JP3860800B2 - Trap device with built-in trap circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a trap circuit built-in filter device, and more particularly to a trap circuit built-in filter device having a structure that suppresses electromagnetic coupling between a resonator constituting the filter circuit and a resonator constituting the trap circuit. It is.
[0002]
[Prior art]
Multilayer dielectric filters using stripline resonators have been widely used in various types of wireless communication devices that utilize the microwave band, and have a built-in trap circuit that combines a multilayer dielectric filter and a trap circuit. Various filter devices such as filter devices have been devised and used.
[0003]
As a conventional filter device with a built-in trap circuit, a device in which a stripline resonator constituting a filter and a stripline resonator constituting a trap circuit are formed inside a dielectric is known (for example, see Patent Document 1). .)
[0004]
FIG. 4 schematically shows an example of a conventional trap circuit built-in type filter device. 4, 11 to 14 are dielectric layers, 21 to 23 are ground electrodes, 40a to 40c are input / output electrodes, 50a to 50c are main transmission lines, and 71 and 72 are external terminal electrodes. It is. Input / output capacitances are formed between the input / output electrodes 40a to 40c and the main transmission lines 50a to 50c facing each other. One end of the main transmission lines 50a to 50c is connected to a ground electrode 23 formed on one side of the long side of the trap circuit built-in filter device 10, and the ground electrode is connected via the ground electrode 23. 21 and 22 are also electrically connected.
[0005]
Here, the strip line resonator A is constituted by the ground electrodes 21 and 22 and the main transmission line 50a, and the strip line resonator B is constituted by the ground electrodes 21 and 22 and the main transmission line 50b. 50c and the stripline resonator C are each comprised.
[0006]
The stripline resonator A and the stripline resonator B are electromagnetically coupled to form a filter circuit, and the stripline resonator C operates as a trap circuit.
[0007]
Furthermore, one input / output electrode 40a of the filter circuit is connected to an input-side external terminal electrode 71 formed on one side surface on the short side of the filter device 10 with a built-in trap circuit, and the other input / output of the filter circuit. The electrode 40b is connected to an output-side external terminal electrode 72 formed on the other side surface on the long side of the trap circuit built-in type filter device 10. The trap circuit input / output electrode 40c is connected to the output-side external terminal electrode 72 formed on the other side surface of the long side of the trap circuit built-in type filter device 1. Thus, the trap circuit built-in filter device 10 is configured as a whole.
[0008]
With the above-described conventional trap circuit built-in type filter device, the filter characteristic in which the attenuation pole is formed at a frequency corresponding to the resonance frequency of the stripline resonator C can be obtained by adopting the above configuration.
[0009]
[Patent Document 1]
JP 2002-299904 A (FIG. 1)
[0010]
[Problems to be solved by the invention]
However, in the above-described conventional trap circuit built-in filter device, the length of the main transmission lines 50a to 50c needs to be ¼ of the wavelength of the desired resonance frequency, which increases the size of the device. There was a problem. As a method for reducing the size of the apparatus, a method in which the resonator is a folded type is conceivable. However, if this is done, the stripline resonators constituting the filters arranged close to each other and the folded portions of the stripline resonators constituting the trap circuit are connected to each other. It is predicted that electric field coupling will occur and the characteristics in the passband of the filter will deteriorate.
[0011]
The present invention has been devised in view of the above problems, and an object thereof is to provide a trap device with a built-in trap circuit that is small in size and excellent in passband characteristics.
[0012]
[Means for Solving the Problems]
The filter device with a built-in trap circuit according to the present invention has a ground electrode attached to both main surfaces of a laminate in which a plurality of dielectric layers are laminated, and at least two stripline resonators in the laminate. In the filter device with a built-in trap circuit in which a filter circuit having a trap circuit and a trap circuit having at least one stripline resonator are arranged in parallel, the stripline resonator constituting the filter circuit and the trap circuit has different dielectrics. A main transmission line and a sub-transmission line disposed between body layers, a connection conductor that electrically connects both transmission lines, and a stripline resonator that constitutes the trap circuit; The stripline resonator of the filter circuit adjacent to the stripline resonator is a main transmission line and a subtransmission line. And it is characterized in that it is arranged in the stacking direction of the body at the upper and lower opposite positional relationship.
[0013]
In the filter device with a built-in trap circuit according to the present invention, the sub-transmission line of the stripline resonator constituting the trap circuit is connected to the main transmission line of the stripline resonator of the filter circuit adjacent to the stripline resonator. Compared to the ground electrode, it is arranged.
[0014]
Furthermore, the filter device with a built-in trap circuit according to the present invention is characterized in that the ground electrode is further covered with a dielectric layer.
[0015]
[Action]
According to the present invention, the stripline resonator constituting the filter circuit and the trap circuit includes a main transmission line and a subtransmission line disposed between different dielectric layers, and a connection conductor that electrically connects both transmission lines. The stripline resonator constituting the trap circuit and the stripline resonator of the filter circuit adjacent to the stripline resonator include a main transmission line and a sub-transmission line. They are arranged in a positional relationship upside down in the stacking direction of the stack. Since the stripline resonator is a folded type as described above, the resonance frequency can be lowered by the capacitance generated between the sub-transmission line and the ground electrode, so that the length of the main transmission line can be shortened. The apparatus can be reduced in size. Further, since the sub-transmission line of the stripline resonator constituting the trap circuit and the sub-transmission line of the stripline resonator of the filter circuit adjacent to the stripline resonator are disposed apart from each other, Coupling due to the electric field between them can be reduced, and deterioration of the characteristics in the passband of the filter can be effectively prevented.
[0016]
According to the present invention, the sub-transmission line of the strip line resonator constituting the trap circuit is closer to the ground electrode than the main transmission line of the strip line resonator of the filter circuit adjacent to the strip line resonator. Has been placed. By arranging the sub-transmission line close to the ground electrode, a large capacitance can be obtained with a small sub-transmission line, and the main transmission line can be miniaturized. Therefore, a stripline resonator and a device including the same are provided. It can be downsized. Further, the Q value of the resonator can be increased by arranging the main transmission line and the ground electrode apart from each other.
[0017]
Furthermore, according to the present invention, the ground electrode is further covered with a dielectric layer. Therefore, it is possible to effectively prevent the ground electrode of the trap circuit built-in filter device from inadvertently contacting the hot potential electrode of the circuit board on which the trap circuit built-in filter device is mounted.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings.
[0019]
FIG. 1 is an external perspective view schematically showing a trap circuit built-in type filter device according to an embodiment of the present invention, FIG. 2 is a sectional view taken along the line PP ′ of the trap circuit built-in type filter device of FIG. 1 is an exploded perspective view schematically showing a trap circuit built-in filter device according to an embodiment of the present invention.
[0020]
The trap circuit built-in type filter device 1 shown in these figures is obtained by laminating and firing a dielectric layer made of an unfired green sheet or the like having an electrode layer made of a conductive material deposited on one side by printing or the like. It is created by depositing and firing a conductor film to be used as an electrode or an external terminal electrode.
[0021]
In FIG. 3, reference numerals 11 to 17 denote dielectric layers, which are composed of a dielectric ceramic material and an oxide or a low melting point glass material that can be fired at a low temperature. Examples of dielectric ceramic materials include BaO—TiO ₂ , Ca—TiO ₂ , MgO—TiO _{2, and the} like. As oxidizers for low-temperature firing, BiVO ₄ , CuO, LiO ₂ , B ₂ O ₃ etc. In order to reduce the shape, a material having a high dielectric constant is preferable, and a material having a relative dielectric constant of 15 to 20 is preferably used. The thickness of each dielectric layer is often about 50 μm to 300 μm.
[0022]
A ground electrode 21 is deposited on the top surface of the dielectric layer 11 disposed at the bottom in the thickness direction, and a ground electrode 22 is deposited on the top surface of the dielectric layer 17 disposed at the top in the thickness direction. The sub-transmission line 30c is covered on the upper surface of the dielectric layer 12 disposed on the dielectric layer 11, and the sub-transmission lines 30a and 30b are covered on the upper surface of the dielectric layer 16 disposed below the dielectric layer 17. A capacitance is formed between each electrode and the ground electrode. The input / output electrode 40c is covered on the upper surface of the dielectric layer 13 disposed on the dielectric layer 12, and the input / output electrodes 40a and 40b are covered on the upper surface of the dielectric layer 15 disposed below the dielectric layer 16. It is worn. Input / output capacitances are respectively formed between the input / output electrodes 40a, 40b, and 40c and the sub-transmission lines 30a, 30b, and 30c. Main transmission lines 50a, 50b, and 50c are attached to the upper surface of the dielectric layer 14 disposed between the dielectric layer 13 and the dielectric layer 15. One end portions of the main transmission lines 50a, 50b, and 50c are drawn out to one side surface on the long side of the trap circuit built-in type filter device 1, and the ground electrode 21 is formed by the ground electrode 23 formed on the one side surface of the long side. , 22 are electrically connected. Also, via holes 60a, 60b, 60c are connected to the other end portions of the main transmission lines 50a, 50b, 50c, respectively, and are connected to the sub transmission lines 30a, 30b, 30c by the via holes 60a, 60b, 60c, respectively. Has been.
[0023]
Here, together with the ground electrodes 21 and 22, the stripline resonator A is formed by the main transmission line 50a, the via hole 60a, and the subtransmission line 30a, and the stripline resonance is performed by the main transmission line 50b, the via hole 60b, and the subtransmission line 30b. The strip line resonator C is configured by the main transmission line 50c, the via hole 60c and the sub transmission line 30c.
[0024]
The stripline resonator A and the stripline resonator B are electromagnetically coupled to form a filter circuit, and the stripline resonator C operates as a trap circuit resonator.
[0025]
Furthermore, one input / output electrode 40a of the filter circuit is connected to an input-side external terminal electrode 71 formed on one side surface on the short side of the filter device 1 with a built-in trap circuit, and the other input / output of the filter circuit. The electrode 40b is connected to the output-side external terminal electrode 72 formed on the other side surface on the long side of the filter device 1 with a built-in trap circuit. The trap circuit input / output electrode 40c is connected to the output side external terminal electrode 72 formed on the other side surface of the long side of the trap circuit built-in type filter device 1, and in this way, the trap circuit as a whole is connected. A built-in filter device is configured.
[0026]
The various electrodes are formed of a conductive material mainly composed of Ag or Cu, such as Ag alone, Ag—Pd, Ag—Pt, or Cu alone.
[0027]
In such a trap circuit built-in type filter device of this embodiment, between the stripline resonator B constituting the filter circuit and the stripline resonator C constituting the trap circuit, the sub transmission line is connected to the main transmission line. The position in the stacking direction is turned upside down. That is, in the stripline resonator B, the sub transmission line 30b is disposed above the main transmission line 50b, whereas in the stripline resonator C, the sub transmission line 30c is disposed below the main transmission line 50c. It is arranged. Accordingly, since the sub-transmission lines 30b and 30c are arranged apart from each other, the coupling due to the electric field between them can be reduced, thereby effectively preventing the deterioration of the characteristics in the passband of the filter. be able to.
[0028]
Further, in order to increase the Q value of each SL resonator, it is desirable that the distance between the main transmission lines 50a, 50b, 50c and the ground electrodes 21, 22 is large, and the sub transmission lines 30a, 30b, 30c and the ground electrode When the distance between the first and second electrodes 22 and 22 and the input / output electrodes 40a, 40b, and 40c is smaller, a larger capacitance can be formed with a smaller shape. Therefore, the dielectric layers 12, 13, 16, and 17 are formed relatively thin, and the dielectric layers 14 and 15 are formed relatively thick. Further, the main transmission lines 50a, 50b, 50c are arranged approximately at the center between the ground electrode 21 and the ground electrode 22 in the thickness direction.
[0029]
Note that the present invention is not limited to the above-described embodiment, and various modifications and improvements can be made without departing from the scope of the present invention.
[0030]
In the above-described embodiment, the stripline resonators A and B constituting the filter circuit and the stripline resonator C constituting the trap circuit are connected to the ground potential on the same side surface of the trap device built-in filter device 1. However, a structure in which a different side surface of the filter device 1 with a built-in trap circuit is connected to the ground potential may be used. By adopting such a structure, it is possible to further reduce the coupling due to the electric field by further increasing the distance between the sub-transmission lines located on the open end side of the stripline resonator, and further, between the short-circuited ends of the stripline resonator. The coupling by the magnetic field can be reduced by increasing the distance. Therefore, the electromagnetic coupling between the stripline resonator constituting the filter circuit and the stripline resonator constituting the trap circuit can be further reduced, and the deterioration of the characteristics in the passband of the filter can be further reduced. it can.
[0031]
In the above-described embodiment, the so-called comb line type in which the plurality of stripline resonators constituting the filter circuit are connected to the ground potential on the same side of the trap circuit built-in type filter device 1 is used. It may be an interdigital type connected to the ground potential on the opposite side surface of the mold filter device.
[0032]
Further, in the above-described embodiment, the main transmission line of the stripline resonator is grounded by being connected to the ground electrode 23 formed on the side surface of the trap device built-in type filter device 1. A structure in which one end of a via hole or a through hole is connected near the short-circuit end and the other end of the via hole or the through hole is connected to an electrode having a ground potential may be grounded.
[0033]
Furthermore, in the above-described embodiment, the main transmission line and the sub-transmission line are connected by via holes, but they may be connected by through holes or end faces formed on the side surfaces of the trap circuit built-in filter device. A structure in which electrodes are connected may be used.
[0034]
Furthermore, in the above-described embodiment, in the plurality of stripline resonators constituting the filter circuit, the main transmission line and the subtransmission line are arranged in the same positional relationship in the stacking direction. The transmission line and the sub-transmission line may be arranged in a positional relationship that is upside down in the stacking direction.
[0035]
Furthermore, in the above-described embodiment, an example of a trap circuit built-in type filter device having one trap circuit is shown, but it may be configured to include two or more trap circuits.
[0036]
Furthermore, in the above-described embodiment, the chip-shaped composite filter device has been described as an example. However, for example, the present invention can be applied to a composite filter device having the above-described configuration in a module substrate. Yes.
[0037]
【The invention's effect】
According to the present invention, a stripline resonator constituting a filter circuit and a trap circuit includes a main transmission line and a subtransmission line disposed between different dielectric layers, and a connection conductor that electrically connects both transmission lines. Therefore, it is possible to reduce the size of the stripline resonator and the apparatus including the stripline resonator. The stripline resonator constituting the trap circuit and the stripline resonator of the filter circuit adjacent to the stripline resonator are such that the main transmission line and the subtransmission line are positioned upside down in the stacking direction of the laminate. Since they are arranged in the relationship, it is possible to effectively prevent the deterioration of the characteristics in the passband of the filter.
[0038]
According to the present invention, the sub-transmission line of the strip line resonator constituting the trap circuit is closer to the ground electrode than the main transmission line of the strip line resonator of the filter circuit adjacent to the strip line resonator. Since it is arranged, the apparatus can be miniaturized and the Q value of the resonator can be increased.
[0039]
Furthermore, according to the present invention, since the ground electrode is further covered with a dielectric layer, the ground electrode of the filter device with a built-in trap circuit is the hot potential electrode of the circuit board on which the filter device with a built-in trap circuit is mounted. It is possible to effectively prevent unintentional contact.
[Brief description of the drawings]
FIG. 1 is an external perspective view schematically showing a trap circuit built-in filter device according to an embodiment of the present invention.
2 is a cross-sectional view taken along the line PP ′ of the trap device with a built-in trap circuit of FIG. 1;
FIG. 3 is an exploded perspective view schematically showing a trap circuit built-in filter device according to an embodiment of the present invention.
FIG. 4 is an exploded perspective view schematically showing a conventional trap circuit built-in filter device.
[Explanation of symbols]
1: Filter device with built-in trap circuit 11-17: Dielectric layers 21-23: Earth electrodes 30a-30c: Sub-transmission lines 40a-40c: Input / output electrodes 50a-50c: Main transmission lines 60a-60c: Via hole 71: Input Side external terminal electrode 72: output side external terminal electrode

Claims (3)

A ground electrode is attached to both main surfaces of a laminate in which a plurality of dielectric layers are laminated, a filter circuit having at least two stripline resonators inside the laminate, and at least one strip In the trap circuit built-in type filter device formed by arranging a trap circuit having a line resonator in parallel,
The stripline resonator constituting the filter circuit and the trap circuit includes a main transmission line and a subtransmission line disposed between different dielectric layers, and a connection conductor that electrically connects both transmission lines. The strip line resonator constituting the trap circuit and the strip line resonator of the filter circuit adjacent to the strip line resonator are configured such that a main transmission line and a sub transmission line are stacked in the stacking direction of the stacked body. A trap circuit built-in type filter device, wherein the filter device is disposed in an upside down positional relationship. The sub-transmission line of the stripline resonator constituting the trap circuit is arranged closer to the ground electrode than the main transmission line of the stripline resonator of the filter circuit adjacent to the stripline resonator. The filter device with a built-in trap circuit according to claim 1. 3. The trap circuit built-in filter device according to claim 1, wherein the ground electrode is further covered with a dielectric layer.

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