JP2004312184A - Dual mode band-pass filter, duplexer and radio communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dual mode band-pass filter with an excellent degree of design freedom capable of easily obtaining a desired bandwidth and the filter characteristics at the center frequency. <P>SOLUTION: The dual mode band-pass filter 1 includes: a resonator electrode 3 provided to a dielectric substrate 2; input output coupling circuits 5, 6 coupled to the resonator electrode 3; ground electrodes 9, 10 arranged in opposition to the resonator electrode 3 via part of the dielectric substrate; and a via-hole electrode 4 projected orthogonally to the resonator electrode in the dielectric substrate from at least one direction of the resonator electrode 3 so that two resonance modes caused in the resonator electrode 3 are combined. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a dual mode bandpass filter used as a band filter in a communication device in a microwave to millimeter wave band, a duplexer using the dual mode bandpass filter, and a wireless communication device.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, various types of dual-mode bandpass filters have been proposed as bandpass filters used in a high-frequency region (see Non-Patent Document 1 below).
[0003]
In the dual-mode bandpass filter described in Non-Patent Document 1, the input line and the output line are arranged to be coupled to the resonator electrode so as to form a central angle of 90 ° with the center of the circular resonator pattern. In addition, an open-end stripline stub is provided at a central angle of 135 ° from the input line and the output line, thereby coupling the two resonance modes.
[0004]
In the above-mentioned Non-Patent Document 1, an input / output line is coupled to a center portion of two adjacent sides of a square resonator pattern, and a notch is provided in a corner portion facing the corner portion formed by the two sides. Discloses a structure in which two resonance modes are coupled.
[0005]
However, in the dual-mode bandpass filter as described in Non-Patent Document 1, the coupling between the two resonance modes cannot be sufficiently increased, and it is difficult to widen the passband. In addition, there are restrictions on the shape of the resonator pattern, and the degree of freedom in design is low.
[0006]
On the other hand, in the following Patent Document 1, two resonance modes generated in a resonator electrode are coupled by forming a through hole in a resonator electrode having an arbitrary shape and adjusting the size of the through hole. This indicates that characteristics as a dual mode bandpass filter can be obtained. In the dual mode bandpass filter described in Patent Literature 1, there is no restriction on the shape of the resonator electrode, and the pass band width can be increased.
[0007]
Patent Document 2 below discloses a dual mode bandpass filter that has excellent design flexibility and can easily obtain a desired bandwidth, similarly to the dual mode bandpass filter described in Patent Document 1. Is disclosed.
[0008]
As shown in FIGS. 19 and 20, in a dual mode bandpass filter 101 described in Patent Document 2, a resonator electrode 103 is formed on an upper surface 102a of a dielectric substrate 102. Further, a ground electrode 104 is formed on the entire lower surface of the dielectric substrate 102. Then, via hole electrodes 105 and 106 are formed to extend upward from the ground electrode 104. The via hole electrode 105 is configured such that the upper end does not reach the upper surface 102a of the dielectric substrate 102 as shown in FIG. The via hole electrode 106 has the same configuration. Here, a capacitor formed between the via-hole electrodes 105 and 106 and the resonator electrode 103 is added so that two resonance modes generated in the resonator electrode 103 are coupled.
[0009]
[Non-patent document 1]
"Miniature Dual Mode Microstrip Filter," J. Am. A. Curtis and S.M. J. Fiedzuisako 1991, IEEE MTT-S Digest
[Patent Document 1]
JP 2001-237609 A
[Patent Document 2]
JP-A-2002-171107
[0010]
[Problems to be solved by the invention]
In the dual mode bandpass filters described in Patent Documents 2 and 3, there is no restriction on the shape of the resonator electrode, the design flexibility is excellent, and a desired bandwidth can be easily obtained.
[0011]
However, in the dual-mode bandpass filter described in Patent Document 2, when input and output are coupled by a multilayer capacitor in order to adjust impedance, there is a problem that the shape of the input and output coupling line is limited. That is, since a through hole is formed in the resonator electrode, when the above-mentioned laminated capacitance is to be obtained by the input / output coupling line and the resonator electrode, the through hole is provided, so that the input / output coupling line is not provided. In some cases, the shape is limited, and a sufficiently large capacitance cannot be obtained, and the impedance cannot be increased in some cases.
[0012]
On the other hand, in the dual-mode bandpass filter described in Patent Document 2, since the capacitance of one of the two resonance modes is changed, a via extending from the ground plane if the resonator is separated from the ground plane. The length of the electrode has increased the number of processing steps.
[0013]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned disadvantages of the prior art, to reduce the number of processing steps, to provide a high degree of freedom in design, to easily obtain a desired bandwidth, and to easily obtain a desired impedance. An object of the present invention is to provide a dual-mode bandpass filter that can obtain desired frequency characteristics easily.
[0014]
[Means for Solving the Problems]
According to a broad aspect of the present invention, a dielectric substrate, a resonator electrode provided on the dielectric substrate, an input / output coupling circuit coupled to the resonator electrode, and a resonator electrode and a dielectric substrate A ground electrode disposed so as to face through a part thereof, so that two resonance modes generated in the resonator electrode are coupled from each other from at least one surface of the resonator electrode in the dielectric substrate. A dual-mode bandpass filter, comprising: a via-hole electrode protruding orthogonally to the resonator electrode.
[0015]
In a specific aspect of the dual-mode bandpass filter according to the present invention, the resonator portion where the via hole electrode is formed generates a relatively strong resonance electric field as compared with the remaining resonator electrodes.
[0016]
In another specific aspect of the dual mode bandpass filter according to the present invention, a plurality of the via hole electrodes are provided.
In the dual mode bandpass filter according to the present invention, the planar shape of the resonator electrode is not particularly limited, but may be, for example, a circle, a rectangle, a rhombus, or a polygon.
[0017]
In one more specific aspect of the dual-mode bandpass filter according to the present invention, the ground electrode has first and second ground electrodes disposed above and below a resonator electrode, thereby forming a triplate type filter. Is provided.
[0018]
The duplexer according to the present invention is characterized in that it is configured using a dual-mode bandpass filter configured according to the present invention, and the wireless communication device according to the present invention includes a dual-mode band configured according to the present invention. It has a pass filter or a duplexer constructed according to the invention.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.
[0020]
FIGS. 1A and 1B are a plan view of a dual mode bandpass filter according to a first embodiment of the present invention and a cross-sectional view taken along line AA in FIG.
The dual-mode bandpass filter 1 has a rectangular plate-shaped dielectric substrate 2. In the present embodiment, the dielectric substrate 2 is constituted by a multilayer ceramic substrate mainly composed of Ba, Al, and Si having a relative dielectric constant (εr = 6.27) and a dielectric loss tangent (tan δ = 0.001). . However, in the present embodiment and the following embodiments, the dielectric material constituting the dielectric substrate 2 is not particularly limited, and a synthetic resin such as a fluororesin, or an appropriate dielectric material containing Ba, Al, or Si as a main component. The dielectric substrate 2 can be formed using ceramics.
[0021]
The dimensions of the dielectric substrate 2 are not particularly limited, but are 4.5 × 3.2 × 1.0 mm in this embodiment.
A resonator electrode 3 is formed in the dielectric substrate 2. FIG. 1C is a plan sectional view of a portion where the resonator electrode 3 is provided. The resonator electrode 3 has a circular shape. In this embodiment, the resonator electrodes 3 are arranged such that the center of the circular resonator electrode 3 coincides with the center when the dielectric substrate 2 is viewed in plan. However, the resonator electrode 3 may be arranged at a position shifted from the center when the dielectric substrate 2 is viewed in plan.
[0022]
The dimensions of the resonator electrode 3 are not particularly limited, but the radius of the resonator electrode 3 is 1.1 mm.
In this embodiment, the via-hole electrode 4 is formed so as to protrude downward from the lower surface of the resonator electrode 3. The via hole electrode 4 has a columnar shape, and is formed such that the tip does not reach a ground electrode 10 described later. As shown in FIG. 1C, the formation position of the via hole electrode 4 is shifted from the center of the dielectric substrate 2 by a distance x in the short side direction of the dielectric substrate 2. In this embodiment, the distance x is 0.8 mm.
[0023]
The diameter of the via hole electrode 4 was 0.2 mm, and the length was 0.15 mm.
Above the resonator electrode 3, input / output coupling circuits 5, 6 are arranged so as to face each other via a dielectric substrate layer which is a part of the dielectric substrate 2. As shown in FIG. 2B, the input / output coupling circuits 5 and 6 are arranged so as to extend from the end faces 2c and 2d of the dielectric substrate 2 in the center direction. It is separated by a central region of the dielectric substrate.
[0024]
The input / output coupling circuits 5 and 6 partially face the resonator electrode 3 and are coupled to the resonator electrode 3 by capacitance.
Input / output electrodes 7 and 8 are formed on the end surfaces 2 c and 2 d of the dielectric substrate 2 so as to be electrically connected to the input / output coupling circuits 5 and 6. The input / output electrodes 7, 8 are formed so as to extend vertically in the center of the end faces 2c, 2d.
[0025]
On the other hand, in the dielectric substrate 2, a first ground electrode 9 is formed above a position where the input / output coupling circuits 5, 6 are provided. The ground electrode 9 is formed so as not to reach the end faces 2c and 2d.
[0026]
Similarly, a second ground electrode 10 shown in FIG. 2A is formed below the resonator electrode 3. The second ground electrode 10 is also formed so as not to reach the end faces 2c and 2d.
[0027]
Ground electrodes 12 and 13 are also formed on a pair of side surfaces of the dielectric substrate 2.
Therefore, all of the ground electrodes 9, 10, 12, and 13 face the resonator electrode 3 via a part of the dielectric substrate 2, and in particular, the ground electrodes 9 and 10 resonate via the dielectric substrate layer. The device electrode 3 is opposed to the surface.
[0028]
The resonator electrode 3, the via hole electrode 4, the input / output coupling circuits 5, 6, the input / output electrodes 7, 8, and the ground electrodes 9, 10, 12, 13 are made of an appropriate conductive material. In this example, the semiconductor device is made of Cu.
[0029]
In the dual-mode bandpass filter 1, an input voltage is applied between one of the input / output coupling circuits 5 and 6 and the ground electrodes 9 and 10, and the other of the input / output coupling circuits 5 and 6 and the ground electrodes 9 and 10 are applied. The output is taken between. In this case, a plurality of resonance modes occur in the resonator electrode 3, but the via-hole electrode 4 is arranged at a position shifted from the center of the resonator electrode 3, and resonance occurs in a portion where the via-hole electrode 4 is provided. The electric field is enhanced as compared with the resonator electrode portion where the via hole electrode 4 is not provided. Further, since the via hole electrode 4 is arranged so that the two resonance modes are coupled, the two resonance modes are coupled, and the other of the input / output coupling circuits 5 and 6 and the ground electrodes 9 and 10 are connected. Characteristics as a bandpass filter can be taken out between them.
[0030]
This will be described with reference to FIG. FIG. 3 is a diagram illustrating frequency characteristics of the dual mode bandpass filter of the present embodiment. In FIG. 3, the dashed line indicates the reflection characteristics, and the solid line indicates the transmission characteristics. As is clear from FIG. 3, according to the present embodiment, it is possible to obtain a dual-mode bandpass filter having good frequency characteristics in the 28 GHz band. It is considered that this is because the distribution of the resonance electric field in the resonator electrode 3 was partially strengthened by the above-described via hole electrode 4 and the two resonance modes were coupled.
[0031]
In the dual-mode bandpass filter 1 of the present embodiment, a dual-mode bandpass filter can be configured only by providing the via-hole electrode 4 on the resonator electrode 3 as described above. Accordingly, there is no restriction on the coupling positions of the input / output coupling circuits 5 and 6, and the shape of the resonator electrode 3 is not particularly limited. Therefore, the dual-mode bandpass filter 1 greatly enhances the design flexibility. In addition, by adjusting the size and position of the via-hole electrode 4, it is possible to easily provide a dual-mode bandpass filter having different bandwidths and frequency characteristics, as will be apparent from embodiments described later.
[0032]
FIG. 4 is a front sectional view for explaining a dual mode bandpass filter according to a second embodiment of the present invention, and is a diagram corresponding to FIG. 1 (c) showing the first embodiment. FIG. 3 is a plan sectional view of a portion where a resonator electrode is formed. In the dual mode bandpass filter 11 of the second embodiment, the dual mode bandpass filter of the first embodiment is changed except that the formation position of the via hole electrode 4 is changed as shown in FIG. 1 is configured in the same manner.
[0033]
That is, in the dual-mode bandpass filter 11, the formation position of the via hole electrode 4 is a distance x1 from the center of the resonator electrode 3 in the short side direction of the dielectric substrate 2 and a distance y1 in the long side direction of the dielectric substrate 2. The position is shifted. Here, the distance x1 is 0.8 mm and the distance y1 is 0.2 mm. FIG. 5 shows the frequency characteristics of the dual mode bandpass filter 11 configured as described above. In FIG. 5, the frequency characteristics of the dual mode bandpass filter 1 of the first embodiment are also shown for comparison.
[0034]
In FIG. 5, the dashed line and the solid line show the reflection characteristics and the pass characteristics of the first dual mode bandpass filter, respectively, and the broken lines B1 and B2 show the reflection characteristics of the dual mode bandpass filter of the second embodiment. And transmission characteristics.
[0035]
As is clear from FIG. 5, even when the formation position of the via hole electrode 4 is changed as described above, it is possible to obtain the characteristics as a dual mode bandpass filter as in the case of the first embodiment. It can be seen that the frequency characteristic can be changed by adjusting the position of the via hole electrode 4.
[0036]
FIG. 6 is a plan sectional view of a dual-mode bandpass filter according to a third embodiment of the present invention, and is a diagram corresponding to FIG. 1C shown for the first embodiment. In the dual-mode bandpass filter 21 of the third embodiment, a plurality of via-hole electrodes 4a and 4b are formed so as to project downward from the lower surface of the resonator electrode 3. In the dual mode bandpass filter 1 of the present invention, a plurality of via hole electrodes 4 a and 4 b may be provided so as to protrude downward from the lower surface of the resonator electrode 3.
[0037]
FIG. 7 is a diagram showing the frequency characteristics of the dual mode bandpass filter 21 of the third embodiment and the frequency characteristics of the dual mode bandpass filter 1 of the first embodiment. The alternate long and short dash line and the solid line show the reflection and pass characteristics of the dual mode bandpass filter 1 of the first embodiment, and the broken lines C1 and C2 show the reflection characteristics of the dual mode bandpass filter 21 of the third embodiment. And transmission characteristics.
[0038]
As described above, in the dual mode bandpass filter of the present invention, the characteristics as a dual mode bandpass filter can be obtained by forming the via hole electrode. The characteristics can be changed in various ways. This will be described with reference to FIGS.
[0039]
In the dual mode bandpass filter 1 of the first embodiment, as shown in FIG. 8, the distance x3 in the short side direction of the dielectric substrate 2 from the center of the resonator electrode 3 of the via hole electrode 4 is set to 0, 0.4 mm and Three types of dual-mode bandpass filters having a size of 0.8 mm were manufactured. FIGS. 9 and 10 are diagrams respectively showing the reflection characteristics and the pass characteristics of the three types of dual mode bandpass filters obtained in this way.
[0040]
As is clear from FIGS. 9 and 10, by shifting the via hole electrode 4 from the center of the dielectric substrate 2 along the short side direction of the dielectric substrate 2, the bandwidth changes and the distance x3 increases. It can be seen that the bandwidth increases as the bandwidth increases. Therefore, it can be seen that the bandwidth can be easily adjusted by shifting the via hole electrode 4 from the center of the resonator electrode 3 along the short side direction of the dielectric substrate 2.
[0041]
In the dual mode bandpass filter 1, the frequency can also be adjusted by changing the size of the cross section of the via hole electrode 4. This will be described with reference to FIGS. As shown in FIG. 11, in the dual mode bandpass filter 1, the via hole electrode 4 is arranged at the center of the resonator electrode 3, and the diameter R of the via hole electrode 4 is set to 0.1 mm, 0.2 mm, 0.3 mm, Four types of dual mode bandpass filters having a thickness of 0.4 mm were produced. FIGS. 12 and 13 show the reflection characteristics and the transmission characteristics of the four types of dual-mode bandpass filters manufactured as described above.
[0042]
As is clear from FIGS. 12 and 13, it is understood that the center frequency of the filter increases as the diameter of the via hole electrode 4 increases. That is, it can be seen that by increasing the cross-sectional area of the via hole electrode 4, frequency adjustment can be performed so as to increase the center frequency of the filter.
[0043]
In the dual-mode bandpass filter 1, the frequency can also be adjusted by adjusting the length of the via-hole electrode 4. As shown in FIGS. 14A and 14B, in the dual mode bandpass filter 1, the via hole electrode 4 is arranged at the center of the resonator electrode 3, and the length of the via hole electrode 4, that is, the via hole electrode 4 Three types of dual-mode bandpass filters 1 having lengths z of 0.125, 0.15, and 0.175 mm from the lower surface of the resonator electrode 3 to the tip of the via hole electrode 4 were manufactured. FIG. 15 and FIG. 16 are diagrams respectively showing the reflection characteristics and the pass characteristics of the three types of dual mode bandpass filters thus configured. As is clear from FIGS. 15 and 16, it is understood that the bandwidth can be increased by increasing the length Z of the via-hole electrode 4.
[0044]
As apparent from FIGS. 8 to 16 described above, in the dual mode bandpass filter 1, the position of the via hole electrode 4 with respect to the resonator electrode 3, the diameter of the via hole electrode 4, the length of the via hole electrode 4, and the like are changed. Thus, it can be seen that a dual-mode bandpass filter having various center frequencies and bandwidths can be easily configured as the dual-mode bandpass filter 1.
[0045]
Further, as is apparent from the third embodiment described above, it can be seen that bandpass filters having various frequency characteristics can be easily provided by providing a plurality of via hole electrodes 4a and 4b.
[0046]
In the above-described embodiment and experimental example, the resonator electrode 3 has a circular shape. However, as shown in FIGS. 17A and 17B, a polygonal resonator electrode such as a triangle or a pentagon is used. 31 and 32 may be used, and the planar shape of the resonator electrode 3 is not particularly limited, and the resonator electrode 3 may be configured so that the periphery has an irregular shape.
[0047]
Also, the cross-sectional shape of the via hole electrode 4 is not limited to a circle but may be an appropriate shape such as a rectangle.
Further, in the dual-mode bandpass filter 1, the via-hole electrode 4 is bonded to the lower surface of the resonator electrode 3, but a via-hole electrode extending in a direction orthogonal to the resonator electrode 3 is provided on the upper surface of the resonator electrode 3. Is also good. Further, via-hole electrodes extending in a direction orthogonal to the resonator electrode 3 may be provided on both the upper surface and the lower surface of the resonator electrode 3.
[0048]
Further, the input / output coupling circuits 5 and 6 may be arranged at the same height position as the resonator electrode 3 and separated from the resonator electrode 3.
In the dual mode bandpass filter 1, ground electrodes 9 and 10 are formed above and below the resonator electrode 3 to form a triplate structure. However, the first and second ground electrodes are formed on the dielectric substrate 2. It may be formed on each of the upper surface 2a and the lower surface 2b.
[0049]
Next, an embodiment of a duplexer and a wireless communication device using a dual mode bandpass filter according to the present invention will be described with reference to FIG.
FIG. 18 is a block diagram showing a main part of a wireless communication apparatus 300 having a duplexer DPX using the dual mode bandpass filter.
[0050]
The duplexer DPX of the present embodiment has first and second bandpass filters BPF1 and BPF2 composed of dual mode bandpass filters configured according to the present invention. One ends of the first and second bandpass filters BPF1 and BPF2 are connected to the first and second ports P1 and P2 of the duplexer DPX, respectively, and the other ends of the bandpass filters BPF1 and BPF2 are commonly connected. , And the third port P3 of the duplexer DPX.
[0051]
Further, the first port P1 is connected to the transmitting unit TX, and the second port P2 is connected to the receiving unit RX. Further, the third port P3 of the duplexer DPX is connected to the antenna ANT.
[0052]
The duplexer of the present embodiment has the first and second band-pass filters BPF1 and BPF2 composed of the dual-mode band-pass filter of the present invention, so that the duplexer is excellent in design flexibility and easily obtains a desired bandwidth. be able to. In addition, since the wireless communication device 300 includes the duplexer DPX, communication quality can be easily improved.
[0053]
【The invention's effect】
In the dual-mode bandpass filter according to the present invention, the resonator electrode is disposed in the dielectric substrate, and the resonator electrode is provided from at least one surface of the resonator electrode so that two resonance modes of the resonator electrode are coupled. A via-hole electrode is arranged so as to be orthogonal to the electrode, whereby two resonance modes are coupled to obtain a characteristic as a dual-mode bandpass filter. Therefore, there are few restrictions on the coupling point of the input / output coupling circuit to the resonator electrode, and by changing the number, formation position, dimensions, etc. of the via-hole electrodes, a dual-mode bandpass filter with various bandwidths and center frequencies can be easily formed. Can be configured.
[0054]
Therefore, according to the present invention, not only the degree of freedom in design can be greatly increased, but also a dual mode bandpass filter having a desired bandwidth and center frequency can be easily provided.
[0055]
In the case where a plurality of the via hole electrodes are provided, it is possible to provide a dual mode bandpass filter having further various frequency characteristics by adjusting the number, position, and size of the plurality of via hole electrodes. . When a ground electrode is further provided so as to face the resonator electrode via a part of the dielectric substrate, the resonance electric field can be effectively confined in a portion surrounded by the ground electrode. .
[0056]
In particular, when the ground electrode has the first and second ground electrodes arranged above and below the resonator, a dual-mode bandpass filter having a triplate structure can be provided according to the present invention.
[0057]
Since the duplexer according to the present invention includes the dual-mode bandpass filter configured according to the present invention, the degree of freedom in design is increased, and a desired frequency characteristic such as a bandwidth can be easily obtained.
[0058]
Further, since the wireless communication device according to the present invention has the dual-mode bandpass filter or the duplexer configured according to the present invention, the wireless communication device is excellent in design flexibility and can easily obtain a desired frequency characteristic. The communication quality can be easily increased.
[Brief description of the drawings]
1A is a plan view of a dual mode bandpass filter according to a first embodiment of the present invention, FIG. 1B is a cross-sectional view taken along line AA in FIG. 1A, and FIG. FIG. 4 is an enlarged cross-sectional plan view of a portion where an electrode is formed.
FIG. 2A is a schematic plan sectional view showing a shape of a first ground electrode of the dual mode bandpass filter according to the first embodiment, and FIG. 2B is provided with an input / output coupling circuit. (C) is a plan sectional view at a height position where a resonator electrode is provided, and (d) is a schematic plan sectional view showing a shape of a lower second ground electrode.
FIG. 3 is a diagram illustrating frequency characteristics of the dual mode bandpass filter according to the first embodiment.
FIG. 4 is a schematic plan sectional view illustrating a dual mode bandpass filter according to a second embodiment.
FIG. 5 is a diagram illustrating frequency characteristics of the dual mode bandpass filters according to the second embodiment and the first embodiment.
FIG. 6 is a schematic plan sectional view illustrating a dual mode bandpass filter according to a third embodiment.
FIG. 7 is a diagram illustrating frequency characteristics of the dual mode bandpass filters according to the third embodiment and the first embodiment.
FIG. 8 is a schematic plan sectional view illustrating a structure in which the position of a via-hole electrode is changed in the dual mode bandpass filter of the first embodiment.
FIG. 9 is a diagram showing a change in reflection characteristics when a position of a via hole electrode is shifted in a short side direction of a dielectric substrate.
FIG. 10 is a diagram showing a change in transmission characteristics when a position of a via hole electrode is shifted in a short side direction of a dielectric substrate.
FIG. 11 is a schematic plan sectional view illustrating a structure in which the diameter of a via hole electrode is changed.
FIG. 12 is a diagram showing a change in reflection characteristics when the diameter of a via hole electrode is changed.
FIG. 13 is a diagram showing a change in transmission characteristics when the diameter of a via hole electrode is changed.
14A and 14B are a schematic plan sectional view and a schematic front sectional view for explaining a structure in which the length of a via hole electrode is changed.
FIG. 15 is a diagram showing a change in reflection characteristics when the length of a via hole electrode is changed.
FIG. 16 is a diagram showing a change in transmission characteristics when the length of a via hole electrode is changed.
FIGS. 17A and 17B are schematic plan views for explaining a modification of the planar shape of the resonator electrode.
FIG. 18 is a schematic block diagram illustrating a wireless communication device incorporating a duplexer configured according to the present invention.
FIG. 19 is a perspective view illustrating an example of a conventional dual mode bandpass filter.
FIG. 20 is a schematic front sectional view showing a main part of the dual mode bandpass filter shown in FIG. 19;
[Explanation of symbols]
1: Dual mode bandpass filter
2. Dielectric substrate
2a ... upper surface
2b ... lower surface
2c, 2d ... end face
2e, 2f ... side surface
3. Resonator electrode
4: Via hole electrode
4a, 4b ... via hole electrode
5, 6 ... I / O coupling circuit
7, 8 ... input / output electrodes
9, 10 ... first and second ground electrodes
11 ... Dual mode band pass filter
12, 13 ... ground electrode
21 ... Dual mode bandpass filter
31, 32 ... resonator electrodes
300 wireless communication device
DPX ... Duplexer
P1 to P3: first to third ports
BPF1, BPF2 ... First and second bandpass filters
ANT ... antenna
RX: Receiver
TX ... transmission unit

Claims (7)

A dielectric substrate;
A resonator electrode provided on the dielectric substrate,
An input / output coupling circuit coupled to the resonator electrode;
A ground electrode disposed so as to face the resonator electrode through a part of the dielectric substrate,
A via hole electrode protruding from at least one surface of the resonator electrode so as to be orthogonal to the resonator electrode in the dielectric substrate so that two resonance modes generated in the resonator electrode are coupled. Features a dual-mode bandpass filter. 2. The dual-mode bandpass filter according to claim 1, wherein the resonator portion in which the via hole electrode is formed is a resonator electrode portion that generates a relatively strong resonance electric field as compared with the remaining resonator electrodes. 3. 3. The dual mode bandpass filter according to claim 1, wherein a plurality of said via hole electrodes are provided. The dual mode bandpass filter according to any one of claims 1 to 3, wherein the planar shape of the resonator electrode is a circle, a rectangle, a rhombus, or a polygon. 5. The dual-mode bandpass filter according to claim 1, wherein said ground electrode has first and second ground electrodes disposed above and below said resonator electrode. A duplexer comprising at least one dual-mode bandpass filter according to claim 1. A wireless communication device comprising at least one of the dual-mode bandpass filter according to claim 1 and the duplexer according to claim 6.

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