JP2006101134A - Dielectric substance resonator, dielectric substance filter, and radio communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dielectric substance resonator which can remarkably improve the design accuracy of a resonance frequency and can simplify processes, and also to provide a dielectric substance filter using the resonator. <P>SOLUTION: The dielectric substance resonator without any via conductor by arranging an upper electrode 4a and a lower electrode 4b on both surfaces of a dielectric substance board 1, and forming a resonance hole 3 to an internal metallized layer 2 formed therein. The dielectric substance resonators are arranged in a plurality of stages and a laminated waveguide 6 formed of the string of the via conductor 5 is used for an input and an output of a signal in order to form a dielectric substance filter. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a dielectric resonator and a dielectric filter used in the millimeter wave band, and a wireless communication device using the dielectric filter.

In recent years, communication systems such as a wireless LAN have been studied in the millimeter wave band, and research on passive elements used therefor has been actively conducted.
The problem of passive elements in the millimeter wave band is miniaturization and cost reduction. The problem with miniaturization is that the machining accuracy capable of mass production is small for small dimensions. Usually, if the technology that is mass-produced in the microwave band is applied to millimeter waves, the parts become too small, and therefore, the processing accuracy that can be mass-produced increases the dimensional variation. For this reason, the unit price of the parts was high.

Conventionally, a dielectric resonator having a rectangular laminated waveguide structure as shown in FIG. 9 has been proposed as a laminated dielectric resonator used in the millimeter wave band. The dielectric resonator includes a dielectric substrate 1 in which a plurality of dielectric layers are stacked, a lower conductor 4b and an upper conductor 4a arranged in contact with the dielectric substrate 1, and an inner layer of the dielectric substrate 1. The conductor 2 having the rectangular resonance hole portion 3 and the via conductor 5 connecting the lower conductor 4b and the upper conductor 4a are provided. A dielectric resonator is formed by surrounding the resonant hole 3 with the via conductor 5. The resonance mode is a TE ₁₀ mode in which an electric field perpendicular to the lower conductor 4b and the upper conductor 4a is generated. In this structure, size reduction is achieved as compared with the conventional waveguide structure.

Further, by connecting the input / output terminal of the dielectric resonator and the dielectric resonator with an iris of a via conductor, a multilayer dielectric filter with an input / output unit can be configured. In addition, coupling between dielectric resonators can be realized by connecting a plurality of dielectric resonators having the same structure with irises of via conductors.
JP-A-10-303618

  However, when designing the multilayer dielectric filter, the resonance frequency may deviate from the design value if the via conductors are misaligned. The change in the resonance frequency becomes a design error when manufacturing the dielectric filter. For this reason, it is necessary to accurately arrange a large number of vias in the dielectric resonator. Similarly, the positions of via conductors for coupling between input / output and dielectric resonators must be arranged with high accuracy. For this reason, it is difficult to manufacture without adjustment and with a high yield, and as a result, there is a problem that costs increase.

  The present invention can greatly improve the design accuracy of the resonance frequency by adopting a structure without vias in the dielectric resonator, and can simplify the process and realize a low cost. An object of the present invention is to provide a body filter and a wireless communication device using the dielectric filter.

The dielectric resonator according to the present invention is configured such that a resonant hole is formed in the inner conductor layer of the dielectric substrate disposed between the lower conductor and the upper conductor.
This dielectric resonator can create a resonant space with one inner conductor layer and upper and lower conductors without using via conductors, allowing high-accuracy design of the resonance frequency and further improving processing accuracy Can also be expected. The resonant hole of the inner conductor layer can be manufactured with high accuracy using a technique such as printing.

The resonance hole portion may be circular.
In the case of a circle, the TE ₀₁₁ mode in which the electric field rotates in the circumferential direction can be easily used as the resonance mode.
The dielectric filter of the present invention includes a lower conductor and an upper conductor, a dielectric substrate that is disposed in contact with the lower conductor and the upper conductor and laminated with a plurality of dielectric layers, and at least an inner portion of the dielectric substrate. An inner conductor layer having a plurality of resonance holes provided in one layer; and a laminated waveguide formed by a via conductor row in the dielectric substrate, wherein the resonance holes have a predetermined The open end of the multilayer waveguide faces one of the plurality of resonance holes of the inner conductor layer, and a signal is input by the multilayer waveguide. Alternatively, output is performed.

According to this configuration, since the dielectric resonators are formed in parallel in the lateral direction, a low-height dielectric filter can be realized. Further, since a laminated waveguide formed by via conductor rows is used for signal input or output to the dielectric filter, it is possible to reduce the size.
The shape of the resonance hole portion may be circular, and when it is circular, the TE ₀₁₁ mode in which the electric field rotates in the circumferential direction can be easily used as the resonance mode.

If the via conductor row has a structure in which the opening diameter increases in a taper or horn shape as it approaches the resonance hole portion of the inner conductor layer, electromagnetic coupling between the multilayered waveguide and the resonance portion of the dielectric filter is achieved. Can be made stronger.
Even in the structure in which the opening diameter of the via conductor row expands in a step shape at a position close to the resonance hole portion of the inner conductor layer, similarly to the above, between the laminated waveguide and the resonance portion of the dielectric filter. Electromagnetic coupling can be made stronger.

The resonance hole portion of the inner conductor layer is separated from the opening end portion of the multilayer waveguide by the inner conductor layer having a predetermined length. Since a closed space can be secured on the inner conductor layer, a decrease in the Q value of the resonator can be prevented, and insertion loss can be improved.
Further, if the resonance hole portion of the inner conductor layer and the opening end portion of the multilayer waveguide are directly connected, the multilayer waveguide and the resonance hole of the inner conductor layer are formed. It is possible to strengthen the coupling with the resonance part formed by the part, and to adjust the band of the dielectric filter.

According to the invention, the plurality of dielectric layers in which via holes for forming the via conductor row are formed, the lower conductor, the upper conductor, and the inner conductor layer having the plurality of resonance holes. Can be integrally formed by simultaneous firing to produce a dielectric filter, an inexpensive dielectric filter can be produced by a simple production process.
Furthermore, according to the present invention, by providing the dielectric filter in a wireless communication device, it is possible to provide a wireless communication device such as a millimeter-wave radar, a wireless LAN, a hot spot, an ad hoc wireless system, etc. that is low cost, small, and excellent in performance can do.

  As described above, according to the present invention, a conductor is disposed on both surfaces of a dielectric substrate, and an internal conductor layer having a resonance hole is provided on at least one layer inside the dielectric substrate, thereby having a small and highly accurate structure. A dielectric filter that can be expected to achieve low cost, small size, and high performance, particularly in the millimeter wave band, by installing the dielectric resonator in a multilayer wiring board or semiconductor package. Can be realized. And the radio | wireless communication apparatus using it can be provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a diagram showing the structure and electric field distribution of a dielectric resonator according to the present invention. The dielectric resonator particularly uses a TE ₀₁₁ mode in which an electric field rotates in the circumferential direction.
In the conventional single dielectric resonator using the via conductor shown in FIG. 9, the TE ₁₀ mode is used. If there is no via conductor, the electromagnetic field is radiated.

  In FIG. 1, the dielectric resonator has a dielectric substrate 1 in which a plurality of dielectric layers are laminated on a lower conductor 4b serving as a ground, and an upper conductor 4a is arranged on the dielectric substrate 1. is doing. In the dielectric layer inside the dielectric substrate 1, an internal metallized layer 2 in which a resonance hole portion (hereinafter referred to as “resonance portion”) 3 is formed is disposed. The resonating part 3 has a circular shape, and the lower conductor 4b, the upper conductor 4a, and the inner metallized layer 2 are arranged in parallel to each other.

The dielectric substrate 1 has an internal metallized layer 2 formed of a conductor such as copper foil on an organic dielectric substrate 1 such as glass epoxy resin, or an inorganic dielectric such as a ceramic material. A material formed by disposing the internal metallized layer 2 on the body substrate 1 and firing it at the same time as the dielectric substrate 1 is used.
Since the dielectric substrate 1 can be used for downsizing the entire structure by increasing the dielectric constant, it is preferable to use a ceramic material having a relative dielectric constant ε of 4 to 25, which is higher than that of the resin substrate. In addition, when a ceramic material is used, since the dielectric loss is generally lower than that of the resin substrate, it is effective for increasing the Q of the dielectric resonator.

Examples of the ceramic material include those in which a wiring conductor layer is formed of a conductor such as copper foil on an organic dielectric substrate such as glass epoxy resin, or various wirings on an inorganic dielectric substrate such as a ceramic material. A conductor layer formed by firing simultaneously with a dielectric substrate is used.
When used as a module, the dielectric substrate 1 can obtain a sufficient electrostatic capacity even in a small area by increasing the dielectric constant, shorten the stripline length, and provide for the miniaturization of the entire structure. Therefore, a ceramic material having a relatively high relative dielectric constant ε of 4 to 25 is used.

Examples of the ceramic material include (1) a ceramic material whose main component is Al ₂ O ₃ , AlN, Si ₃ N ₄ , SiC, and a firing temperature of 1100 ° C. or higher, and (2) 1100 ° C. or lower made of a mixture of metal oxides. A low-temperature fired ceramic material fired at 1050 ° C. or lower, (3) a group of low-temperature fired ceramic materials fired at 1100 ° C. or lower, particularly 1050 ° C. or lower, comprising glass powder or a mixture of glass powder and ceramic filler powder At least one selected from is selected.

As the mixture of (2), ceramic materials such as BaO—TiO ₂ , Ca—TiO ₂ , MgO—TiO _2, etc. are used, and these ceramic materials include SiO ₂ , Bi ₂ O ₃ , CuO, A material to which auxiliary agents such as Li ₂ O and B ₂ O ₃ are appropriately added is used.
The glass composition (3) contains at least SiO ₂ and contains at least one of Al ₂ O ₃ , B ₂ O ₃ , ZnO, PbO, alkaline earth metal oxide, and alkali metal oxide. Use the contained one. Specifically, SiO ₂ —B ₂ O ₃ —RO system, SiO ₂ —BaO—Al ₂ O ₃ —RO system, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —RO system, SiO ₂ —Al ₂ Examples of the composition include an O ₃ -RO system, and a composition in which ZnO, PbO, Pb, ZrO ₂ , TiO _{2 and the} like are blended with these systems. In addition, the glass is an amorphous glass even if it is fired, and by firing, alkali metal silicate, quartz, cristobalite, cordierite, mullite, enstatite, anorthite, serdian, spinel, garnite, dio Crystallized glass that precipitates at least one crystal of pside, ilmenite, willemite, dolomite, petalite, and substituted derivatives thereof is used.

Further, as the ceramic filler in (3), Al ₂ O ₃ , SiO ₂ (quartz, cristobalite), forsterite, cordierite, mullite, ZrO ₂ , mullite, forsterite, enstatite, spinel, magnesia, AlN, Examples include at least one selected from the group consisting of titanates such as Si ₃ N ₄ , SiC, MgTiO ₃ , and CaTiO ₃ , and glass 20 to 80% by mass and filler 20 to 80% by mass. desirable.

  On the other hand, since the internal metallized layer 2 is formed by simultaneous firing with the dielectric substrate 1, various combinations are made according to the firing temperature of the ceramic material forming the dielectric substrate 1. For example, when the ceramic material is (1), a conductor material mainly containing at least one selected from the group consisting of tungsten, molybdenum, manganese, and copper is preferably used. Moreover, it is good also as a mixture with copper etc. for resistance reduction. When the ceramic material is the low-temperature fired ceramic material of (2) or (3) above, a low-resistance conductor material mainly containing at least one selected from the group consisting of copper, silver, gold, and aluminum is used.

Since the internal metallized layer 2 can be formed of a low-resistance conductor, it is desirable to form the internal metallized layer 2 using the low-temperature fired ceramic material (1) or (2).
A specific method for manufacturing the multilayer substrate will be described. Based on alumina, mullite, forsterite, aluminum nitride, silicon nitride, glass, etc., ceramic green sheets are prepared by adding and mixing known sintering aids and compounds such as titanates that contribute to higher dielectric constants. create.

  A conductor layer to be the inner metallized layer 2 is formed on the surface of one ceramic green sheet. The conductor layer is formed by applying a conductive paste containing the metal to the surface of the ceramic green sheet or attaching a metal foil made of the metal. In addition, a through hole is formed in the ceramic green sheet at a portion where the via conductor is formed, and a conductive paste is applied to the side surface of the through hole, or the entire through hole is filled with the conductive paste.

The ceramic green sheets are laminated, thermocompression bonded under a required pressure and temperature, and fired.
The diameter of the internal metallization layer 2 is D. The thickness of the dielectric layer between the inner metallized layer 2 and the upper conductor 4a is h1, and the thickness of the dielectric layer between the inner metallized layer 2 and the lower conductor 4b is h2. Of the thicknesses h1 and h2 of the dielectric layer, the larger one is defined as h.

  The thickness h of the dielectric layer and the relative dielectric constant ε of the dielectric are selected so as to attenuate a high frequency signal having a resonating frequency. More specifically, the dielectric substrate 1 has a parallel plate structure sandwiched between the inner metallized layer 2 and the upper conductor 4a and between the inner metallized layer 2 and the lower conductor 4b. In order to prevent radio waves from jumping out from the end of the parallel plate, it is necessary to design in a frequency region that does not exceed the cutoff frequency fc of the parallel plate. In the conventional microwave band, it was not necessary to consider much, but since the wavelength is short in the millimeter wave band, the sample having a thick dielectric layer h and a high relative dielectric constant ε may exceed the cutoff frequency fc. Arise. The cutoff frequency fc of the parallel plate is expressed by the following equation (μ is the relative permeability of the dielectric).

fc = 1 / 2h√ (με)
Therefore, it is necessary to select the thickness h of the dielectric layer and the relative dielectric constant ε so that the frequency to be used does not exceed the cutoff frequency fc.
This dielectric resonator uses the TE ₀₁₁ mode, and the electric field becomes zero on the surfaces of the upper conductor 4a and the lower conductor 4b, and then increases as the center of the dielectric substrate 1 is approached. For this reason, the electric field can be effectively confined by the resonating part 3 of the internal metallized layer 2, and a resonator having a high Q value can be configured.

FIG. 2A is a plan sectional view showing an example of the dielectric filter structure of the present invention. FIG. 2 (b) shows a longitudinal sectional view of the dielectric filter of the present invention.
2A and 2B, in the dielectric filter, the dielectric substrate 1 is disposed on the lower conductor 4b serving as the ground, and the resonance unit 3a is disposed on the dielectric substrate 1. The internal metallized layer 2 in which the resonance part 3b is formed is provided, and the upper conductor 4a is disposed on the upper surface of the dielectric substrate 1. A coupling coefficient between the dielectric resonators is set by adjusting an interval x between the two resonance parts 3a and 3b.

The laminated waveguide 6 is configured by arranging two rows of via conductors 5 connecting the upper conductor 4a and the lower conductor 4b at a constant pitch. The ends of the laminated waveguide 6 are separated from each other by the distance E so as to face the resonance unit 3a and the resonance unit 3b. The laminated waveguide 6 inputs / outputs signals to / from the dielectric filter.
With the above structure, a dielectric filter having functions such as a band-pass filter and a band rejection filter can be configured by setting the resonance frequency difference between the two dielectric resonators to a predetermined value. It is also possible to create an attenuation pole outside the band.

FIG. 3 is a plan sectional view (a) and a longitudinal sectional view (b) showing another structural example of the dielectric filter of the present invention.
4 is a side sectional view (a), a plan sectional view (b), and a longitudinal sectional view (c) showing the dimensions of each part of the dielectric filter of FIG.
3 and 4, an upper conductor 4a and a lower conductor 4b are arranged above and below the dielectric substrate 1, and a plurality of resonance portions 3a and 3b are provided in the dielectric substrate 1 at a predetermined interval. The place where the internal metallization layer 2 is provided has the same structure as FIGS. 2 (a) and 2 (b).

In the structures of FIGS. 3 and 4, the resonance hole portion of the laminated waveguide 6 constituted by the via conductor 5 is expanded so that desired strong coupling is obtained, and the vicinity of the resonance portion 3a and the resonance portion 3b. It is the structure provided in.
That is, in the structure of FIG. 3 and FIG. 4, the interval w between the two rows of via conductors 5 is set to the interval W over the constant length E near the resonance hole portion of the multilayer waveguide 6 as it approaches the resonance portion 3a. It expands in a tapered shape until it becomes. As a result, the electric field distribution is widened in the lateral direction (a direction perpendicular to the signal propagation direction) to obtain strong electromagnetic coupling to the resonating unit 3a.

Note that the internal metallized layer 2 is left over the length e between the resonant hole portion of the laminated waveguide 6 and the opening of the resonant portion 3a. This is to prevent the resonance Q value from being lowered by making the resonance portion 3a a closed space in a plan view.
FIG. 5 is a plan sectional view (a) and longitudinal sectional views (b) and (c) showing still another structural example of the dielectric filter of the present invention.

In this FIG. 5 as well, similar to the structures of FIGS. 3 and 4, the resonance of the laminated waveguide 6 constituted by the via conductor 5 so that a desired strong coupling is obtained between the input / output waveguide portions. The hole portion is widened to provide a structure provided in the vicinity of the resonance portion 3a and the resonance portion 3b.
However, in the structure of FIGS. 3 and 4, the interval w between the two rows of via conductors 5 is increased in a tapered shape until the interval W becomes closer to the resonance portion 3 a. In the structure of FIG. Over a certain length E near the resonant hole of the waveguide 6, the distance between the two rows of via conductors 5 is expanded stepwise so that the distance from w to W is changed. As a result, the electric field distribution is widened in the lateral direction (a direction perpendicular to the signal propagation direction) to obtain strong electromagnetic coupling to the resonating unit 3a. In the structure of FIG. 5, the internal metallized layer 2 is directly connected without leaving the internal metallized layer 2 between the resonant hole portion of the laminated waveguide 6 and the opening of the resonant portion 3a. The amount of coupling can be adjusted by adjusting the interval W and the length E. As a result, although the Q value of the resonance is slightly lowered, stronger electromagnetic coupling can be obtained as compared with FIGS.

Although the embodiments of the present invention have been described above, the embodiments of the present invention are not limited to the above-described embodiments. For example, the number of stages of resonators installed in the dielectric filter is not limited to two but can be any number. Also, the resonance mode is not necessarily the TE ₀₁₁ mode. In addition, various modifications can be made within the scope of the present invention.

First, a single dielectric resonator (FIG. 1) at 60 GHz was designed. The analysis of the resonance frequency and the Q value was performed using the mode matching method software for the axially symmetric structure and the finite element method software HFSS manufactured by Ansoft. When the diameter D of the resonance portion is 3.05 mm, the thickness t of the internal metallized layer 2 is 0.01 mm, and the thickness h of the dielectric substrate 1 is 1.81 mm, in the mode matching method, the resonance frequency f0 is 60 GHz and HFSS F0 = 60.3 GHz. In HFSS, this is the effect of approximating the analysis of a circle to a 32-gon. When the conductivity of the electrode and the conductor is 5.8 × 10 ⁶ S / m and the dielectric loss tangent tan δ = 1 × 10 ⁻³ , the analysis of the Q value of the single dielectric resonator is mode matching. In the law, Q = 840, and in HFSS, Q = 750.

Using the dimensions of the single dielectric resonator, the design of a bandpass dielectric filter with a center frequency of 60.3 GHz, a bandwidth of 600 MHz, and a two-stage Chebyshev characteristic shown in FIG. 4 was performed by HFSS.
In reality, a laminated waveguide is formed with via conductors, but here, the calculation is performed with a portion of the laminated waveguide using via conductors as a normal waveguide because of mesh and memory.

First, the coupling coefficient K ₁₂ was calculated. As a result, the change of the coupling coefficient K ₁₂ with respect to the interval x of the dielectric resonator is shown in FIG. From this, when x = 0.55 mm, a necessary coupling coefficient K ₁₂ = 0.012 was obtained.
Next, external Q and Qe were calculated by HFSS. Signal input / output to the resonator is performed by a laminated waveguide having a width w and a thickness H, and the coupling portion with the resonator is e = 0.1 mm, E = 0.1 mm as shown in FIG. It has a horn antenna shape of 1.475 mm. The external Q was adjusted by the width W. The change of Qe with respect to W is shown in FIG. From FIG. 7, when W = 2.0 mm, necessary Qe = 100 was obtained.

From the above, the design values satisfying the specifications for the dielectric filter are the dielectric resonator coupling coefficient k ₁₂ = 0.012 and the external Q and Qe = 100.
Finally, the value of x was finely adjusted while checking the matching state of the dielectric filter to obtain W = 2.1 mm.
The dimensions obtained as described above were input, and the transmission characteristic S parameter of the dielectric filter was calculated using HFSS. The calculation result of the S parameter is shown in FIG. From this result, it was confirmed that the desired characteristics of the band-pass dielectric filter were obtained, and the possibility of practical use was obtained.

(a) is a plan sectional view showing a structural example of a TE ₀₁₁ mode dielectric resonator of the present invention, and (b) is a longitudinal sectional view. (a) is a plan sectional view showing a structural example of a dielectric filter of the present invention, and (b) is a longitudinal sectional view. (a) is a plan sectional view showing another structural example of the dielectric filter of the present invention, and (b) and (c) are longitudinal sectional views, respectively. FIG. 4 is a side sectional view (a), a plan sectional view (b), and a longitudinal sectional view (c) showing examples of dimensions of the dielectric filter of FIG. 3. (a) is a plan sectional view showing still another structural example of the dielectric filter of the present invention, and (b) and (c) are longitudinal sectional views, respectively. It is a graph which shows the change of the coupling coefficient k with respect to the space | interval x of a dielectric resonator. It is a graph which shows the change of Qe with respect to opening width W of a laminated waveguide. It is a graph which shows the result of the simulation of the transmission characteristic of a band pass dielectric filter. (a) is a plan sectional view showing the structure of a conventional TE ₁₀ mode dielectric resonator, and (b) is a longitudinal sectional view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dielectric substrate 2 Internal metallization layers 3, 3a, 3b Resonance part, resonance hole part 4a Upper electrode 4b Lower electrode 5 Via conductor 6 Multilayer waveguide

Claims (12)

  A dielectric substrate in which a plurality of dielectric layers are laminated and disposed between and in contact with the lower conductor and the upper conductor, and a resonance provided on at least one layer inside the dielectric substrate. A dielectric resonator comprising an inner conductor layer having a hole.   The dielectric resonator according to claim 1, wherein the resonant hole is circular. 3. The dielectric resonator according to claim 1, wherein a TE ₀₁₁ mode is used as a resonance mode. A dielectric substrate on which a plurality of dielectric layers are stacked, arranged in contact between the lower conductor and the upper conductor, and a plurality of layers provided on at least one layer inside the dielectric substrate; An inner conductor layer having a resonance hole portion of the multilayered waveguide formed by a via conductor row in the dielectric substrate,
The resonant holes are juxtaposed at a predetermined interval,
The opening end of the multilayer waveguide faces one of the plurality of resonance holes of the inner conductor layer,
A dielectric filter, wherein at least one or both of signal input and output is performed by the laminated waveguide.   The dielectric filter according to claim 4, wherein the resonance hole is circular. 6. The dielectric filter according to claim 4, wherein a TE ₀₁₁ mode is used as a resonance mode.   7. The dielectric filter according to claim 4, wherein an opening diameter of the via conductor row expands in a taper shape or a horn shape as approaching a resonance hole portion of the inner conductor layer. 8.   7. The dielectric filter according to claim 4, wherein an opening diameter of the via conductor row expands in a step shape at a position close to a resonance hole portion of the inner conductor layer.   The resonance hole portion of the inner conductor layer and the opening end portion of the multilayer waveguide are separated by the inner conductor layer having a predetermined length. Dielectric filter.   The dielectric filter according to any one of claims 4 to 8, wherein the resonance hole portion of the inner conductor layer and the opening end portion of the multilayer waveguide are directly connected.   The plurality of dielectric layers formed with via holes for forming the via conductor row, the lower conductor, the upper conductor, and the inner conductor layer having the plurality of resonance holes are integrally formed by simultaneous firing. The dielectric filter according to any one of claims 4 to 10, which is formed.   A wireless communication device equipped with the dielectric filter according to claim 4.

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