JP3911507B2 - Multilayer dielectric filter - Google Patents

Description

  The present invention relates to a multilayer dielectric filter having a stripline resonator.

  This type of multilayer dielectric filter is used in, for example, a wireless communication device such as a mobile phone, and is required to be small in size, low in profile, and low in loss. As such a laminated dielectric filter, one having a coupling adjustment electrode for generating a coupling capacitance between stripline resonators is known (see, for example, Patent Document 1). In this multilayer dielectric filter, an attenuation pole can be formed in the vicinity of the low frequency side of the pass frequency band by the coupling capacitance between the resonators by the coupling adjustment electrode, and noise on the low frequency side can be removed. . However, by providing this coupling adjustment electrode, spurious due to resonance of the coupling adjustment electrode itself occurs on the high frequency side of the pass frequency band. Then, due to the spurious generated, noise is generated in the signal on the high frequency side in the pass frequency band, and the signal quality on the high frequency side is deteriorated.

In order to solve this problem, in the multilayer dielectric filter described in Patent Document 1, the dielectric constants of the dielectric layer provided with the resonance electrode and the dielectric layer provided with the coupling adjustment electrode are set to the surrounding layers. The dielectric constant is higher. By setting the dielectric constant of the dielectric layer in this way, the spurious is shifted so as to deviate from the desired frequency band, and deterioration of signal quality in the desired frequency band is suppressed.
JP 2003-198206 A

  However, in the multilayer dielectric filter described in Patent Document 1, noise removal on the high frequency side is insufficient, and sufficient signal quality on the high frequency side cannot be obtained.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a multilayer dielectric filter that can sufficiently suppress deterioration in signal quality.

The multilayer dielectric filter of the present invention is a multilayer dielectric filter including a stripline resonator, which is located on the first dielectric layer and the stripline resonator. A first laminated portion having three or more resonant electrodes, a second dielectric layer, and second resonant electrodes that are not adjacent to each other on the second dielectric layer. A second stacked portion having an adjustment electrode positioned so that at least a part thereof overlaps when viewed from the thickness direction of the dielectric layer, a connection electrode electrically connecting the adjustment electrodes to each other, and a resonance electrode Three or more strip electrodes that are provided opposite to each resonance electrode at a position sandwiched between the two laminated portions, are grounded, and form a capacitor capacitance with each resonance electrode; Lower dielectric constant than dielectric layer 2 A third laminated portion having a third dielectric layer, wherein one of the first and second laminated portions is the other of the first and second laminated portions and a third laminated portion. The connection electrode is located on the surface on which the adjustment electrode of the second dielectric layer is located, and the resonance electrode located between the resonance electrodes that are not adjacent to each other is seen from the thickness direction. It is located so that it may not overlap.

The multilayer dielectric filter of the present invention is a multilayer dielectric filter including a stripline resonator, and is located on the first dielectric layer and the first dielectric layer, and each is stripline. A first laminated portion having three or more resonant electrodes constituting the resonator, a second dielectric layer, and resonant electrodes that are not adjacent to each other among the resonant electrodes on the second dielectric layer; A second laminated portion having an adjustment electrode positioned so that at least a part thereof overlaps when viewed from the thickness direction of the second dielectric layer, and a connection electrode for electrically connecting the adjustment electrodes to each other; and a resonance electrode Three or more belt-like electrodes that are provided opposite to each resonance electrode at a position sandwiched between the first and second laminated portions, are grounded, and form a capacitor capacitance with each resonance electrode; And more dielectric than the second dielectric layer A third laminated portion having a low third dielectric layer, wherein one of the first and second laminated portions is the other of the first and second laminated portions and the third laminated portion. The connection electrode is located between the stacked electrodes, and the connection electrode is located on the surface on which the adjustment electrode of the second dielectric layer is located. It is located along the edge of the electrode.

  In these multilayer dielectric filters, three or more resonant electrodes constituting the stripline resonator are present in the first multilayer part. An adjustment electrode that is positioned so that at least a part of each of the resonance electrodes that are not adjacent to each other overlaps each other when viewed from the thickness direction of the dielectric layer, and a connection electrode that connects the adjustment electrodes is the second stacked By being present in the portion, a coupling capacitance is generated between the non-adjacent resonant electrodes. Due to this coupling capacitance, an attenuation pole is formed on the lower side of the pass frequency band in the multilayer dielectric filter. Further, the adjustment electrode and the connection electrode generate spurious on the high frequency side of the pass frequency band. In this multilayer dielectric filter, the connection electrode and the resonance electrode located between the resonance electrodes that are not adjacent to each other are positioned so as not to overlap when viewed from the thickness direction, or the connection electrode is a resonance electrode. Since it is located along the edge, parasitic elements generated between the resonance electrode and the connection electrode are reduced, and spurious is attenuated. In addition, since this multilayer dielectric filter has the third dielectric layer having a low dielectric constant in the third multilayer portion, a low dielectric constant layer exists in the vicinity of the connection electrode. For this reason, the influence of resonance of the connection electrode is reduced, and spurious due to the resonance is attenuated. As a result, according to these laminated dielectric filters, signal quality deterioration is sufficiently suppressed.

  Moreover, it is preferable that a 3rd laminated part is adjacent to a 2nd laminated part in the thickness direction. In this case, since the third dielectric layer having a low dielectric constant is close to the adjustment electrode and the connection electrode provided in the second stacked portion, the influence of the resonance of the connection electrode is effectively reduced, resulting from the resonance. The spurious is effectively attenuated.

  According to the multilayer dielectric filter of the present invention, signal quality deterioration can be sufficiently suppressed.

  A multilayer dielectric filter according to an embodiment of the present invention will be described. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.

(First embodiment)
As shown in FIGS. 1, 2, and 3, the multilayer dielectric filter F1 is a bandpass filter including three stripline resonators 51a, 51b, and 51c. The multilayer dielectric filter F1 exhibits frequency characteristics as shown in FIG. 4 due to the action of the stripline resonators 51a, 51b, and 51c, and has a pass frequency band of about 2200 to 2500 MHz.

  The multilayer dielectric filter F1 includes a multilayer body 3, ground external electrodes 5 and 7, an input external electrode 9, and an output external electrode 11. The laminated body 3 has laminated portions S1, S2, S3, S4, S5, S6, S7, S8, S9, and S10 formed in a rectangular plate shape. The stacked body 3 has a rectangular parallelepiped shape by stacking these stacked portions in the thickness direction of the dielectric layers in this order.

  The stacked portions S2, S5, S6, S7, and S10 include dielectric layers R2, R5, R6, R7, and R10, and internal electrodes P2, P5, P6, P7, and P10 screen-printed on the dielectric layers. have. The stacked portions S1, S3, S4, S8, and S9 include dielectric layers R1, R3, R4, R8, and R9 that are not provided with internal electrodes.

The dielectric layers R3, R4, R8, and R9 are made of a material having a lower dielectric constant than the dielectric layers R5, R6, and R7. For example, the former is made of glass ceramics and the relative dielectric constant ε _r is ε _r = 6, and the latter is made of ceramics and ε _r = 75. That is, the multilayer dielectric filter F1 has a low dielectric constant dielectric on one side so as to sandwich a multilayer portion (hereinafter referred to as “high dielectric constant portion”) S5, S6, and S7 including a dielectric layer having a high dielectric constant. A layered portion including layers (hereinafter referred to as “low dielectric constant portion”) S3, S4 (third laminated portion) and a low dielectric constant portion S8, S9 (third laminated portion) on the other side are formed. is doing. The dielectric layers R1, R2, and R10 are also made of glass ceramics and have a low dielectric constant portion with ε _r = 6.

  The ground external electrodes 5 and 7 are provided in contact with the side surfaces 17 and 21 of the multilayer body 3, respectively. The input external electrode 9 is provided in contact with the side surface 15, and the output external electrode 11 is provided in contact with the side surface 19.

  The internal electrode P2 provided in the stacked unit S2 functions as a shield electrode, and the internal electrode P10 formed in the stacked unit S10 functions as another shield electrode. The internal electrodes P2 and P10 are both exposed on both the side surface 17 and the side surface 21 of the laminate 3, and are in contact with the ground external electrodes 5 and 7 and are electrically connected to both the ground external electrodes 5 and 7. Has been.

  One end of the internal electrode P6 provided in the stacked portion S6 (first stacked portion) is in contact with the ground external electrode 5 at the side surface 17 and is electrically connected to the ground external electrode 5. The other end side of the internal electrode P6 is branched into three, which are resonance electrodes 25a, 25b, and 25c extending in a strip shape in the direction toward the side surface 21. The front end portions on the side surface 21 side of the resonance electrodes 25a, 25b, and 25c are open ends that do not reach the side surface 21, and the distances from the side surface 17 of the edge portions of the respective front ends are made equal. The resonance electrodes 25a, 25b, and 25c have predetermined inductances, respectively, and constitute stripline resonators 51a, 51b, and 51c, respectively. Branch portions extend from the side edges of the resonance electrodes 25a and 25c toward the side surfaces 15 and 19, respectively. These branches are exposed to the side surfaces 15 and 19, respectively, and are in contact with the input external electrode 9 and the output external electrode 11, respectively. That is, the resonance electrode 25a is electrically connected to the input external electrode 9 via the branch portion, and the resonance electrode 25c is electrically connected to the output external electrode 11 via the branch portion.

  One end of the internal electrode P5 provided in the stacked portion S5 is in contact with the ground external electrode 7 on the side surface 21 and is electrically connected to the ground external electrode 7. The other end side of the internal electrode P5 is branched into three, which are strip-like electrodes 27a, 27b, 27c extending in the direction toward the side surface 17. The end portions on the side surface 17 side of the strip electrodes 27a, 27b, and 27c are open ends that do not reach the side surface 17. The strip electrodes 27a, 27b, and 27c are positioned so as to face the resonance electrodes 25a, 25b, and 25c, respectively, with the dielectric layer R5 interposed therebetween. With such a configuration, capacitances 53a, 53b, and 53c are generated by the strip electrodes 27a, 27b, and 27c, the resonance electrodes 25a, 25b, and 25c, and the dielectric layer R5 sandwiched therebetween, respectively. Become. The pass frequency band in the multilayer dielectric filter 1 is adjusted by the capacitances 53a, 53b, and 53c.

  The internal electrode P7 provided in the stacked portion S7 (second stacked portion) has adjustment electrodes 29a and 29c having a rectangular shape and a connection electrode 29d that connects them, and has a U-shape in plan view as a whole. Presented. The adjustment electrodes 29a and 29c are disposed at positions corresponding to the tip of the resonance electrode 25a and the tip of the resonance electrode 25c, respectively, with the dielectric layer R6 interposed therebetween, as viewed from the thickness direction of the dielectric layer R7. Each has a shape overlapping the tip. The resonance electrode 25a and the resonance electrode 25c are not adjacent to each other on the dielectric layer R6, and are arranged with one resonance electrode 25b existing between them. With such a configuration, capacitances 55a and 55c are respectively generated by the adjustment electrodes 29a and 29c, the resonance electrodes 25a and 25c, and the dielectric layer R6 sandwiched therebetween. The connection electrode 29d is provided to extend so as to connect the adjustment electrode 29a and the adjustment electrode 29c, and electrically connects the adjustment electrode 29a and the adjustment electrode 29c.

  By configuring the internal electrode P7 as described above, a coupling capacitance including the capacitances 55a and 55c is formed between the resonance electrode 25a and the resonance electrode 25c. This coupling capacitance is larger than the capacitance generated between the adjacent resonance electrode 25a and the resonance electrode 25b or between the resonance electrode 25b and the resonance electrode 25c. By providing the internal electrode P7 as described above, an attenuation pole in the frequency characteristic of the multilayer dielectric filter F1 is formed, and the low frequency side of the pass frequency band can be sharply attenuated (around 1900 MHz in FIG. 4). reference). Further, if the shape of the adjustment electrodes 29a and 29c is changed, the frequency and amount of attenuation at which the attenuation pole is generated can be adjusted. Therefore, the internal electrode P7 has a function as an attenuation pole adjustment electrode. .

  However, in the multilayer dielectric filter F1, when the internal electrode P7 is provided, spurious is generated on the high frequency side of the pass frequency band due to the resonance of the connection electrode 29d itself (see around 6500 MHz in FIG. 4). In order to suppress high-frequency noise in the multilayer dielectric filter F1 and sufficiently suppress deterioration in signal quality, it is necessary to attenuate spurious noise that causes this noise.

  Therefore, in the multilayer dielectric filter F1, as shown in FIG. 5, the connection electrode 29d and the resonance electrode 25b are disposed in a positional relationship so as not to overlap each other when viewed from the thickness direction of the dielectric layer R7. That is, the connection electrode 29d is positioned so as to cross between the position corresponding to the edge on the side surface 21 side of the resonance electrode 25b and the side surface 21. The connection electrode 29d connects the edge on the side surface 21 side of the adjustment electrode 29a and the edge on the side surface 21 side of the adjustment electrode 29c while bypassing the position corresponding to the resonance electrode 25b to the side surface 21 side. . As described above, the connection electrode 29d bypasses the position corresponding to the resonance electrode 25b, so that the distance and the facing area between the resonance electrode 25b and the connection electrode 29d are larger than when the connection electrode 29d does not bypass (see FIG. 7). Become. Therefore, the electrostatic capacitance of the parasitic element 57 generated between the resonance electrode 25b and the connection electrode 29d is reduced, and as a result, the high frequency side spurious is attenuated.

  As described above, the multilayer dielectric filter F1 includes the high dielectric constant portions S5, S6, and S7 in which the stripline resonator is formed, the low dielectric constant portions S3 and S4, and the low dielectric constant portions S8 and S9. The structure is sandwiched between. For this reason, a layer having a low dielectric constant is present in the vicinity of the connection electrode 29d. As a result, the influence of resonance of the connection electrode 29d itself is reduced, and spurious due to the resonance is attenuated. In particular, in the multilayer dielectric filter F1, since the multilayer part S8 adjacent to the multilayer part S7 in the thickness direction of the dielectric layer R7 is a low dielectric constant part, the connection electrode 29d and the low dielectric constant part are close to each other. Will exist and the spurious will be effectively attenuated.

  As described above, the multilayer dielectric filter F1 can suppress signal quality deterioration by attenuating spurious.

(Second Embodiment)
As shown in FIG. 6, the difference between the multilayer dielectric filter F2 and the multilayer dielectric filter F1 is the shape of the internal electrode provided in the multilayer portion S7. An internal electrode P27 is provided in place of the internal electrode P7 in the multilayer portion S7 of the multilayer dielectric filter F2. The internal electrode P27 includes adjustment electrodes 29a and 29c and a connection electrode 29e that connects them. The connection electrode 29e connects portions of the adjustment electrodes 29a and 29c that are closest to the side surface 21 among the edge portions 31a and 31c facing each other. That is, when viewed from the thickness direction of the dielectric layer R7, the connection electrode 29e is positioned along the edge 25h at the tip of the resonance electrode 25b. Even with such an arrangement of the connection electrode 29e, the distance and the facing area between the resonance electrode 25b and the connection electrode 29e are larger than in the case shown in FIG. 7, and therefore, the same as the multilayer dielectric filter F1. The effect is obtained.

  FIG. 8 shows the frequency characteristics at 6000 to 8000 MHz for the multilayer dielectric filter F1 and multilayer dielectric filter F2 of the above embodiment and the multilayer dielectric filter F3 as a comparative example. Note that the multilayer dielectric filter F3 of the comparative example is different from the multilayer dielectric filter F1 in the shape of the internal electrode provided in the multilayer portion S7 as shown in FIG. Instead of the internal electrode P7, an internal electrode P37 is provided in the multilayer portion S7 of the multilayer dielectric filter F3. The internal electrode P37 includes adjustment electrodes 29a and 29c and a connection electrode 29f that connects them. The connection electrode 29f connects the vicinity of the centers of the edges 31a and 31c of the adjustment electrodes 29a and 29c that face each other. Yes. That is, in the multilayer dielectric filter F3, the connection electrode 29f and the resonance electrode 25b are in a positional relationship as seen from the thickness direction of the dielectric layer R7.

  As shown in FIG. 8, in the multilayer dielectric filter F1 and the multilayer dielectric filter F2, the spurious is attenuated compared to the multilayer dielectric filter F3, and the attenuation at 6000 to 8000 MHz is large. In particular, it can be seen that the multilayer dielectric filter F1 has a large attenuation. Thus, according to the multilayer dielectric filter F1 and the multilayer dielectric filter F2, it can be seen that spurious can be attenuated and deterioration of signal quality is suppressed on the high frequency side of the pass frequency band. Further, in the multilayer dielectric filter F1 and the multilayer dielectric filter F2, by changing the positions of the connection electrodes 29d and 29e, spurious can be reduced without causing a large decrease in the Q value.

  In the above embodiment, the low dielectric constant portions S3 and S4 and the low dielectric constant portions S8 and S9 are provided on both one side and the other side of the high dielectric constant portions S5, S6 and S7. The rate part may be provided only on either side of the high dielectric constant part. In the above embodiment, since the low dielectric constant portions S3 and S4 and the low dielectric constant portions S8 and S9 are in a two-layer set, the low dielectric constant portion is thick, which is preferable in terms of further reducing spurious. The low dielectric constant portion is not limited to the two-layer set, but may be one layer at a time. In the multilayer dielectric filter F1, the multilayer part S8 adjacent to the multilayer part S7 provided with the internal electrode P7 is a low dielectric constant part, but a high dielectric constant is provided between the multilayer part S7 and the multilayer part S8. A rate part may be included.

  In the above embodiment, the present invention is applied to a multilayer dielectric filter having three stripline resonators. However, the present invention can also be applied to a multilayer dielectric filter having four or more stripline resonators. It is. In the multilayer dielectric filter in this case, the adjustment electrodes are arranged so that the adjustment electrodes correspond to the pair of resonance electrodes arranged so that one or more other resonance electrodes exist between each other. They are connected to each other by a connection electrode. Then, all of the one or more shared electrodes positioned between the pair of resonance electrodes and the adjustment electrode are positioned so as not to overlap each other when viewed from the thickness direction of the dielectric layer, or the connection electrode is resonant. It is located along the entire edge of the electrode.

It is a perspective view which shows a laminated dielectric filter. It is a disassembled perspective view which shows a laminated dielectric filter. It is a circuit diagram which shows a laminated dielectric filter. It is a graph which shows the frequency characteristic of a laminated dielectric filter. It is a top view of the laminated body of a laminated dielectric filter. It is a top view of the laminated body of the laminated dielectric filter which concerns on a modification. It is a top view of the laminated body of the laminated dielectric filter which concerns on a modification. It is a graph which shows the frequency characteristic of a laminated dielectric filter.

Explanation of symbols

F1 ... multilayer dielectric filter, 3 ... laminate, 25a, 25b, 25c ... resonant electrode, 27a, 27b, 27c ... strip electrode, 29a, 29c ... adjustment electrode, 29d, 29e ... connection electrode, 51a, 51b, 51c ... Strip line resonator, S6 ... Laminated part (first laminated part), S7 ... Laminated part (second laminated part), S3, S4, S8, S9 ... Laminated part (third laminated part), R6 ... Dielectric layer (first dielectric layer), R7 ... Dielectric layer (second dielectric layer), R3, R4, R8, R9 ... Dielectric layer (third dielectric layer), F2, F3 ... Multilayer dielectric filter.

Claims (3)

A laminated dielectric filter comprising a stripline resonator,
A first laminated portion having a first dielectric layer and three or more resonant electrodes that are located on the first dielectric layer and each form the stripline resonator;
The second dielectric layer and at least a part of the resonant electrode not adjacent to each other on the second dielectric layer so as to overlap each other when viewed from the thickness direction of the second dielectric layer. A second laminated portion having an adjustment electrode positioned and a connection electrode that electrically connects the adjustment electrodes;
At least three or more resonance electrodes that are provided to face each resonance electrode at a position sandwiching the resonance electrode with the second laminated portion, are grounded, and form a capacitor capacitance with each resonance electrode. A strip electrode;
A third laminated portion having a third dielectric layer having a dielectric constant lower than that of the first and second dielectric layers,
One of the first and second stacked portions is located between the other of the first and second stacked portions and the third stacked portion,
The connection electrode does not overlap with the resonance electrode positioned between the resonance electrodes that are not adjacent to each other on the surface of the second dielectric layer on which the adjustment electrode is located when viewed from the thickness direction. A laminated dielectric filter, characterized by being located in
A laminated dielectric filter comprising a stripline resonator,
A first laminated portion having a first dielectric layer and three or more resonant electrodes that are located on the first dielectric layer and each form the stripline resonator;
The second dielectric layer and at least a part of the resonant electrode not adjacent to each other on the second dielectric layer so as to overlap each other when viewed from the thickness direction of the second dielectric layer. A second stacked portion having an adjustment electrode positioned and a connection electrode for electrically connecting the adjustment electrodes;
At least three or more resonance electrodes that are provided to face each resonance electrode at a position sandwiching the resonance electrode with the second laminated portion, are grounded, and form a capacitor capacitance with each resonance electrode. A strip electrode;
A third laminated portion having a third dielectric layer having a dielectric constant lower than that of the first and second dielectric layers,
One of the first and second stacked portions is located between the other of the first and second stacked portions and the third stacked portion,
The connection electrode is formed on the edge of the resonance electrode located between the resonance electrodes that are not adjacent to each other as viewed from the thickness direction on the surface of the second dielectric layer on which the adjustment electrode is located. A laminated dielectric filter, characterized by being positioned along the same.
  3. The multilayer dielectric filter according to claim 1, wherein the third multilayer portion is adjacent to the second multilayer portion in the thickness direction.

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