JPH0263207A - Magnetostatic wave device - Google Patents

Abstract

PURPOSE:To reduce power consumption by adjusting the frequency of a magnetostatic wave device not by a current flowing to a coil but by a distortion given to a magnetic film. CONSTITUTION:The operating center of an external magnetic field is decided by permanent magnets 12, 12' and a voltage is applied to a piezoelectric substance 14 to vary the frequency and delay time of the magnetostatic wave device to deform a chip 10 through the expansion and contraction thereby causing a pressure to the magnetic film. Thus, the frequency of the magnetostatic wave is varied by varying the magnetic anisotropy. Thus, an external magnetic field is applied by the permanent magnets 12, 12' to adjust the frequency by a piezoelectric substance, the power is less and the power consumption of the magnetostatic wave device is less.

Description

[Detailed Description of the Invention] (Summary) Regarding magnetostatic wave devices such as microwave band resonators, filters, and delay lines that utilize magnetostatic waves, the purpose of this invention is to reduce the power consumption of devices that propagate through magnetic materials. A magnetostatic wave device that utilizes magnetostatic waves is configured to apply stress to a magnetic material to generate strain, thereby changing magnetic anisotropy, thereby changing the propagation characteristics of magnetostatic waves.

[Industrial application field]

The present invention relates to magnetostatic wave devices such as microwave band resonators, filters, and delay lines that utilize magnetostatic waves.

In recent years, interest in signal processing devices in the microwave band of 1 to 26 GHz has been increasing as communications have become higher frequency (e.g. mobile radio, high-definition television, satellite communication, etc.), and resonators in these frequency bands, The development of magnetostatic wave devices that use the magnetic moment in magnetic materials as a signal processing medium is progressing, as elements that can be used as filters, delay lines, etc., and that play a complementary role to surface acoustic wave elements and dielectric elements. There is.

When a DC magnetic field is applied to a magnetic material, the magnetic moment precesses around the direction of the magnetic field, but when a high-frequency magnetic field with the same frequency as the precession is applied perpendicular to the DC magnetic field, the magnetic moment absorbs energy from the high-frequency magnetic field. The precession continues without attenuation. This phenomenon is called magnetic resonance phenomenon.

Low loss ferrite (e.g. yttrium iron garnet)
(YIG)), it is possible to generate various resonance and propagation modes due to the spatial distribution of the magnetized magnetic moment, and among these, the one with almost no energy due to the electric field is called the magnetostatic wave mode.

(b) shows the chip 4 in the magnetic path of the permanent magnet 7.
In this method, a permanent magnet 7 generates a central magnetic field, and the coil 8 compensates for the displacement from the central magnetic field.

[Conventional technology]

The conventional magnetostatic wave device is, for example, YI as shown in Figure 3.
On a magnetic film l such as G, an input voltage transducer 2 and an output output juicer 3 formed by microstrip lines are provided, and a bias magnetic field H6 is applied, and a high frequency is inputted to the input output juicer 2. As a result, a magnetostatic wave S is generated, and this magnetostatic wave propagates to the output transducer 3 and is converted into an electric signal again. In this case, in order to change the resonance frequency, delay time, etc. of the magnetic film, the external magnetic field applied to the chip was changed by changing the current flowing through the magnetic field generating coil.

FIG. 4 is a diagram showing a conventional external magnetic field applying means, (a
), the chip 4 is placed in the gap between the electromagnets 5, and the external magnetic field is entirely generated by the coil 6. ) can change the magnetic field over a very wide range, but has the disadvantage of high power consumption. Furthermore, although the method shown in FIG. 4(b) consumes less power than the former, it also consumes power when maintaining a constant magnetic field. In any case, there is a problem in that when a coil is used to change the external magnetic field, power consumption inevitably increases.

An object of the present invention is to provide a magnetostatic wave device with low power consumption.

[Means to solve the problem]

FIG. 1 is a diagram for explaining the present invention in detail.

The magnetic material used in magnetostatic wave devices has a magnetostriction constant of 0.
YIG and the like are used. When stress is applied to a magnetic film whose magnetostriction constant is not O and the film is strained, the magnetic anisotropy changes and a strain-induced anisotropic magnetic field Hk is generated. There is a relationship between stress σ and Hk as follows: Hk=−3σλ/M s (1). Here, λ is the magnetostriction constant, and Ms is the saturation magnetization. Therefore, applying stress σ is equivalent to applying a magnetic field of Hk. As shown in Figure 1, when a magnetic film on a substrate with length a and thickness t is distorted by height Z, the stress σ generated inside the magnetic film is σ=12zE/ (1-v)a” t (2
). Here, E is Young's modulus and ν is Poisson's ratio. From equations (1) and (2), GGG i with a thickness of 0.5 mm
Calculating for the case of a YIG film on a plate, when the chip size is l c +++ and lum distortion is applied, Hk is 1.7.
0e occurs. The elastic limit is about 40μm, so ±700e
It is possible to induce a certain degree of anisotropic magnetic field.

[For production]

Generally, the frequency of magnetostatic wave devices is 2.8 per 10e.
MHz changes. Therefore, the 400 MHz center frequency can be varied by stress.

〔Example〕

FIG. 2 is a sectional view showing an embodiment of the present invention.

In the figure, 10 is a chip of a magnetostatic wave device, 11 is a magnet yoke, 12 and 12' are permanent magnets, 13 is a chip holder, and 14 is a piezoelectric body.

In this embodiment, a chip 10 of a magnetostatic wave device is housed in a box-shaped chip holder 13, the center of the chip IO is supported from below by a piezoelectric body 14, and both ends of the chip 10 are mounted in the chip holder 13 from above. The chip holder 13 containing the chip is placed in a magnetic circuit made up of a permanent magnet 12, 12' and a magnet yoke 11.

In this embodiment configured in this way, the permanent magnets are 12°12'.
The operation center of the external magnetic field is determined by , and in order to change the frequency and delay time of the magnetostatic wave device, a voltage is applied to the piezoelectric material 14 and the chip 10 is deformed by the expansion and contraction, thereby generating stress in the magnetic film. , whereby the frequency of the magnetostatic wave can be changed by changing the magnetic anisotropy.

According to this embodiment, an external magnetic field is applied by a permanent magnet,
Since the frequency is adjusted using a piezoelectric material, the power required is extremely small, making it possible to reduce the power consumption of magnetostatic wave devices.

〔Effect of the invention〕

As explained above, according to the present invention, the frequency of the magnetostatic wave device is adjusted not by the current flowing through the coil but by the strain applied to the magnetic film, so that the strain can be applied by a piezoelectric material or the like, thereby reducing power consumption. becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the present invention in detail, FIG. 2 is a sectional view showing an embodiment of the present invention, FIG. 3 is a diagram showing a chip of a conventional magnetostatic wave device, and FIG. 4 is a diagram showing a conventional magnetostatic wave device chip. FIG. 3 is a diagram showing external magnetic field application means of the magnetostatic wave device. In the figure, 10 is a chip of a magnetostatic wave device, 11 is a magnet yoke, 12 and 12' are permanent magnets, and 13 is a chip holder 14 which is a piezoelectric material.

Claims (2)

[Claims] 1. A magnetostatic wave device that uses magnetostatic waves propagating in a magnetic material, which is characterized by applying stress to the magnetic material to create distortion, thereby changing the magnetic anisotropy, thereby changing the propagation characteristics of the magnetostatic waves. Magnetostatic wave device. 2. 2. The magnetostatic wave device according to claim 1, wherein said stress is generated by a piezoelectric element.