JP4926031B2 - Filter device - Google Patents

Description

  The present invention relates to a filter device used in, for example, a wireless communication device such as a mobile phone, a wireless LAN (Local Area Network), a UWB (Ultra Wide Band), and other various communication devices.

  In recent years, wireless communication devices have been used in various applications such as mobile phones and wireless LANs, and the frequencies used in each wireless communication device are close to each other. In order to selectively pass only signals in the desired frequency band, and to prevent unwanted signals from being mixed in the signal band close to the low frequency side and high frequency side of the pass band so that high quality communication can be performed. A filter device having band pass characteristics having attenuation poles in the low frequency side and high frequency side attenuation bands of the pass frequency band is mounted.

  Along with the increase in information transmission capacity, wireless communication devices have secured the information transmission capacity by expanding the use bandwidth by increasing the frequency and bandwidth in the usable frequency band. Therefore, a filter device having a wide pass band and having an attenuation pole in the vicinity of the pass band (having a steep attenuation characteristic) has been demanded. In addition, a filter device in which a plurality of dielectrics and electrodes are stacked is employed in response to demands for miniaturization and thinning of wireless communication devices. For example, as shown in an exploded perspective view in FIG. 13, a plurality of dielectric conductors 11 (13a, 13a, 13d) and internal insertion output electrodes 15b and 16b are embedded, and a strip line type laminated dielectric in which the resonator outer conductor 12a and the external input / output electrodes 15a and 16a are provided on the outer surface of the dielectric chip 11. It is a filter.

  Since such a filter device has only a relatively weak coupling between adjacent resonator inner conductors 13, an attenuation pole is generated at a position away from the pass band on the high frequency side (high frequency side), and the characteristics of the pass band are ensured. However, the amount of attenuation on the higher frequency side than the pass band is insufficient.

On the other hand, as shown in FIG. 13, the intra-resonator conductors 13a and 13d are arranged in an interdigital type in which the short-circuit ends and the open ends are alternated, and the short-circuit ends of the adjacent resonator inner conductors 13a and 13d. There is known one in which a short-circuit end connection pattern 14 that connects adjacent resonator outer conductors 12a and 12a is embedded (see, for example, Patent Document 1). According to this, by changing the position of the layer that forms the short-circuited end connection pattern 14 and the pattern shape such as the pattern width, an attenuation pole can be set at an arbitrary frequency in the vicinity of the passband to obtain a steep attenuation characteristic. It can be done.
JP 11-88009 A

  In recent years, UWB, which has been attracting attention as a new communication means, realizes large-capacity data transfer using a wide frequency band over a short distance of about 10 m. For example, according to the provisions of the US FCC (Federal Communication Commission) It is planned to use a very wide frequency band of 3.1 to 10.6 GHz. And in Japan, avoiding the 5.15 GHz to 5.25 GHz used in the wireless LAN IEEE802.11.a, the low band using the band of about 3.4 GHz to 4.8 GHz and the band of about 7.25 GHz to 10.25 GHz are used. Standards divided into high bands are being drafted. For this reason, a low-band filter uses (passes) a wide band of about 3.4 GHz to 4.8 GHz, but attenuates at 5.15 GHz, which is only 0.35 GHz away, and attenuates very steeply. Characteristics are required.

  However, in the conventional filter device, only one attenuation pole can be generated on each of the low band side and the high band side from the pass band, and therefore, the filter apparatus attenuates steeply on both sides of a wide pass band such as a UWB low band. When the pole is formed, the attenuation characteristic has a jumping of the attenuation characteristic on the high frequency side and the low frequency side further than the attenuation pole. Therefore, the attenuation amount in the band used in the wireless LAN on the high frequency side of the pass band is not sufficient. There was a problem of interference with the wireless LAN.

  The present invention has been devised in view of the above problems, and its purpose is to make it possible to generate attenuation poles more steeply on the low-frequency side and the high-frequency side than the passband, and more easily than the passband. Another object of the present invention is to provide a filter device that can sufficiently secure the attenuation amount on the low frequency side and the high frequency side, and can be used for UWB, for example.

The filter device according to the present invention includes a laminate in which a plurality of dielectric layers are laminated, a ground electrode disposed so as to face the laminate, and a plane so as to be electromagnetically coupled to each other in the laminate. A plurality of four or more resonator electrodes in which short-circuited ends and open ends are alternately arranged side by side, and the dielectric layer is disposed between the resonator electrodes in the stacked body. Is electrically connected to the short-circuited end of the resonator electrode facing and opposite to the short-circuited end of one of the first- stage or final-stage resonator electrodes, and the other end is connected to one resonator electrode and the short-circuited end. The coupling electrode electrically connected to the short-circuited end of the resonator electrode facing and opposite to the short-circuited end of the resonator electrode other than the first-stage and the final-stage other than the first-stage, and the first-stage resonator electrode Input terminal electrode connected to And it is characterized by comprising an output electrode connected to said resonator electrode of the final stage.

  The filter device according to the present invention is characterized in that, in the above configuration, an internal ground electrode is formed so as to surround a plurality of the resonator electrodes in a plan view between the dielectric layers where the resonator electrodes are arranged. It is what.

  The filter device according to the present invention is characterized in that, in the above-mentioned configuration, the coupling electrode has a ground electrode facing portion facing the ground electrode or the internal ground electrode branched between the one end and the other end. It is what.

  In the filter device of the present invention, in each of the above configurations, the ground electrode is opposed to the ground electrode with the dielectric layer between the ground electrode and the resonator electrode, and the open ends of the plurality of resonator electrodes And a plurality of capacitive electrodes electrically connected to each other.

  Further, the filter device of the present invention is characterized in that, in the above configuration, a part of the capacitance electrode is disposed so as to face the internal ground electrode with the dielectric layer interposed therebetween.

  In the filter device of the present invention, in each of the above configurations, the input terminal electrode has a shape along the first-stage resonator electrode so as to face the first-stage resonator electrode with the dielectric layer interposed therebetween. An internal input terminal electrode that is disposed and electromagnetically couples with the first-stage resonator electrode, and is formed on the outer surface of the laminate, and is connected to the internal input terminal electrode on the open end side of the first-stage resonator electrode. An external input terminal electrode, and the output terminal electrode has a shape along the resonator electrode at the final stage, and is disposed so as to face the resonator electrode at the final stage with the dielectric layer interposed therebetween. An internal output terminal electrode that is electromagnetically coupled to the resonator electrode of the final stage, and is formed on the outer surface of the laminate, and is connected to the internal output terminal electrode on the open end side of the final stage of the resonator electrode. An external output terminal electrode And it is characterized in Rukoto.

  Moreover, the filter device of the present invention is arranged in the above-described configuration so as to be electromagnetically coupled to one of the resonator electrodes in the stacked body other than between the resonator electrodes, one end being a short-circuited end and the other end being It has at least one damped resonator electrode which is an open end.

  In the filter device according to the present invention, in the above configuration, the damped resonator electrode has a shape in which the open end is branched into a plurality, and the length from the short-circuited end to each tip of the open end is different. It is characterized by this.

According to the filter device of the present invention, one end is opposed to the short-circuit end of one resonator electrode at the first stage or the last stage and is electrically connected to the short-circuit end of the opposed resonator electrode, and the other end is one resonance. A coupling electrode electrically connected to the short-circuited end of the resonator electrode opposite to the short-circuited end of the resonator electrode other than the first stage and the final stage other than the first stage and the short-circuited end on the same side Between the signal transmitted by the (capacitive) coupling between the side-by-side resonator electrodes and the signal transmitted by the (dielectric) coupling between the plurality of resonator electrodes facing the coupling electrode by the coupling electrode Since the phase difference of 180 ° occurs in each other and cancel each other, an attenuation pole is formed at a position close to the high band side of the pass band of the filter, and the attenuation amount on the high band side of the pass band is increased. Can be a filter device .

  According to the filter device of the present invention, when the internal ground electrode is formed so as to surround the plurality of resonator electrodes in a plan view between the dielectric layers where the resonator electrodes are arranged, the plurality of internal ground electrodes are formed. By encircling the periphery of the resonator electrode, leakage of electromagnetic waves generated from the resonator electrode to the periphery can be reduced. This effect is particularly useful for preventing adverse effects on other regions of the module substrate when the filter device of the present invention is formed in a partial region of the module substrate.

  Further, according to the filter device of the present invention, when the coupling electrode has a ground electrode facing portion that faces the ground electrode or the internal ground electrode branched between one end and the other end, the ground electrode facing portion and the ground electrode or Since the coupling with the internal ground electrode increases and the impedance of the coupling electrode decreases, the (dielectric) coupling between the plurality of resonator electrodes facing the coupling electrode by the coupling electrode can be strengthened, The attenuation pole can be brought close to the pass band of the filter (shifted to the low frequency side). As a result, the attenuation on the high frequency side of the pass band becomes steeper, and the filter device can have a more excellent attenuation characteristic on the high frequency side of the pass band.

  According to the filter device of the present invention, the ground electrode is opposed to the ground electrode with the dielectric layer interposed between the ground electrode and the resonator electrode, and electrically connected to the open ends of the plurality of resonator electrodes. When there are a plurality of capacitive electrodes, the distance between the capacitive electrode and the ground electrode is shorter than the distance between the resonator electrode and the ground electrode, which increases the coupling between the resonator electrode and the ground electrode. Therefore, the length of each resonator electrode can be shortened, and a smaller filter device can be provided.

  According to the filter device of the present invention, when a part of the capacitor electrode is disposed so as to face the internal ground electrode with the dielectric layer in between, the internal ground electrode is a dielectric having a resonator electrode formed thereon. It is formed between the same dielectric layers as the interlayer, and if the capacitor electrode is opposed so as to be coupled to the internal ground electrode, the wiring length of the through conductor or the like for electrical connection between the resonator electrode and the capacitor electrode may be shortened. Therefore, unnecessary inductance due to this wiring can be reduced, and a filter device having excellent filter characteristics free from secondary resonance due to the inductance of the wiring between the electrodes can be obtained.

  According to the filter device of the present invention, the input terminal electrode has a shape along the first stage of the resonator electrode and is disposed so as to face the first stage of the resonator electrode with the dielectric layer interposed therebetween. An output terminal comprising an internal input terminal electrode that is electromagnetically coupled to the first stage, and an external input terminal electrode that is formed on the outer surface of the laminate and is connected to the internal input terminal electrode at the open end side of the first stage of the resonator electrode. An internal output terminal electrode in which the electrode has a shape along the final stage of the resonator electrode and is disposed so as to face the final stage of the resonator electrode across the dielectric layer, and is electromagnetically coupled to the final stage of the resonator electrode And an external output terminal electrode formed on the outer surface of the laminate and connected to the internal output terminal electrode on the open end side of the final stage of the resonator electrode, the input terminal electrode and the first stage resonance Between the output electrode and the output terminal electrode and the final resonator electrode In the meantime, the coupling due to the magnetic field and the coupling due to the electric field are added to produce a strong coupling, so that the passband is wider than that which can be realized by a filter using a conventional quarter wavelength resonator. However, it is possible to provide a filter device having a flat and low-loss pass characteristic over the entire wide passband without greatly increasing the insertion loss at the frequency located between the resonance frequencies of the respective resonance modes. it can.

  Further, according to the filter device of the present invention, at least one in which the one end is a short-circuited end and the other end is an open end is disposed so as to be electromagnetically coupled to one of the resonator electrodes in the laminated body other than between the resonator electrodes. When there are two damped resonator electrodes, the damped resonator electrode can form an damped pole that functions as a reaction resonator (notch filter) between the damped pole of the resonator electrode and the passband, so that the desired pass A filter device having a steep attenuation characteristic that has a band and eliminates an unnecessary signal at a specific frequency can be obtained.

  Further, according to the filter device of the present invention, the damped resonator electrode has a shape in which the open end is branched into a plurality, and the length from the short-circuited end to each tip of the open end is different. Since a plurality of attenuation poles can be formed according to the electrical length from the short-circuited end to the open end branched off, the length from the shorted end to the open end branched off can be adjusted. By adjusting the positions of the plurality of attenuation poles, a filter device having a steeper attenuation characteristic can be easily obtained.

  The filter device of the present invention will be described in detail below. 1 to 7 are exploded perspective views showing examples of embodiments of the filter device of the present invention. 1 to 6, 1a is a dielectric layer, 1 is a laminate formed by laminating a dielectric layer 1a, 2a is a ground electrode, 2b is an internal ground electrode, 3a to 3d are resonator electrodes, and 3a is the first stage. Resonator electrode, 3d is the last-stage resonator electrode, 4 is a coupling electrode, 4a is a ground electrode facing portion, 5 is an input terminal electrode, 5a is an external input terminal electrode, 5b is an internal input terminal electrode, and 6 is an output terminal electrode , 6a are external output terminal electrodes, 6b is an internal output terminal electrode, and 7 is a capacitive electrode. In addition, the broken line has a through conductor penetrating through the dielectric layer 1a for electrically connecting the conductor layers (for example, the first-stage resonator electrode 3a and the input terminal electrode 5) located above and below the dielectric layer 1a. Is shown.

The filter device of the present invention includes a laminated body 1 in which a plurality of dielectric layers 1 a are laminated, ground electrodes 2 a and 2 a arranged so as to face each other with the laminated body 1 interposed therebetween, and the laminated body 1. Three or more resonator electrodes 3 a to 3 d in which the short-circuited ends and the open ends are alternately arranged side by side in a plan view so as to be electromagnetically coupled, and the resonator electrodes 3 a to 3 d in the stacked body 1 It is disposed with the dielectric layer 1a interposed therebetween, and one end thereof is electrically connected to the short-circuited end of the resonator electrode 3a opposite to the short-circuited end of the first- stage or final-stage resonator electrode 3a. end, electrically shorted end opposite resonator electrodes 3c with short-circuit end and one resonator electrodes 3a faces the shorting end of the other resonator electrodes 3c other than the first stage and the last stage on the same side Connected coupling electrode 4 and first stage resonator The input terminal electrode 5 is connected to the electrode 3a, and the output terminal electrode 6 is connected to the final-stage resonator electrode 3d.

According to the filter device of the present invention, one end is electrically connected to the short-circuit end of the opposing resonator electrodes 3a with facing the shorting end of the one resonator electrodes 3a of the first stage or the final stage, the other end, One resonator electrode 3a is electrically connected to the short-circuited end of the resonator electrode 3c opposite to the short-circuited end of the resonator electrode 3c other than the first-stage and final-stage other than the first-stage and the last-stage on the same side. Since the coupling electrode is provided, a signal transmitted by (capacitive) coupling between the side-by-side resonator electrodes 3 a, 3 b, 3 b, 3 c, 3 c, and 3 d and a plurality of the coupling electrodes 4 facing the coupling electrode 4 180 ° between the signal transmitted by the (dielectric) coupling between the resonator electrodes 3a and 3c
Therefore, the filter device has an excellent attenuation characteristic in which an attenuation pole is formed on the high frequency side of the pass band of the filter and the attenuation amount on the high frequency side of the pass band is increased. it can.

  The ground electrodes 2a and 2a are disposed on almost the entire surface excluding the periphery of the input terminal electrode 5 and the output terminal electrode 6 on the upper and lower surfaces of the laminate 1 in which the dielectric layers 1a are laminated, and are connected to the ground potential. ing.

  The resonator electrodes 3a, 3b, 3c, and 3d are arranged side by side and aligned between one layer of the multilayer body 1, and are electromagnetically coupled (edge coupled) to each other. The smaller distance between the adjacent resonator electrodes 3a, 3b, 3b, 3c, 3c, 3d is preferable because strong coupling can be obtained and the pass band can be easily widened. In order to satisfactorily form at equal intervals so as not to short-circuit each other, for example, the thickness is set to about 0.05 to 0.5 mm. The resonator electrodes 3a, 3b, 3c, and 3d are preferably formed in an elongated strip shape so that they are arranged side by side and are electromagnetically coupled to each other. The resonator electrodes 3a to 3d may be aligned side by side in a plan view so as to be electromagnetically coupled to each other in the multilayer body 1. Normally, for example, as shown in FIG. 1, four resonator electrodes 3a to 3d are arranged between one dielectric layer 1a and 1a, but the resonator electrodes 3a and 3c are arranged as one dielectric layer 1a and 1a. The resonator electrodes 3b and 3d may be disposed between the other dielectric layers 1a and 1a with one dielectric layer 1a interposed therebetween. This arrangement is preferable because there is no short-circuit between adjacent resonator electrodes, and the formation thereof is facilitated. However, the number of dielectric layers 1a is increased and the thickness of the filter device is increased.

  In addition, as in the example illustrated in FIGS. 1 to 7, the resonator electrodes 3 a to 3 d are alternately arranged side by side with short-circuit ends and open ends in a plan view (arranged in an interdigital manner). As a result, the coupling between the resonator electrodes 3a to 3d is performed by adding the coupling by the magnetic field and the coupling by the electric field, thereby generating a stronger coupling between the resonator electrodes 3a to 3d. The frequency interval between the resonance frequencies can be adjusted beyond a band that can be realized by a filter using a conventional quarter wavelength resonator, and a filter device having a wide pass band can be obtained. Further, the coupling between the resonator electrodes 3a to 3d arranged in the interdigital type is a strong magnetic field coupling, and it is not necessary to reduce the pattern width of the resonator electrodes 3a to 3d to increase the magnetic field. By increasing the pattern width of 3d, the electrical resistance of the resonator electrodes 3a to 3d can be reduced, and the Q value (quality factor) indicating the sharpness of the sharp resonance of the resonator can be increased. As a result, a filter device having a wide passband and a steep attenuation characteristic, for example, suitable for a bandpass filter for UWB applications can be obtained.

  In the example shown in FIGS. 1 to 7, four resonator electrodes 3a to 3d are provided. However, five or more resonator electrodes may be provided, and the number of resonator electrodes is such that the loss does not increase. I just need it. For UWB low-band applications, four are preferred from the balance of loss and attenuation characteristics.

  The resonator electrodes 3a, 3b, 3c, and 3d form a stripline resonator together with the upper and lower ground electrodes 2a and 2a, and the short-circuit ends are connected to the upper and lower ground electrodes 2a and 2a and connected to the ground potential. This functions as a quarter wavelength resonator. As shown in FIGS. 1 and 2, the resonator electrodes 3a, 3b, 3c, 3d are connected to the upper and lower ground electrodes 2a, 2a between the resonator electrodes 3a-3d formed between the resonator electrodes 3a-3d. , 3c, 3d are provided with a conductor layer for connecting the short-circuited ends, and the conductor layer is connected to a through conductor (not shown), or the conductor layer is extended to the end of the dielectric layer 1a. What is necessary is just to connect by the end surface conductor (not shown) formed in the end surface (side surface of the laminated body 1) of the dielectric material layer 1a. When the conductor layer for connecting the short-circuit ends of the resonator electrodes 3a, 3b, 3c, and 3d is not provided, the resonator electrodes 3a, 3b, 3c, and 3d are connected to the ground electrodes 2a and 2a through the through conductors. Alternatively, the short-circuit ends of the resonator electrodes 3a to 3d may be extended to the end of the dielectric layer 1a, and the ground electrodes 2a and 2a may be formed by the end face conductor formed on the end face of the dielectric layer 1a (side face of the multilayer body 1). You may connect to. When connected by an end face conductor, the end face conductor can function as a shield layer that reduces leakage of electromagnetic waves generated from the resonator electrodes 3a to 3d to the surroundings. It is preferable to arrange the electrode conductors 3a to 3d in a double or more manner around the electrodes 3a to 3d and arrange the through conductors as far as possible as viewed from the side surface, because the function of the shield becomes more remarkable. As shown in FIGS. 1 and 2, when a conductor layer for connecting the short-circuit ends of the resonator electrodes 3a, 3b, 3c, and 3d is provided, the short-circuit ends of the resonator electrodes 3a, 3b, 3c, and 3d are grounded. Since it becomes easy to connect to electrode 2a * 2a, it is preferable.

  Further, as in the examples shown in FIGS. 3 to 5 and 7, the filter device of the present invention has a planar view between the dielectric layers 1 a and 1 a in which the resonator electrodes 3 a to 3 d are formed in the above configuration. The internal ground electrode 2b is preferably formed so as to surround the plurality of resonator electrodes 3a to 3d. By doing in this way, the internal ground electrode 2b surrounds the periphery of the resonator electrodes 3a to 3d, whereby leakage of electromagnetic waves generated from the resonator electrodes 3a to 3d to the periphery can be reduced. This effect is particularly useful in preventing adverse effects on other regions of the module substrate when the filter device is formed in a partial region of the module substrate. The internal ground electrode 2b is a conductor layer for connecting the short-circuit ends of the resonator electrodes 3a, 3b, 3c, and 3d, and a conductor formed on both sides of the array of the resonator electrodes 3a, 3b, 3c, and 3d. It is an annular thing consisting of layers. If the connection between the ground electrode 2a and the resonator electrodes 3a, 3b, 3c, 3d is also performed at the portions of the internal ground electrode 2b located on both sides of the array of the resonator electrodes 3a, 3b, 3c, 3d, the resonator electrode 3a Leakage of electromagnetic waves generated from ˜3d to the surroundings can be reduced more effectively.

  The distance between the internal ground electrode 2b and the resonator electrodes 3a and 3d is such that the Q value of the filter does not decrease and the loss of the passband does not increase by affecting the magnetic field generated by the resonator electrodes 3a and 3d. The distance between the resonator electrodes 3a, 3d and the ground electrode 2a is preferably larger than the distance between the resonator electrodes 3a, 3d and the ground electrode 2a.

  The coupling electrode 4 has the same short-circuited end as that of one resonator electrode 3a through one or more resonator electrodes 3b among the resonator electrodes 3a to 3d arranged in an interdigital manner. For example, in the example shown in FIG. 4, the coupling between the adjacent first-stage resonator electrode 3a and the second-stage resonator electrode 3b is performed in order to increase the weak coupling between the other resonator electrodes 3d. When the coupling between the second-stage resonator electrode 3b and the third-stage resonator electrode 3c increases, the center frequency of the basic filter formed by the resonator electrodes 3a to 3d and the ground electrodes 2a and 2a shifts. As a result, the filter characteristics in the pass band change, and the design of the attenuation characteristics by adding the coupling electrode 4 becomes complicated. Also, the line width of the portion (connecting portion) connecting the portion (one end portion) facing the first-stage resonator electrode 3a and the portion facing the third-stage resonator electrode 3c (other end portion) in the coupling electrode 4 Is large, the coupling electrode 4 itself functions as a ground electrode. Therefore, by affecting the magnetic field generated by the resonator electrodes 3a to 3d, the Q value of the filter decreases and the loss of the passband increases. End up. Therefore, the connecting portion is provided so as to be orthogonal to the second-stage resonator electrode 3b in order to reduce the area facing the second-stage resonator electrode 3b and thereby reduce the coupling as much as possible. It is preferable to make it small enough not to become too large, specifically about 0.1 mm. Further, as in the example shown in FIG. 2, the connecting portion is further formed at a position away from the second-stage resonator electrode 3b with one or more dielectric layers 1a interposed therebetween, and one end portion and The coupling electrode 4 may be formed by connecting to the other end. By doing so, the distance between the connecting portion and the second-stage resonator electrode 3b is increased, and unnecessary coupling between them can be reduced.

  Depending on the number of dielectric layers 1a between the coupling electrode 4 and the resonator electrodes 3a and 3c, the distance between the coupling electrode 4 and the resonator electrodes 3a and 3c can be changed, or the pattern width and length of the coupling electrode 4 can be changed. The electromagnetic field between the coupling electrode 4 and the resonator electrodes 3a and 3c is changed by changing the area where the coupling electrode 4 and the resonator electrodes 3a and 3c overlap depending on the pattern shape and the position in plan view. The degree of coupling can be adjusted, and the frequency at which the attenuation pole occurs can be set arbitrarily. Sufficient coupling is obtained between the resonator electrodes 3a and 3c, and coupling with the resonator electrodes 3b and 3d other than the two resonator electrodes 3a and 3c to be coupled due to a positional shift at the time of manufacturing the filter device is achieved. One end and the other end of the coupling electrode 4 are band-shaped along the shape of the resonator electrodes 3a and 3c so that the width is smaller than that of the resonator electrodes 3a and 3c so as not to occur. Is good.

  The coupling electrode 4 is shaped so that the coupling between the first-stage resonator electrode 3a and the third-stage resonator electrode 3c by a magnetic field is strengthened as in the examples shown in FIGS. It is preferable to use a U-shape (U-shape) in which the ends opposite to the connection portions of the resonator electrodes 3a and 3c of the one end and the other end of the resonator are connected to each other.

  Further, as in the example shown in FIGS. 3 and 7, a plurality of coupling electrodes 4 may be provided. For example, in the example shown in FIGS. 3 and 7, the coupling electrode 4 that couples the first-stage resonator electrode 3a and the third-stage resonator electrode 3c, the second-stage resonator electrode 3b, and the last-stage resonator. Two coupling electrodes 4 for coupling the electrode 3d are provided. In this way, particularly when there are four or more even-numbered resonator electrodes 3a to 3d, one end is coupled to the first-stage resonator electrode 3a, and one is coupled to the last-stage resonator electrode 3d. If the two coupling electrodes 4 and 4 are arranged symmetrically so that the same degree of coupling can be obtained, the balance of the reflection characteristics on the input side and the output side is improved, which is preferable.

  When the number of resonator electrodes 3a to 3d is an odd number, the coupling between the first-stage resonator electrode 3a and the last-stage resonator electrode 3d is the smallest, so that the coupling electrode 4 that couples them is used. Is preferred. At this time, for example, when there are five resonator electrodes 3a to 3d, a coupling electrode that couples the first-stage resonator electrode 3a, the third-stage resonator electrode 3c, and the last-stage resonator electrode 3d. However, if the first-stage resonator electrode 3a and the last-stage resonator electrode 3d are coupled to each other, the effect of coupling with the resonator electrode 3c between them is hardly exhibited. The coupling electrode 4 may be used to couple the resonator electrode 3a and the final-stage resonator electrode 3d. Further, the coupling of the first-stage resonator electrode 3a and the final-stage resonator electrode 3d improves the balance of reflection characteristics between the input side and the output side, so that only this one coupling electrode 4 is sufficient.

  Further, in the filter device of the present invention, in the configuration described above, as in the example shown in FIGS. 2 to 7, the coupling electrode 4 has a ground electrode 2a or 2a or an internal ground electrode branched between one end and the other end. It is preferable to have a ground electrode facing portion 4a facing 2b. According to this, since the coupling between the ground electrode facing portion 4a and the ground electrodes 2a and 2a or the internal ground electrode 2b is increased and the impedance of the coupling electrode 4 is decreased, a plurality of the coupling electrodes 4 opposed to the coupling electrode 4 are formed. The (dielectric) coupling between the resonator electrodes 3a and 3c can be strengthened and the attenuation pole on the high frequency side can be brought close to the pass band of the filter (shifted to the low frequency side). As a result, the attenuation on the high frequency side of the pass band becomes steeper, and the filter device can have a more excellent attenuation characteristic on the high frequency side of the pass band.

  As shown in FIGS. 2, 3 and 6, the ground electrode facing portion 4a is a dielectric closer to the ground electrode 2a than between the dielectric layers 1a and 1a where the one end and the other end of the coupling electrode 4 are formed. It may be arranged between the body layers 1a and 1a and connected by through conductors, or when there is an internal ground electrode 2b as in the examples shown in FIGS. 4 and 7, the dielectric in which the coupling electrode 4 is disposed You may arrange | position and connect between layer 1a * 1a. In the former case, the amount of coupling between the coupling electrode 4 and the ground electrode 2a can be easily adjusted by adjusting the thickness of at least one dielectric layer 1a between the coupling electrode 4 and the ground electrode 2a. The position (frequency) at which the high-frequency attenuation pole appears can be adjusted. At this time, as in the example shown in FIGS. 2, 3 and 6, the dielectric layer 1a, in which the coupling electrode 4 is arranged, is drawn out by a through conductor extending from one end of the coupling electrode 4 toward the ground electrode 2a. When the ground electrode facing portion 4a is provided between the dielectric layers 1a and 1a different from between 1a, it is preferable that the ground electrode facing portion 4a does not protrude inward from the first-stage resonator electrode 3a in plan view. . Since one end of the coupling electrode 4 exists between the ground electrode facing portion 4a and the first-stage resonator electrode 3a, the coupling between the ground electrode facing portion 4a and the first-stage resonator electrode 3a is small. The ground electrode facing portion 4a having a large area is preferably provided so as to protrude outside the first-stage resonator electrode 3a and the last-stage resonator electrode 3d in plan view. In order to further reduce the coupling between the ground electrode facing portion 4a that is a part of the coupling electrode 4 and the resonator electrodes 3a to 3d, the ground electrode facing portion 4a extends along one end (or the other end) of the coupling electrode 4. It is preferable that it is in the shape of a strip and is smaller in width and length than one end (or the other end) of the coupling electrode 4 so that it does not protrude from one end when viewed in plan. Further, the electrical connection between the ground electrode facing portion 4a and one end of the coupling electrode 4 may be branched and extended between the dielectric layers 1a and 1a and then connected by a through conductor. The ground electrode facing portion 4a is preferably shaped and arranged so as not to overlap with the resonator electrodes 3a to 3d in plan view so that the coupling with the resonator electrodes 3a to 3d becomes small. In the latter case, for example, when the coupling electrode 4 is formed by printing a conductive paste on a ceramic green sheet, the ground electrode facing portion 4a can be formed at the same time. As in the example shown in FIG. 5, the arrangement and connection of the ground electrode facing portion 4a may include both the former and the latter. In any case, the length of the portion (the connection portion between one end of the coupling electrode 4 and the ground electrode facing portion 4a) that branches from the coupling electrode 4 and reaches the ground electrode facing portion 4a is an unnecessary inductance. The shorter one is preferable to reduce.

  FIG. 8A is a plan view of the dielectric layer 1a on which the resonator electrodes 3a to 3d and the internal ground electrode 2b in the example shown in FIG. 4 are viewed from above, and the resonator electrodes 3a to 3d and the bottom thereof. The example of the overlap with the coupling electrode 4 (shown by a broken line) formed on the dielectric layer 1a is shown. FIGS. 8B to 8F are plan views similar to FIG. 8A and show examples of different shapes of the ground electrode facing portion 4a. As described above, since the coupling electrode 4 should not overlap with the other resonator electrodes 3b and 3c, the example shown in FIGS. 8A, 8B and 8C is preferable. In order to shorten the length of the connecting portion between the one end portion of the coupling electrode 4 and the ground electrode facing portion 4a, the example shown in FIG. The connection portion between the ground electrode facing portion 4a and the coupling electrode 4 has a width that is small enough that the inductance does not become too large, like the connection portion between the one end portion and the other end portion of the coupling electrode 4. Is preferably about 0.1 mm.

  Further, in the filter device of the present invention, the dielectric layer 1a is sandwiched between the ground electrode 2a and the resonator electrodes 3a, 3b, 3c, 3d in the above configuration as in the examples shown in FIGS. It is preferable to have a plurality of capacitive electrodes 7 facing the ground electrode 2a and electrically connected to the open ends of the plurality of resonator electrodes 3a, 3b, 3c, 3d, respectively. As a result, the distance between the capacitive electrode 7 and the ground electrode 2a is shorter than the distance between the resonator electrodes 3a, 3b, 3c, 3d and the ground electrode 2a, thereby the resonator electrodes 3a, 3b, 3c, 3d and the ground electrode 2a. And the C-coupling (capacitive coupling) between the resonator electrodes 3a, 3b, 3c, 3d and the ground electrode 2a is strengthened, so that each of the resonator electrodes 3a, 3b, 3c, 3d The length can be shortened, and a smaller filter device can be provided.

  Further, the filter device of the present invention is arranged in such a configuration that a part of the capacitive electrode 7 is opposed to the internal ground electrode 2b with the dielectric layer 1a interposed therebetween as in the example shown in FIG. Is preferred. FIG. 9 is a cross-sectional view showing an example of the AA cross section of the filter device shown in FIG. The internal ground electrode 2b is formed between the same dielectric layers 1a and 1a as the dielectric layers 1a and 1a on which the resonator electrodes 3a to 3d are formed, so that the capacitive electrode 7 is coupled to the internal ground electrode 2b. When compared with the case where the capacitive electrode 7 is coupled so as to be coupled only to the ground electrode 2a (in the case of the capacitive electrode 7a shown by a broken line in FIG. 9), the resonator electrodes 3a to 3d and the capacitive electrode Since the wiring length of a through conductor or the like for electrical connection with the wiring 7 can be shortened, unnecessary inductance due to this wiring can be reduced, and a filter having excellent filter characteristics free from secondary resonance due to inductance It can be a device. In addition, even when the wiring length of the through conductor or the like for electrical connection between the resonator electrodes 3a to 3d and the capacitive electrode 7 is the same, an electrostatic capacitance is added between the capacitive electrode 7 and the internal ground electrode 2b. Therefore, the capacitance between the open ends of the resonator electrodes 3a to 3d and the ground potential is further increased, and the length of the resonator electrodes 3a to 3d can be shortened. The filter device can be obtained.

  Capacitance electrode 7 and resonator electrodes 3a-3d are electrically connected by a through conductor. When the capacitive electrode 7 and the resonator electrodes 3a to 3d overlap in plan view, the coupling between the resonator electrodes 3a to 3d and the ground electrode 2a is reduced by the overlapping area, and for example, the resonator electrode 3a When the capacitor electrode 7 connected to the other resonator electrode 3b to 3d overlaps in plan view, the coupling amount between the first-stage resonator electrode 3a and the other resonator electrodes 3b to 3d changes. 6 and FIG. 7, the capacitive electrode 7 has an elongated shape such as a rectangle or an ellipse, the open ends of the resonator electrodes 3 a to 3 d and one end of the capacitive electrode 7 are connected, and the capacitive electrode 7 The other end of the electrodes may be oriented in the direction of extending the open ends of the resonator electrodes 3a to 3d.

  In the example shown in FIG. 6 and FIG. 7, the capacitor electrode 7 is provided one by one below the resonator electrodes 3 a to 3 d with the dielectric layer 1 a interposed therebetween. It may be provided one above the other, or one above each of the resonator electrodes 3a to 3d, or one above each below or below.

  The input terminal electrode 5 and the output terminal electrode 6 may be electrically connected by a wiring conductor such as a through conductor as in the examples shown in FIGS. 1, 2, and 4 to 6, but the dielectric layer 1a It may be arranged so as to face the resonator electrodes 3a and 3d with the electrode interposed therebetween, and may be electromagnetically coupled to the resonator electrodes 3a and 3d, respectively. In this case, as in the example shown in FIGS. 3 and 7, the input terminal electrode 5 has a shape along the first-stage resonator electrode 3a so as to face the first-stage resonator electrode 3a with the dielectric layer 1a interposed therebetween. Are formed on the outer surface of the multilayer body 1 and connected to the internal input terminal electrode 5b at the open end side of the first-stage resonator electrode 3a. The external input terminal electrode 5a is provided, and the output terminal electrode 6 has a shape along the resonator electrode 3d at the final stage and faces the final stage 3d of the resonator electrode 3 with the dielectric layer 1a interposed therebetween. The internal output terminal electrode 6b disposed on the outer surface of the multilayer body 1 and electromagnetically coupled to the final-stage resonator electrode 3d and the open end side of the final-stage resonator electrode 3d are formed on the outer surface of the multilayer body 1. And an external output terminal electrode 6a connected to each other. Preferred. With such a configuration, the coupling by the magnetic field and the coupling by the electric field are added between the input terminal electrode 5 and the first stage resonator electrode 3a and between the output terminal electrode 6 and the last stage resonator electrode 3d. Since strong coupling occurs, even if the passband is wider than the band that can be realized by a filter using a conventional quarter wavelength resonator, the insertion loss at the frequency located between the resonance frequencies of the respective resonance modes is small. It is possible to provide a filter device that has a flat and low-loss pass characteristic over the entire wide passband without greatly increasing. As a result, the filter device has a wide passband and has a steep attenuation characteristic, and is suitable for a bandpass filter for UWB applications, for example.

  The connection between the internal input terminal electrode 5b and the external input terminal electrode 5a and the connection between the internal output terminal electrode 6b and the external output terminal electrode 6a pass through the dielectric layer 1a as in the examples shown in FIGS. What is necessary is just to carry out by the penetration conductor which does. Further, the internal input terminal electrode 5b, the external input terminal electrode 5a, the internal output terminal electrode 6b, and the external output terminal electrode 6a can be extended to the end portions of the dielectric layer 1a and connected by end face conductors. When the connection between the resonator electrodes 3a to 3d and the ground electrodes 2a and 2a is performed by an end face conductor, the end face conductor can be formed simultaneously with other electrodes by printing a conductor paste or the like, which is advantageous in manufacturing.

  FIG. 10 is an exploded perspective view similar to FIG. 1. In FIG. 10, 8 is a damped resonator electrode. In the filter device of the present invention, as shown in the example shown in FIG. 10, in each of the above configurations, the resonator electrodes 3 a to 3 d are disposed in the multilayer body 1 other than between the resonator electrodes 3 a, 3 b, 3 b, 3 c, 3 c, 3 d. It is preferable to have at least one damped resonator electrode 8 which is arranged to be electromagnetically coupled to one, one end is a short-circuited end and the other end is an open end. The attenuation resonator electrode 8 can form an attenuation pole that functions as a reaction resonator (notch filter) between the attenuation poles of the resonator electrodes 3a to 3d and the passband, and thus has a desired passband, In addition, it is possible to obtain a filter device having a steep attenuation characteristic in which unnecessary signals at a specific frequency are removed.

  The damped resonator electrode 8 has a dielectric different from that between the dielectric layers 1a and 1a in which the resonator electrodes 3a to 3d are formed, for example, as shown in FIG. Arranged between the body layers 1a and 1a to be electromagnetically coupled to one of the resonator electrodes 3a to 3d, one end is a short-circuited end connected to the ground electrodes 2a and 2a, and the other end is connected to the other. There is no open end. The connection between the damped resonator electrode 8 and the ground electrodes 2a and 2a is performed by extending the short-circuited end of the damped resonator electrode 8 to the end of the dielectric layer 1a as shown in FIG. It may be connected by an end face conductor (not shown) formed on (side surface of the laminated body 1) or may be connected by a through conductor.

  The damped resonator electrode 8 is electromagnetically coupled to one of the resonator electrodes 3a to 3d, and a desired attenuation characteristic can be obtained by adjusting the coupling amount. For example, when a desired coupling amount is not obtained, even if a steep attenuation characteristic is obtained outside the pass band and in a band very close to the cutoff frequency, the high-frequency side of the attenuation pole by the attenuation resonator electrode 8 is obtained. While the damping characteristic jumps (between the attenuation poles), when the desired coupling amount is obtained, such a damping characteristic jump does not occur, and a steep and no jumping damping characteristic can be obtained. it can.

  The number of the damped resonator electrodes 8 is preferably set as a pair so as to be point-symmetric with respect to the center of the region where the resonator electrode 3 is formed. In this case, even when the displacement of the filter device is produced and the coupling between the damped resonator electrode 8 and the resonator electrode 3 changes in the direction in which one is strengthened, the other is weakened. Since the total coupling amount does not change greatly, it is easy to make a product with a small deviation from the design value.

  In the filter device according to the present invention, the damped resonator electrode 8 preferably has a shape in which the open end is branched into a plurality, and the length from the short-circuited end to each tip of the open end is preferably different. . From this, a plurality of attenuation poles can be formed according to the electrical length from the short-circuited end of the damped resonator electrode 8 to each end of the open end branched off, so that each end of the open end branched off from the short-circuited end can be formed. By adjusting the positions of the plurality of attenuation poles, the filter device having a steeper attenuation characteristic can be easily obtained.

  The shape of the damped resonator electrode 8 may be adjusted in accordance with the amount of coupling with the resonator electrodes 3a to 3d. However, as a whole, the shape of the damped resonator electrode 8 is a strip shape along the resonator electrodes 3a to 3d and the open end is Those branched into a plurality are preferred.

  The shape of the open end of the damped resonator electrode 8 is not particularly limited as long as the length from the short-circuited end to each end of the open end is different, and the shape from the short-circuited end is not particularly limited. (A so-called curved Y-shape in this example) may be used, and the main body from the short-circuit end to the open end may be similarly curved. Further, the number of branches may be branched not only to two but also to three or more than that. The length from the short-circuited end to the tip of each open end and the number of branches may be set according to the required attenuation frequency and the number of attenuation poles depending on the required filter characteristics.

  Planar arrangement of the coupling electrode 4, the input terminal electrode 5, the output terminal electrode 6, the capacitive electrode 7, and the damped resonator electrode 8 with respect to the resonator electrodes 3 a to 3 d and distances from each other (dielectric layer interposed therebetween) The thickness or number of layers 1a is not particularly limited, and may be set so as to adjust the coupling between each electrode and the resonator electrodes 3a to 3d so as to obtain a desired attenuation characteristic.

As the dielectric layer 1a, for example, alumina, mullite, aluminum nitride, BaO—TiO ₂ series, CaO—TiO ₂ series, MgO—TiO ₂ series, ceramic materials such as glass ceramics, or tetrafluoroethylene resin (polytetra PTFE), tetrafluoroethylene-ethylene copolymer resin (tetrafluoroethylene-ethylene copolymer resin; ETFE), tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin (tetrafluoroethylene-perfluteroalkyl vinyl ether) Fluorine resin such as copolymer resin (PFA), glass epoxy resin, and organic resin material such as polyimide are used. The shape and dimensions (thickness, width, length) of the dielectric layer 1a made of these materials are set according to the frequency used, the application, and the like. In the case of a ceramic material, low-temperature fired ceramics that can be fired simultaneously with a conductor material made of a low-resistance metal such as Au, Ag, or Cu that can transmit a higher frequency signal is preferable.

  In the ground electrode 2a, the internal ground electrode 2b, the resonator electrodes 3a to 3d, the coupling electrode 4, the input terminal electrode 5, the output terminal electrode 6, the capacitor electrode 7, and the damped resonator electrode 8, the dielectric layer 1a is made of a ceramic material. In this case, it is formed of a metallized layer containing a metal such as W, Mo, Mo—Mn, Au, Ag, or Cu as a main component. When the dielectric layer 1a is made of a resin material, a metal layer formed by a thick film printing method, various thin film forming methods, a plating method or a foil transfer method, or a plating layer on such a metal layer is formed. For example, Cu layer, Cr—Cu alloy layer, Cr—Cu alloy layer with Ni plating layer and Au plating layer deposited, TaN layer with Ni—Cr alloy layer and Au plating layer Examples thereof include those deposited, those obtained by depositing a Pt layer and an Au plating layer on a Ti layer, and those obtained by depositing a Pt layer and an Au plating layer on a Ni—Cr alloy layer. The thickness and width are set according to the frequency and application of the transmitted high-frequency signal.

  Dielectric layer 1a, ground electrode 2a, internal ground electrode 2b, resonator electrodes 3a to 3d, coupling electrode 4, ground electrode facing portion 4a, input terminal electrode 5, output terminal electrode 6, capacitor electrode 7, damped resonator electrode 8 A conventionally known method may be used to form. For example, if the dielectric layer 1a is made of glass ceramics, first prepare green sheets of glass ceramics to be the dielectric layers 1a, and print a conductor paste such as Ag in a predetermined shape on the green sheets by screen printing. The ground electrode 2a, the internal ground electrode 2b, the resonator electrodes 3a to 3d, the coupling electrode 4, the ground electrode facing portion 4a, the input terminal electrode 5, the output terminal electrode 6, the capacitor electrode 7, and the damped resonator electrode 8 are applied. An electrode pattern is formed. Next, a green body with these electrode patterns formed thereon is stacked and pressure-bonded, for example, to produce a laminate, and this laminate is formed by firing at 850 to 1000 ° C. Thereafter, a plating film such as Ni plating or Au plating is formed on the conductor layer exposed on the outer surface. If the dielectric layer 1a is made of an organic resin material, for example, the ground electrode 2a, the internal ground electrode 2b, the resonator electrodes 3a to 3d, the coupling electrode 4, the ground electrode facing portion 4a, the input terminal electrode on the organic resin sheet 5, by transferring Cu foil processed into electrode pattern shapes of output terminal electrode 6, capacitive electrode 7 and damped resonator electrode 8, and laminating organic resin sheets to which Cu foil is transferred and bonding them with an adhesive Form.

  The connection conductor connecting the ground electrode 2a and the short-circuit ends of the resonator electrodes 3a to 3d is a through conductor formed in the dielectric layer 1a located between them or an end face formed on the end face of the dielectric layer 1a. By forming in the form of a conductor, the degree of freedom in designing the filter device formed inside the laminated dielectric layers 1a is improved, and a more compact and high-performance filter device can be obtained.

  When the dielectric layer 1a is made of ceramics such as glass ceramics, the through conductors and the side conductors serving as the connection conductors are, for example, the ground electrode 2a, the internal ground electrode 2b, the resonance in the manufacturing method described above. Before forming the electrode patterns of the resonator electrodes 3a to 3d, the coupling electrode 4, the ground electrode facing portion 4a, the input terminal electrode 5, the output terminal electrode 6, the capacitor electrode 7, and the damped resonator electrode 8, the mold is formed on the green sheet. It can be formed by filling a similar conductor paste into a through-hole formed in advance by processing or laser processing by a printing method or the like, and the end face conductor is, for example, a short circuit of the electrode patterns of the resonator electrodes 3a to 3d. After forming the green sheet laminate with the end exposed at the end face, the same conductor paste is printed on the side of the green sheet laminate. It can be. In addition, the end face conductor is formed so that a through hole having a width about the width of the resonator electrodes 3a to 3d is formed in the green sheet, and the short-circuit end of the electrode pattern of the resonator electrodes 3a to 3d is in contact with the through hole. Thereafter, the conductive paste can be printed on the inner surface of the through hole before or after the green sheet is laminated, or can be formed by filling the through hole and cutting at the portion of the through hole. Similarly, when the dielectric layer 1a is made of a resin-based material, an organic resin sheet is used instead of the green sheet, and a through conductor is formed in the through hole by printing or plating a conductor paste, or a side conductor is formed by a thin film method or the like. May be formed. In order to expose the short-circuit ends of the electrode patterns of the resonator electrodes 3a to 3d on the side surfaces of the stacked body, the short-circuit ends of the electrode patterns of the resonator electrodes 3a to 3d are located at the end of the green sheet (or organic resin sheet). Or after laminating green sheets (organic resin sheets) on which the electrode patterns of the resonator electrodes 3a to 3d are formed, the short-circuit ends of the electrode patterns of the resonator electrodes 3a to 3d are laminated so as to be exposed on the side surfaces. Just cut your body.

Specifically, a filter device as a bandpass filter having a passband center frequency of 3.9 GHz, which is used in the UWB low-band standard, has the form shown in FIG. 7, for example, as the dielectric layer 1a. Glass ceramics with a relative dielectric constant of 9.4 is used, and the ground electrode 2a, internal ground electrode 2b, resonator electrodes 3a to 3d, coupling electrode 4, input terminal electrode 5, output terminal electrode 6, capacitor electrode 7 and through metal are Ag metalized. It is obtained by using. Glass ceramics having a relative dielectric constant of 9.4 include, for example, 50% by mass of crystallized glass mainly composed of PbO, B ₂ O ₃ , SiO ₂ , Al ₂ O ₃ , ZnO and an alkaline earth metal oxide as glass components. And what consists of 50 mass% of alumina as a filler component may be used.

  At this time, the dielectric layer 1a has a thickness of 400 μm, 75 μm, 75 μm, and 350 μm in order from the top. The ground electrodes 2a and 2a have dimensions of 3.35 mm × 5.0 mm, and the internal ground electrode 2b has outer dimensions of 3.35 mm × 5.0 mm and inner dimensions (opening dimensions) of 2.945 mm × 3.5 mm. In this opening, resonator electrodes 3a, 3b, 3c, 3d having dimensions of 0.4 mm × 3.35 mm are aligned side by side at intervals of 0.155 mm, 0.135 mm, 0.155 mm, and each short-circuited end is connected to the internal ground electrode 2b. The distance between each open end and the internal ground electrode 2b is 0.15 mm, and the distance between the resonator electrodes 3a and 3d and the internal ground electrode 2b is 0.45 mm. The internal ground electrode 2b and the ground electrodes 2a and 2a on the upper and lower surfaces of the laminate 1 are connected by through conductors having a diameter of 0.1 mm arranged on the outer periphery. The input terminal electrode 5 is arranged so that the 0.3 mm × 3.35 mm internal input terminal electrode 5 b overlaps with the open end side of the first-stage resonator electrode 3 a in a range of 0.3 mm × 3.35 mm in plan view, and 0.2 mm × 0.25. The external input terminal electrode 5a of mm is connected by a through conductor having a diameter of 0.1 mm. Similarly, the output terminal electrode 6 is arranged such that the 0.3 mm × 3.35 mm internal output terminal electrode 6 b overlaps with the open end side of the final stage resonator electrode 3 d by 0.3 mm × 3.35 mm in plan view, and is 0.2 mm × 0.25. The external output terminal electrode 6a of mm is connected by a through conductor having a diameter of 0.1 mm.

  The coupling electrode 4 has a U shape in which one end of two 0.1 mm × 1.15 mm facing portions (one end and the other end) is connected by a 0.99 mm × 0.1 mm connecting portion. One of the two coupling electrodes 4, 4 is 0.1 mm × 1.05 in a plan view when the two opposing portions are short-circuited to the first-stage resonator electrode 3 a and the third-stage resonator electrode 3 c, respectively. 0.1 mm × 0.1 in which the connection portion is disposed on the open end side of the first-stage resonator electrode 3a and the third-stage resonator electrode 3c, and the other end portion of the facing portion overlaps the internal ground electrode 2b. It is connected to the internal ground electrode 2b by a through conductor having a diameter of 0.1 mm at the center of the mm portion. Also, the other coupling electrode 4 is connected so that the two opposing portions overlap with the short-circuited ends of the second-stage resonator electrode 3b and the final-stage resonator electrode 3d in a range of 0.1 mm × 1.05 mm in plan view. At the center of the 0.1 mm × 0.1 mm portion where the other end of the opposing portion overlaps with the internal ground electrode 2b, with the other portion disposed on the open end side of the second-stage resonator electrode 3b and the final-stage resonator electrode 3d. It is connected to the internal ground electrode 2b by a through conductor having a diameter of 0.1 mm.

  Two 0.15 mm × 0.6 mm ground electrode facing portions 4a and 4a are respectively spaced outside the resonator electrode 3a and the outside of the resonator electrode 3d by 0.625 mm from the one and the other coupling electrodes 4 and 4, respectively. In addition, the opposing portions of the one and the other coupling electrodes 4 and 4 are arranged in parallel so that one end thereof is aligned and overlapped with the internal ground electrode 2b, and the other end is connected to the one and the other with a connecting portion of 0.625 mm × 0.1 mm. It connects with the opposing part of the other coupling electrodes 4 and 4.

  The capacitive electrode 7 is a convex shape in which two rectangles of 0.2 mm × 0.4 mm and 0.4 mm × 0.6 mm are connected, and overlaps with the internal ground electrode 2b within a range of 0.4 mm × 0.6 mm, and the resonator electrodes 3a, 3b, 3c, It arrange | positions so that it may overlap with the open end part of 3d in the range of 0.2 mm x 0.25 mm by planar view, and it connects by the through-conductor with a diameter of 0.1 mm in the center of the overlapping part.

  The filter characteristics of the filter device (Example 1) of the present invention in such an example are as shown by a solid characteristic curve in the diagram of FIG. Further, with respect to the filter characteristics of the first embodiment, the filter characteristics obtained in the filter device (second embodiment) of the present invention that does not have only the ground electrode facing portions 4a and 4a are shown in the diagram of FIG. The characteristic curve is shown by a broken line, and as shown by the solid line in the diagram of FIG. Furthermore, the filter characteristics of the filter apparatus (comparative example) that does not have only the coupling electrode 4 with respect to the filter apparatus of the second embodiment are as shown by a broken line characteristic curve in the diagram of FIG. In the diagrams shown in FIGS. 11 and 12, the vertical axis represents insertion loss (unit: dB), and the horizontal axis represents frequency (unit: GHz).

  From the filter characteristics shown in FIG. 11, the filter characteristics of the filter device according to the second embodiment are such that an attenuation pole is formed on the high frequency side of the pass band of the filter and the attenuation on the high frequency side is larger than that of the pass band. You can see that Then, in the conventional filter device having the crank-type coupling electrode 14 as shown in FIG. 13, the same four-stage resonator electrode as in the second embodiment is used, and the first-stage farthest, not the adjacent resonator electrode, is used. The attenuation characteristics are the same as when the short-circuited end of the resonator electrode 3a and the fourth-stage resonator electrode are coupled.

  From the filter characteristics shown in FIG. 12, the filter characteristics of the filter device of the present invention according to the first embodiment are similar to the filter characteristics of the filter device according to the second embodiment. Yes (shifted to the low frequency side). This indicates that the attenuation on the high frequency side of the pass band becomes steeper and the filter device has a more excellent attenuation characteristic on the high frequency side of the pass band.

  From the above, the filter device of the present invention has one end opposed to the short-circuited end of one resonator electrode 3a and is electrically connected to the short-circuited end of the opposed resonator electrode 3a, and the other end is one resonance. Since the short-circuited end of the other resonator electrode 3c having the short-circuited end on the same side as the resonator electrode 3a has a coupling electrode electrically connected to the short-circuited end of the opposed resonator electrode 3c, A signal transmitted by (capacitive) coupling between the resonator electrodes 3a, 3b, 3b, 3c, 3c, 3d and a plurality of resonator electrodes 3a, 3c facing the coupling electrode 4 by the coupling electrode 4 ( A phase difference of 180 ° is generated between the signals transmitted by the (dielectric) coupling and cancels each other, so that an attenuation pole is formed at the high side of the pass band of the filter, and attenuation at the high side of the pass band Excellent damping characteristics with increased amount It can be seen that the in is. When the coupling electrode 4 has the ground electrode facing portion 4a facing the ground electrodes 2a and 2a or the internal ground electrode 2b branched between one end and the other end, the ground electrode facing portion 4a and the ground electrodes 2a and 2a Alternatively, since the coupling with the internal ground electrode 2b increases and the impedance of the coupling electrode 4 decreases, the coupling electrode 4 strengthens (dielectric) coupling between the plurality of resonator electrodes 3a and 3c facing the coupling electrode 4. The attenuation pole on the high frequency side can be brought close to the pass band of the filter (shifted to the low frequency side). This shows that the attenuation on the high frequency side of the pass band becomes steeper, and the attenuation characteristics on the high frequency side of the pass band are more excellent.

  Note that the conventional filter device has a structure that does not have the capacitor electrode 7 as compared with the comparative example. In such a conventional filter device, in order to have an attenuation pole at the same frequency as the filter device of the present invention (and the filter device of the comparative example), the resonator electrodes 3a to 3d must be lengthened. In addition to the increase in the size of the filter device, there is a jump in the attenuation characteristic on the higher frequency side than the attenuation pole, and the filter characteristic is not sufficiently attenuated in the attenuation band relative to the band used in the wireless LAN. End up.

It is a disassembled perspective view which shows typically an example of embodiment of the filter apparatus of this invention. It is a disassembled perspective view which shows typically an example of embodiment of the filter apparatus of this invention. It is a disassembled perspective view which shows typically an example of embodiment of the filter apparatus of this invention. It is a disassembled perspective view which shows typically an example of embodiment of the filter apparatus of this invention. It is a disassembled perspective view which shows typically an example of embodiment of the filter apparatus of this invention. It is a disassembled perspective view which shows typically an example of embodiment of the filter apparatus of this invention. It is a disassembled perspective view which shows typically an example of embodiment of the filter apparatus of this invention. (A)-(f) is a top view which shows an example of embodiment of the filter apparatus of this invention, respectively. It is sectional drawing which shows an example of the AA cross section of the filter apparatus shown in FIG. It is a disassembled perspective view which shows typically an example of embodiment of the filter apparatus of this invention. It is a figure which shows the transmission characteristic (filter characteristic) of the filter apparatus shown in FIG. It is a figure which shows the transmission characteristic (filter characteristic) of the other filter apparatus of this invention. It is a disassembled perspective view which shows the conventional filter apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Laminated body 1a ... Dielectric layer 2a ... Ground electrode 2b ... Internal ground electrode 3a-3d ... Resonator electrode 3a ... First stage resonator electrode 3d ... Final stage Resonator electrode 4... Coupling electrode 4 a .. ground electrode facing portion 5... Input terminal electrode 5 a .. external input terminal electrode 5 b .. internal input terminal electrode 6. ..External output terminal electrode 6b ... Internal output terminal electrode 7 ... Capacitance electrode 8 ... Damping resonator electrode

Claims (8)

A laminate in which a plurality of dielectric layers are laminated;
A ground electrode disposed so as to face each other with the laminate interposed therebetween;
Four or more resonator electrodes in which the short-circuited ends and the open ends are alternately arranged side by side in a plan view so as to be electromagnetically coupled to each other in the stacked body;
The resonator electrode is disposed with the dielectric layer sandwiched between the resonator electrode and the resonator electrode in the stacked body, and one end of the resonator electrode is opposed to the short-circuited end of the resonator electrode of the first stage or the last stage. face with is connected to the short-circuit end electrically, the other end, one of the resonator electrodes and the short-circuit end is opposed to the short-circuited end portion of the other of said resonator electrodes other than the first stage and the last stage on the same side A coupling electrode electrically connected to a short-circuited end of the resonator electrode;
An input terminal electrode connected to the resonator electrode of the first stage;
A filter device comprising an output terminal electrode connected to the resonator electrode in the final stage.   2. The filter device according to claim 1, wherein an internal ground electrode is formed so as to surround a plurality of the resonator electrodes in a plan view between the dielectric layers where the resonator electrodes are arranged.   3. The filter according to claim 1, wherein the coupling electrode has a ground electrode facing portion that faces the ground electrode or the internal ground electrode that is branched between the one end and the other end. apparatus.   A plurality of capacitive electrodes that are opposed to the ground electrode across the dielectric layer between the ground electrode and the resonator electrode and are electrically connected to open ends of the plurality of resonator electrodes, respectively. The filter device according to claim 1, wherein the filter device is a filter device.   5. The filter device according to claim 4, wherein a part of the capacitance electrode is disposed so as to face the internal ground electrode with the dielectric layer interposed therebetween. The input terminal electrode has a shape along the first-stage resonator electrode, and is disposed so as to face the first-stage resonator electrode with the dielectric layer interposed therebetween, and is electromagnetically coupled to the first-stage resonator electrode. An internal input terminal electrode; and an external input terminal electrode formed on the outer surface of the laminate and connected to the internal input terminal electrode on the open end side of the first-stage resonator electrode, and the output terminal electrode Is arranged in a shape along the resonator electrode in the final stage, and is disposed so as to face the resonator electrode in the final stage with the dielectric layer in between, and is electromagnetically coupled to the resonator electrode in the final stage. An output terminal electrode; and an external output terminal electrode formed on an outer surface of the laminate and connected to the internal output terminal electrode on the open end side of the final stage of the resonator electrode. Any one of claims 1 to 5 Filter device as claimed.   It is arranged to be electromagnetically coupled to one of the resonator electrodes in the laminate other than between the resonator electrodes, and has at least one damped resonator electrode having one end short-circuited and the other end open. The filter device according to claim 1, wherein:   8. The filter device according to claim 7, wherein the damped resonator electrode has a shape in which the open end is branched into a plurality, and the length from the short-circuited end to each tip of the open end is different.

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