JP2010239461A - Dual-mode band pass filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dual-mode band pass filter which has improved Q0, low loss and further, has small variation in electrical characteristics, such as filter characteristics. <P>SOLUTION: In the dual-mode band pass filter 1, at first and second intermediate height positions on a dielectric substrate 2, a first resonator electrode 3 and a second resonator electrode 4 are formed, respectively, and the first and second resonator electrodes 3, 4 have openings 3a, 4a at the center, respectively, so as to obtain pass bands by canceling degeneration of a plurality of resonance modes, and the resonator electrodes 3, 4 are then electrically connected by a resonator connecting electrode 5 inside the dielectric substrate 2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a dual mode bandpass filter used as a bandpass filter in, for example, a microwave to millimeter wave band communication device, and more specifically, provides an opening in a metal film to solve the degeneration of a plurality of resonance modes. Thus, the present invention relates to a dual mode bandpass filter in which a passband is formed.

  For example, a dual-mode bandpass filter in which a passband is formed by solving the degeneration of a plurality of resonance modes that occur in a metal film is known as a bandpass filter for microwave to millimeterwave bands. For example, Patent Document 1 below discloses a dual mode bandpass filter shown in FIGS. 13 (a) to 13 (c). This dual mode bandpass filter 1001 has a dielectric substrate 1002. A first ground electrode 1003 and input / output electrodes 1004 and 1005 are formed on the upper surface of the dielectric substrate 1002. A second ground electrode 1006 is formed on the lower surface of the dielectric substrate 1002.

  Ground electrodes 1007 and 1008 are formed on the side surface of the dielectric substrate 1002. A resonator electrode 1009 is formed at an intermediate height position of the dielectric substrate 1002. The resonator electrode 1009 has an opening 1009a. By forming the opening 1009a in the rectangular resonator electrode 1009, the resonator electrode 1009 is decoupled from the resonance mode of vibration propagating in the long side direction and the resonance mode of vibration propagating in the short side direction. Thus, characteristics as a band pass filter can be obtained. A resonator electrode 1009 is disposed between the first and second ground electrodes 1005 and 1006, thereby forming a triplate structure.

Japanese Patent Laid-Open No. 2002-28086

  In the dual-mode bandpass filter 1001 described in Patent Document 1, in the resonator electrode 1009, current concentrates on the portion along the long side and the short side of the resonator electrode 1009 and in the vicinity thereof. Further, the resonance frequency f0 in the resonator electrode 1009 depends on the outer shape of the resonator electrode 1009, in particular, the length of the long side and the short side.

  In the dual mode bandpass filter, it is necessary to increase the unloaded Q of the resonator, that is, Q0 in order to reduce the insertion loss. The Q0 of the resonator depends on the electrode thickness of the resonator electrode 1009 and the shape of the outer edge of the resonator electrode. For example, Q0 can be increased by increasing the electrode thickness of the resonator electrode 1009. However, if the electrode film thickness is too thick, a high Q0 could not actually be obtained due to the skin effect at high frequencies.

Furthermore, in the resonator electrode 1009, and the edge of the opening 1009a, when the interval _{W 0} between the outer edge of the resonator electrode 1009 becomes narrow, the portion which is narrow, current concentration occurs. This also has a problem that Q0 is lowered.

  The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, to increase the Q0 which is the no-load Q of the resonator, to reduce the loss of the filter, and to reduce the variation in electrical characteristics. It is to provide a dual mode bandpass filter that can be made small.

  A dual mode bandpass filter according to the present invention is formed partially at a dielectric substrate having first and second main surfaces and at a first height position of the dielectric substrate, and an input signal is When applied, a plurality of resonance modes are generated, a first resonator electrode in which an opening for coupling the plurality of resonance modes is formed, a first height position of the dielectric substrate, Are partially formed at different second height positions, and a plurality of resonance modes are generated when an input signal is applied, and an opening for coupling the plurality of resonance modes is formed. A second resonator electrode; and a plurality of first ground electrodes formed on or in the first main surface of the dielectric substrate so as to face the first resonator electrode via a dielectric layer; It faces the second resonator electrode through a dielectric layer. A plurality of second ground electrodes formed on or inside the second main surface of the dielectric substrate, and a ground provided so as to electrically connect the first and second ground electrodes. Connection electrodes, input / output terminals formed on the first or second main surface of the dielectric substrate, and the first and second resonator electrodes at different portions of the first and second resonator electrodes A pair of input / output coupling circuits coupled, the input / output terminal, an input / output connection electrode electrically connecting the input / output coupling circuit, and the first and second resonator electrodes are electrically connected And a resonator connection electrode provided in the dielectric substrate. In the present invention, the plurality of first ground electrodes and the plurality of second ground electrodes are arranged above and below the first and second resonator electrodes to constitute a triplate structure.

  In a specific aspect of the dual-mode bandpass filter according to the present invention, a notch extending outward from the edge of the opening is formed so that the openings of the first and second resonator electrodes can solve the degeneration of the resonance mode. Have. By forming this notch, the first and second resonator electrodes can degenerate a plurality of resonance modes and form a passband.

  In another specific aspect of the dual mode bandpass filter according to the present invention, the resonator connection electrode is disposed in a portion of the resonator electrode where the degree of current concentration is stronger than the remaining portion. In this case, when a current flows through the resonator connection electrode, a magnetic field is generated, and the resonator connection electrode functions as an inductor. For this reason, the resonance frequency of the resonator electrode is lowered, and in order to return the resonance frequency to the predetermined resonance frequency, the opening portion may be reduced. As a result, the gap between the outer peripheral edge of the resonator electrode and the opening portion is reduced. What is necessary is just to widen an interval. Therefore, the degree of current concentration can be relaxed, and Q0 can be further increased.

  In still another specific aspect of the dual mode bandpass filter according to the present invention, the resonator electrode has a rectangular shape, and the portion where the current concentration is strong is a corner portion of the resonator electrode, The resonator connection electrode is disposed in at least one corner portion. In this case, Q0 can be further increased.

  According to still another specific aspect of the dual-mode bandpass filter according to the present invention, a plurality of the resonator connection electrodes are provided, and at least one resonator connection electrode extends in a direction in which the resonator connection electrode extends. The area of the orthogonal cross section is different from the area of the cross section of the remaining resonator connection electrodes. In this case, the value of inductance generated by the resonator connection electrode can be adjusted, and thereby the resonance characteristics and the filter characteristics can be adjusted.

  According to still another specific aspect of the dual-mode bandpass filter according to the present invention, the first and second resonator electrodes have substantially the same size, and the first resonator electrode and the second resonator. It arrange | positions so that an electrode may overlap in planar view. In this case, the variation in the electrical characteristics of the dual mode bandpass filter can be further reduced.

  According to still another specific aspect of the dual-mode bandpass filter according to the present invention, at least one of the first and second resonator electrodes is disposed in the opening and insulated from the resonator electrode. And a third ground connection electrode provided to extend in the thickness direction of the dielectric substrate so as to electrically connect the inner electrode to the first or second ground electrode. Is further provided. In this case, the attenuation characteristic on the high frequency side can be further enhanced.

  In still another specific aspect of the dual-mode bandpass filter according to the present invention, the input / output coupling circuit is formed at a height position between the first resonator electrode and the second resonator electrode. Has been. In this case, the balance of the coupling degree of the input / output coupling circuit with respect to the first resonance electrode and the second resonance electrode can be increased, and the coupling can be strengthened. Therefore, the filter characteristics can be adjusted in a wider range.

  In the dual mode bandpass filter according to the present invention, the first resonator electrode provided at the first height position of the dielectric substrate and the second height position different from the first height position are provided. The first and second resonator electrodes are each decoupled from the plurality of resonance modes, and a characteristic as a bandpass filter is obtained. The resonance current can be distributed to the first and second resonator electrodes, whereby Q0 can be increased and the loss can be reduced. In addition, since each of the first resonator electrode and the second resonator electrode has characteristics as a bandpass filter, the influence of variations in electrode formation can be reduced, and Q0 and resonators can be reduced. Variations in the resonator f0 and resonance mode coupling amount due to the electrodes can be reduced, and variations in filter characteristics can be reduced.

1 is an exploded perspective view of a dual mode bandpass filter according to a first embodiment of the present invention. (A) is a typical perspective view for demonstrating the 1st, 2nd resonator electrode of the dual mode band pass filter of 1st Embodiment, (b) is a 2nd resonator electrode. FIG. (A) is a schematic plan view showing a current distribution in the first resonator electrode, and (b) is a schematic plan view showing a current intensity distribution in the second resonator electrode. It is a figure which shows the attenuation amount-frequency characteristic of each layer in the structure which laminated | stacked the several resonator electrode. It is a figure which shows the attenuation amount-frequency characteristic of each layer in the structure which laminated | stacked the several resonator electrode, and is a figure which expands and shows the frequency characteristic shown in FIG. It is a figure which shows the attenuation amount-frequency characteristic of one Embodiment of this invention, and the attenuation amount-frequency characteristic of the dual mode band pass filter which has only the resonator electrode of one layer prepared for the comparison. (A)-(d) is each typical top view for demonstrating the example of the connection position of the via-hole electrode to a resonator electrode, respectively. In one Embodiment of this invention, it is a figure which shows the attenuation amount-frequency characteristic in each modification which changed the position of the resonator connection electrode. (A) is a schematic plan view of a resonator electrode for explaining an example in which the resonator connection electrode is provided in a portion where the current concentration degree is weak, and (b) is a resonator in the portion where the current concentration degree is strong. It is a typical top view for demonstrating the structure which provided the connection electrode. Each attenuation-frequency characteristic of the dual mode band-pass filter of the comparative example, the embodiment in which the resonator connection electrode is arranged in the portion where the current concentration degree is weak, and the embodiment in which the resonator connection electrode is arranged in the portion where the current concentration degree is strong FIG. In one embodiment of the present invention, the resonator connection electrode connecting the first and second resonator electrodes is provided in a strong portion and the second embodiment in which the current concentration degree is weak. It is a figure which shows the attenuation amount-frequency characteristic of each dual mode band pass filter of 1st Embodiment. In one embodiment of the present invention, the resonator connection electrode connecting the first and second resonator electrodes is provided in a strong portion and the second embodiment in which the current concentration degree is weak. It is a figure which shows the attenuation amount-frequency characteristic of each dual mode band pass filter of 1st Embodiment which is, and is an enlarged view of the attenuation amount-frequency characteristic shown in FIG. (A)-(c) is a perspective view, front sectional drawing, and top view of the conventional dual mode band pass filter.

  Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

  FIG. 1 is an exploded perspective view of a dual mode bandpass filter according to an embodiment of the present invention. The dual mode bandpass filter 1 has a dielectric substrate 2. In FIG. 1, each layer of the dielectric substrate 2 is schematically disassembled. The dielectric substrate 2 has a first main surface 2a that is an upper surface, a second main surface 2b that is a lower surface, side surfaces 2c and 2d, and end surfaces 2e and 2f.

  The dielectric substrate 2 has a rectangular plate shape. In addition, in this embodiment, the dielectric substrate 2 can be formed of an appropriate dielectric material such as an LTCC (Low Temperature Coated Ceramics) substrate, and a resin such as a liquid crystal polymer. A substrate may be used.

  A first resonator electrode 3 is formed at a first height position inside the dielectric substrate 2. The second resonator electrode 4 is formed at a second intermediate height position different from the first intermediate height position. In the present embodiment, the first intermediate height position is located on the first main surface 2a side, and the second intermediate height position is located on the second main surface 2b side. The 1st resonator electrode 3 and the 2nd resonator electrode 4 are arrange | positioned so that it may overlap through a dielectric substrate layer.

  FIG. 2A is a schematic perspective view showing the laminated structure of the first and second resonator electrodes 3 and 4.

  As shown in FIG. 2A, the first resonator electrode 3 has an opening 3a in the center. The opening 3a has a rectangular shape located at the center, and a rectangular notch 3b smaller than the rectangular portion of the opening 3a is formed at the center of each side of the opening 3a. Yes. That is, the notch 3b is formed in each side of the opening 3a so as to be continuous with the rectangular opening 3a.

  The second resonator electrode 4 has a shape substantially equal to that of the first resonator electrode 3. Accordingly, the second resonator electrode 4 has a rectangular opening 4a, as in the first resonator electrode 3, as shown in FIG. A rectangular notch 4b is opened at the center of each side of the opening 4a.

  The first and second resonator electrodes 3 and 4 have substantially the same shape, and are disposed so as to overlap when the dielectric substrate 2 is viewed in plan.

  As will be described later, since the resonator electrodes 3 and 4 have substantially the same shape and are positioned so as to overlap when viewed in plan, the formation variations of the resonator electrodes 3 and 4 are averaged, that is, the electrodes Since variations in formation can be absorbed, variations in electrical characteristics can be reduced.

  In the resonator electrodes 3 and 4, when an input signal is applied, the first and second resonance modes are generated. The resonance currents in the resonance modes have a distribution. FIGS. 3A and 3B are schematic plan views showing current distributions in the first and second resonator electrodes 3 and 4. Here, it means that the current flows weakly in the order of the areas indicated by hatching X1 to X4 in FIGS. 3 (a) and 3 (b). That is, a region indicated by hatching X1 is a portion where the current flows most strongly.

  FIGS. 3A and 3B are diagrams showing current distributions in the first and second resonator electrodes 3 and 4, respectively. Here, the shapes of the openings 3a and 4a are clearly shown. 3A and 3B are also referred to in the description of the openings 3a and 4a.

  A circle Z inside each corner portion shown in FIGS. 2B and 3B is a resonator composed of via-hole electrodes connecting the first and second resonator electrodes 3 and 4, as shown in FIG. This corresponds to the portion where the connection electrode 5 is located. That is, the lower ends of the resonator connection electrodes 5 are respectively connected to the vicinity of the four corner portions of the rectangular resonator electrode 4. The resonator connection electrode 5 is formed of a via hole electrode extending in the thickness direction of the dielectric substrate layer. The upper end of the resonator connection electrode 5 is electrically connected to the lower surface of the first resonator electrode 3. Therefore, the first and second resonator electrodes 3 and 4 are electrically connected by the resonator connection electrode 5.

  On the other hand, in the present embodiment, the input / output coupling electrodes 8 and 9 are formed at the third intermediate height position, which is below the second intermediate height position. The input / output coupling electrodes 8 and 9 are provided so as to be capacitively coupled to the first and second resonator electrodes 3 and 4, respectively. In this embodiment, the input / output coupling electrodes 8 and 9 are provided at a third intermediate height position different from the first and second intermediate height positions, but are provided at other height positions. May be. That is, the input / output coupling electrodes 8 and 9 may be provided at the first intermediate height position, or may be provided at the second intermediate height position. Alternatively, preferably, the input / output coupling electrodes 8 and 9 are provided at a height position between the first and second intermediate height positions.

  More preferably, input / output coupling electrodes 8 and 9 are provided at a central height position between the first and second intermediate heights. Thereby, as shown in FIG. 1B, the first and second resonator electrodes 3 and 4 provided at the first and second intermediate height positions and the input / output coupling electrodes 8 and 9 The distances can be made equal, and the variation in electrical characteristics can be further reduced.

  As shown in FIG. 1, connection electrodes 10 and 11 whose upper ends are connected to the lower surfaces of the input / output coupling electrodes 8 and 9 are formed of via-hole electrodes. The lower ends of the connection electrodes 10, 11 electrically connected to the input / output coupling electrodes 8, 9 reach the lower surface 2 b of the dielectric substrate 2, and the input / output electrodes 12 formed on the lower surface of the dielectric substrate 2. , 13 are electrically connected.

  On the other hand, a first ground electrode 14 is formed above the first intermediate height position so as to sandwich the first and second intermediate height positions, and a second ground electrode 15 is formed below the first intermediate height position. Is formed. That is, the first and second resonator electrodes 3 and 4 are sandwiched between the first and second ground electrodes 14 and 15. Therefore, the dual mode bandpass filter 1 of this embodiment has a triplate structure in which the resonator electrode portion is sandwiched between the upper and lower ground electrodes.

  A plurality of ground connection electrodes 16 that electrically connect the first ground electrode 14 and the second ground electrode 15 are formed of via-hole electrodes. That is, the upper end of each ground connection electrode 16 is electrically connected to the lower surface of the first ground electrode 14, the lower end is electrically connected to the second ground electrode 15, and the second It penetrates the ground electrode 15 and reaches the lower surface of the dielectric substrate 2. Then, it is electrically connected to a third ground electrode 17 formed on the lower surface of the dielectric substrate 2. The third ground electrode 17 covers not only the lower surface 2b of the dielectric substrate 2 but also the side surfaces 2c and 2d of the dielectric substrate 2, and the upper surface 2a of the dielectric substrate 2 is provided on each long side of the pair of long sides. It is provided so as to form a stripe-shaped region along.

  Accordingly, the periphery of the dielectric substrate 2 is covered with the third ground electrode 17 except for the central portion in the width direction of the upper surface 2a and the end surfaces 2e and 2f. On the lower surface 2b, the aforementioned input / output electrodes 12 and 13 are formed so as to be electrically insulated from the third ground electrode 17.

  In the present embodiment, the first ground electrode 14 and the second ground electrode 15 are formed in the dielectric substrate, but may be formed on the outer surface of the dielectric substrate. That is, the first ground electrode 14 is formed on the upper surface 2 a of the dielectric substrate 2, and the second ground electrode 15 is formed on the lower surface 2 b of the dielectric substrate 2, and also serves as a part of the third ground electrode 17. Also good.

  The electrode material for forming the electrodes such as the resonator electrodes 3 and 4 and the ground electrodes 14, 15, and 17 is not particularly limited. An electrode can be formed. Further, the resonator connection electrode 5 made of via-hole electrodes, the input / output connection connection electrodes 10 and 11, the ground connection electrode 16, and the like can also be formed of an appropriate conductive material similar to the above.

  In actual production, an electrode film formed at each height position is formed on the dielectric sheet forming each layer by an appropriate method. About this formation method, it can carry out by appropriate methods, such as thin film formation methods, such as vapor deposition, plating, or sputtering, or application | coating and hardening of an electrically conductive paste. Furthermore, by forming a through hole in the green sheet and filling the through hole with a conductive paste, a via hole electrode such as the resonator connection electrode 5 can be formed. That is, the via hole electrode can be formed by laminating a plurality of green sheets filled with conductive paste in the through holes.

  In the present embodiment, the ground connection electrode 21 is disposed in the center of the openings 3 a and 4 a of the resonator electrodes 3 and 4 so as to be insulated from the resonator electrodes 3 and 4. Since the ground connection electrode 21 is provided at the center of the openings 3a and 4a, it is possible to improve the attenuation characteristics at high frequencies of the dual mode bandpass filter. This is a known technical effect as described in Japanese Patent Application No. 2003-39889.

  Next, the operation and characteristics of the dual mode bandpass filter of this embodiment will be described.

  In the dual mode bandpass filter 1 of the present embodiment, when an input signal is applied from one of the input / output electrodes 12, 13, the first and second resonator electrodes 3, 4 A resonance mode occurs. In this case, in the first and second resonator electrodes 3 and 4, the generated first and second resonance modes are coupled, and the openings 3 a and 4 a and the notches 3 b and 4 b are formed so as to form a pass band. Is provided. More specifically, the first and second resonator electrodes 3 and 4 having a rectangular shape generate two resonance modes orthogonal to each other. The openings 3a and 4a and the notches are formed so as to solve the degeneration of the two resonance modes, that is, to make the resonance characteristics of the two resonance modes different and so that the pass band is formed by the resonance characteristics of the two resonance modes. 3b and 4b are formed.

  Accordingly, a frequency characteristic having a pass band can be obtained in the first resonator electrode 3, and a frequency characteristic that forms a pass band can be obtained in the second resonator electrode 4 as well. Thus, since the pass band is obtained by devising the shape of the resonator electrodes 3 and 4, the degree of freedom of arrangement of the input / output coupling electrodes 8 and 9 and the input / output electrodes 12 and 13 is increased. Therefore, the design freedom of the dual mode bandpass filter can be increased. In addition, various passbands can be easily formed.

  Further, in the present embodiment, the first and second resonator electrodes 3 and 4 are formed, and the first and second resonator electrodes 3 and 4 are electrically connected by the resonator connection electrode 5. ing.

  Therefore, compared with the conventional dual mode bandpass filter having only one resonator electrode, the resonance current can be distributed to the first and second resonator electrodes, thereby increasing Q0. it can. Therefore, the dual mode bandpass filter 1 can reduce the loss. In addition, since a pass band is obtained in each of the first and second resonator electrodes 3 and 4, the influence of variations in electrode formation can be reduced. Accordingly, it is possible to reduce variations in resonance frequency due to Q0 and resonator electrodes, variations in coupling amounts of the first and second resonance modes, and the like. As a result, variations in filter characteristics of the dual mode bandpass filter can be reduced.

  This will be described based on a specific experimental example.

  4 and 5 are diagrams showing attenuation-frequency characteristics of the dual mode bandpass filter of the above embodiment. Here, for comparison, the characteristics of the dual mode band-pass filter of the first comparative example configured in the same manner as in the above embodiment except that only one resonance electrode is provided are combined. Show. For further comparison, in addition to the first and second resonator electrodes, the first resonator according to the first embodiment in which a third resonator electrode is disposed below the second resonator electrode. A modified dual mode bandpass filter was also prepared.

  4 and 5, the solid line shows the result of the first comparative example, the broken line shows the result of the first embodiment, and the alternate long and short dash line shows the result of the modified example. From FIG. 4 and FIG. 5, the characteristics of the dual mode bandpass filters of the first comparative example, the first embodiment, and the second embodiment were as follows.

First comparative example: maximum insertion loss in the passband = 1.55 dB, passband width = 1.999 GHz, center frequency f0 = 25.639 GHz, Q0 = 78.49
First Embodiment: Maximum insertion loss in passband = 1.48 dB, passband width = 1.972 GHz, center frequency f0 = 25.641 GHz, Q0 = 82.84
Modification: Maximum insertion loss in the pass band = 1.45 dB, pass band width = 2.183 GHz, center frequency f0 = 25.653 GHz, Q0 = 82.80

  As described above, it can be seen that the loss in the passband can be reduced and Q0 can be increased according to the first embodiment and the modification as compared with the first comparative example. In particular, compared to the first embodiment having a two-layer structure, the loss can be further reduced according to the modification example having the three-layer structure.

  This is because when two or three resonator electrodes having substantially the same shape are stacked and connected to each other through the resonator connection electrodes, the plurality of resonator electrodes have the same potential, and as a result, a portion where current flows strongly Will be distributed. Therefore, the conductor loss is reduced and the Q value is improved.

  Therefore, in order to confirm the effect of connecting a plurality of resonator electrodes with the resonator connection electrode, the first and second resonator electrodes are stacked via the dielectric substrate layer, provided that the resonator connection electrode 5 A dual mode band-pass filter constructed as described in the first embodiment except that no connection was made was prepared, and the frequency characteristics were measured. FIG. 6 shows frequency characteristics of the dual mode bandpass filter of the first comparative example and the second comparative example having no resonator connection electrode prepared as described above. As can be seen from FIG. 6, in the second comparative example, as indicated by the arrow A, it can be seen that some ripples are generated in the passband. This is presumably because the first and second resonator electrodes are not electrically connected, so that a phase difference occurs between the first resonator electrode and the second resonator electrode.

  That is, as in the present embodiment, if the first and second resonator electrodes 3 and 4 are connected by the resonator connection electrode 5 and do not have the same potential, the Q value of the resonator can be increased. However, it can be seen that unnecessary resonance occurs. In other words, according to the present invention, since the first and second resonator electrodes 3 and 4 are electrically connected to each other by the resonator connection electrodes, ripples caused by such unwanted resonance are effectively suppressed. In addition, good filter characteristics can be obtained.

  As is apparent from FIGS. 4 and 5, in the present invention, not only the first and second resonator electrodes but also a third resonator electrode or a larger number of resonator electrodes are formed. It may be.

  Next, the number of resonator connection electrodes 5 connecting the first and second resonator electrodes 3 and 4 was varied to produce a plurality of dual mode bandpass filters, and their frequency characteristics were measured. . More specifically, as shown in plan views in FIGS. 7A to 7D, the resonator connection electrodes 5 are arranged. FIG. 7A corresponds to the first embodiment, and four resonator connection electrodes 5 are arranged inside four corner portions of the resonator electrode 4. In FIG. 7B, one resonator connection electrode 5 electrically connects the resonator electrode 4 and the resonator electrode 3 (not shown) inside one corner portion of the resonator electrode 4. That is, the resonator electrodes 3 and 4 are electrically connected only by one resonator connection electrode 5.

  In FIG. 7C, the resonator connection electrodes 5 are respectively arranged inside the two corner portions at the diagonal positions, and in FIG. 7D, they are positioned on both sides of the pair of sides, not in the diagonal direction. Resonator connection electrodes 5 were respectively arranged inside the corner portions.

  FIG. 8 shows the frequency characteristics of the four types of dual mode bandpass filters. In FIG. 8, the solid line indicates the result of the embodiment shown in FIG. 7A, the broken line indicates in FIG. 7B, the alternate long and short dash line in FIG. 7C, and the alternate long and two short dashes line in FIG. The result in the case shown in d) is shown.

  As can be seen from FIG. 8, even if the number of resonator connection electrodes 5 is changed, the frequency characteristics of the dual mode bandpass filter hardly change. As will be described below, this corresponds to a portion where the strength of the resonance current is weak at the time of resonance in the vicinity of the corner portion of the resonator electrode. Therefore, it can be seen that, if the resonance current is weak, the frequency characteristics hardly change even if the number and formation positions of the resonator connection electrodes 5 are changed.

  9A and 9B show the structure of the first embodiment in which the resonator connection electrode 5 is provided in a portion where the current intensity is weak, and the resonator connection electrode 5 is provided in a portion where the current intensity is strong. It is a typical top view for demonstrating the structure of the 2nd modified example.

  In the second modification, the resonator connection electrode 5 is connected to the first and second resonator electrodes at the corner portion of the resonator electrode 4, that is, at the corner portion, directly above the four corner portions. The electrodes 5 were electrically connected. Other configurations are the same as those of the first embodiment for the second modification.

  FIG. 10 shows the dual-mode bandpass filter of the first comparative example having only the above-described one-layer resonator electrode, and the dual-mode of the first embodiment and the second modification prepared as described above. -It is a figure which shows the frequency characteristic of a band pass filter.

  In FIG. 10, the solid line indicates the result of the first comparative example, the broken line indicates the result of the first embodiment, and the alternate long and short dash line indicates the result of the second modification.

  As described above, according to the first embodiment, it is possible to reduce the insertion loss as compared with the first comparative example having only one resonator electrode.

  Furthermore, it can be seen that the frequency characteristics are greatly different between the second modification and the first comparative example. That is, in the first embodiment and the first comparative example, the passband and the like do not change so much, whereas in the second modification, the passband width changes greatly and the frequency characteristic itself changes greatly. I understand that. This is considered to be due to the following reason.

  If the resonator connection electrode 5 is provided in a portion where the current is strong, the current also flows through the resonator connection electrode 5, which increases the conductor loss and is not preferable. However, in the resonator electrodes 3 and 4 that obtain the passband by providing the resonator electrode with an opening and a notch, when the via hole electrode constituting the resonator connection electrode 5 is connected to a portion where the current is strong, the first The frequency characteristic itself is significantly different from the frequency characteristic having a single layer resonator electrode as in the comparative example.

  In this case, assuming that the passband or the like when the resonator electrode is a single layer or the resonator connection electrode 5 is configured in a portion where the current is weak is the target frequency characteristic, the resonator connection electrode is present in the portion where the current is strong. It is necessary to adjust the frequency characteristics when forming 5 to the target frequency characteristics. When this adjustment is performed, the method may be adjusted so as to increase the portion where the inductance is reduced. In other words, in the resonator electrodes 3 and 4, the direction in which the distance between the outer edge of the penetrating portion including the openings 3 a and 4 a and the notches 3 b and 4 b and the outer peripheral edge of the resonator electrodes 3 and 4 is increased. You may adjust to. Therefore, as a result, the Q value can be increased as the resonator characteristics.

  11 and 12 show a second example in which the resonator connection electrode 5 is provided in a portion where the current intensity is weak so as to approach the filter characteristics of the dual-mode bandpass filter of the single-layer resonator electrode shown in FIG. It is a figure which shows each filter characteristic of 3rd Embodiment which adjusted the frequency characteristic as mentioned above by providing a resonator connection electrode in a part with strong embodiment and current intensity. In FIG. 11, the solid line indicates the result of the second embodiment, and the broken line indicates the result of the third embodiment.

  According to the filter characteristics shown in FIGS. 11 and 12, the insertion loss, bandwidth, and the like are as follows.

Second embodiment: insertion loss in pass band = 1.44 dB, bandwidth = 2.76 GHz, center frequency f0 = 25.645 GHz, Q0 = 80.70
Third embodiment: insertion loss in passband = 1.43 dB, passband width = 21.118 GHz, center frequency f0 = 25.632 GHz, Q0 = 79.69

  Therefore, in either case where the resonator connection electrode 5 is provided in a portion where the current is weak or in the case where the resonator connection electrode 5 is provided in the portion where the current is strong, the frequency is adjusted to obtain substantially the same frequency characteristics. In this case, almost the same Q value can be obtained, and it can be seen that the Q value can be effectively increased as compared with the first comparative example described above.

  As described above, the Q value can be increased by providing a resonator connection electrode at a location where the current is strong, although the resonance frequency fr is reduced, but the opening of the resonator is reduced and the width W described above is increased. It can be considered that the Q value can be increased.

  In the resonator electrodes 3 and 4, the corner portion is the portion with the strongest current concentration. It can be seen that the current concentration becomes weaker as the distance from the corner portion increases. Therefore, preferably, as described above, it is desirable to provide the resonator connection electrode 5 immediately above the corner portion, and thereby Q0 can be further effectively increased.

  Further, the corner portion may not be the portion as long as the current concentration in the resonator electrodes 3 and 4 is strong. That is, by providing the resonator connection electrode 5 in a portion where the current concentration is strong, the distance W (see FIG. 3B) between the opening and the outer peripheral edge of the resonator electrode can be increased. Q0 can be effectively increased by the relaxation.

  As described above, the number of resonator connection electrodes 5 may be one or a plurality, and when arranged in a portion where the current intensity is weak, the difference in frequency characteristics due to the difference in the number hardly occurs. However, when a plurality of resonator connection electrodes are provided, the area of the cross section of at least one resonator connection electrode, that is, the area of the cross section perpendicular to the extending direction of the resonator connection electrode 5 is set to the remaining resonator connection electrodes 5. It is desirable to make it different from the cross-sectional area. Thereby, the inductance value generated by the resonator connection electrode 5 can be varied, and the frequency characteristics of the filter can be adjusted. In this case, when the resonator connection electrode 5 is a via hole electrode, the diameter of the via hole electrode may be different from the diameter of the via hole electrode of the other resonator electrode.

DESCRIPTION OF SYMBOLS 1 ... Dual mode band pass filter 2 ... Dielectric substrate 2a ... 1st main surface 2b ... 2nd main surface 2c, 2d ... Side surface 2e ... 1st end surface 2f ... 2nd end surface 3 ... 1st resonance Resonator electrodes 3, 4 ... second resonator electrodes 3a, 4a ... openings 3b, 4b ... notches 4 ... second resonator electrodes 5 ... resonator connection electrodes 8, 9 ... input / output coupling electrodes 10, 11 ... connections Electrodes 12, 13 ... Input / output electrodes 14 ... First ground electrode 15 ... Second ground electrode 16 ... Ground connection electrode 17 ... Third ground electrode 21 ... Ground connection electrode

Claims (8)

A dielectric substrate having first and second main surfaces;
The dielectric substrate is partially formed at a first height position, and a plurality of resonance modes are generated when an input signal is applied, and an opening for coupling the plurality of resonance modes is formed. A first resonator electrode,
The dielectric substrate is partially formed at a second height position different from the first height position, and a plurality of resonance modes are generated when an input signal is applied. The plurality of resonance modes A second resonator electrode in which an opening for coupling is formed;
A plurality of first ground electrodes formed on or inside the first main surface of the dielectric substrate so as to face the first resonator electrode via a dielectric layer;
A plurality of second ground electrodes formed on or inside the second main surface of the dielectric substrate so as to face the second resonator electrode via a dielectric layer;
A ground connection electrode provided to electrically connect the first and second plurality of ground electrodes;
Input / output terminals formed on the first or second main surface of the dielectric substrate;
A pair of input / output coupling circuits coupled to the first and second resonator electrodes at different portions of the first and second resonator electrodes, the input / output terminals, and the input / output coupling circuit are electrically connected. I / O connection electrodes connected to
A resonator connection electrode provided in the dielectric substrate so as to electrically connect the first and second resonator electrodes, the plurality of first ground electrodes, and a plurality of second electrodes; A dual mode bandpass filter in which a ground plate is disposed above and below the first and second resonator electrodes to form a triplate structure.   2. The dual mode bandpass filter according to claim 1, wherein the openings of the first and second resonator electrodes have a notch extending outward from the edge of the opening so that the resonance mode is degenerated.   3. The dual mode bandpass filter according to claim 1, wherein the resonator connection electrode is disposed in a portion of the resonator electrode where current concentration is stronger than that of the remaining portion.   The resonator electrode has a rectangular shape, the portion where the current concentration is strong is a corner portion of the resonator electrode, and the resonator connection electrode is disposed in at least one corner portion. 4. The dual mode bandpass filter according to 3.   A plurality of the resonator connection electrodes are provided, and an area of a cross section perpendicular to the extending direction of the resonator connection electrode of at least one resonator connection electrode is different from an area of a cross section of the remaining resonator connection electrodes. The dual mode bandpass filter according to any one of claims 1 to 4.   The size of the 1st, 2nd resonator electrode is substantially equal, and it arrange | positions so that a 1st resonator electrode and a 2nd resonator electrode may overlap in planar view. A dual mode bandpass filter according to claim 1.   In at least one of the first and second resonator electrodes, an inner electrode that is insulated from the resonator electrode in the opening, and the inner electrode is connected to the first or second ground electrode. The dual mode band according to any one of claims 1 to 6, further comprising a third ground connection electrode provided to extend in a thickness direction of the dielectric substrate so as to be electrically connected. Path filter.   The dual mode according to any one of claims 1 to 7, wherein the input / output coupling circuit is formed at a height position between the first resonator electrode and the second resonator electrode.・ Band pass filter.

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