JP2007208893A - Superconductive filter device, and filter characteristic adjustment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To precisely perform fine adjustment of the characteristics of a microstrip type resonator constituting a superconductive filter by simple constitution. <P>SOLUTION: A superconductive filter device comprises two or more microstrip type resonators 11 formed of superconductive material on a dielectric substrate, and characteristic adjustment members 12 provided at each of the microstrip type resonators and movable in parallel to the microstrip type resonators at a position of a fixed height from the microstrip type resonators. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  With the spread of mobile phones, high-speed and large-capacity transmission technology has become indispensable. In base stations for mobile communications, a filter receiver is installed in the immediate vicinity of the antenna installed near the top of the tower, so that loss due to routing cables can be reduced and high-quality communication can be performed. ing. Since it is close to the antenna, downsizing of the filter device becomes important. This is because if the filter itself becomes large, it becomes difficult to transport and install the device.

  A superconductor is a promising wiring material for a microstrip line type filter because it has a surface resistance much lower than that of a normal electrical conductor even in a high frequency region.

  FIG. 1A shows a pattern example of a hairpin type superconducting reception filter as a microstripline type filter. On the dielectric substrate 106, a plurality of hairpin resonators 101a to 101g formed of a superconductor film are disposed between the signal input / output lines 103, and adjacent resonances are coupled to obtain filter characteristics. A superconducting film is also formed on the entire back surface of the dielectric substrate 106 as a ground electrode (not shown).

  In general semi-coaxial filters and dielectric filters used at room temperature, the greater the number of resonators (stages), the steeper the frequency cutoff characteristic that separates the signal passband from other regions, but the filter itself also increases. . Even if a good electrical conductor such as copper (Cu) or silver (Ag) is used as the wiring material of the microstrip line type resonator, the electrical resistance hinders the passage of signals and causes a loss. On the other hand, when a superconducting filter is used, transmission loss is small even if it is multi-staged, and a small filter is possible.

  In the future, transmission and reception of large-capacity signals such as voice and images are expected to increase, and in order to cope with the shortage of frequency resources, guard bands set between channels to prevent mutual interference and broadband communication The possibility of improvement can be expanded by using a superconducting filter.

  In actual use, as shown in FIG. 1B, the dielectric substrate 106 on which the resonator pattern 101 is formed is housed in a metal package 130 capable of high-frequency shielding, and is a coaxial connector that is electrically connected to the connection electrode 105. Signals are input and output via 131.

  In a superconducting filter for reception, as shown in FIG. 1, a plurality of hairpin resonators 101 are often arranged and used as a filter. At this time, the resonance frequency of each resonator is deviated from a predetermined value due to variations in the thickness and material characteristics of the dielectric substrate 106 and the patterning dimension deviation of the resonator 101, and ideal filter characteristics are obtained. It may not be obtained.

  In addition, if the dielectric constant of the dielectric substrate 106 is increased in order to reduce the size of the filter, the wiring pattern becomes finer in order to achieve a predetermined wiring impedance, and the deviation of the substrate thickness and patterning dimension is greatly characteristic. Will be affected.

In order to adjust the characteristic deviation, as shown in FIG. 1B, the dielectric or conductor characteristic adjusting rod 102 is moved closer to the resonator 101 from the top plate (not shown) of the metal package 130, and the resonator 101 and The adjusted resonance frequency is adjusted depending on the distance between the two (see, for example, Patent Document 1 and Non-Patent Document 1).
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

  However, as shown in FIG. 1B, when adjusting the adjustment rod 102 in the vertical direction from above the resonator 101, the range of the resonance frequency shift amount is limited, or the planar circuit of the resonator filter is used. Could be damaged.

  Therefore, it is an object to provide a superconducting filter device capable of adjusting the amount of deviation of the resonance frequency stably and over a relatively wide range without damaging the manufactured resonator pattern, and a method for adjusting the filter characteristics. And

  In order to solve the above problems, in the present invention, a dielectric or conductor characteristic adjustment rod is inserted from the side of the package, and the characteristic adjustment rod is resonated at a certain height above the microstrip resonator pattern. Move parallel to the vessel. The resonance frequency is adjusted by the amount of overlap between the resonator and the characteristic adjustment rod.

Specifically, in the first aspect, the superconducting filter device is:
(A) a plurality of microstrip resonators formed of a superconducting material on a dielectric substrate;
(B) a characteristic adjusting member that is provided for each of the microstrip resonators and is movable in parallel to the microstrip resonator at a certain height from the microstrip resonator. Including.

  In a favorable configuration example, the characteristic adjusting member is movable along the longitudinal direction of the microstrip resonator.

  As one configuration example, one characteristic adjusting member is provided for each of the microstrip resonators, and is inserted so as to be movable in the longitudinal direction of the microstrip resonator.

  Alternatively, two characteristic adjusting members are provided for each of the microstrip resonators, and are inserted so as to be movable in parallel from both directions along the longitudinal direction of the microstrip resonator.

In a second aspect, a method for adjusting a superconducting filter device having a plurality of microstrip resonators formed of a superconducting material is provided. This method
(A) For each of the plurality of microstrip resonators, a characteristic adjusting member formed of a dielectric or a conductor is disposed at a certain height from the microstrip resonator,
(B) The characteristic adjusting member is horizontally moved in parallel with the microstrip resonator to adjust the resonance frequency of each microstrip resonator.

  With a simple configuration, the characteristics of the resonator constituting the superconducting filter can be finely adjusted accurately.

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

  FIG. 2 is a diagram for explaining the principle of the present invention. 2A is a perspective view with the metal package omitted, and FIG. 2B is a vertical sectional view with the metal package housed. A plurality of hairpin type resonator patterns 11 and signal input / output lines 13 are formed on a dielectric substrate 16 with a superconductive material. The signal input / output line 13 is connected to the coaxial connector 31 of the metal package 30 by the connection electrode 15. A ground film 18 is formed on the entire back surface of the dielectric substrate 16 with a superconductive material.

  A characteristic adjusting member 12 is inserted from the side surface of the package 30 in parallel with the resonator 11 at a certain height above the resonator 11. In the example of FIG. 2B, the characteristic adjusting member 12 is a screw-type rod. The characteristic adjusting member 12 is a dielectric or a conductor, and a corresponding characteristic adjusting member 12 is used for each resonator 11. The characteristic adjusting member 12 is not disposed between the adjacent resonators 11 but is located above the corresponding resonators 11 at a certain height, and is bidirectional as shown in FIG. As indicated by the arrows, the amount of horizontal movement, that is, the amount of overlap with the resonator 11 is adjusted.

  In FIG. 3, the characteristic adjustment rod 12 is inserted in parallel with the resonator 11, and the change in the resonance frequency in the method of this embodiment (FIG. 2) in which the amount of overlap is changed, and the characteristic adjustment rod 102 is inserted from the vertical direction. It is a figure explaining the Example which compares the conventional method (FIG. 1) which changes the distance between the resonator 101 and the rod front-end | tip.

As a sample, the hairpin pattern of the resonator 11 of FIG. 3A and the signal input / output line are formed on one side of a LaAlO ₃ substrate 16 having a diameter of 2 inches in which YBCO (Y—Ba—Cu—O system) films are formed on both sides. Thirteen patterns are formed using a photolithography technique. The width A of the hairpin resonator 11 is about 0.7 mm, and the microstrip line width is 0.17 mm. The resonator 11 has a resonance frequency in the vicinity of 4 GHz.

  This is diced to about 33 × 11 mm, which is the size of the resonator filter device, and the connection electrode 15 is formed at the end of the signal input / output line 13. The connection electrode has a structure of Au / Pd / Cr and is formed by vapor deposition. On the back surface, the YBCO film is used as it is as a ground electrode, or an Ag film is deposited.

  As shown in FIG. 3B, this sample is put in a metal package 30, and the connection electrode 15 and the central conductor (not shown) of the coaxial connector 31 are connected. As a joining method at this time, any of wire bonding and tape bonding by ultrasonic thermocompression bonding and solder bonding may be used. Also good.

  In order to carry out the comparative example, as shown in FIG. 4, a superconducting filter device 40 having a conventional configuration is obtained by covering a lid of a metal package having a structure in which an alumina screw 19 can be inserted from the top of the resonator 11. At this time, the initial position of the alumina screw 19 is measured, and the distance from the alumina screw 19 to the resonator 11 is determined from the rotational speed of the alumina screw and the pitch of the thread.

  As shown in FIG. 5, this superconducting filter device 40 is set on a cold plate 51 in a heat insulating vacuum container 50 of a cooling device, evacuated to 10 Pa to 3 Pa, and then cooled to 70K. Cooling is performed by combining the refrigerator expansion unit 55 and the refrigerator compression unit 56. Since the superconducting characteristics can be improved as the temperature becomes lower at this time, it is desirable to use the actual device at a lower temperature. However, in this comparative experiment, the cooling temperature is set to 70K. The refrigerators 55 and 56 may be any type (pulse tube, Stirling, GM, etc.) as long as the sample can be cooled.

  The coaxial connector 31 of the superconducting filter device 40 and the hermetic coaxial connector 58 of the heat insulating vacuum container 50 are connected by a coaxial cable 54 to input / output signals to / from the heat insulating vacuum container 50. The hermetic coaxial connector 58 is further connected to the network analyzer 57 by the coaxial cable 54, and the change in the resonance frequency of the resonator 11 (see FIG. 4) is measured.

  That is, a driver 53 that can be rotated in vacuum and a viewing window 52 are provided at the port of the heat insulating vacuum container 50, and the resonator 53 is rotated by the driver 53 while confirming the position of the alumina screw 19 from the window 52. The change in the resonance frequency is examined by changing the distance between 11 and the alumina screw 19.

  Similarly, a change in the resonance frequency when the level adjustment method of the present invention is used is examined using an electromagnetic field simulator.

FIG. 6 is a conceptual diagram of a resonator model produced as a simulation model of the embodiment of the present invention. From the opening side of the hairpin resonator 11 on the LaAlO ₃ substrate 16 produced in FIG. 3A, an alumina (dielectric) rod 12 is formed as a characteristic adjusting member 12 with a height of 0.1 mm from the surface of the resonator 11. And move horizontally along the longitudinal direction of the hairpin in parallel with the resonator 11. The width of the alumina rod 12 is set to 0.7 mm in accordance with the width of the hairpin resonator. The alumina rod 12 is moved horizontally as indicated by a double-headed arrow to change the amount (length) of overlap with the resonator 11, and electromagnetic field simulation is performed to examine the change in the resonance frequency.

  FIG. 7A is a graph showing electromagnetic field simulation results of the resonance frequency when the alumina rod 12 is horizontally moved directly above the resonator 11 as shown in FIG. 6, and FIG. 7B is shown in FIG. 7 is a graph showing a change in resonance frequency when the alumina screw 19 is brought close to the resonator 11 in the vertical direction.

  In FIG. 7A, the horizontal axis represents the distance (mm) where the alumina rod 12 overlaps the resonator 11, and the vertical axis represents the resonance frequency. The amount of change in the resonance frequency is as wide as about 60 MHz, and the adjustment range is wide. In addition, since the gradient of the change in the resonance frequency is relatively gentle, fine adjustment of the resonance frequency is easy by changing the amount of insertion of the alumina rod 12 in the horizontal direction. Furthermore, since the resonance frequency changes almost linearly until the overlapping amount of the alumina rods 12 is about 3.0 mm, the rod position adjustment for obtaining a desired resonance frequency is easy.

  In FIG. 7B, the horizontal axis represents the vertical distance (mm) between the resonator 11 and the vertical axis represents the resonance frequency. The characteristics of the resonator are not affected until the tip of the alumina screw 19 is brought close to the resonator 11 by about 0.2 mm. When the resonator 11 is further brought closer to 0.2 mm above the resonator 11, the resonance frequency changes. However, since the inclination of the change is steep, fine adjustment is difficult. Further, the amount of change in the resonance frequency is about 20 MHz, and the adjustment range is narrow.

  As described above, in the method of this embodiment, the resonance frequency can be finely adjusted accurately and easily by moving the characteristic adjusting member 12 horizontally on the resonator 11 with respect to the individual resonators 11. become. In addition, there is no risk of contact with the resonator 11 and damage. As a result, a highly reliable superconducting filter device in which the resonance frequency is unified as the entire device is realized.

  FIG. 8 is a view showing a modification of the superconducting filter device 10 of FIG. In the configuration of FIG. 2A, one characteristic adjusting member 12 is provided in each resonator 11, and the characteristic adjusting member 12 is inserted from the opening side of the hairpin. In the configuration of FIG. 8, two characteristic adjusting members 12 are provided for each resonator 11, and the characteristic adjusting members 12 are inserted from both the opening side and the U-shaped side of the hairpin. With this configuration, there is an effect that the moving amount of each characteristic adjusting member 12 can be reduced.

  9A and 9B show another example of a resonator pattern to which the present invention is applied. The present invention is applied not only to a hairpin type microstrip pattern, but also to a spiral resonator 21 as shown in FIG. 9A and an S-shaped resonator 31 as shown in FIG. 9B. In the example of FIG. 9, one characteristic adjusting member 12 is used for each resonator 21, 31. However, as shown in FIG. 8, the characteristic adjusting member 12 is bidirectionally connected to each resonator 21, 31. It is good also as a structure which inserts and adjusts the amount of overlap.

  The characteristic adjusting member 12 is not limited to a dielectric such as alumina, but may be a conductor such as metal. 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.
(Appendix 1) A plurality of microstrip resonators formed of a superconducting material on a dielectric substrate;
A superconducting device provided for each of the microstrip resonators and including a characteristic adjusting member that is movable relative to the microstrip resonator at a certain height from the microstrip resonator. Filter device.
(Supplementary note 2) The superconducting filter device according to supplementary note 1, wherein the characteristic adjusting member is movable along a longitudinal direction of the microstrip resonator.
(Additional remark 3) The said characteristic adjustment member is provided with respect to each of the said microstrip type | mold resonator,
The superconducting filter device according to claim 1, wherein the microstrip resonator is inserted so as to be movable along the longitudinal direction of the microstrip resonator.
(Additional remark 4) Two said characteristic adjustment members are provided with respect to each of the said microstrip type | mold resonator,
The superconducting filter device according to appendix 1, wherein the microstrip resonator is inserted so as to be movable in parallel from both directions along the longitudinal direction of the microstrip resonator.
(Appendix 5) The microstrip resonator is a hairpin resonator,
The superconducting filter device according to appendix 1, wherein the characteristic adjusting member is inserted from the opening side of the hairpin resonator so as to be movable along the longitudinal direction.
(Additional remark 6) The said characteristic adjustment member is a rod of a dielectric material or a conductor, The superconducting filter device of Additional remark 1 characterized by the above-mentioned.
(Additional remark 7) It further has the metal package which accommodates the dielectric substrate in which the said microstrip type resonator was formed,
The superconducting device according to claim 1, wherein the characteristic adjusting member is inserted into the package from a side surface of the metal package so as to be parallel to the microstrip resonator by a screw type or a trimmer type. Filter device.
(Supplementary note 8) A method of adjusting a superconducting filter device having a plurality of microstrip resonators formed of a superconducting material,
For each of the plurality of microstrip resonators, a characteristic adjusting member formed of a dielectric or a conductor is disposed at a certain height from the microstrip resonator,
A method for adjusting a superconducting filter device, wherein the characteristic adjusting member is horizontally moved in parallel with the microstrip resonator to adjust the resonance frequency of each microstrip resonator.
(Supplementary Note 9) One characteristic adjusting member is provided for each of the microstrip resonators,
The superconducting filter device according to claim 8, wherein the resonance frequency of the microstrip resonator is adjusted by moving the characteristic adjusting member in parallel along the longitudinal direction of the microstrip resonator. Adjustment method.
(Supplementary Note 10) Two of the characteristic adjusting members are provided for each of the microstrip resonators,
The super frequency according to appendix 8, wherein the frequency of the microstrip resonator is adjusted by moving the characteristic adjusting member from both directions along the longitudinal direction of the microstrip resonator. Method for adjusting a conductive filter device.

It is a figure explaining the adjustment method of the conventional hairpin type | mold superconducting filter pattern (resonator). 2A and 2B are views for explaining the principle of the present invention, in which FIG. 2A is a perspective view with a metal package omitted, and FIG. 2B is a cross-sectional view with the metal package housed. FIG. 3A is a diagram illustrating an example of the present invention, FIG. 3A is an example of a resonator pattern used in the example, and FIG. 3B is a diagram illustrating a mounted state of the resonator. It is a figure which shows the structure for implementing a comparative example. It is a schematic block diagram of the measurement system of a resonant frequency. It is the schematic of the resonator model used for electromagnetic field simulation regarding adjustment of the superconducting filter characteristic of embodiment. FIG. 7A is a graph showing a change in resonance frequency (electromagnetic field simulation result) according to the embodiment, and FIG. 7B is a graph showing a change in resonance frequency of the conventional method. It is a modification of the characteristic adjustment of the superconducting filter device which concerns on embodiment. It is a figure which shows another example of the resonator pattern to which the characteristic adjustment of this invention is applied.

Explanation of symbols

10 Superconducting filter device 11 Resonator 12 Characteristic adjusting member (alumina rod)
13 Signal I / O Line 14 Ground Film 16 Dielectric Substrate 30 Metal Package

Claims (5)

A plurality of microstrip resonators formed of a superconducting material on a dielectric substrate;
A superconducting device provided for each of the microstrip resonators and including a characteristic adjusting member that is movable relative to the microstrip resonator at a certain height from the microstrip resonator. Filter device.   The superconducting filter device according to claim 1, wherein the characteristic adjusting member is movable along a longitudinal direction of the microstrip resonator. One characteristic adjusting member is provided for each of the microstrip resonators,
The superconducting filter device according to claim 1, wherein the microstrip resonator is inserted so as to be movable along the longitudinal direction of the microstrip resonator. Two of the characteristic adjusting members are provided for each of the microstrip resonators,
The superconducting filter device according to claim 1, wherein the superconducting filter device is inserted so as to be movable in parallel from both directions along the longitudinal direction of the microstrip resonator. A method for adjusting a superconducting filter device having a plurality of microstrip resonators formed of a superconducting material, comprising:
For each of the plurality of microstrip resonators, a characteristic adjusting member formed of a dielectric or a conductor is disposed at a certain height from the microstrip resonator,
A method for adjusting a superconducting filter device, wherein the characteristic adjusting member is horizontally moved in parallel with the microstrip resonator to adjust the resonance frequency of each microstrip resonator.

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