JP2002016403A - Dielectric filter, antenna duplexer and communication device - Google Patents

Abstract

(57) Abstract: A small-sized laminated dielectric filter used in high-frequency wireless devices such as mobile phones, etc., by increasing insertion loss in a pass band caused by a short circuit between a load capacitance electrode and a shield electrode. Provided is a multilayer dielectric filter that can solve the problem of deteriorating characteristics and reduce insertion loss. SOLUTION: At least one of a plurality of resonator electrodes 11a, 11b, 11c formed on a surface of a dielectric substrate 1e.
The shape of one resonator electrode is different from the shape of the other resonator electrodes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small-sized dielectric filter mainly used in high-frequency radio equipment such as a portable telephone, particularly a strip line type resonance electrode arranged on a dielectric substrate and electromagnetically coupled to each other. The present invention relates to a dielectric filter having a reduced structure.

[0002]

2. Description of the Related Art In recent years, a large number of dielectric filters have been used as high-frequency filters for portable telephones. Filters are promising in the future. An example of a conventional planar dielectric filter will be described below with reference to the drawings.

FIG. 6 is an exploded perspective view showing the structure of a conventional planar-type dielectric filter. The basic structure of the laminated-type dielectric filter shown in FIG. 1f, a shield electrode 2a on the upper surface of the dielectric substrate 1b, and a load capacitance electrode 3 on the upper surface of 1c.
a, 3b, 3c are input / output coupling electrodes 4 on the upper surface of 1d.
The resonator electrodes 6a, 6b, 6c are formed on the upper surface of 1e, and the shield electrode 2b is formed on the upper surface of 1f.

On the left and right side surfaces of the laminated dielectric substrate, end electrodes 7a and 7b connected to the shield electrodes 2a and 2b to form ground terminals are provided. On the rear surface of the laminated dielectric substrate, the shield electrodes 2a and 2b and the resonance electrodes are formed. An end face electrode 8 is formed which connects the common short-circuited ends of the device electrodes 6a, 6b, 6c and serves as a ground terminal. End electrodes 9a, 9b, 9c formed on the front surface of the laminated dielectric substrate are resonant electrodes 6a, 6b, 6c.
Of the load capacitance electrodes 3a, 3
b, 3c. End surface electrodes 10a and 10b on the left and right side surfaces of the laminated dielectric substrate are connected to input / output coupling electrodes 4a and 4b to form input / output terminals.

FIG. 7 shows a cross section of a part of the dielectric filter taken along the line AA shown in FIG. 6. The resonance frequency required in the laminated dielectric filter having such a configuration is shown in FIG. The load capacitance electrode 3 (3) is disposed so as to face the open end of the resonator electrode 6 (6a, 6b, 6c).
a, 3b, 3c) was adjusted by the capacitance C of the parallel plate capacitor formed.

[0006]

However, in the above-mentioned conventional dielectric filter, the load capacitance electrode 3 is provided inside the dielectric.
There is a problem that the filter characteristics are degraded due to the conductor loss as the load capacitance electrode due to the arrangement of a, 3b, and 3c and the increase in the insertion loss in the pass band due to the short-circuit portion between the load capacitance electrode and the shield electrode.

The present invention has been made to solve the above problems, and
An object of the present invention is to provide a dielectric filter that can reduce insertion loss in a pass band, particularly a laminated dielectric filter.

[0008]

According to the present invention, there is provided a dielectric filter comprising a plurality of resonator electrodes, wherein the plurality of resonator electrodes are electromagnetically coupled to each other. The shape of at least one of the resonator electrodes is different from the shape of the other resonator electrodes, and the resonance frequency is adjusted by freely controlling the shapes of the plurality of resonator electrodes. can do.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a dielectric filter according to an embodiment of the present invention will be described with reference to the drawings, in which the same parts as those in FIG.

FIG. 1 is an exploded perspective view of an integrally laminated dielectric filter according to an embodiment of the present invention. The point that the present invention differs from the conventional dielectric filter is that the upper surface of the dielectric substrate 1e is different. The basic configuration is the same as that of the conventional example shown in FIG. 6 except that the dielectric substrate 1c on which the load capacitance electrode is mounted is omitted. Is omitted.

Next, FIG. 2A shows the first embodiment of the present invention, and FIG. 2B shows the shapes of the resonator electrodes 11a, 11b and 11c according to another embodiment of the first embodiment. Are respectively shown.

2 (a) and 2 (b), the upper part of the dielectric substrate 1e in FIG. 2 (a) and (b) shows the open end of the resonator electrode, and the lower part shows the short-circuited end with the shield electrode.
Is formed in a rectangular shape having a length of L ₁ and a width of W ₁ . Similarly, the resonator electrode 11b has a rectangular shape having a length of L ₂ and a width of W _2.
c is formed in a rectangular shape having a length of L ₃ and a width of W ₃ .

FIG. 2A shows three resonator electrodes 11a and 1a.
The resonator electrode 11b disposed at the center of the resonator composed of the resonator electrodes 1b and 11c has the shape of another resonator electrode 11b.
a, 11b and resonator electrodes 11a and 11b connected to the input / output terminals respectively have the same shape, that is, L ₁ = L ₃ ≠ L ₂ , W ₁ = W ₃ ≠ W ₂ It shows an example having a dimensional relationship, and is usually used as a bandpass filter or a notch filter.

FIG. 2B shows a shape in which the length and width of the three resonator electrodes 11a, 11b and 11c constituting the resonator are all different, that is, L ₁ ≠ L ₃ ≠ L ₂ and W ₁ ≠. W ₃ ≠
Shows an embodiment in the dimensional relationship of W _2, and resonator electrodes 11a and 11c which connect to input and output terminals are formed with the structure of the asymmetric is used as a receiver filter or the transmitting filter of the antenna duplexer be able to.

Next, the second to seventh embodiments of the present invention will be described.
The difference in the shape of the resonator electrode in the first embodiment will be described with reference to FIG.

FIG. 3A shows the shape of the resonator electrodes 21a, 21b, 21c in the second embodiment. The dimensions of the resonator electrodes 21a, 21b, 21c are L1ＬL2 = L3, W1 = W2 = W3.

Similarly, in the third embodiment shown in FIG. 3B, L1 = L2 = L3, W1 ≠ W2 = W3, and in the fourth embodiment shown in FIG. 3C, L1 = L2 ≠ L3, W1 = W2 =
W3, in the fifth embodiment shown in FIG.
2 ≠ L3, W1 ≠ W2 = W3, and in the sixth embodiment shown in FIG. 3E, L1ＬL2 ≠ L3, W1 = W2 = W3 and FIG.
In the seventh embodiment shown in (f), L1 = L2 ≠ L3,
W1 ≠ W2 = W3.

Next, eighth and ninth embodiments of the present invention will be described with reference to FIGS. 4 (a) and 4 (b).

As shown in FIG. 4, the shapes of the resonator electrodes in the eighth and ninth embodiments are different from those of the resonator electrodes in the first to eighth embodiments, and a plurality of resonator electrodes are provided. Of at least one of the resonator electrodes is formed of two rectangles having different widths and lengths. That is, as is apparent from FIG. 4, the shape of one resonator electrode is different from the shapes of the resonator electrodes in the first to eighth embodiments in that a wide portion is provided.

FIG. 4A shows three resonator electrodes 81a and 81a.
On the open end side of the rectangular resonator electrode 81c having a length L ₃ and a width W ₃ of 1b and 81c, there is a wide portion 82c having a shape having a length l ₃ and a width w ₃ . Here, 81a has a length L ₁ and a width W ₁ , 81b has a length L ₂ and a width W ₂ , and 8
1c is the width W ₃ in the length L _3.

FIG. 4B shows a wide portion 92c having a shape of length l ₃ and width w ₃ substantially at the center of a resonator electrode 91c having a shape of length L ₃ and width W _3. Is provided. Here, 91a has a length L ₁ and a width W ₁ , and 91b
The length L _2, the width W _2, 91c is the width W ₃ in the length L _3.

In the eighth and ninth embodiments, FIG.
(A) As shown in FIG. 4 (b), of the three resonator electrodes, the left ends of the resonator electrodes 81c and 91c in the figure are provided with wide portions 82c and 92c, respectively. In addition to the above, it is possible to provide a wide portion at a place where a plurality of resonator electrodes are required.

As described above, in the dielectric filter according to the present invention, the dimensions of each resonator electrode forming the resonator are made different from the dimensions of the other resonator electrodes based on a predetermined design. The required resonance frequency is determined.

Therefore, the load capacitance electrode provided opposite to the open end of the resonator electrode for adjusting the resonance frequency in the conventional configuration is not required, and the dielectric substrate for mounting the load capacitance electrode is not required. Can be omitted. Furthermore, since no load capacitance electrode is formed, current does not flow into the short-circuit portion, so that conductor loss at the short-circuit portion can be reduced. Therefore, the Q value of the resonator is improved, and the insertion loss of the filter is effectively reduced. Becomes possible.

Although the first to ninth embodiments have been described above with respect to the shape of the resonator electrode which is a feature of the present invention, the mutual shape relationship of the resonator electrode according to the present invention is as described above. Not limited to the embodiment, the dimensions of the plurality of resonator electrodes, that is, at least one of the width and length of the electrodes are made different from the dimensions of the other resonator electrodes, and the mutual dimensional relationship is optimally designed. By doing so, the resonance frequency can be controlled.

In each of the above embodiments, the case has been described in which each of the resonator electrodes has a short-circuited end connected to the end face electrode 8 and an open end at the other end. It is possible to obtain the same effect in a dielectric filter having an open end.

Next, in a tenth embodiment of the present invention, any one of the dielectric filters in the first to ninth embodiments is used to separate a transmission wave and a reception wave of a communication device such as a mobile phone. As shown in FIG. 5, a dielectric filter according to the present invention is disposed at both ends of a matching circuit connected to an antenna, as shown in FIG. Since the conventional coaxial resonator having a large space factor used for the antenna can be eliminated, an extremely miniaturized duplexer can be obtained.

Further, by using the dielectric filter or antenna duplexer according to the present invention for a communication device such as a mobile phone, it is possible to realize a communication device having excellent characteristics and being extremely miniaturized. .

[0029]

As is apparent from the above embodiment, the present invention relates to the shape of the resonator electrode forming the dielectric filter, and relates to the width or length of at least one of the plurality of resonator electrodes. The resonance frequency is controlled by making the size different from the dimensions of the other resonator electrodes, and the resonance frequency is controlled.Therefore, the number of electrodes constituting the filter, that is, the load capacitance electrode and the end face electrode can be reduced. In addition, it is possible to prevent filter characteristics from deteriorating due to conductor loss. Also, since the number of electrode layers to be printed can be reduced, steps such as electrode printing can be reduced, which is also effective in reducing manufacturing costs.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a dielectric filter according to an embodiment of the present invention.

FIGS. 2A and 2B are plan views of a resonator electrode according to the first embodiment of the present invention.

FIGS. 3 (a) to 3 (f) are plan views of resonator electrodes according to second to seventh embodiments of the present invention, respectively.

FIG. 4A is a plan view of a resonator electrode according to an eighth embodiment of the present invention, and FIG. 4B is a plan view of a resonator electrode according to a ninth embodiment of the present invention.

FIG. 5 is a block diagram of an antenna duplexer according to a ninth embodiment of the present invention.

FIG. 6 is an exploded perspective view of a conventional dielectric filter.

FIG. 7 is a sectional view of a conventional dielectric filter.

[Explanation of symbols]

1a, 1b, 1c, 1d, 1e, 1f Dielectric substrate 2a, 2b Shield electrode 3, 3a, 3b, 3c Load capacitance electrode 4a, 4b Input / output coupling electrode 5a, 5b Interstage coupling electrode 6, 6a, 6b , 6c resonator electrodes 7a, 7b, 9, 9a, 9b, 9c, 10a, 10b
End electrode 11a, 11b, 11c, 81a, 81b, 81c, 9
1a, 91b, 91c Resonator electrode 82c, 92c Wide part

Continued on the front page (72) Inventor Toshio Ishizaki 1006 Kazuma Kadoma, Kazuma, Osaka Prefecture F-term (reference) in Matsushita Electric Industrial Co., Ltd. JA01 KA13

Claims (9)

[Claims] 1. A dielectric filter comprising a plurality of resonator electrodes, wherein said resonator electrodes are electromagnetically coupled to each other, wherein at least one of said plurality of resonator electrodes has a shape of at least one resonator electrode. A dielectric filter having a size different from that of another resonator electrode. 2. A dielectric filter comprising a plurality of resonator electrodes, wherein said resonator electrodes are electromagnetically coupled to each other, wherein at least one of said plurality of resonator electrodes has a shape of at least one resonator electrode. A dielectric filter having dimensions different from those of other resonator electrodes, and wherein resonator electrodes connected to input / output terminals have the same shape. 3. A dielectric filter comprising a plurality of resonator electrodes, wherein said resonator electrodes are electromagnetically coupled to each other, wherein at least one of said plurality of resonator electrodes has a shape of at least one resonator electrode. A dielectric filter having dimensions different from those of other resonator electrodes and different shapes of resonator electrodes connected to a plurality of input / output terminals, respectively. 4. At least one of a plurality of resonator electrodes
4. The dielectric filter according to claim 1, wherein a wide portion is provided at an arbitrary position of the resonator electrodes. 5. An end face of a back surface of a dielectric substrate comprising a plurality of resonator electrodes formed on a surface of a dielectric substrate, wherein one end of each of the plurality of resonator electrodes is integrated in a laminated structure via a short-circuited end. The dielectric filter according to any one of claims 1 to 4, wherein the dielectric filter has a structure connected to the electrode and the other end is open. 6. A structure comprising a plurality of resonator electrodes formed on a surface of a dielectric substrate, wherein both ends of the plurality of resonator electrodes form open ends.
5. The dielectric filter according to any one of items 1 to 4. 7. The dielectric filter according to claim 1, wherein the plurality of dielectric substrates constituting the laminated dielectric filter have different relative dielectric constants. 8. An antenna duplexer, wherein the dielectric filter according to claim 1 is used for one or both of a transmission filter and a reception filter. 9. A communication device using the dielectric filter according to any one of claims 1 to 7 or the duplexer according to claim 8.