JPH07122904A - Band-pass filter - Google Patents

Abstract

PURPOSE:To provide a band-pass filter with improved shield effect provided with a pole on the side of a high frequency higher than a passing band by turning the inductance of an inductance element disposed opposite to a resonator to an appropriate size. CONSTITUTION:Five plate-like members are mutually stacked up. Then, the stacked plate-like members are pressed in a direction orthogonal to a surface direction and a calcination processing is performed thereafter. Thus, five green sheets G1-G5 are practically joined into one, one dielectric substrate 13 is formed and two conductor patterns P2, two planar spiral coils 11a and 11b and a planar inductance element 12 are arranged respectively in a buried state. Then, the two conductor patterns P2 disposed inside the dielectric substrate 13 and the conductor pattern P1 on a surface are arranged so as to mutually face oppositely and two planar capacitors 14a and 14b are constituted. Thus, the two resonators 15a and 15b are electrically coupled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bandpass filter, and more particularly to a bandpass filter in which a plurality of resonators composed of a planar spiral coil and a planar capacitor are formed inside a dielectric.

[0002]

2. Description of the Related Art Conventionally, LC has been used as a bandpass filter.
Filters, helical filters, dielectric filters, etc. are widely used. Among these, a helical filter and a dielectric filter are generally used as a filter used in a high frequency region.

The frequency response characteristics when the helical filter and the dielectric filter for the high frequency region are used as a bandpass filter, as shown by the symbol (b) in FIG. 6, have a mountain shape with no poles before and after the passband. It is a characteristic of.

[0004]

This type of band pass filter has a low impedance due to capacitive coupling due to the distributed capacitance of the band pass filter, especially on the high frequency side higher than the pass band, so that the impedance shown in the frequency response characteristic is attenuated. The amount becomes small and it becomes a mountain shape without poles. Therefore, the actual situation is that the filter has a poor shielding effect on the high frequency side.

The present invention has been made to solve the above-mentioned problems of the conventional bandpass filter.
An object of the present invention is to provide a bandpass filter having a configuration capable of downsizing and height reduction (thinning), which has a high attenuation effect on a high frequency side higher than a passband and has a good shielding effect. It is in.

[0006]

In order to achieve the above object, in the present invention, a resonator composed of a planar spiral coil and a planar capacitor is formed inside a dielectric substrate,
A plurality of the resonators are connected so as to have a pass band characteristic, and a planar inductance element facing the resonators is arranged.

Further, according to the present invention, a plurality of planar spiral coils formed on one plane inside the dielectric substrate and one side of the plurality of planar spiral coils are opposed to each other. A plurality of resonators are formed by the plurality of planar capacitors arranged, and the plurality of resonators are connected to each other so as to have pass band characteristics. On the other side, a planar inductance element facing these is arranged inside the dielectric substrate.

Further, in the present invention, the planar spiral coil, the planar capacitor and the planar inductance element are each formed by printing using a conductive paste, and the planar spiral coil is formed by printing.
The planar capacitor and the planar inductance element are electrically connected by a via hole provided in the dielectric substrate.

[0009]

[Function] By making the inductance of the inductance element disposed opposite to the resonator composed of the planar spiral coil and the planar capacitor appropriate size, resonance occurs with the distributed capacitance of the bandpass filter, and the frequency response A pole is generated in the attenuation amount in the characteristic.

Moreover, by disposing the planar spiral coil, the capacitor and the inductance element, each of which is formed in a planar shape by printing, inside the dielectric substrate, it is less likely to be deformed by external pressure, and the size and size are reduced. It is possible to reduce the height.

The loss of the bandpass filter having such a pole is not so large as compared with the case where the inductance element is not provided.

[0012]

Embodiments of the bandpass filter according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a bandpass filter 1 according to the present invention.
FIG. 2 is a perspective view showing the configuration of No. 0, and the bandpass filter 10 of this example is formed by stacking five flat plate-shaped members 1, 2, 3, 4, 5 on one another.

The above-mentioned flat plate-shaped members 1, 2, 3, 4, 5 are
Green sheets G ₁ , G ₂ , G ₃ made of dielectric material,
The G _4, G ₅ are provided respectively as the substrate, the green sheets _{G 1, G 2, G 3} , G 4, G 5 outer surface each predetermined conductor pattern on the are printed molded.

Specifically, the conductor pattern P ₁ which is an external shield conductor is provided on the surface of the green sheet G ₁ of the flat plate-shaped member 1, and the surface of the green sheet G ₂ of the flat plate-shaped member 2 is used for a capacitor. _On the surface of the green sheet G ₃ of the flat plate-shaped member 3, _two conductor patterns P ₂ which are internal conductors are two conductor patterns P which are conductors for the spiral coil.
₃ is on the surface of the green sheet G ₄ of the flat member 4,
Conductor pattern P which is a conductor for an inductance element
₄ is on the back surface of the green sheet G ₅ of the flat member 5,
Conductor pattern (ground electrode) that is an external shield conductor
P ₅ and the impedance matching tap terminal P _t , which serves as an input / output terminal for the spiral coil, are formed by screen printing (print printing or the like) using a conductor paste as a material.

Thus, the conductor pattern P ₃ is formed into the planar spiral coils 11a and 11b, and the conductor pattern P ₃ is formed.
Reference numeral ₄ is a planar inductance element.

Further, the above-mentioned green sheets G ₁ , G ₂ ,
Through holes are formed in appropriate places of G ₃ , G ₄ , and G ₅ , and a plurality of via holes V ₁ , V ₂ , V ₃ , V _{4 formed} by filling the through holes with a conductive paste. , V ₅ are provided respectively.

Flat plate-shaped members 1, 2,
As shown in FIGS. 1 and 2, for example, 3, 4, 5 are sequentially stacked from above, so that the flat plate-shaped member 1 is the uppermost layer and the flat-plate-shaped member 5 is the lowermost layer. ing. Then, the planar spiral coils 11a, 1
The flat plate-shaped member 3 having 1b (conductor pattern P ₃ ) is a flat-plate-shaped member 2 having the internal conductor (conductor pattern P ₂ ) for the capacitor and the flat inductance element 12 (conductor pattern P ₄ ). It is configured so as to be sandwiched between 4 and 4.

Then, the dielectric green sheet G ₁ ,
_{G 2, G 3, G 4} , G 5 the conductor pattern P ₁ formed by printing _{on, P 2, P 3, P} 4, P 5, the electrical connection between the upper and lower P _t is, via holes V ₁ ~ V ₁₂ (see FIGS. 1 to 5) is appropriately formed. Specifically, the via holes V _1, V _2, V _3, V _{4, and} V ₅ are electrically connected to the outer shield conductors P ₁ and P _5, and the via holes V 1
The internal conductor P ₂ for capacitors and the planar spiral coils 11a and 11b are electrically connected at ₆ and the spiral coils 11a and 11b are connected at via holes V ₇ and V ₁₂ .
The electrical connection between the planar inductance element 12 is made, via holes V _7, V _8, the planar inductance element 12 at V ₁₂ and the planar spiral coil 11a, 11
An electrical connection is made to the tap terminal P _t which is an input / output terminal to b, and the planar spiral coils 11a and 11b are electrically connected to the ground electrode P ₅ at the via holes V _9, V _{10 and} V ₁₁ . It is supposed to be done.

The method of manufacturing the bandpass filter 10 in this example will be described below.

First, as described above, the dielectric green sheets G ₁ , G ₂ , G ₃ , G ₄ and G ₅ are formed on the conductor patterns P ₁ ,
P ₂ , P ₃ , P ₄ , P ₅ , P _t and via hole V ₁ ,
_{V 2, V 3, V 4} , V 5, V 6, V 7, V 8, V 9, V
Flat plate-shaped members 1, 2, 3 formed by forming V ₁₀ , V ₁₁ and V ₁₂
4, 5 are manufactured, and these flat plate-shaped members 1, 2, 3, 4,
5 are stacked on top of each other as shown in FIG. Then, the stacked flat plate-shaped members 1, 2, 3, 4, 5
Is pressed in a direction orthogonal to the plane direction, and thereafter, firing treatment is performed.

As a result, the five green sheets G ₁ ,
As shown in FIG. 5, G ₂ , G ₃ , G ₄ , and G ₅ are substantially combined to form one dielectric substrate 13,
Inside the dielectric substrate 13, the two conductor patterns P ₂ , the two planar spiral coils 11a and 11b, and the planar inductance element 12 are arranged in a buried state. Then, the two conductor patterns P ₂ disposed inside the dielectric substrate 13 and the conductor pattern P _{1 described} above are disposed so as to face each other to form two planar capacitors 14a and 14b (see FIG. 5). ).

Therefore, the two flat plate-shaped spiral coils 11a and 11b are arranged on one plane inside the dielectric substrate 13, and the spiral coils 11a and 11b are formed.
Two planar capacitors 14a and 14b are arranged facing each other on the upper part of b. Then, one resonator 15a is formed by the flat spiral coil 11a and the flat capacitor 14a.
1b and a planar capacitor 14ba to form one resonator 1
5b is formed, and two resonators 15a, 15 are formed as a whole.
b is formed.

Thus, the above-mentioned two resonators 15a, 1
5b are electrically coupled to each other, thereby forming a bandpass filter having a predetermined passband characteristic.

Further, in this example, as clearly shown in FIGS. 1 and 5, a planar inductance element 12 is added in addition to the two resonators 15a and 15b.
That is, the planar inductance element 12 is disposed correspondingly below the planar spiral coils 11a and 11b, and thus the planar inductance element 12 is disposed to face the two resonators 15a and 15b. It is supposed to be done.

In this example, the dielectric green sheets G ₁ , G ₂ , G ₃ , G ₄ , G ₅ are 1000.
It is preferable to use a low-temperature fired green sheet that can be fired at a temperature of not more than 0 ° C., and examples thereof include alumina / glass green sheets. When such a material is used, silver or copper, which is a material with less signal loss, can be used as a metal material for forming the conductor patterns P ₂ , P ₃ , and P ₄ . Further, as the outer shield conductors (P ₁ , P ₅ ), Ag-Pd alloy or the like can be used in addition to silver and copper.

When the frequency response characteristic of the bandpass filter 10 of this example was measured, the characteristic indicated by the symbol (a) in FIG. 6 was obtained. As is clear from this characteristic, it was confirmed that the bandpass filter 10 of the present example has a pole in the attenuation amount in the frequency region higher than the predetermined pass frequency band. Then, when compared with the frequency response characteristic of the band pass filter having no planar inductance element 12 (characteristic indicated by reference numeral (b) in FIG. 6), the loss of the band pass filter 10 of this example is It was confirmed that it was almost the same as in the case of not providing 12.

The embodiment of the present invention has been described above.
The present invention is not limited to this embodiment, and various modifications and changes can be made based on the technical idea of the present invention.

For example, the disposition position of the via hole V ₇ of the dielectric green sheet G ₃ is not limited to the position shown in FIG.
The positions can be changed to the positions shown in FIGS. By appropriately setting the position of the via hole V ₇ to an appropriate position, the impedance can be changed and impedance matching with other circuits can be achieved. At this time, the inductance element 12 changes its shape according to the position of the via hole V ₇ . Further, in the above-described embodiment, the two planar spiral coils 11a and 11b are wound in the same direction.
It may be wound in the opposite direction as shown in FIG.

In the above-described embodiment, the planar capacitors 14a, 1 are provided above the planar spiral coils 11a, 11b.
4b is arranged and the planar inductance element 12 is arranged below it. However, the present invention is not limited to this, and the planar capacitors 14a and 14b are arranged above the planar spiral coils 11a and 11b. This planar capacitor 1
The planar inductance element 12 may be arranged on the upper part of 4a, 14b. That is, the planar spiral coils 11a and 11b and the planar capacitor 14a,
The planar inductance element 12 may be embedded in the dielectric substrate 13 so as to correspond to the resonators 15a and 15b composed of 14b.

Further, in the above-described embodiment, the band-pass filter 10 including two resonators is manufactured by forming the two spiral coils 11a and 11b on the surface of each of the green sheets G ₃ and G _4. I tried to do it,
Three or more conductor patterns P ₃ and P ₄
It is also possible to form a bandpass filter formed on the surfaces of the green sheets G ₃ and G ₄ and including three or more resonators.

Further, in the above-described embodiment, one planar inductance element 12 is provided, but each resonator 1
You may make it form the two planar inductance elements corresponding to 5a and 15b, respectively.

Furthermore, in the above embodiment, the surface of the dielectric green sheet G _3, and G _4, the conductive pattern P ₃ and P ₄ constituting the planar spiral coil 11a, and 11b
However, by forming the conductor patterns P ₃ and P ₄ together with other circuits, a multifunctional dielectric substrate having the bandpass filter according to the present invention built-in or compounded is manufactured. It is also possible to do so.

[0034]

As described above, according to the present invention, a resonator composed of a planar spiral coil and a planar capacitor is formed, and a planar inductance element facing the resonator is arranged. Due to the presence of the planar inductance element, the distributed capacitance of the resonator and the planar inductance element resonate with each other, and a pole is generated in the attenuation amount in the attenuation characteristic. Therefore, according to the present invention, it is possible to provide a bandpass filter having a pole on the high frequency side higher than the frequency passband and having a good shielding effect.

Since the planar capacitor is arranged so as to face the planar spiral coil, it can be directly electrically connected to the planar capacitor having a large electrostatic capacity via the via hole. Therefore, it is possible to provide a band-pass filter that can easily reduce the size and height (thinner) by reducing the number of flat spiral coils.

Further, according to the bandpass filter of the present invention, the flat spiral coil having a great influence on the bandpass characteristic is arranged (embedded) inside the solid dielectric substrate. Even if the flat spiral coil is formed by printing, there is no possibility of being easily deformed by external pressure. Furthermore, since the flat spiral coil is formed on one plane inside the dielectric substrate, that is, in one layer, there is no gap between layers and the shape of the coil is always constant as compared with the case where the coil is formed by dividing each layer. Since it becomes constant, variations in influence on characteristics can be reduced, and a filter showing stable bandpass characteristics can be provided.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a configuration before manufacturing of a bandpass filter according to the present invention.

FIG. 2 is a perspective view of the bandpass filter as seen from above.

FIG. 3 is a plan view of the bandpass filter.

FIG. 4 is a bottom view of the bandpass filter.

5 is a cross-sectional view taken along the line AA in FIG.

FIG. 6 is a characteristic diagram showing the frequency response characteristic (attenuation characteristic).

FIG. 7 is a plan view showing a modified example of a via hole in a dielectric green sheet in which a planar spiral coil is formed.

FIG. 8 is a plan view showing another modified example of the via hole in the dielectric green sheet on which the planar spiral coil is formed.

FIG. 9 is a plan view showing still another modified example of the via hole in the dielectric green sheet in which the planar spiral coil is formed.

FIG. 10 is a plan view showing still another modified example of the via hole in the dielectric green sheet in which the planar spiral coil is formed.

[Explanation of symbols]

1, 2, 3, 4, 5 Substrate 10 Band-pass filter 11a, 11b Planar spiral coil 12 Planar inductance element 13 Dielectric substrate 14a, 14b Planar capacitor 15a, 15b Resonator G ₁ , G ₂ , G ₃ , Green sheets P ₁ , P ₂ , P ₃ , P ₄ , P ₅ , _Pt conductor patterns V ₁ , V ₂ , V ₃ , V ₄ , V ₅ , V ₆ , V ₇ made of G ₄ , G ₅ dielectrics , V ₈ , V
₉ , V _10, V _11, V ₁₂ via hole

Claims (3)

[Claims] 1. A resonator comprising a planar spiral coil and a planar capacitor is formed inside a dielectric substrate, and a plurality of the resonators are connected so as to have a pass band characteristic, and the resonator is opposed to these resonators. A band-pass filter having a planar inductance element that is provided. 2. A plurality of planar spiral coils formed on one plane inside a dielectric substrate, and arranged on one side of the plurality of planar spiral coils so as to face each other. A plurality of resonators are formed by a plurality of planar capacitors, the plurality of resonators are connected to each other so as to have pass band characteristics, and these resonators are connected to each other on the other side of the plurality of planar spiral coils. A band-pass filter, in which a planar inductance element facing to is disposed inside the dielectric substrate. 3. The planar spiral coil, the planar capacitor, and the planar inductance, which are formed by printing the planar spiral coil, the planar capacitor, and the planar inductance element, respectively, by printing using a conductor paste as a material. The band pass filter according to claim 1 or 2, wherein the elements are electrically connected by via holes provided in the dielectric substrate.