JP2630109B2 - Magnetostatic wave element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetostatic wave element, and more particularly, to a magnetostatic wave element used, for example, as a resonator, for example, used as an oscillator.

[0002]

2. Description of the Related Art A conventional variable frequency oscillator using a magnetostatic wave resonator as a background of the present invention is disclosed in C-688 of the Spring Meeting of the Institute of Electronics, Information and Communication Engineers in 1988. FIG. 12 is an illustrative view showing this variable frequency oscillator. This variable frequency oscillator 1 includes a magnetostatic wave resonator 2.

As shown in FIGS. 13 and 14, the magnetostatic wave resonator 2 includes a 1 mm long and 1 mm wide GGG (gadolinium, gallium, garnet) substrate 2a. A YIG (yttrium, iron, garnet) thin film 3 having a thickness of 18 μm is formed. On this YIG thin film 3, a strip conductor 4 having a width of 0.05 mm is formed at the center in one direction. Further, ground conductor 5 made of, for example, metal is formed on the entire other main surface of GGG substrate 2a. As shown in FIG. 12, input / output terminals 6a and 6b are connected to one end and the other end of the strip conductor 4, respectively. Note that Y
A DC magnetic field is applied to the IG thin film 3 in a direction perpendicular to its main surface, for example, by two electromagnets 7a and 7b. One input / output terminal 6 of the magnetostatic wave resonator 2
a is grounded, and the other input / output terminal 6b is connected to the source of the FET8. The gate of the FET 8 is grounded via a feedback inductor. The drain of the FET 8 is connected to a load via the matching circuit 9.

The magnetostatic wave resonator 2 of the variable frequency oscillator 1
Then, as shown in FIGS. 15A to 15D, the distribution of the standing wave of the magnetostatic wave in the resonance mode is such that both ends in one direction of the YIG thin film 3 resonate, and the YIG thin film 3 Generates a standing wave with nodes at both ends. In the magnetostatic wave resonator 2, since the strip conductor 4 is arranged at the center of the YIG thin film 3 in one direction, the mode (m = 2, 4, 4) that is oddly symmetric with respect to the center of the YIG thin film 3 in one direction. 6, ...
•) are not excited and are even symmetric modes (m = 1, 3,
5,...) Are excited. Note that this magnetostatic wave resonator 2
, The mode (m = 1) becomes the basic mode, and the modes (m = 3, 5,...) Become higher-order modes.

However, in this variable frequency resonator 1,
The resonance characteristics of the magnetostatic wave resonator 2 are shown in FIG.
An unnecessary resonance R occurs in addition to the fundamental mode resonance R1. Therefore, the variable frequency oscillator 1 satisfies the oscillation condition at the time of unnecessary resonance, and may cause spurious oscillation.

The unnecessary resonance R in the magnetostatic wave resonator 2 is
In order to suppress this, it has been proposed to increase the width of the strip conductor 4 to, for example, 0.4 mm. When the width of the strip conductor 4 is increased to 0.4 mm, as shown in FIG. 17, the unnecessary resonance R is suppressed, and the fundamental mode resonance R1 satisfies the oscillation condition.

[0007]

However, even when the width of the strip conductor 4 is widened, unnecessary resonance in the higher-order mode is large, so that oscillation may occur in the higher-order mode.

[0008] Therefore, a main object of the present invention is to provide a magnetostatic wave device having a small unnecessary resonance in a higher-order mode.

[0009]

SUMMARY OF THE INVENTION This invention includes a rectangular ferrimagnetic base, and two transducers being spaced apart on one major surface of the full E Li magnetic substrate, the two transducers, The ferrimagnetic substrate is disposed at each position where the ferrimagnetic substrate is divided substantially one-to-two to one in one direction,
Each of the two transducers has a width approximately one-third of the length in one direction of the ferrimagnetic substrate, and further , the directions of the high-frequency signals flowing through the two transducers are opposite.
This is a magnetostatic wave element.

[0010]

When the magnetostatic wave element is used, for example, as a magnetostatic wave resonator, the ferrimagnetic base resonates at both ends in one direction as nodes, and a standing wave of a magnetostatic wave having the both ends as nodes is generated . In this case, two transducers are disposed in respective positions to divide substantially 1: 2: 1 in one direction ferrimagnetic <br/> group members, and flows to the two transducers
The direction of the high-frequency signal is reversed.
Since the phases of the signals flowing through the two transducers are different from each other by approximately 180 °, m = 1, 3, 5,.
The unnecessary resonance mode is canceled out by the two transducers and is hardly excited.

Since the two transducers are arranged at positions that divide the ferrimagnetic substrate approximately one-to-two to one in one direction, the unnecessary resonance modes of m = 4, 8,. Are almost point symmetric with respect to the transducer of the first embodiment and are hardly excited.

Further, since each of the two transducers has a width substantially one-third of the length in one direction of the ferrimagnetic substrate, the effective width of the transducer becomes substantially equal to the wavelength of the mode of m = 6, and m = The unnecessary resonance mode of No. 6 is
Hardly excited.

Incidentally, the unnecessary resonance mode of m = 10 or more is
Since it is minute, it hardly affects resonance.
On the other hand, the mode of m = 2 is excited as a fundamental mode and resonates.

[0014]

According to the present invention, it is possible to obtain a magnetostatic wave element which resonates with the fundamental mode and has small unnecessary resonance with respect to the higher-order mode.

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the accompanying drawings.

[0016]

FIG. 1 is a perspective view showing an embodiment of the present invention, and FIG. 2 is a sectional view taken along line II-II in FIG.
FIG. 3 is an illustrative view showing one example of an oscillation device using the magnetostatic wave element shown in FIGS. 1 and 2.

The oscillation device 10 shown in FIG. 3 includes a magnetostatic wave element 12 used as a resonator. The magnetostatic wave element 12
As shown in FIG. 1 and FIG.
It includes a 0 mm rectangular GGG (gadolinium, gallium, garnet) substrate 14. On one main surface of the GGG substrate 14, for example, a 113 μm-thick YIG (yttrium, iron, garnet) thin film 1 is used as a ferrimagnetic substrate.
6 are formed. The YIG thin film 16 has, for example, a saturation magnetization of 1.78 kGauss.

On the YIG thin film 16, two transducers 18 made of, for example, rectangular strip conductors are provided.
And 20 are formed parallel and spaced apart. In this case, the center lines in the width direction of these transducers 18 and 20 are arranged on respective lines L1 and L2 that divide the YIG thin film 16 in a lengthwise direction substantially 1: 2: 1. Also, these transducers 18 and 20
Are respectively 1 / the length of the YIG thin film 16 in the longitudinal direction.
It has a width of 3.

On the other hand, a ground conductor 22 made of, for example, a metal is formed on the other main surface of the GGG substrate 14.

As shown in FIG. 3, one end of one transducer 18 is connected to the input / output terminal 2 via a line 23a.
4 and the other end is grounded. Further, one end of the other transducer 20 is grounded, and the other end is connected to the input / output terminal 24 via the line 23b. In this case, the length of the line 23a from one end of one transducer 18 to the input / output terminal 24 is selected to be substantially the same as the length of the line 23b from the other end of the other transducer 20 to the input / output terminal 24. Therefore, the phase at one end of one transducer 18 and the other end of the other transducer 20 becomes substantially 0 °. Therefore, the phase of the signal flowing through the transducers 18 and 20 is approximately 1
80 °.

Further, in this magnetostatic wave resonator 12, YI
Above one main surface and below the other main surface of the G thin film 16,
Electromagnets 26a and 26b are arranged respectively. A magnetic field is applied to the magnetostatic wave resonator 12 by the electromagnets 26a and 26b in a direction perpendicular to the main surface of the YIG thin film 16.

The input terminal 2 of the magnetostatic wave resonator 12
4 is connected to the source S of the FET 28. This FET
The gate G of 28 is grounded via the feedback inductor 30. The drain D of the FET 28 is connected to the matching circuit 3
2 and connected to a load 34.

In this oscillation device 10, FIGS.
As shown in (f), the YIG thin film 1 of the magnetostatic wave resonator 12
6, the both ends in the longitudinal direction resonate as nodes, and a standing wave is generated. In this case, the two transducers 18 and 2
0 are located at respective positions that divide the YIG thin film 16 approximately one-to-two to one in one direction, and the phases of the signals flowing through the transducers 18 and 20 are made to differ by approximately 180 °. , M = 1,3,
The unwanted resonance modes of 5,... Are canceled out by the transducers 18 and 20 and are hardly excited.

Also, since the two transducers 18 and 20 are arranged at respective positions that divide the YIG thin film 16 approximately one-to-two in one direction, m = 4
The unnecessary resonance modes of 8,... Are almost point-symmetric with respect to the respective transducers 18 and 20, and are hardly excited.

Further, the two transducers 18 and 20 each have a length of 1 / one of the length in one direction of the YIG thin film 16.
3 so that transducers 18 and 20
Becomes substantially the same as the wavelength of the mode where m = 6, and m
The unnecessary resonance mode of = 6 is hardly excited. The transducers 18 and 20 and the YIG thin film 16
Are coupled by a high frequency magnetic field excited around the transducers 18 and 20. In this case, the high-frequency magnetic field is generated in a range wider than the width of the transducers 18 and 20, and the transducers 18 and 20 are coupled to the YIG thin film 16 in a range wider than the width of the transducers 18 and 20. Therefore, in order to hardly excite the unnecessary resonance mode of the mode of m = 6, the width of the transducers 18 and 20 may be approximately ほ ぼ of the length in one direction of the YIG thin film 16.
May be shorter than approximately 1/3 of the length in one direction. In addition, since the unnecessary resonance mode of m = 10 or more is very small, it hardly affects the resonance. On the other hand, m = 2
Mode is excited as a fundamental mode and resonates.

That is, in the magnetostatic wave element 12, as shown in FIG. 5, the degree of resonance is large with respect to the fundamental mode of m = 2, and m = 4, 6, 8,.
It is clear that the unwanted resonance for the higher-order modes is small. Further, in the magnetostatic wave element 12, as shown in FIG. 6, the resonance characteristics are compared with those of the conventional magnetostatic wave resonator 2 shown in FIGS.
It is clear that unnecessary resonance is suppressed and unnecessary resonance in the higher-order mode is reduced. Therefore, in the oscillation device 10 using the magnetostatic wave resonator 12, unnecessary resonance in the higher-order mode hardly occurs.

In the magnetostatic wave element 12, since the length in one direction of the YIG thin film 16 is formed to be 10 mm, the wavelength λg in the fundamental mode where m = 2 is 10 mm.
Becomes Therefore, the phase constant β obtained by the equation β = 2π / λg is 628 rad in the fundamental mode where m = 2.
/ M. Similarly, in this magnetostatic wave element 12, m
= 4, 6 and 8 are 1257 rad / m, 1885 rad / m and 2513 rad / m, respectively. Further, the magnetostatic wave element 1
In 2, the measured value of the frequency in each mode of the m = 2, 4, 6 and 8, respectively, 2.440GH _z, 2.4
85GH _z, 2.528GH _z and 2.571GH _z
Met.

FIG. 7 is a graph showing the relationship between the measured values of the frequency and the phase constant in each mode of the magnetostatic wave element 12. Further, the graph of FIG. 7 shows the relationship between the frequency of the magnetostatic wave device 12 and the calculated value of the phase constant. As is clear from the graph shown in FIG. 7, in the magnetostatic wave element 12, the relationship between the frequency and the phase constant is almost the same between the calculated value and the measured value. Therefore, the magnetostatic wave element 12 is easy to design.

In the oscillation device 10 shown in FIG. 3, one end of one of the transducers 18 and the other transducer 20 are used to make the phases of the signals flowing through the two transducers 18 and 20 of the magnetostatic wave element 12 approximately 180 °. Is connected to the input / output terminal 24, and the other end of the one transducer 18 and one end of the other transducer 20 are grounded. For example, as shown in FIG. 2
4a, one end of the other transducer 18 may be grounded, and the other end of one transducer 18 may be connected to the other end of the other transducer 20.

FIG. 9 is a perspective view showing a modification of the embodiment shown in FIGS. In the magnetostatic wave element 12 shown in FIG. 9, the transducers 18 and 20 are each configured by a parallel strip line.

FIG. 10 is a perspective view showing another modification of the embodiment shown in FIGS. In the magnetostatic wave element 12 shown in FIG. 10, the dielectric layer 36 is formed on one entire main surface of the YIG thin film 16, and the transducers 18 and 20 are formed on the surface of the dielectric layer 36.

FIG. 11 is a perspective view showing another embodiment of the present invention. The magnetostatic wave element 12 of this embodiment is a dielectric substrate 3
8 inclusive. The dielectric substrate 38 has a principal surface slightly wider than the principal surface of the YIG thin film 16 or the GGG substrate 14.
Then, two transducers 18 and 20 are formed on one main surface of the dielectric substrate 38. in this case,
The two transducers 18 and 20 are formed from one end to the other end in the width direction of the dielectric substrate 38. Also, the two transducers 18 and 20 are YIG
The central portion longer than the width of the thin film 16 is Y
The IG thin film 16 is formed to have a width of 1/3 of the length in the longitudinal direction, and both ends thereof are formed to be narrow. Also, the two transducers 18 and 20 are YIG
The thin film 16 is formed in parallel with an interval of 1/2 of the length in the longitudinal direction.

Then, the YIG thin film 1 on the GGG substrate 16
4 is bonded to one main surface of the dielectric substrate 38 across the two transducers 18 and 20.
In this case, the YIG thin film 16 is placed one-to-two to one in the longitudinal direction.
The YIG thin film 14 is adhered to the dielectric substrate 38 so that the transducers 18 and 20 are arranged at the respective positions where the transducers are divided. The ground conductor 22 is formed on the entire other main surface of the dielectric substrate 38.

In this embodiment, since the ends of the transducers 18 and 20 which do not overlap the YIG thin film 16 in plan view are used as connecting portions, even if a line or the like is connected to the ends of the transducers 18 and 20, Characteristics hardly change. Further, in this embodiment, the ground conductor 2 extends over a wider area than the main surface of the YIG thin film 16 in plan view.
2 are formed, the transducers 18 and 20
Unnecessary direct waves can be suppressed.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is an illustrative view showing one example of an oscillation device using the magnetostatic wave element shown in FIGS. 1 and 2;

FIG. 4 is an illustrative view showing a standing wave distribution of a magnetostatic wave in a resonance mode of the magnetostatic wave element shown in FIGS. 1 and 2;

FIG. 5 is a graph showing a frequency characteristic of the magnetostatic wave device shown in FIGS. 1 and 2;

FIG. 6 is a diagram showing resonance characteristics of the magnetostatic wave device shown in FIGS. 1 and 2;

FIG. 7 is a graph showing the relationship between the frequency and the phase constant of the magnetostatic wave device shown in FIGS. 1 and 2.

8 is a plan view showing another connection example of the transducer of the magnetostatic wave element shown in FIGS. 1 and 2. FIG.

FIG. 9 is a perspective view showing a modification of the embodiment shown in FIGS. 1 and 2;

FIG. 10 is a perspective view showing another modified example of the embodiment shown in FIGS. 1 and 2;

FIG. 11 is a perspective view showing another embodiment of the present invention.

FIG. 12 is an illustrative view showing one example of a variable frequency oscillator using a conventional magnetostatic wave resonator as a background of the present invention.

13 is a perspective view showing a conventional magnetostatic wave resonator used in the variable frequency oscillator shown in FIG.

14 is a sectional view taken along line XIV-XIV in FIG.

FIG. 15 is an illustrative view showing a standing wave distribution of a magnetostatic wave in a resonance mode of the magnetostatic wave resonator shown in FIGS. 13 and 14;

FIG. 16 is a graph showing resonance characteristics of the magnetostatic wave resonator shown in FIGS. 13 and 14;

FIG. 17 is a graph showing resonance characteristics of the magnetostatic wave resonator shown in FIGS. 13 and 14 when the width of the transducer is increased.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Oscillator 12 Magnetostatic wave element 14 GGG board 16 YIG thin film 18, 20 Transducer 22 Ground conductor

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto, Japan Inventor Murata Manufacturing Co., Ltd. No. 10 Inside Murata Manufacturing Co., Ltd. (56) References JP-A-3-162102 (JP, A) JP-A-1-236723 (JP, A) JP-A-1-233822 (JP, A)

Claims (1)

(57) [Claims] 1. A ferrimagnetic base comprising: a rectangular ferrimagnetic base; and two transducers arranged at an interval on one main surface of the ferrimagnetic base, wherein the two transducers move the ferrimagnetic base in one direction. Each of the two transducers is disposed at a position where the two transducers are divided substantially in a one-to-two-to-one relationship, and each of the two transducers has a width substantially one-third of a length of the ferrimagnetic substrate in the one direction;
Furthermore , the direction of the high-frequency signal flowing through the two transducers
A magnetostatic wave element in which the direction is reversed .