JP2755320B2 - Magnetostatic wave resonator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
Y formed on a non-magnetic substrate such as gallium garnet)
Involved in magnetostatic wave devices using magnetic spin resonance of ferrimagnetic thin films such as IG (yttrium, iron, garnet),
To the extent that it does not affect the resonance characteristics of the operating frequency band,
The present invention relates to an element structure capable of sufficiently separating the frequency of the parasitic resonance due to the structure from the band.

[0002]

2. Description of the Related Art As an element used in a microwave oscillation circuit or the like, a liquid phase epitaxially grown Y on a GGG (gadolinium / gallium / garnet) non-magnetic substrate is used.
There has been proposed a ferrimagnetic thin-film resonance element in which an IG (yttrium-iron-garnet) thin film is processed into a required shape. This ferrimagnetic thin-film resonance element has a high resonance characteristic Q in a microwave band and is magnetically coupled to a microwave transmission line (such as an electrode finger formed by an etching method). It is characterized in that a DC bias magnetic field is applied vertically to the ferrimagnetic thin film and the resonance frequency can be varied by the magnetic field strength. As a resonator utilizing ferrimagnetic thin film resonance, the transmission line is used as an element which facilitates adjustment of coupling between the ferrimagnetic thin film and the transmission line and has a high degree of coupling with the transmission line. Photo etching (etching) on top
Magnetostatic wave devices formed by technology have been proposed. FIG. 4 is a schematic configuration diagram showing an example of the magnetostatic wave element. In FIG. 4B, a magnetostatic wave resonator 8 is formed by forming a YIG thin film 3 on a GGG single crystal substrate 2 by a liquid phase epitaxial method, and forming one or more Au or Al films on the YIG thin film. The electrode finger 5 and pad electrodes 4a and 4b formed on both sides of the electrode finger 5 by a photolithography technique to have a length l ₃ ,
It is cut out to a size of width w ₂ and thickness t. FIG.
As shown in (a), a part of the conductor surface is removed to form a gap g ₂ larger than the length (l ₃ ) of the magnetostatic wave resonator 8,
Then, the conductor plate 11 is formed on one side and the matching stub 7 is formed on the other side. Then the magnetostatic wave resonator 8 was placed in the disconnected portion g ₂ of the DC-disconnected microstrip line 15, connects the pad electrode 4a and the conductor plate 11 plate 1
2a, and the matching stub 7 and the pad electrode 4b are connected by using a connection plate 12b.
6.

[0003]

When the transmission characteristics of the magnetostatic wave element 16 shown in FIG. 4A when the bias magnetic field Ho is not applied are measured, as shown in FIG. The characteristics showed that the loss decreased. The drop in the loss is not caused by the magnetostatic wave since it occurs when the magnetic field is not applied. When the frequency of the lowest order mode of the magnetostatic wave resonance is changed by gradually changing the bias magnetic field, the lowest order mode of the magnetostatic wave resonance is not deteriorated up to the frequency at which the drop occurs. When the frequency approaches the frequency at which the drop occurs, there is a problem that the peak of the lowest order mode is deteriorated and the sharpness Q of resonance is greatly reduced. More specifically, as the magnetostatic wave resonator 8, a YIG film 3 having a thickness of about 40 μm is formed on the GGG single crystal substrate 2, an Au film having a thickness of 1.5 μm is formed on the YIG film, and a Au film is partially formed. Width 30 by removing the membrane
Five electrode fingers 5 having a length of 1 μm and a length of 1 mm, and pad electrodes 4 a and 4 b formed on both sides of the electrode fingers 5, and a length (l ₁ ) of 2 mm and a width (w ₁ ) of 1 using a dicer having a diamond blade.
A resonator cut out to a size of 0.5 mm and a thickness (t) of 0.5 mm was used. And the microstrip line 15 is manufactured by etching, larger becomes than the length of the magnetostatic wave resonator 8 (l _3), to secure the magnetostatic wave resonator 8 to the portion of the gap g _2, the pad electrode 4a and the conductor plate 11 To the copper connection plate 12a
And the pad electrode 4b and the stub 7 are connected to the copper
Then, the magnetostatic wave element 16 was manufactured by soldering with b. Here g ₂₁ · g ₂₂ is the gap which is produced in each interval 0.5 mm. When the transmission characteristics of the magnetostatic wave element 16 when the bias magnetic field Ho was not applied were measured by a network analyzer, the frequency was 9.3 GHz as shown in FIG.
, The characteristic that the passage loss is reduced by about 20 dB. By applying a bias magnetic field Ho, the magnetostatic wave element 1
6, the resonance frequency of the magnetostatic wave element 1 is set to about 9 GHz.
6 was measured, and as shown in FIG.
The characteristic shows that the lowest order mode of the resonance of the magnetostatic wave is affected by the drop and deteriorates. By gradually changing the bias magnetic field, the frequency of the lowest order mode of the magnetostatic wave resonance is set to 5-1.
When the frequency is changed to 3 GHz, the mode is not deteriorated up to 5 to 8 GHz, but when approaching the dropping frequency of 9.3 GHz, the peak of the mode is deteriorated and the resonance is sharp. The degree Q greatly decreased. Here, the length 5 mm of the magnetostatic wave resonator 8 is 9.6 mm in terms of an electrical length, and the wavelength of the microwave propagating through the microstrip line at 9.3 GHz.
It is half the length of 2 mm. An object of the present invention is to sufficiently separate the frequency of the parasitic resonance due to the structure from the band to the extent that the resonance characteristics of the used frequency band are not affected,
An object of the present invention is to provide a magnetostatic wave device having a structure capable of improving deterioration of resonance characteristics of the magnetostatic wave device.

[0004]

According to the present invention, there is provided a magnetostatic wave resonator comprising: means for exciting a magnetostatic wave by a microwave; and a ferrimagnetic thin film through which the magnetostatic wave propagates. The electrical length in the direction is 4 times the wavelength of the microwave propagating in the space containing the ferrimagnetic thin film.
This is a magnetostatic wave resonator characterized in that the number is reduced to 1 / or less. In the present invention, as a means for exciting the magnetostatic wave, a method of passing a microwave current to an electrode formed on the ferrimagnetic thin film may be used, or as a means for exciting the magnetostatic wave, a microstrip may be used. An electrode formed on the line may be used. Hereinafter, the present invention will be described in detail. The present inventors have inferred that the occurrence of the parasitic resonance in the magnetostatic wave resonator is caused by the length of the ferrimagnetic thin film in which the magnetostatic wave propagates in the microwave propagation direction. That is, since the magnetostatic wave resonator is used as a two-terminal element, it is considered that resonance due to the structure occurs with the electric length of the path being a half wavelength. The wavelength of the microwave at the frequency of the parasitic resonance on the electrode formed on the ferrimagnetic thin film was calculated in consideration of the dielectric constant of the substrate and the like. As a result, the half wavelength of the wavelength corresponded to the electrical length of the microwave path of the ferrimagnetic thin film, which is the medium through which the magnetostatic wave propagates. Therefore, in order to sufficiently separate the frequency of the parasitic resonance so as not to affect the resonance characteristics of the operating frequency band, the electrical length of the microwave path of the ferrimagnetic thin film, which is the medium through which the magnetostatic wave propagates, that is, It is necessary to make the length of the magnetostatic wave resonator in the microwave propagation direction sufficiently small. FIG. 8 shows the relationship between the length of the magnetostatic wave resonator in the microwave propagation direction and the amount of parasitic resonance drop due to the structure. When the length of the resonator is equal to the half wavelength of the parasitic resonance, the amount of dip is maximum, and as the length of the resonator becomes shorter, the amount of dip decreases, and the length of the resonator becomes smaller. When the wavelength is less than a quarter wavelength, the characteristic is such that the amount of dip due to parasitic resonance is sufficiently smaller than the amount of dip due to pass loss. That is, according to the present invention, as shown in FIG. 1, a ferrimagnetic thin film 3 is formed on a nonmagnetic substrate 2, electrodes 4a, 4b and 5 are formed on the ferrimagnetic thin film, and the ferrimagnetic thin film 3 is formed by a microwave flowing through the electrodes. In the magnetostatic wave resonator 6 having a structure in which a magnetostatic wave is excited and propagated in the magnetic thin film, the electric length of the microwave path l ₁ of the ferrimagnetic thin film is set to be equal to or less than の of the wavelength of the highest operating frequency. Features. According to another aspect of the present invention, as shown in FIG. 7, a ferrimagnetic thin film 3 is formed on a first nonmagnetic substrate 2, and the ferrimagnetic thin film 3 is formed by electrodes 9 and 10 formed on a second nonmagnetic substrate 15. In a magnetostatic wave resonator having a structure in which a magnetostatic wave is excited and propagated, a path l in the microwave propagation direction of the ferrimagnetic thin film is formed.
₁ is a magnetostatic wave resonator characterized in that the electrical length of the magnetostatic wave resonator is 1/4 or less of the wavelength of the highest operating frequency.

[0005]

According to the magnetostatic wave resonator of the present invention, the frequency of the parasitic resonance due to the structure is sufficiently separated from the band to such an extent that the resonance characteristics of the operating frequency band are not affected, and the resonance characteristics of the magnetostatic wave element are improved. Deterioration could be improved. This is because the electric length of the ferrimagnetic thin film in the microwave propagation direction is set to not more than one-fourth of the wavelength of the microwave propagating in the space including the ferrimagnetic thin film. It is considered that the frequency was set to be twice or more than that of.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments. (Embodiment 1) FIG. 1 shows an embodiment of the present invention. First, as shown in FIG. 1B, a YIG film 3 having a thickness of about 40 μm was formed on a GGG single crystal substrate 2 by a liquid phase epitaxial growth method. Next, an Au film having a thickness of 1.5 μm is formed on the YIG film by a vacuum deposition method, and the Au film is partially removed by a photolithography method to thereby obtain a 30 μm-thick film as shown in FIG.
Five electrode fingers 5 having a size of 1 μm and a length of 1 mm were formed, and pad electrodes 4a and 4b were formed on both sides thereof. Then, the length (l ₁ ) is 2 mm by a dicer having a diamond blade,
A magnetostatic wave resonator 6 having a width (w ₁ ) of 1 mm and a thickness (t) of 0.5 mm was cut out from the wafer. Dielectric 1 with conductor plates on both sides
The length of 4 magnetostatic wave resonator 6 by etching the micro strip line 15 of the structure sandwiching the (l ₁₎ Large comprising forming a gap g ₁ than, copper conductive plate 11 to become a connecting end to the negative resistance circuit And a stub 7 for impedance matching having a length (l ₂ ) and a width (w ₃ ). This gap g ₁
, The magnetostatic wave resonator 6 is fixed to the pad electrode 4a and the conductor plate 11 with a copper connection plate 12a, and the pad electrode 4b
And the stub 7 were soldered together with a copper connection plate 12b to produce the magnetostatic wave element 1. Here, 14 dielectric polytetrafluoroethylene resin, 13 copper ground conductor plate of a microstrip line 15, g ₁₁ · g ₁₂ is the gap made by the spacing 0.5mm, respectively. When the pass characteristic of the magnetostatic wave device 1 when the bias magnetic field Ho was not applied was measured by a network analyzer, a drop in the pass loss was observed in the frequency range of 5 to 13 GHz as shown in FIG. Unique properties were shown. Further, the pass frequency of the magnetostatic wave element 1 was measured by applying a bias magnetic field Ho to set the resonance frequency of the magnetostatic wave element 1 to about 9 GHz. As shown in FIG. The negative electrode showed good characteristics without deterioration. Also, when the bias magnetic field Ho was gradually changed to change the lowest mode frequency of the magnetostatic wave resonance from 5 to 13 GHz, the mode did not deteriorate in the range of 5 to 13 GHz, and the resonance was sharp. The degree Q was large. Where 11
The wavelength of the microwave propagating through the microstrip line at GHz is 16.2 mm. Further, when the length of the resonator in this embodiment is 2 mm, which is converted into an electrical length, it is 3.8.
mm, which is less than a quarter of the wavelength. (Embodiment 2) In this embodiment, a YIG film 3 was formed on a GGG single crystal substrate 2 in the same manner as in the magnetostatic wave element 6 shown in Embodiment 1. Thereafter, a magnetic substrate 17 having a length (l ₁ ) of 2 mm, a width (w ₁ ) of 1 mm and a thickness (t) of 0.5 mm was cut out from the wafer by a dicer having a diamond blade. The microstrip line 15 having a structure in which the dielectric 14 is sandwiched between the conductor plates on both sides is etched by a width of 30 μm.
Five electrode fingers 10 each having a length of m and a length of 1 mm are formed, a copper conductive plate 11 serving as a connection end to a negative resistance circuit, and a width (w ₃ )
Another substrate (second substrate) 9 on which the impedance matching stub 7 was formed was manufactured. The magnetic substrate 17 was fixed to the portion where the electrode fingers 10 were formed, and a magnetostatic wave element 18 was manufactured. When the pass characteristics of the magnetostatic wave element 18 when the bias magnetic field Ho was not applied were measured by a network analyzer, the frequency was 5 to 13 GHz as in FIG.
In the range, the characteristic where no decrease in the passage loss was observed. Further, by applying the bias magnetic field Ho and setting the resonance frequency of the magnetostatic wave element 18 to about 9 GHz and measuring the pass characteristics of the magnetostatic wave element 18, the lowest order mode of the magnetostatic wave resonance was measured as in FIG. The metal did not deteriorate and showed good characteristics. When the frequency of the lowest order mode of the magnetostatic wave resonance is changed from 5 to 13 GHz by gradually changing the bias magnetic field, the mode is not deteriorated from 5 to 13 GHz, and the sharpness Q of the resonance is increased. Showed large characteristics. Similarly, the wavelength of the microwave propagating through the microstrip line at 11 GHz is 16.2 mm, and the length of the resonator of this embodiment, 2 mm, is converted into an electrical length of 3.8.
mm is a value smaller than a quarter of the wavelength.

[0007]

According to the present invention, in a magnetostatic wave resonator comprising means for exciting a magnetostatic wave with a microwave and a ferrimagnetic thin film through which the magnetostatic wave propagates, the magnetostatic wave resonator has a magnetic wave propagating direction in which the ferrimagnetic thin film propagates. By setting the electrical length to less than or equal to one-fourth of the wavelength of the microwave at the highest operating frequency propagating in the space including the ferrimagnetic thin film, the parasitic resonance due to the structure can be reduced to the extent that the resonance characteristics of the operating frequency band are not affected. Can be sufficiently separated from the above-mentioned band to improve the deterioration of the resonance characteristics of the magnetostatic wave element.

[Brief description of the drawings]

FIG. 1A is a diagram showing one embodiment of the present invention, and FIG.
FIG. 3 is an explanatory diagram of a magnetostatic wave resonator of the present invention.

FIG. 2 is a diagram showing measured values of transmission characteristics of one embodiment of the present invention when no magnetic field is applied.

FIG. 3 is a diagram showing actually measured values of transmission characteristics of one embodiment of the present invention when a bias magnetic field is applied.

FIG. 4A is a diagram showing an example of a magnetostatic wave element, and FIG.
FIG. 3 is an explanatory diagram of a magnetostatic wave resonator.

FIG. 5 is a diagram showing measured values of transmission characteristics of an example of a magnetostatic wave element when no magnetic field is applied.

FIG. 6 is a diagram showing measured values of transmission characteristics of an example of a magnetostatic wave element when a bias magnetic field is applied.

FIG. 7 is an explanatory view showing another embodiment of the present invention.

FIG. 8 is a diagram showing the relationship between the length of a magnetostatic wave resonator in the microwave propagation direction and the amount of parasitic resonance drop due to the structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetostatic wave element 2 GGG board 3 YIG film 4a Pad electrode 4b Pad electrode 5 Electrode finger 6 Magnetostatic wave resonator 7 Impedance matching stub 8 Conventional magnetostatic wave resonator 9 Another substrate 10 Electrode formed on another substrate DESCRIPTION OF SYMBOLS 11 Conductor plate for connection 12a Connection plate 12b Connection plate 13 Conductor plate for grounding 14 Dielectric 15 Microstrip line 16 Conventional magnetostatic wave element 17 Magnetic substrate 18 Magnetostatic wave element having electrode fingers formed on another substrate

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01P 1/215 JICST file (JOIS)

Claims (3)

(57) [Claims] 1. A magnetostatic wave resonator comprising: means for exciting a magnetostatic wave by a microwave; and a ferrimagnetic thin film through which the magnetostatic wave propagates, wherein an electric length of the ferrimagnetic thin film in a microwave propagation direction is determined by the ferrimagnetic property. A magnetostatic wave resonator characterized in that it has a wavelength equal to or less than a quarter of a wavelength of a microwave propagating in a space including a thin film. 2. The magnetostatic wave resonator according to claim 1, wherein the means for exciting the magnetostatic wave uses a method of flowing a microwave current to an electrode formed on the ferrimagnetic thin film. 3. The magnetostatic wave resonator according to claim 1, wherein an electrode formed on a microstrip line is used as means for exciting the magnetostatic wave.