JP4454589B2 - Superconducting filter device and filter characteristic adjusting method - Google Patents

Description

  The present invention relates to a superconducting transmission filter device applied to a transmission system of a cryogenic RF front end of a mobile communication base station, and a filter characteristic adjusting method.

  In recent years, with the spread and development of mobile phones, high-speed and large-capacity transmission technology has become indispensable. Superconductors have a very low surface resistance in the high-frequency region as compared with ordinary good electrical conductors, and therefore can be expected to have low-loss and high-Q resonators and are promising as filters for mobile communication base stations. Has been.

  For example, as shown in FIG. 1A, an RF signal received via an antenna 151 is converted into a band filter (BPF) 152R, a low noise amplifier (LNA) 153, and a down converter (D / C) After passing through 154 and demodulator (DEMOD) 155, baseband processing is performed in the baseband unit 156.

  In the transmission system, the signal processed by the baseband unit 156 passes through a modulator (MOD) 157, an up converter (U / C) 158, a high power amplifier (HPA) 159, and a band filter (BPF) 152T, and then an RF signal. As radiated from the antenna 151.

  When the superconducting filter is applied to the band filter 152R on the receiving side, a transmission loss is small and a steep frequency cutoff characteristic is expected. On the other hand, when applied to the band filter 152T on the transmission side, an effect of removing distortion generated by the high power amplifier 159 can be expected.

  As the superconducting filter, a microstrip type superconducting pattern is generally used. As a method for adjusting the frequency characteristics of such a superconducting filter, a method of adjusting the band by arranging a partition plate above the superconductive microstrip pattern and adjusting the size, position, etc. of the partition plate is known. (See, for example, Patent Document 1).

  In this conventional method, as shown in FIG. 1B, a superconducting film 102 is formed on the entire surface of a dielectric substrate 103, and superconducting filter patterns 104a to 104f made of microstrip lines are formed on the other surface. Is formed. Metal partition plates 105a to 105e are fixed to the inner surface of the case 101 facing the filter patterns 104a to 104f in parallel with the direction in which the filter patterns 104a to 104f extend and perpendicular to the filter patterns 104a to 104f. The partition plates 105a to 105e are located above between the microstrip type patterns. The bandwidth can be changed by changing the size and position of the fixed partition plate.

  Similarly, in order to tune the microstrip type superconducting filter, the vertical position of the rod is adjusted by inserting a sapphire rod trimmer into the space above each pattern and rotating the trimmer screw. A method has also been proposed (see Non-Patent Document 1, for example).

Similarly, a method of adjusting a signal coupling degree by inserting a metal or resin screw vertically from above between hairpin resonator patterns (see Patent Document 2) is also known.
JP 2001-102809 A JP 2002-57506 A "Characteristic improvement of superconducting filter by dielectric rod trimming", Hiroshi Mikami et al., IEICE Technical Report SCE2003-6, MW2003-6 (2003-4), p29-35

  By the way, when a superconducting filter is applied to the transmission side, a large amount of power is required to transmit a high-frequency signal, and compatibility between the downsizing of the filter and good power characteristics is a current challenge.

  As one method for solving such a problem, the present inventors have disclosed a two-dimensional circuit type superconducting resonator such as a circle, an ellipse, or a polygon in Japanese Patent Application No. 2004-303301, which is an unpublished prior application. A method has been proposed in which a conductor pattern is disposed above a pattern via a dielectric to generate a coupling corresponding to a desired bandwidth. The conductor pattern is preferably circular or elliptical.

  FIG. 2 is a configuration example of a superconducting filter having a coupling conductor pattern 17 proposed in the course of reaching the present invention. 2A is a top view of the superconducting filter, and FIG. 2B is a cross-sectional view after being stored in the metal package 30. FIG.

  Of the superconducting films covering both surfaces of the base dielectric substrate 11, one film is used as the ground layer 14, and the other film is processed to form a disk-shaped resonator pattern 12 and a feeder line extending in the vicinity thereof. 13 is used as a signal layer. When the dielectric 16 is laminated on the upper side of the signal layer, the effective dielectric constant of the circuit is increased, so that the resonance frequency is lowered and contributes to downsizing. Further, by forming the circular conductor pattern 17 on the surface of the laminated dielectric 16, two resonance modes (so-called “dual mode”) can be generated by one resonator pattern. Unlike the microstrip, the resonator pattern 12 and the dual-mode generating conductor pattern 17 both have shapes defined only by curves. Eliminating structures that tend to cause current concentration, such as straight lines and corners, contributes to downsizing, and at the same time has good power and frequency characteristics.

  However, there is a possibility that a deviation from the design simulation result may occur depending on the material characteristics and mounting state of the laminated dielectric 16 and the material characteristics and position of the dual mode generating conductor pattern 17. When the conductor pattern for generating the dual mode is integrally formed on the laminated dielectric 16, if the deviation is adjusted, several parameters are moved at the same time. desired.

  Accordingly, an object of the present invention is to provide a configuration in which fine adjustment of transmission characteristics of a filter can be easily performed in a superconducting filter device having a two-dimensional graphic type resonator pattern such as a disk shape.

  In the present specification and claims, the term “two-dimensional graphic pattern” or “two-dimensional graphic pattern” is distinguished from a line-shaped or strip-shaped (one-dimensional) pattern, It shall mean a resonator pattern having the shape of a plane figure such as an ellipse or a polygon.

  In order to solve such a new problem, the present invention separates the conductor pattern for generating the dual mode from the laminated dielectric and positions the conductor for generating the dual mode vertically or horizontally from the outside of the package. Make the structure adjustable.

  In addition, conductor patterns for generating a dual mode having a plurality of different sizes are prepared so that the conductor patterns can be easily exchanged.

Specifically, in the first aspect of the present invention, the superconducting filter device is:
(A) a dielectric base substrate;
(B) a two-dimensional figure type resonator pattern formed of a superconducting material on the dielectric base substrate;
(C) a dual mode generating conductor held above the resonator pattern;
(D) a mechanism for moving the position of the dual mode generating conductor.

  In a favorable configuration example, the moving mechanism moves the dual mode generating conductor in the vertical direction above the resonator pattern. In this case, the superconducting filter device has a screw-type or trimmer-type support rod that is attached to the top plate of the package and supports the dual-mode generating conductor so as to be movable up and down.

  Alternatively, the moving mechanism moves the dual mode generating conductor in the horizontal direction along the radial direction of the resonator pattern above the resonator pattern. In this case, the top plate of the package is provided so as to be slidable in the horizontal direction with respect to the package body, and a support bar for supporting the dual mode generating conductor is attached to the package top plate. The package top plate and the indicator bar constitute a moving mechanism.

In a second aspect of the invention, the superconducting filter device is:
(A) a dielectric base substrate;
(B) a two-dimensional figure type resonator pattern formed of a superconducting material on the dielectric base substrate;
(C) a dual-mode generating conductor held above the resonator pattern;
(D) A support rod for supporting the dual mode generating conductor in a replaceable manner.

  The dual mode generating conductor and the laminated dielectric can be controlled independently, and the resonance frequency and bandwidth of the superconducting filter device can be finely adjusted by a simple method.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 3 shows a configuration example of the superconducting filter device 10 according to an embodiment of the present invention. 3A is a horizontal sectional view of the superconducting filter device, and FIG. 3B is a vertical sectional view. The superconducting device 10 includes a dielectric base substrate 11, a superconducting resonator pattern 12 formed in a predetermined shape with a superconducting material on the surface of the dielectric base substrate 11, and a signal extending in the vicinity of the superconducting filter pattern 12. An input / output line (feeder) 13, a ground electrode (ground film) 14 formed on the back surface of the dielectric base substrate 11, and a conductor 27 positioned above the superconducting resonator pattern 12 via a predetermined space, The support rod 18 that supports the conductor 27 so as to be movable in the vertical direction is provided.

  In the example of FIG. 3, a YBCO (Y—Ba—Cu—O-based) material is used as the superconductive material, and an MgO single crystal substrate is used as the dielectric base substrate 11. For the dielectric base substrate 11, any dielectric material having a dielectric constant of 8 to 10 at a frequency of 3 to 5 GHz can be used in addition to the MgO single crystal.

  The superconducting resonator pattern 12 is a disk-shaped two-dimensional graphic pattern excluding straight lines and corners. As a result, current concentration is prevented, and power characteristics and frequency characteristics are maintained favorably. One of the feeders 13 extending from the signal input / output electrode 15 toward the superconducting resonator pattern 12 is used as a signal input, and the other is used as a signal output.

A dielectric substrate 16 such as LaAlO ₃ is stacked on the dielectric base substrate 11. The laminated dielectric substrate 16 has an effect of relaxing current concentration on the superconducting resonator pattern 12. As a stacking method, a LaAlO ₃ single crystal substrate 16 is mounted on the dielectric base substrate 11, and four corners of the substrate are fixed to the metal package 30 with springs (not shown). The laminated dielectric substrate 16 may be any substrate having a dielectric constant exceeding 20 in addition to the LaAlO ₃ single crystal. However, both surfaces of the substrate are smooth and have a thermal expansion coefficient similar to that of the MgO dielectric base substrate 11 even at low temperatures. Similar ones are desirable.

  The conductor 27 held at one end of the support bar 18 is, for example, a circular (disc-shaped) conductor pattern, and is positioned above the superconducting resonator pattern 12, thereby allowing two resonance modes (dual mode). (Hereinafter referred to as “dual-mode generating conductor 27” as necessary). Then, by adjusting the support rod 18 from the outside and adjusting the vertical position of the conductor 27 for generating the dual mode, the coupling state between the two degenerate modes can be changed, and the bandwidth and the like can be adjusted. Can do.

  The other end side of the support bar 18 is attached through the top plate 30 </ b> C of the metal package 30. The support bar 18 can be easily adjusted in the vertical direction by a screw method or a trimmer method. The material of the support rod 18 is preferably selected from materials such as alumina that can be applied to the screw method or the trimmer method and that do not affect the filter characteristics such as dielectric loss.

  The conductor 27 for generating the dual mode may be made of a superconductor. In this case, as shown in FIG. 3C, a YBCO thin film is formed on one surface of another dielectric substrate 29 and processed into a desired pattern to form a superconducting disk pattern 27s for generating a dual mode. Form. The pattern surface on which the superconducting disk pattern 27 s is formed is opposed to the resonator pattern 12, and the surface on which the superconducting disk pattern 27 s is not formed is fixed to the support bar 18 by the adhesive layer 28.

  The size of the base substrate 11 is, for example, 20 × 20 × 0.5 mm, and the YBCO resonator pattern 12 formed on the base substrate 11 has, for example, a diameter of 12.8 mm and a film thickness of 0.5 μm. The size of the laminated dielectric substrate 16 disposed on the base substrate 11 is, for example, 18 × 18 × 0.5 mm. In order to reduce the surface resistance, the thickness of the dual mode generating conductor 27 (or conductor pattern 27s) held by the support rod 18 should be greater than the skin length if a metal material is used. If used, the film thickness should be greater than the magnetic penetration length.

  Hereinafter, the degree of position adjustment of the dual mode generating conductor 27 will be described.

  FIG. 4 is a diagram showing a simulation result when the size of the conductor 27 for generating the dual mode is the same and the distance from the laminated dielectric 16 is changed in the superconducting filter device of FIG. 4A shows a structure in which the conductor pattern 17 is directly formed on the laminated dielectric 16 as in the proposed method of the unpublished earlier application shown in FIG. 2, and FIG. 4B shows the embodiment of FIG. As described above, the conductor 27 is supported above the laminated dielectric 16 so as to be movable up and down.

  FIG. 5 is a graph showing changes in the transmission characteristics (S21) of the superconducting filter device when the configurations of FIGS. 4 (a) and 4 (b) are used. A thick line A in FIG. 5 shows basic characteristics when the conductor pattern 17 having a diameter of 3.8 mm is directly formed on the laminated dielectric 16 as shown in FIG. The other curves B, C, and D are transmission characteristics when the vertical position of the dual mode generating conductor 27 having a diameter of 8 mm is changed. In the one-dot difference line B, the distance (air) between the conductor 27 and the laminated dielectric 16 is set to 0.05 mm, the solid line C is set to 1.0 mm, and the dotted line D is set to 0.15 mm.

  From FIG. 5, it can be seen that the bandwidth decreases as the distance (Air) between the conductor 27 and the laminated dielectric 16 increases. This means that as the conductor pattern 27 is separated, the influence of coupling between the two degenerate modes decreases.

  When this is used, the vertical position of the conductor 27 is adjusted from the outside even when the transmission characteristics deviate from the desired transmission characteristics due to variations in material characteristics and mounting state of the laminated dielectric 16 and variations in material characteristics of the dual mode generating conductor 27. Thus, the resonance frequency and bandwidth can be finely adjusted.

  FIG. 6 shows a superconducting filter device according to an embodiment of the present invention, in which a distance between the conductive disk pattern 27 for generating a dual mode and the laminated dielectric 16 is fixed to 0.1 mm, and desired filter characteristics are obtained. It is a figure which shows the simulation result for the size adjustment of the required conductor 27. FIG.

  FIG. 6A shows a structure in which a conductor pattern 17 having a diameter of 3.8 mm is directly formed on the laminated dielectric 16 as in the proposed method of the unpublished prior application shown in FIG. 2, and FIG. As shown in the embodiment of FIG. 3, the conductors 27 having different sizes are supported above the laminated dielectric 16.

  FIG. 7 is a graph showing changes in the transmission characteristics (S21) of the superconducting filter device when the configurations of FIGS. 6 (a) and 6 (b) are used. A thick line A in FIG. 7 indicates a basic characteristic in the case of FIG. The other curves B, C, and D are transmission characteristics when the size of the dual mode generating conductor 27 is changed at a position 0.1 mm above the laminated dielectric 16. In the one-point difference line B, the diameter of the conductor pattern 27 is set to 7.0 mm, the solid line C is set to 8.0 mm, and the dotted line D is set to 9.0 mm.

  When the distance between the laminated dielectric 16 and the dual mode generating conductor 27 is constant, the influence of coupling between the two degenerate modes is reduced when the size of the conductor 27 is reduced. If this is utilized, the resonant frequency and the bandwidth can be finely adjusted simply by replacing the conductor 27 attached to the tip of the support rod 18.

  As a configuration for facilitating the replacement of the conductor 27, a hole having a diameter that fits the support rod 18 is provided in the conductor 27 in advance. When the conductor 27 is made of a superconductive material, a receiving hole is formed in the dielectric substrate 27 instead of the adhesive layer 28.

8 to 10 are diagrams for explaining a simulation of transmission characteristics when the horizontal position of the conductor 27 for generating the dual mode is changed in the superconducting filter device according to the embodiment of the present invention. )
As shown in FIG. 8, a 3.8 mm diameter conductor 27 is moved horizontally on the laminated dielectric 16 covering the superconducting resonator disk pattern 12 having a diameter of 12.8 mm. The position at 45 degrees from the x-axis, that is, the center of the resonator pattern 12 as the origin, and the midpoint of the symmetrical position with respect to the origin of the two feeders 13 is defined as the original position.

  FIG. 9 shows that the conductor 27 is moved from the original position horizontally by Δx = −0.1 mm, Δy = 0.1 mm, and Δx = 0.1 mm, Δy = −0.1 mm (moving in the tangential direction). When the horizontal position of the conductor 27 is moved by Δx = 0.1 mm, Δy = 0.1 mm, and Δx = −0.1 mm, Δy = −0.1 mm (moving in the radial direction). FIG. 10 is a simulation result of the transmission characteristics when the conductor 27 is moved ± 0.5 mm in the Δx and Δy directions from the original position.

  As shown in FIGS. 9B and 9D, the conductor 27 is tangential to the resonator pattern 12, that is, Δx = −0.1 mm, Δy = 0.1 mm, and Δx = 0.1 mm, Δy = Even when moving by -0.1 mm, there is almost no change in the input reflection characteristics (S11) and the transmission characteristics (S21) at the original position. Similarly, as shown in FIGS. 10B and 10D, even when the tangential direction is shifted by ± 0.5 mm, the transmission characteristics (S21) are almost as shown by the curves B and D. The same.

  On the other hand, as shown in FIGS. 9A and 10A, when the conductor 27 is shifted to the outside along the radius of the resonator pattern 12, the bandwidth and the ripple become large and shift to the low frequency side. That is, there is an effect that the coupling coefficient is increased.

  On the contrary, as shown in FIGS. 9C and 10C, when the conductor 27 is shifted inward along the radius of the resonator pattern 12, the bandwidth and the ripple are reduced and shifted to the high frequency side. .

  From this, even when the characteristics of the superconducting filter device are shifted due to variations in material characteristics of the dual mode generating conductor 27 and variations in material characteristics and mounting state of the multilayer dielectric 16, the horizontal position of the conductor 27 is resonated. It can be seen that the desired characteristics can be controlled by changing along the radial direction of the vessel pattern 12.

  As a configuration for easily changing the horizontal position of the conductor 27, the top plate 30 </ b> C of the metal package 30 having the support rod 18 is configured to be movable in the radial direction of the resonator pattern 12. For example, a groove is provided on the diagonal of the upper surface of the metal package main body constituting the housing, and an edge-shaped protrusion is formed on the corresponding diagonal of the top plate 30C so that the top plate 30C is slid in the groove. be able to.

  As described above, since the dual mode generating conductor 27 can be configured independently of the laminated dielectric 16, the positional relationship of the conductor 27 with respect to the resonator pattern 12 can be easily controlled.

  As a result, the filter characteristics of the superconducting filter device can be easily adjusted from the outside.

  In the embodiment, the YBCO thin film is used as the superconducting material, but any oxide superconducting material can be used. For example, an RBCO (R—Ba—Cu—O) -based thin film, that is, a superconducting material using Nd, Sm, Gd, Dy, and Ho instead of Y (yttrium) as the R element may be used. Also, BSCCO (Bi-Sr-Ca-Cu-O) system, PBSCCO (Pb-Bi-Sr-Ca-Cu-O) system, CBCCO (Cu-Bap-Caq-Cur-Ox, 1.5 <p <2.5, 2.5 <q <3.5, 3.5 <r <4.5) may be used for the superconducting material.

Finally, the following notes are disclosed regarding the above description.
(Supplementary note 1) a dielectric base substrate;
A two-dimensional graphic resonator pattern formed of a superconducting material on the dielectric base substrate;
A dual mode generating conductor held above the resonator pattern;
And a mechanism for moving the position of the dual mode generating conductor.
(Supplementary note 2) The superconducting filter device according to supplementary note 1, wherein the moving mechanism moves the conductor in a vertical direction above the resonator pattern.
(Supplementary note 3) The superconducting filter device according to supplementary note 1, wherein the moving mechanism moves the conductor in a horizontal direction above the resonator pattern.
(Supplementary note 4) The supplementary note 1 further includes a multilayer dielectric positioned on the resonator pattern, and the dual mode generating conductor is positioned above the multilayer dielectric via an air layer. The superconducting filter device as described.
(Additional remark 5) It further has the package which accommodates the dielectric base substrate in which the said resonator pattern was formed, and the conductor for dual mode generation | occurrence | production,
The superconducting filter according to claim 2, wherein the moving mechanism is a screw-type or trimmer-type support rod attached to the top plate of the package and supporting the dual-mode generating conductor in the package. device.
(Additional remark 6) It further has the package which accommodates the dielectric base substrate in which the said resonator pattern was formed, and the conductor for dual mode generation | occurrence | production,
The package includes a package top plate that is slidable in a horizontal direction with respect to the package body,
The additional mechanism according to claim 3, wherein the moving mechanism includes the slidable package top plate and a support rod attached to the package top plate and supporting the dual mode generating conductor in the package. Superconducting filter device.
(Supplementary note 7) The superconducting filter device according to supplementary note 1, wherein the dual mode generating conductor is a metal and has a film thickness equal to or greater than a skin length.
(Supplementary note 8) The superconducting filter device according to supplementary note 1, wherein the dual mode generating conductor is a superconductor and has a film thickness equal to or greater than a magnetic penetration length.
(Appendix 9) a dielectric base substrate;
A two-dimensional graphic resonator pattern formed of a superconducting material on the dielectric base substrate;
A dual-mode generating conductor held above the resonator pattern;
A superconducting filter device comprising a support rod for supporting the dual mode generating conductor in a replaceable manner.
(Supplementary Note 10) A method for adjusting the filter characteristics of a two-dimensional figure type resonator pattern formed of a superconducting material on a dielectric base substrate,
A dual mode generating conductor is movably held above the resonator pattern,
A filter characteristic adjusting method, comprising: adjusting a filter characteristic of the resonator pattern by changing a position of the dual mode generating conductor with respect to the resonator pattern.
(Additional remark 11) The filter characteristic adjustment method of Additional remark 10 characterized by adjusting the filter characteristic of the said resonator pattern by changing the vertical position of the conductor for dual mode generation with respect to the said resonator pattern.
(Supplementary Note 12) The filter characteristic of the resonator pattern is adjusted by changing the horizontal position of the dual mode generating conductor with respect to the resonator pattern along the radial direction of the resonator pattern. The filter characteristic adjustment method as described in 2.
(Supplementary note 13) A method of adjusting the filter characteristics of a two-dimensional figure type resonator pattern formed of a superconducting material on a dielectric base substrate,
Prepare multiple dual-mode generating conductors of different sizes,
A dual mode generating conductor is held above the resonator pattern in an exchangeable manner,
A filter characteristic adjusting method, wherein the filter characteristics of the resonator pattern are adjusted by exchanging the dual mode generating conductors with different sizes.

FIG. 1A is a general RF front-end diagram of a mobile communication base station, and FIG. 1B shows a conventional superconducting filter adjustment method used in the base station of FIG. 1A. FIG. It is a figure which shows the structural example of the process which reaches the superconducting filter device of this invention. It is a figure which shows the structural example of the superconducting filter device which concerns on embodiment of this invention. It is explanatory drawing of the change measurement of a filter characteristic when the position of the up-down direction of the conductor for dual mode generation | occurrence | production is changed. It is a graph which shows the change of the filter characteristic when changing the position of the up-and-down direction of the conductor for dual mode generation. It is explanatory drawing of the change measurement of a filter characteristic when the size of the conductor for dual mode generation | occurrence | production is changed. It is a graph which shows the change of the filter characteristic when the size of the conductor for dual mode generation is changed. It is a figure for demonstrating the position dependence of the horizontal direction of the conductor for dual mode generation | occurrence | production. It is a figure of the simulation result which shows the change of the filter characteristic when the position of the horizontal direction of the conductor for dual mode generation | occurrence | production is shifted +/- 0.1mm in (DELTA) x and (DELTA) y direction. It is a figure of the simulation result which shows the change of the filter characteristic when the position of the horizontal direction of the conductor for dual mode generation | occurrence | production is shifted +/- 0.5mm in (DELTA) x and (DELTA) y direction.

Explanation of symbols

10 Superconducting filter device 11 Dielectric base substrate 12 Superconducting resonator pattern 13 Feeder (signal input / output line)
14 Ground film 16 Multilayer dielectric 18 Support rod 27, 27s Dual mode generating conductor 30 Metal package 30C Metal package top plate

Claims (5)

A dielectric base substrate;
A two-dimensional graphic resonator pattern formed of a superconducting material on the dielectric base substrate;
A dual mode generating conductor held above the resonator pattern;
And a mechanism for moving the position of the dual mode generating conductor. And further comprising a laminated dielectric positioned on the resonator pattern,
The superconducting filter device according to claim 1, wherein the dual mode generating conductor is positioned above the laminated dielectric via an air layer. A dielectric base substrate;
A two-dimensional graphic resonator pattern formed of a superconducting material on the dielectric base substrate;
A dual-mode generating conductor held above the resonator pattern;
A superconducting filter device comprising a support rod for supporting the dual mode generating conductor in a replaceable manner. A method for adjusting the filter characteristics of a two-dimensional graphic resonator pattern formed of a superconducting material on a dielectric base substrate,
A dual mode generating conductor is movably held above the resonator pattern,
A filter characteristic adjusting method, comprising: adjusting a filter characteristic of the resonator pattern by changing a position of the dual mode generating conductor with respect to the resonator pattern. A method for adjusting the filter characteristics of a two-dimensional graphic resonator pattern formed of a superconducting material on a dielectric base substrate,
Prepare multiple dual-mode generating conductors of different sizes,
A dual mode generating conductor is held above the resonator pattern in an exchangeable manner,
A filter characteristic adjusting method, wherein the filter characteristics of the resonator pattern are adjusted by exchanging the dual mode generating conductors with different sizes.

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