Filter device

Abstract

The invention provides a filter device capable of obtaining necessary attenuation characteristics even when the filter device is miniaturized. A filter device (100) according to the present disclosure is provided with an insulator (3), a first coil element (L1), an external electrode (4e), a second coil element (L2), an external electrode (4a), an electrode pattern (7a), an electrode pattern (7b), and an external electrode (4d). The insulator (3) has a pair of main surfaces facing each other and side surfaces connecting the main surfaces. The first coil element (L1) constitutes a coil having a planar spiral shape in an insulator (3). The second coil element (L2) overlaps at least a portion of the first coil element (L1) in a plan view from one of the main surfaces, and forms a spiral coil within the insulator (3).

Description

Technical Field

[0001] The present disclosure relates to filter devices. Background Art

[0002] In recent years, with the advancement of communication technology, communication terminals have become required to support multiple frequency bands and various communication methods. Therefore, communication terminals are equipped with filter devices such as low-pass filters that set the passband and attenuation band of the signal. For example, Japanese Patent No. 7021723 (Patent Document 1) describes a low-pass filter device comprising two coil elements connected in series in a signal path and a capacitor connected in shunt to the signal path. Prior art literature Patent Literature

[0003] Patent Document 1: Japanese Patent No. 7021723 Summary of the Invention Problems to be solved by the invention

[0004] However, as the devices incorporating filter devices become smaller, the filter devices themselves also need to be smaller. When miniaturizing the electronic components that make up the filter device, which are housed within a single insulator, the proximity of the two coil elements increases the effects of magnetic field coupling between them. Increasing the effects of magnetic field coupling between the two coil elements in the filter device makes it impossible to achieve the required attenuation characteristics.

[0005] Therefore, an object of the present disclosure is to provide a filter device that can obtain necessary attenuation characteristics even when reduced in size. Means for solving problems

[0006] A filter device according to one embodiment of the present disclosure includes an insulator, a first coil element, a first external electrode, a second coil element, a second external electrode, a first electrode pattern, a second electrode pattern, and a third external electrode. The insulator has a pair of main surfaces facing each other and side surfaces connecting the main surfaces. The first coil element forms a planar spiral coil within the insulator. The first external electrode is electrically connected to one end of the first coil element. The second coil element overlaps with at least a portion of the first coil element when viewed from one of the main surfaces, forming a spiral coil within the insulator. The second external electrode is electrically connected to one end of the second coil element. The first electrode pattern is electrically connected to the other end of the first coil element and the other end of the second coil element, and is formed within the insulator. The second electrode pattern is arranged opposite to the first electrode pattern to form a first capacitor. The third external electrode is electrically connected to the second electrode pattern. Effects of the Invention

[0007] According to one embodiment of the present disclosure, by including a first coil element forming a planar spiral coil and a second coil element forming a spiral coil, the influence of magnetic field coupling between the two coil elements is suppressed, thereby achieving necessary attenuation characteristics even with miniaturization. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a perspective view of the filter device according to the first embodiment. Figure 2 It is an exploded perspective view showing the structure of the filter device according to the first embodiment. Figure 3 This is a circuit diagram of the filter device according to the first embodiment. Figure 4 This is a graph showing the transmission characteristics of the low-pass filter of the filter device according to the first embodiment. Figure 5 This is a graph showing the transmission characteristics of the high-pass filter of the filter device according to the first embodiment. Figure 6 This is a perspective view of a filter device according to the second embodiment. Figure 7 It is an exploded perspective view showing the structure of a filter device according to the second embodiment. Figure 8 This is a graph showing the transmission characteristics of the low-pass filter of the filter device according to the second embodiment. Figure 9 This is a graph showing the transmission characteristics of the high-pass filter of the filter device according to the second embodiment. DETAILED DESCRIPTION

[0009] Hereinafter, as an example of the filter device involved in the embodiment, a duplexer is described in detail with reference to the accompanying drawings. It should be noted that the same or equivalent parts in the accompanying drawings are marked with the same reference numerals, and their descriptions are not repeated. In addition, the filter device involved in the embodiment is not limited to a duplexer. The filter device involved in the embodiment only needs to include at least the structure of the low-pass filter described below. In addition, for the low-pass filter described below, a third-order T-type LC filter circuit is used for description, but a fifth-order T-type LC filter circuit or a higher-order T-type LC filter circuit may also be used.

[0010] (Implementation 1) [Structure of filter device] First, a filter device according to Embodiment 1 will be described with reference to the drawings. Figure 1 It is a perspective view of the filter device 100 according to the first embodiment. Figure 2It is an exploded perspective view showing the structure of the filter device 100 according to the first embodiment. Figure 3 is a circuit diagram of the filter device 100 according to the first embodiment. Figure 1 and Figure 2 In FIG. 1 , the short side direction of the filter device 100 is defined as the X direction, the long side direction is defined as the Y direction, and the height direction is defined as the Z direction.

[0011] The filter device 100 is a duplexer formed by combining two filter circuits, one for a low-pass filter on the low-frequency side and one for a high-pass filter on the high-frequency side. The filter device 100 is a rectangular parallelepiped chip component, and is composed of an insulator 3 formed by stacking multiple insulating substrates (insulator layers). In addition, the stacking direction of the insulating substrate is the Z direction, and the direction of the arrow represents the upper direction. In addition, the insulating substrate is composed of materials such as insulating materials with borosilicate glass as the main component, aluminum oxide, zirconium oxide, polyimide resin, and other insulating resins. In addition, sometimes the interface of the multiple insulating substrates of the insulator 3 is not clear enough due to sintering, curing, etc.

[0012] The insulator 3 has a pair of main surfaces facing each other. Figure 1 The main surface on the lower side is the mounting surface, which is opposite to the circuit substrate. Figure 1 The main surface on the lower side is called the bottom surface. Figure 1 The upper main surface of the insulator 3 is referred to as a top surface. When viewed from the top surface side among the main surfaces, the insulator 3 includes a first region 100a constituting a low-pass filter and a second region 100b constituting a high-pass filter.

[0013] The first region 100a includes Figure 3 As shown in the circuit diagram, the low-pass filter LPF is composed of the first coil element L1, the second coil element L2, and the first capacitor C1. The first coil element L1 and the second coil element L2 are connected in series to the signal path connecting the first terminal P1 and the second terminal P2, and the first capacitor C1 is connected in shunt to the signal path. Figure 1 and Figure 2 As shown, in the first region 100 a of the insulator 3 , the first coil element L1 , the second coil element L2 , and the first capacitor C1 are arranged in this order from the top surface side to the bottom surface side of the insulator 3 .

[0014] The first coil element L1 forms a spiral coil in the insulator 3. Figure 2As shown, the circuit includes a first coil pattern 1a and a first coil pattern 1b in a planar spiral shape. First coil pattern 1a is formed on insulating substrate 3b, and first coil pattern 1b is formed on insulating substrate 3c. One end of first coil pattern 1a is electrically connected to one end of first coil pattern 1b via external electrode 4e (first external electrode). Furthermore, the other ends of first coil pattern 1a and first coil pattern 1b are electrically connected via via conductor 11.

[0015] The first coil element L1 is formed by connecting the first coil pattern 1a and the first coil pattern 1b of the same shape in parallel. Generally speaking, when increasing the inductance of a planar spiral coil, the number of turns needs to be increased, so a large area is required within the surface of the insulating substrate. Therefore, in the first coil element L1, in order to ensure the required inductance within the insulator 3 with limited space, the first coil pattern 1a and the first coil pattern 1b of the same shape are connected in parallel. In addition, by connecting the first coil pattern 1a and the first coil pattern 1b in parallel, a Figure 3 As shown in the circuit diagram of FIG. 1 , the second capacitor C2 is connected in parallel with the first coil element L1.

[0016] Below the first coil element L1, a second coil element L2 is arranged, which is a helical coil in an insulator 3. Figure 2 As shown, the second coil element L2 includes a second coil pattern 2a, a second coil pattern 2b, and a second coil pattern 2c, each forming a portion of a spiral coil. The second coil pattern 2a is formed on an insulating substrate 3d, the second coil pattern 2b is formed on an insulating substrate 3e, and the second coil pattern 2c is formed on an insulating substrate 3f.

[0017] One end of the second coil pattern 2a is electrically connected to the other ends of the first coil pattern 1a and the first coil pattern 1b via a via conductor 11, connecting the first coil element L1 and the second coil element L2 in series. The other end of the second coil pattern 2a is electrically connected to one end of the second coil pattern 2b via a via conductor 12. The other end of the second coil pattern 2b is electrically connected to one end of the second coil pattern 2c via a via conductor 13. The other end of the second coil pattern 2c is electrically connected to the external electrode 4a (second external electrode). In this way, the second coil patterns 2a to 2c formed on different insulating substrates 3e to 3f are electrically connected using via conductors 12 and 13, thereby forming the spiral-shaped second coil element L2.

[0018] A first capacitor C1 is disposed below the second coil element L2. The first capacitor C1 includes Figure 2The electrode pattern 7a (first electrode pattern) and the electrode pattern 7b (second electrode pattern) arranged opposite to the electrode pattern 7a are shown. The electrode pattern 7a is formed on the insulating substrate 3g, and the electrode pattern 7b is formed on the insulating substrate 3h.

[0019] Electrode pattern 7a is electrically connected to second coil pattern 2a via via conductor 14. Since second coil pattern 2a is also electrically connected to first coil pattern 1a via via conductor 11, electrode pattern 7a is electrically connected to first coil element L1 and second coil element L2. Electrode pattern 7b is electrically connected to external electrode 4d (third external electrode).

[0020] In addition to the electrode pattern 7a, the insulating substrate 3g also has an electrode pattern 8a. The electrode pattern 8a is electrically connected to the external electrode 4a and is arranged opposite to the electrode pattern 8b formed on the insulating substrate 3h. The electrode pattern 8b is arranged opposite not only to the electrode pattern 8a but also to the electrode pattern 7a. Therefore, the electrode pattern 8a and the electrode pattern 8b form a Figure 3 The third capacitor C3 is shown in the circuit diagram. In addition, Figure 3 In the circuit diagram, the first terminal P1 corresponds to the external electrode 4e (first external electrode), the second terminal P2 corresponds to the external electrode 4a (second external electrode), and GND corresponds to the external electrode 4d (third external electrode).

[0021] The second region 100b includes Figure 3 As shown in the circuit diagram, the high-pass filter HPF is composed of the fourth capacitor C4, the third coil element L3, the fourth coil element L4, the fifth capacitor C5, and the fifth coil element L5. The fourth capacitor C4, the third coil element L3, the fourth coil element L4, and the fifth capacitor C5 are connected in series to the signal path connecting the first terminal P1 and the third terminal P3, and the fifth coil element L5 is connected in shunt to the signal path. Figure 1 and Figure 2 As shown, in the second region 100 b of the insulator 3 , a fourth capacitor C4 , a third coil element L3 , a fourth coil element L4 , a fifth capacitor C5 , and a fifth coil element L5 are arranged inside the insulator 3 .

[0022] The fourth capacitor C4 comprises Figure 2 The electrode pattern 9a (fourth electrode pattern) shown is arranged opposite to the electrode pattern 9a, and the electrode pattern 9b (third electrode pattern) is arranged opposite to the electrode pattern 9a. The electrode pattern 9a is formed on the insulating substrate 3g, and the electrode pattern 9b is formed on the insulating substrate 3h. The electrode pattern 9a is electrically connected to the third coil pattern 5a via the via conductor 15. The electrode pattern 9b is electrically connected to the external electrode 4e (first external electrode).

[0023] like Figure 2As shown, the third coil element L3 includes a third coil pattern 5a and a third coil pattern 5b forming part of a spiral coil. The third coil pattern 5a is formed on the insulating substrate 3b, and the third coil pattern 5b is formed on the insulating substrate 3c.

[0024] One end of the third coil pattern 5a is electrically connected to the electrode pattern 9a via a via conductor 15, connecting the fourth capacitor C4 and the third coil element L3 in series. The other end of the third coil pattern 5a is electrically connected to one end of the third coil pattern 5b via a via conductor 16. In this way, the third coil patterns 5a and 5b, formed on different insulating substrates 3b to 3c, are electrically connected by the via conductor 16, forming the spiral-shaped third coil element L3.

[0025] like Figure 2 As shown, the fourth coil element L4 includes a fourth coil pattern 6a, a fourth coil pattern 6b, a fourth coil pattern 6c, a fourth coil pattern 6d, and a fourth coil pattern 6e, which form a portion of a spiral coil. The fourth coil pattern 6a is formed on the insulating substrate 3b, the fourth coil pattern 6b is formed on the insulating substrate 3c, the fourth coil pattern 6c is formed on the insulating substrate 3d, the fourth coil pattern 6d is formed on the insulating substrate 3e, and the fourth coil pattern 6e is formed on the insulating substrate 3f.

[0026] One end of the fourth coil pattern 6a is electrically connected to the other end of the third coil pattern 5b via a via conductor 17, connecting the third coil element L3 and the fourth coil element L4 in series. The other end of the fourth coil pattern 6a is electrically connected to one end of the fourth coil pattern 6b via a via conductor 18. The other end of the fourth coil pattern 6b is electrically connected to one end of the fourth coil pattern 6c and the fourth coil pattern 6d via a via conductor 19. The other ends of the fourth coil pattern 6c and the fourth coil pattern 6d are electrically connected to one end of the fourth coil pattern 6e via a via conductor 20. In this way, the fourth coil patterns 6a to 6e, formed on different insulating substrates 3b to 3f, are electrically connected by via conductors 18 to 20, forming the spiral-shaped fourth coil element L4.

[0027] The fifth capacitor C5 comprises Figure 2 The electrode pattern 10a (sixth electrode pattern) and the electrode pattern 10b (fifth electrode pattern) arranged opposite to the electrode pattern 10a are shown. The electrode pattern 10a is formed on the insulating substrate 3g, and the electrode pattern 10b is formed on the insulating substrate 3h.

[0028] The electrode pattern 10a is electrically connected to the external electrode 4c (fifth external electrode), and the electrode pattern 10b is electrically connected to the other end of the fourth coil pattern 6e via the via conductor 21, connecting the fifth capacitor C5 and the fourth coil element L4 in series.

[0029] like Figure 2 As shown, the fifth coil element L5 includes a fifth coil pattern 5c and a fifth coil pattern 5d that form a portion of a spiral coil. The fifth coil pattern 5c is formed on the insulating substrate 3d, and the fifth coil pattern 5d is formed on the insulating substrate 3e.

[0030] One end of the fifth coil pattern 5c and the fifth coil pattern 5d is electrically connected to the third coil pattern 5b via a via conductor 17. The third coil pattern 5b is also electrically connected to the fourth coil pattern 6a via a via conductor 17. Thus, the fifth coil element L5 is electrically connected to the third coil element L3 and the fourth coil element L4. The other ends of the fifth coil pattern 5c and the fifth coil pattern 5d are electrically connected to the external electrode 4f (fourth external electrode).

[0031] An electrode pattern 9a is formed on the insulating substrate 3g. The electrode pattern 9a is arranged opposite not only the electrode pattern 9b but also the electrode pattern 10b. Therefore, the electrode pattern 9a and the electrode pattern 10b constitute Figure 3 The sixth capacitor C6 is shown in the circuit diagram. In addition, Figure 3 In the circuit diagram, the third terminal P3 corresponds to the external electrode 4c (fifth external electrode), and GND corresponds to the external electrode 4f (fourth external electrode).

[0032] Figure 2 The coil pattern and electrode pattern shown are formed on the insulating substrates 3a to 3i by printing. In addition, the electrode pattern constituting a part of the external electrodes 4a to 4f is formed on the insulating substrates 3a and 3i. Figure 2 The plurality of insulating substrates 3a to 3i shown are stacked and subjected to processes such as sintering and curing. External electrodes 4a to 4f are formed on the side surfaces of the insulator 3 after the sintering and curing processes.

[0033] [Characteristics of filter device] like Figure 1 and Figure 2As shown, the filter device 100 includes a low-pass filter LPF, which connects in series the first coil element L1 constituting a planar spiral coil and the second coil element L2 constituting a spiral coil, and connects the first capacitor C1 in shunt. In order to achieve miniaturization, the filter device 100 needs to stack the first coil element L1 and the second coil element L2 in the longitudinal direction (Z direction), and the distance between the two coil elements becomes closer. However, in the filter device, if the influence caused by the magnetic field coupling between the two coil elements increases, it may not be possible to obtain the necessary attenuation characteristics. Therefore, in the filter device 100, by making the first coil element L1 constitute a planar spiral coil, the influence of the magnetic field coupling between the two coil elements can be reduced compared to the case of stacking two spiral coils in the longitudinal direction.

[0034] Unlike spiral coils, which have coil wiring wound in a spiral shape, flat spiral coils have coil wiring wound on a single plane. Therefore, the magnetic field intensity generated by a flat spiral coil in a direction perpendicular to the plane on which the coil wiring is wound is smaller than that of a spiral coil. Consequently, when a single coil is a flat spiral coil, the magnetic field coupling between coil elements is weakened compared to when two spiral coils are stacked vertically.

[0035] Figure 4 This is a graph showing the transmission characteristics of the low-pass filter of the filter device 100 according to the first embodiment. Figure 5 Graph showing the transmission characteristics of the high-pass filter of the filter device 100 according to the first embodiment. Figure 4 and Figure 5 In the figure, the horizontal axis is frequency and the vertical axis is loss.

[0036] exist Figure 4 In FIG. 1 , graph A is a simulation result of the return loss (ReturnLoss) on the input side of the low-pass filter of the filter device 100. In addition, graph B is a simulation result of the insertion loss (InsertionLoss) in the low-pass filter of the filter device 100. Figure 4 Graph B shows that filter device 100 functions as a low-pass filter (LPF) with two attenuation peaks near approximately 1.9 GHz and 2.7 GHz. Furthermore, in Graph B, at marker m1, the insertion loss at a frequency of 0.96 GHz is relatively low, at -0.443 dB, while at marker m2, the insertion loss at a frequency of 1.71 GHz is relatively high, at -33.487 dB.

[0037] On the other hand, Figure 5Graph C shows the simulation results of the input-side return loss of the high-pass filter of filter device 100. Graph D shows the simulation results of the insertion loss of the high-pass filter of filter device 100. In Graph D, at marker m3, the insertion loss at a frequency of 0.96 GHz is relatively high, at -32.703 dB. At marker m4, the insertion loss at a frequency of 1.71 GHz is relatively low, at -0.423 dB. In other words, filter device 100 functions as a high-pass filter (HPF) that allows signals at a frequency of 1.71 GHz to pass.

[0038] In the filter device 100, if the influence of the magnetic field coupling between the first coil element L1 and the second coil element L2 increases, Figure 4 The attenuation between the two attenuation poles shown in the curve B of FIG increases. However, as Figure 4 As shown in the graph B, the attenuation between the two attenuation poles does not increase. This shows that by changing the first coil element L1 from a spiral coil to a flat spiral coil, the influence of the magnetic field coupling between the two coil elements is suppressed.

[0039] From the perspective of suppressing the effects of magnetic field coupling between the two coil elements, it is preferred that the axis of the planar spiral shape of the first coil element L1 does not overlap the axis of the spiral shape of the second coil element L2 when viewed from the top surface of the insulator 3. Here, the axis of the planar spiral shape of the first coil element L1 refers to the central axis of the coil wiring wound in a planar spiral shape, and the axis of the spiral shape of the second coil element L2 refers to the central axis of the coil wiring wound in a spiral shape.

[0040] Furthermore, when the filter device 100 is configured as a duplexer, the inductance of the first coil element L1 is preferably greater than the inductance of the second coil element L2 from the perspective of preventing the attenuation pole of the low-pass filter LPF from appearing in the passband of the high-pass filter HPF. Furthermore, since the first coil element L1 is a planar spiral coil, the coil wiring needs to be extended to increase the inductance. However, if the coil wiring of the first coil element L1 is extended, the surface ( Figure 1 Since the area occupied by the first coil element L1 in the XY plane (in FIG. 1 ) increases, the width of the coil wiring needs to be smaller than the width of the coil wiring of the second coil element L2.

[0041] While the filter device 100 has been described as having a planar spiral first coil element L1 disposed on the first terminal P1 side, which serves as the input side, a spiral second coil element L2 may also be disposed on the first terminal P1 side. Furthermore, by disposing the planar spiral first coil element L1, which has a high insertion loss, on the first terminal P1 side and disposing the high-Q spiral second coil element L2 in the subsequent stage, the transmission characteristics of the low-pass filter can be further improved.

[0042] The filter device 100 is described as follows Figure 1 and Figure 2 The illustration shows a case where the first coil element L1, the second coil element L2, and the first capacitor C1 are arranged in order from the top to the bottom of the insulator 3 in the first region 100a. In the case of a duplexer configured with a high-pass filter provided in the second region 100b of the insulator 3, as in the filter device 100, the first coil element L1, the second coil element L2, and the first capacitor C1 are preferably arranged in this order due to limitations such as the need to form the coil patterns of the low-pass filter and the high-pass filter on the same insulating substrate. However, if this limitation is not a concern, the first coil element L1, the second coil element L2, and the first capacitor C1 do not need to be arranged in this order from the top to the bottom of the insulator 3; they may be arranged in a different order.

[0043] (Implementation Method 2) In the filter device 100 according to the first embodiment, the first coil element L1 of the first coil element L1 and the second coil element L2 constituting the low-pass filter is configured as a planar spiral coil. When the first coil element L1 is configured as a planar spiral coil, the surface ( Figure 1 The area occupied by the first coil element L1 in the XY plane (of the filter device) increases. Therefore, it is believed that when miniaturizing the filter device, it is impossible to achieve the required inductance using only a planar spiral coil. Therefore, in the filter device according to Embodiment 2, the first coil element L1 is configured to include a spiral coil in addition to the planar spiral coil.

[0044] A filter device according to Embodiment 2 will be described with reference to the drawings. Figure 6 It is a perspective view of a filter device 100A according to the second embodiment. Figure 7 : is an exploded perspective view showing the structure of the filter device 100A according to the second embodiment. Figure 6 and Figure 7 In the filter device 100A shown in FIG. Figure 1 and Figure 2The same components of the filter device 100 are denoted by the same reference numerals, and detailed description thereof will not be repeated.

[0045] The filter device 100A is a duplexer that combines two filter circuits: a low-pass filter on the low-frequency side and a high-pass filter on the high-frequency side. When viewed from the top of the principal surface, the insulator 3 includes a first region 100a that forms the low-pass filter and a second region 100b that forms the high-pass filter.

[0046] like Figure 6 and Figure 7 As shown, in the first region 100 a of the insulator 3 , the first coil element L1 , the second coil element L2 , and the first capacitor C1 are arranged in this order from the top surface side to the bottom surface side of the insulator 3 .

[0047] The first coil element L1 includes a first portion forming a planar spiral coil within the insulator 3 and a second portion forming a spiral coil. Figure 7 As shown, the first portion of the first coil element L1 includes a first coil pattern 1a and a first coil pattern 1b, both of which are planar spirals. First coil pattern 1a is formed on insulating substrate 3b, while first coil pattern 1b is formed on insulating substrate 3c. One end of first coil pattern 1a is electrically connected to one end of first coil pattern 1b via external electrode 4e (first external electrode). Furthermore, the other ends of first coil pattern 1a and first coil pattern 1b are electrically connected via via conductor 11.

[0048] like Figure 7 As shown, the second portion of the first coil element L1 includes a spiral-shaped first coil pattern 1c. The first coil pattern 1c is formed on an insulating substrate 3d. One end of the first coil pattern 1c is electrically connected to the other ends of the first coil pattern 1a and the other end of the first coil pattern 1b via a via conductor 11. The other end of the first coil pattern 1c is electrically connected to one end of the second coil pattern 2a of the second coil element L2, which is formed on the same insulating substrate 3d.

[0049] A first coil pattern 1c and a second coil pattern 2a are formed on the same insulating substrate 3d. The first coil pattern 1c (the second portion of the first coil element L1) is preferably positioned closer to the second region 100b than the second coil element L2. This reduces the effect of the magnetic field from the high-pass filter's coil element on the second coil element L2, improving the transmission characteristics of the low-pass filter. Of course, as long as the effect of the magnetic field from the high-pass filter's coil element is minimal, the second coil element L2 can also be positioned closer to the second region 100b than the second portion of the first coil element L1.

[0050] Furthermore, by forming the first coil pattern 1c and the second coil pattern 2a on the same insulating substrate 3d, the axis of the planar spiral shape (first portion) of the first coil element L1 and the axis of the spiral shape of the second coil element L2 can be further offset when viewed from the top surface. Furthermore, the first coil pattern 1c does not need to be formed on the same insulating substrate 3d as the second coil pattern 2a; it can also be formed on a separate insulating substrate.

[0051] The other end of the first coil pattern 1c is electrically connected to the electrode pattern 7a through the via conductor 14. Since the other end of the first coil pattern 1c is also electrically connected to one end of the second coil pattern 2a, the electrode pattern 7a is electrically connected to the first coil element L1 and the second coil element L2.

[0052] As described above, since the first coil element L1 includes the spiral second portion (first coil pattern 1c) in addition to the planar spiral first portion (first coil pattern 1a and first coil pattern 1b), the inductance required for design can be ensured even when the filter device 100A is miniaturized.

[0053] Figure 8 This is a graph showing the transmission characteristics of the low-pass filter of the filter device 100A according to the second embodiment. Figure 9 Graph showing the transmission characteristics of the high-pass filter of the filter device 100A according to the second embodiment. Figure 8 and Figure 9 In the figure, the horizontal axis is frequency and the vertical axis is loss.

[0054] exist Figure 8 Graph E is a simulation result of the return loss on the input side of the low-pass filter of the filter device 100A. Graph F is a simulation result of the insertion loss in the low-pass filter of the filter device 100A. Figure 8 Graph F shows that filter device 100A functions as a low-pass filter (LPF) with two attenuation peaks near approximately 1.8 GHz and 2.6 GHz. Furthermore, in Graph F, at marker m5, the insertion loss at a frequency of 0.96 GHz is relatively low, at -0.428 dB, while at marker m6, the insertion loss at a frequency of 1.71 GHz is relatively high, at -36.858 dB.

[0055] In the filter device 100A, the first coil element L1 is configured to include a second spiral portion (first coil pattern 1c) in addition to a first planar spiral portion (first coil pattern 1a and first coil pattern 1b). As a result, the inductance of the first coil element L1 of the filter device 100A is larger than that of the filter device 100, resulting in an insertion loss of -0.443 dB ( Figure 4 ) improved to -0.428dB( Figure 8 ).

[0056] On the other hand, Figure 9 Graph G shows the simulation results of the input-side return loss of the high-pass filter of filter device 100A. Graph H shows the simulation results of the insertion loss of the high-pass filter of filter device 100A. In Graph H, at marker m7, the insertion loss at a frequency of 0.96 GHz is relatively high, at -33.139 dB. At marker m8, the insertion loss at a frequency of 1.71 GHz is relatively low, at -0.417 dB. This shows that filter device 100A functions as a high-pass filter (HPF) that allows signals at a frequency of 1.71 GHz to pass.

[0057] (Way) (1) The filter device according to the present disclosure includes: an insulator having a pair of main surfaces facing each other and a side surface connecting the main surfaces; a first coil element forming a planar spiral coil within the insulator; a first external electrode electrically connected to one end of the first coil element; a second coil element overlapping at least a portion of the first coil element when viewed from above from one of the main surfaces and forming a spiral coil within the insulator; a second external electrode electrically connected to one end of the second coil element; a first electrode pattern electrically connected to the other end of the first coil element and the other end of the second coil element, and formed within the insulator; a second electrode pattern disposed opposite to the first electrode pattern and constituting a first capacitor; and A third external electrode is electrically connected to the second electrode pattern.

[0058] Thus, the filter device according to the present disclosure includes a first coil element forming a planar spiral coil and a second coil element forming a spiral coil, thereby suppressing the influence of magnetic field coupling between the two coil elements and achieving necessary attenuation characteristics even with miniaturization.

[0059] (2) In the filter device described in (1), the inductance of the first coil element is larger than the inductance of the second coil element.

[0060] (3) In the filter device described in (1) or (2), When viewed in plan from one of the principal surfaces, the axis of the planar spiral shape of the first coil element does not overlap with the axis of the spiral shape of the second coil element.

[0061] (4) In the filter device described in any one of (1) to (3), The first coil element includes a second portion forming a spiral coil in addition to a first portion forming a planar spiral coil.

[0062] (5) In the filter device described in (4), The insulator is formed by stacking a plurality of insulating substrates. The first portion of the first coil element and the second coil element are formed on different insulating substrates, The second portion of the first coil element and a portion of the second coil element are formed on the same insulating substrate.

[0063] (6) In the filter device described in any one of (1) to (5), The first coil element, the second coil element, and the first capacitor are arranged in this order from one surface side to the other surface side of the main surface.

[0064] (7) In the filter device described in any one of (1) to (3), When viewed from above from one of the main surfaces, the insulator includes a first region constituting a low-pass filter and a second region constituting a high-pass filter, the first region including the first coil element, the second coil element, and the first capacitor. The second area includes: a third electrode pattern electrically connected to the first external electrode; a fourth electrode pattern disposed opposite to the third electrode pattern and constituting a second capacitor; a third coil element, one end of which is electrically connected to the fourth electrode pattern and forms a spiral coil within the insulator; a fourth coil element, one end of which is electrically connected to the other end of the third coil element and forms a spiral coil within the insulator; a fourth external electrode electrically connected to the other end of the fourth coil element; a fifth coil element, one end of which is electrically connected to the other end of the third coil element and forms a spiral coil within the insulator; a fifth electrode pattern, electrically connected to the other end of the fifth coil element and formed within the insulator; a sixth electrode pattern disposed opposite to the fifth electrode pattern and constituting a third capacitor; and A fifth external electrode is electrically connected to the sixth electrode pattern.

[0065] (8) In the filter device described in (7), The first coil element further includes a second portion forming a spiral coil in addition to the first portion forming a planar spiral coil. The second portion is provided at a position closer to the second region than the second coil element.

[0066] The embodiments disclosed herein are to be considered in all respects as illustrative and non-limiting. The scope of the present invention is indicated not by the above description but by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims. Description of Reference Numerals

[0067] 3 insulator; 3a to 3i insulating substrates; 4a to 4f external electrodes; 100, 100A filter device; C1 first capacitor; C2 second capacitor; C3 third capacitor; C4 fourth capacitor; C5 fifth capacitor; C6 sixth capacitor; L1 first coil element; L2 second coil element; L3 third coil element; L4 fourth coil element; L5 fifth coil element.

Claims

1. A filter device comprising: an insulator having a pair of main surfaces facing each other and a side surface connecting the main surfaces; a first coil element forming a planar spiral coil within the insulator; a first external electrode electrically connected to one end of the first coil element; a second coil element overlapping at least a portion of the first coil element when viewed from above from one of the main surfaces and forming a spiral coil within the insulator; a second external electrode electrically connected to one end of the second coil element; a first electrode pattern electrically connected to the other end of the first coil element and the other end of the second coil element, and formed within the insulator; a second electrode pattern disposed opposite to the first electrode pattern and constituting a first capacitor; as well as A third external electrode is electrically connected to the second electrode pattern.

2. The filter device according to claim 1, wherein The inductance of the first coil element is greater than the inductance of the second coil element.

3. The filter device according to claim 1, wherein When viewed in plan from one of the principal surfaces, the axis of the planar spiral shape of the first coil element does not overlap with the axis of the spiral shape of the second coil element.

4. The filter device according to claim 1, wherein The first coil element includes a second portion forming a spiral coil in addition to a first portion forming a planar spiral coil.

5. The filter device according to claim 4, wherein The insulator is formed by stacking a plurality of insulating substrates. The first portion of the first coil element and the second coil element are formed on different insulating substrates, The second portion of the first coil element and a portion of the second coil element are formed on the same insulating substrate.

6. The filter device according to any one of claims 1 to 5, wherein The first coil element, the second coil element, and the first capacitor are arranged in this order from one surface side to the other surface side of the main surface.

7. The filter device according to any one of claims 1 to 3, wherein: When viewed from above from one of the main surfaces, the insulator includes a first region constituting a low-pass filter and a second region constituting a high-pass filter, the first region including the first coil element, the second coil element, and the first capacitor. The second area includes: a third electrode pattern electrically connected to the first external electrode; a fourth electrode pattern disposed opposite to the third electrode pattern and constituting a second capacitor; a third coil element, one end of which is electrically connected to the fourth electrode pattern and forms a spiral coil within the insulator; a fourth coil element, one end of which is electrically connected to the other end of the third coil element and forms a spiral coil within the insulator; a fourth external electrode electrically connected to the other end of the fourth coil element; a fifth coil element, one end of which is electrically connected to the other end of the third coil element and forms a spiral coil within the insulator; a fifth electrode pattern, electrically connected to the other end of the fifth coil element and formed within the insulator; a sixth electrode pattern, arranged opposite to the fifth electrode pattern, constituting a third capacitor; as well as A fifth external electrode is electrically connected to the sixth electrode pattern.

8. The filter device according to claim 7, wherein The first coil element further includes a second portion forming a spiral coil in addition to the first portion forming a planar spiral coil. The second portion is provided at a position closer to the second region than the second coil element.

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