JP2006014112A - Dielectric filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filter in which optimal input/output coupling can be obtained even if a gap between inner conductor formation holes holding an input/output electrode therebetween is made narrow for small-sizing. <P>SOLUTION: A dielectric filter of the present invention includes a plurality of resonators each of which is configured by forming a plurality of through-holes covering an inner conductor connecting first and second faces which are confronted, in an approximately hexagonal dielectric block having said first and second faces and by forming an outer conductor on an outer surface of the dielectric block excepting for the first face, and an input/output electrode provided on the first face so as to be capacitively coupled with the resonators between adjacent resonators. In this dielectric filter, a ground electrode extending from the outer conductor is provided on the first face between the input/output electrode and a resonator adjacent to the input/output electrode. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a dielectric filter, and more particularly, to a small-sized dielectric filter in which a plurality of dielectric resonators are formed in a single dielectric block.

  In mobile communication devices such as cellular phones, various dielectric filters including a duplexer are used. According to the prior art, when a plurality of filters are configured in a single dielectric block, the configuration is as shown in FIG. 4 (see, for example, Patent Document 1).

  In FIG. 4, the dielectric filter includes a substantially hexahedral dielectric block 1 having a first end face 1a and a second end face 1b facing each other, and a first hexagonal dielectric block 1 and the first end face 1a. A plurality of through holes 6 formed in the dielectric block 1 over the second end surface 1b, an inner conductor 3 formed on the inner wall of the through hole 6, and the first end surface (open end surface) from the inner conductor 3 ) And the input / output electrode 14 between adjacent inner conductor forming holes, and are insulated from the outer conductor 5 and the outer conductor formed on the outer surface of the dielectric block 1. And the external connection electrode 4 formed on the outer surface. The coupling electrode 13 couples the resonators to each other, and the coupling electrode 13 formed in the resonator at the input / output stage is also used to obtain external coupling with the input / output electrode 14. The input / output electrode 14 is capacitively coupled to a resonator adjacent thereto via a coupling electrode. In this example, the inner conductor forming hole 6d portion acts as a trap, and the inner conductor forming holes 6a, 6b, and 6c portions act as bandpass filters (BPF). The input / output electrode is shared as the trap and the input / output electrode of the band-pass filter. The input / output electrode 14 is connected to the external connection electrode 4 and is connected to an external circuit.

  FIG. 5 is an enlarged view of a portion sharing the input / output coupling of the plurality of filters in FIG. In the input / output section of FIG. 5, the gaps a and b formed between the coupling electrode 13 and the input / output electrode 14 extending from the inner conductor are adjusted so that each filter can obtain optimum characteristics. The output coupling is adjusted. For example, the gap (a or b) is narrowed when input / output coupling, that is, capacitive coupling is desired to be increased, and the gap is increased when input / output coupling, ie, capacitive coupling is desired to be weakened.

Japanese Patent No. 3205337

  However, in order to meet the recent demand for miniaturization, when the gap between the inner conductor forming holes sandwiching the input / output electrodes is narrowed, there is a case where a gap cannot be secured even if the input / output coupling is weakened. For example, as shown in FIG. 6, the input / output electrodes cannot be made thinner even if the gap of the portion a is widened. To optimize the input / output coupling, the gap between the inner conductor forming holes must be widened. Therefore, further downsizing becomes difficult.

  As another solution, there is a method of shortening the length of the input / output electrode extending from the external connection electrode. In this case, the input / output coupling of the other filter is also weakened, and optimum characteristics are obtained with both filters. Will not be able to.

  An object of the present invention is to provide a filter capable of obtaining optimum input / output coupling even when the inner conductor forming holes sandwiching the input / output electrodes are narrowed in order to reduce the size.

  In order to solve such a problem, a plurality of substantially hexahedral dielectric blocks having first and second surfaces facing each other are coated with an inner conductor connecting the first surface and the second surface. A plurality of resonators formed by forming an outer conductor on the outer surface of the dielectric block excluding the through hole and the first surface, and the resonator so as to be capacitively coupled between adjacent resonators. In a dielectric filter having an input / output electrode provided on a first surface, a ground extending from the outer conductor to the first surface between the input / output electrode and a resonator adjacent to the input / output electrode. There is provided a dielectric filter characterized in that an electrode is provided.

  Further, the dielectric filter is provided in which a coupling electrode is formed on the first surface of the resonator capacitively coupled to the input / output electrode, extending from an inner conductor of the resonator.

  Furthermore, one embodiment of the dielectric filter of the present invention is characterized in that the coupling electrode is not formed in a region closer to the input / output electrode than the center of the through hole of the resonator.

  By forming an input / output electrode between adjacent resonators, and forming an installation electrode extending from the outer conductor, the optimal input / output coupling can be achieved even if the interval between the resonator through holes sandwiching the input / output electrode is narrow. An obtained small filter can be obtained.

  FIG. 1 is an enlarged perspective view of an input / output portion of an embodiment according to the present invention. The parts omitted in FIG. 1 are substantially the same as those in FIG. The difference from the conventional configuration shown in FIG. 4 is that, as shown in FIG. 1, a ground electrode 15 extending from the outer conductor between the coupling electrode 13 extending from the inner conductor 3 and the input / output electrode 14 at the first end face. Is formed.

  As shown in FIG. 1, in this embodiment, the input / output electrodes sharing the input / output coupling of the plurality of filters and the coupling electrode extending from the inner conductor of the resonator corresponding to the input / output stage of one filter are used. By providing a ground electrode extending from the outer conductor, it is possible to obtain optimum input / output coupling in both filters without enlarging the gap between the coupling electrode and the input / output electrode, thereby realizing a reduction in size of the filter. be able to.

  FIG. 2 is a plan view of the conductor pattern on the open surface (first surface) of FIG. Co1 and Co4 are coupling capacitances generated between the coupling electrodes 13c and 13d extending from the inner conductor of the resonator corresponding to the input / output stage of each filter and the input / output electrode 14. Co2 is a capacitance generated between the coupling electrode 13c and the ground electrode 15 extending from the outer conductor. Co3 is a capacitance generated between the input / output electrode 14 and the ground electrode 15 extending from the outer conductor. The input / output coupling constituted by Co1, Co2, and Co3 is smaller than that when there is no ground electrode extending from the outer conductor. Therefore, the optimum input / output coupling can be obtained without enlarging the gap between the coupling electrode and the input / output electrode, which is advantageous for downsizing.

  FIG. 3 is an enlarged perspective view of an input / output portion in the second embodiment according to the present invention. The parts omitted in FIG. 3 are substantially the same as those in FIG. In FIG. 3, the input / output electrode side of the coupling electrode 13 extending from the inner conductor 3 of the input / output stage to the open surface (first surface) is omitted. That is, the coupling electrode is not formed in a region closer to the input / output electrode than the center of the through hole of the resonator. In this case, the input / output coupling is formed by the capacitance generated between the vicinity of the open end of the inner conductor and the input / output electrode. Input / output coupling can be further reduced by using an electrode extending from the electrode. As a result, even if the distance between the resonator in the input / output stage and the input / output electrode is further shortened, the optimum input / output coupling can be formed, and further miniaturization can be realized.

  In the present embodiment, the configuration in which the ground electrode is formed between one of the two resonators adjacent to the input / output electrode is described, but the ground electrode is formed between the other resonator. Alternatively, two ground electrodes may be formed between both resonators and the input / output electrodes. It is preferable to form a ground electrode only between one of the two resonators and the input / output electrode because the filter can be further downsized.

  The present invention can be applied to all input / output electrodes sharing the input / output coupling of a plurality of filters. The present invention can also be applied to an antenna duplexer.

It is an expansion perspective view of the input-output part in embodiment of the dielectric filter of this invention. It is a top view of the conductor pattern in the open surface (1st surface) of FIG. It is an expansion perspective view of the input-output part in 2nd Embodiment of the dielectric material filter of this invention. It is a perspective view of the conventional dielectric filter. It is an expansion perspective view of the input-output part of the conventional dielectric filter. It is an expansion perspective view of the input-output part of the conventional dielectric filter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dielectric block 1a 1st surface 1b 2nd surface 3 Inner conductor 4 External connection electrode 5 Outer conductor 6, 6a-6d Through-hole 13, 13c, 13d Coupling electrode 14 Input / output electrode 15 Ground electrode

Claims (3)

  Excludes a plurality of through-holes covered with an inner conductor connecting the first surface and the second surface to a substantially hexahedral dielectric block having first and second surfaces facing each other and the first surface A plurality of resonators configured by forming an outer conductor on the outer surface of the dielectric block, and an input / output provided on the first surface so as to be capacitively coupled to the resonator between adjacent resonators A dielectric filter having an electrode, wherein a ground electrode extending from the outer conductor is provided on the first surface between the input / output electrode and a resonator adjacent to the input / output electrode. Body filter.   2. The dielectric filter according to claim 1, wherein a coupling electrode is formed on the first surface of the resonator capacitively coupled to the input / output electrode so as to extend from an inner conductor of the resonator. . 3. The dielectric filter according to claim 2, wherein the coupling electrode is not formed in a region closer to the input / output electrode than the center of the through hole of the resonator.

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