes.

18. The low pass filter according to claim 17, wherein the plurality of outer electrodes are provided on a lowermost layer of the multilayer body.

19. The low pass filter according to claim 1, wherein

the first LC parallel resonator further includes a third capacitor electrically connected in parallel with the first inductor;

the first capacitor conductor layer is electrically connected only to the first inductor, and overlaps the second inductor when seen in plan view from the lamination direction;

the low pass filter further includes a plurality of outer electrodes electrically connected to the first LC parallel resonator and the second LC parallel resonator; and

the low pass filter further includes a fourth inductor electrically connected between the first ground conductor layer and one of the plurality of outer electrodes.

20. The low pass filter according to claim 19, wherein the plurality of outer electrodes are provided on a lowermost layer of the multilayer body.