CN1003971B - tuned oscillator - Google Patents

Abstract

The disclosed tuned oscillator includes an active element, a resonator electrically connected to the active element, and a magnetic circuit made by utilizing a ferromagnetic resonance phenomenon and supplying a magnetic field to the resonator. The resonator is composed of a YIG thin film magnetic resonance element formed by a thin film forming process, and utilizes uniform mode ferromagnetic resonance in the YIG thin film and works under the external magnetic field of a magnetic circuit.

Description

Tuned oscillator

The present invention relates to a tuning oscillator used as a local oscillator in a tuning circuit in a radio, a television, or the like, and a scanning oscillator in a spectrum analyzer, a microwave test instrument, or the like.

In the prior art, such an oscillator uses a body of ytterbium iron garnet (here YIG denotes ytterbium, iron and garnet, but various types of additives may be contained therein), i.e., a YIG ball (as disclosed in japanese patent application No. 32671/1979), which has various characteristics such as a high resonance characteristic Q value up to a microwave band, can be made small in outer shape size because its resonance frequency is independent of the volume of YIG, and its response frequency can be linearly changed in a broad band when changing the bias applied to the YIG ball, and so on.

However, the above-described oscillator also has a disadvantage in that a YIG ball is used in the oscillator. Such a tuned oscillator is difficult to integrate on a substrate of a MIC (thin film hybrid microwave integrated circuit), and thus reduces the structural flexibility. Moreover, such a YIG tuned oscillator has the disadvantage that matching must be achieved by adjusting the wires and the ribbons forming the YIG ball coupling loop and by adjusting the position between the coupling loop and the YIG body, rendering the tuned oscillator highly susceptible to vibrations.

In view of the above, the present invention provides a tuned oscillator that improves upon the above disadvantages.

According to the present invention, since a YIG thin-film magnetic resonance element formed by a so-called thin-film forming process such as a liquid-phase epitaxial growth technique, sputtering, a chemical liquid-phase growth process or the like is used as a resonator, YIG can be sufficiently utilized effectively, and the disadvantage that the ball is vulnerable to breakage is improved.

According to the present invention, there is provided a tuned oscillator comprising an active element, a resonator made of a magnetic material utilizing a magnetic resonance phenomenon and electrically connected to the active element, and a magnetic circuit for supplying a magnetic field to the resonator, in which case the resonator is constituted by YIG (ytterbium, iron, and garnet) thin film magnetic resonance elements using a thin film forming technique, and utilizing a uniform mode of magnetic resonance within the YIG thin film.

FIG. 1 is a cross-sectional view of an embodiment of a tuned oscillator according to the present invention;

FIG. 2 is a plan view of a practical configuration of an oscillator circuit;

FIG. 3 is a cross-sectional view taken along line A-A of FIG. 2;

FIG. 4 is a block diagram illustrating an oscillating circuit;

FIG. 5 is a block diagram of an example oscillator circuit;

FIG. 6 is a Smith chart summarizing the principles of oscillation;

FIGS. 7, 8, 9, 12, 13, 14, 15 and 17 are diagrams respectively summarizing the invention;

FIGS. 10 and 16 are perspective views schematically illustrating a YIG thin film magnetic oscillation element;

FIG. 11 is a cross-sectional view of FIG. 10;

fig. 18 to 25 are various embodiments of the oscillation circuit according to the present invention.

Reference numeral 1 denotes a yoke, 2 denotes an air gap, 3 denotes an oscillation circuit substrate, 4 and 5 denote magnetic poles, respectively, 6 denotes a coil, 33 is a microstrip line, 35 is a YIG thin film magnetic resonance element, 37 is a transistor, and 38 is an impedance matching circuit.

Embodiments of the inventive tuned oscillator will now be further described with the aid of the drawing.

In the present embodiment, as shown in fig. 1, there is provided a yoke 1 made of a magnetic material such as permalloy or the like, in which a magnetic gap 2 is formed, and a substrate 3 containing an oscillation circuit is placed in the magnetic gap 2. A coil 6 is wound around at least one of the poles 4 and 5, the poles being oppositely disposed to form the magnetic gap 2 of the yoke 1, and a varying current is fed to the coil 6, thereby completing the means for providing a varying magnetic field.

Fig. 2 is a plan view of an example of a practical structure of a substrate 3 including a resonance circuit, and fig. 3 is a sectional view taken along line a-a in fig. 2. As shown in fig. 2 and 3, a ground conductor 32 is formed on a first main surface of a dielectric substrate 31 formed of a material such as alumina, and a microstrip line 33 is formed on a second main surface of the dielectric substrate 31, one end of which is electromagnetically coupled to the ground conductor 32 by a connecting conductor 34, the microstrip line 33 and a YIG thin-film magnetic resonance element 35. The YIG thin-film magnetic resonance element 35 is constituted as follows: a thin film of a ferromagnetic material YIG is formed on one main surface of, for example, a GGG (ytterbium gallium garnet) substrate 36 using a thin film forming process such as sputtering, a chemical vapor deposition method (CVD method), a liquid phase epitaxial growth method (LPE method), or the like, and the YIG thin film is formed into a circular shape using, for example, a photolithography process. In fig. 2 and 3, reference numeral 37 denotes a bipolar high-frequency transistor, reference numeral 38 denotes an impedance matching circuit, reference numeral 39 denotes a dc blocking MOS (metal oxide semiconductor) capacitor, and in the present embodiment, the base B of the bipolar transistor 37 is connected to a ground pad 40 coupled to the ground conductor 32 through an impedance wire 41, the emitter E is connected to the side of the YIG thin-film magnetic resonance element 35, and the collector C is connected to the side of the impedance matching circuit 38, thus constituting a common-base series feedback oscillator.

The oscillation principle and the oscillation condition using the YIG thin-film magnetic resonance element 35 as a resonator will be further described in brief. Further, the oscillation circuit using a resonator or the YIG thin-film magnetic resonance element 35, not the output circuit portion but the feedback circuit will be described further. Fig. 4A and 4B show block diagrams of the oscillation circuit, and in fig. 4A and B, reference numeral 42 denotes a YIG thin film resonance circuit, reference numeral 43 denotes a negative resistance circuit, reference numeral 44 denotes an impedance matching circuit and reference numeral 45 denotes a load, and reference numeral 46 denotes a load impedance in fig. 4B, which includes the impedance of the matching circuit.

In FIG. 4, Γ y represents a reflection coefficient on the YIG feedback circuit side as viewed from the YIG thin film resonator circuit side and Γ N represents a reflection coefficient on the active element side as viewed from the end point A as viewed from the negative resistance circuit side, and these may be represented by an impedance Z as viewed from the end point A_YAnd Z_NIs expressed by

Γy=Z_Y-Z_O/Z_Y+Z_O …（1）

Γ_N=Z_N-Z_O/Z_N+Z_O …（2）

Where Z represents the characteristic impedance of the circuit (50. omega.)

Stable oscillation conditions can be expressed as Γ y Γ N ═ 1 … (3) using reflection coefficients Γ y and Γ N

Since the reflection coefficients Γ y and Γ N are both complex, equation (3) may be rewritten with the amplitude and phase separated as follows:

i.e. | Γ_Y｜｜Γ_N｜＝1 …（4）

θ_Y+θ_N＝0 …（5）

Since the YIG feedback circuit as a passive element circuit has a positive equivalent resistance corresponding to the loss of the YIG thin film resonator, | Γ y | > 1 is generated in equation (1), and in turn, in order to establish the oscillation condition given by equation (4), the condition of | Γ N | > 1 must be established, and thus the impedance Z obtained by equation (2) must have a negative resistance characteristic.

The negative resistance circuit 43 may be a 2-terminal active element as a negative resistance element in fig. 4, or may be constituted by a three-terminal active element or a feedback element, and a high-frequency bipolar transistor is used as a three-terminal active element in the examples of fig. 2 and 3, and constitutes a common-base series feedback type oscillation circuit shown in fig. 5. The letter X noted in fig. 5 denotes a reactance circuit.

Although stable oscillation conditions of the oscillation circuit have been described, the following conditions must be established to start oscillation of the oscillation circuit.

｜Γ_Y｜｜ ${\Gamma }_{N^S}$ ｜＞1 …（6）

Namely, it is

${\mathrm{｜\Gamma }}_Y\mathrm{｜＞}\frac{1}{{\mathrm{｜\Gamma }}_{N^S}｜}$

…（7）

Where Γ NS is the Γ N value of Γ N at small signals. When the oscillation circuit starts oscillation, the active element operates at a large amplitude, the absolute value of the negative resistance becomes small, and 1/| Γ N | becomes gradually large. When equation (2) is established, the oscillation of the oscillation circuit starts to enter a steady state. On the basis of the above explanation, the operating principle of the YIG oscillating circuit will be briefly described by means of the smith chart of fig. 6.

As shown in FIG. 6, when at small signals, the signal amplitude is small, 1/Γ_NIs in the state of curve C, which is correspondingly close to the interior of the smith chart, and when the active element is operating at large amplitude, it experiences the state represented by curve D, with the direction of movement represented by the arrow.

In the YIG oscillation circuit described in conjunction with fig. 2 and 3, when the YIG thin-film magnetic resonance element 35 is not resonating, it is only a microstrip line whose end portion is short-circuited, making Γ y an arc line denoted by a in fig. 6, and as is clear from fig. 6, since the reflection coefficient Γ N has an amplitude, the oscillation-starting phase condition given by equation 95) cannot be satisfied, and therefore, oscillation cannot be generated.

If the YIG thin-film magnetic resonance element 35 is placed in the DC magnetic field, then at frequency f₁And f₂Frequency f between_oAt a resonant frequency of f_oThe locus of the reflection coefficient Γ y is shown as B in fig. 6. At a frequency f_oIn the vicinity, the oscillation start amplitude condition given by the formula (7) and the oscillation start phase condition given by the formula (5) are satisfied at the same time, and thus oscillation starts. When the oscillation starts with 1/Γ N moving from curve C to curve D in FIG. 6, equations (4) and (5) are simultaneously true at frequency f, such that the oscillator current is at the oscillation frequency f_oAnd operates stably.

If, in this principle, the YIG thin-film element 35 has a resonant frequency f when the applied DC field voltage is varied₁To f₂The range is varied, and the oscillation circuit oscillates in a frequency range around the resonance frequency.

In this embodiment, the resonator is formed by a thin filmThe YIG thin film magnetic resonance element manufactured by the manufacturing process. In this case, pseudo response (magnetostatic mode) needs to be suppressed. More specifically, a magnetic resonance element made of a single crystal ball (YIG single crystal ball) has advantages of a magnetostatic mode, difficulty in excitation, and obtaining a single co-resonance mode by a uniform precession mode. The magnetic resonance element made of the YIG thin film has a disadvantage in that the magnetostatic mode excitation is large although it is placed in a highly uniform high-frequency magnetic field because it is not uniform inside the DC magnetic field. When a direct current magnetic field is applied perpendicularly to the surface of a disk-shaped specimen made of a ferromagnetic material, analysis of the magnetic mode exhibited appears in the literature (journal of applied physics, volume 48, No. 7 1977, page 3001-3007), in which each mode is represented by an (N, N) M diagram having N nodes in the circumferential direction, N nodes in the radius direction, and (M-1) nodes in the thickness direction, and the uniformity of the high-frequency magnetic field across the entire specimen is excellent, (1, N)₁The series become the dominant magnetostatic modes. FIG. 7 shows the results of the ferromagnetic response of a circular YIG film tested in a cavity resonator at a frequency of 9GHz, where (1, N)₁The series of magnetostatic modes are strongly excited. When the above-mentioned microwave element such as a filter or the like is constituted by this sample, a uniform mode or a magnetostatic mode (1, 1) is adopted₁In this case, all other magnetostatic modes will be pseudo-responsive, and thus there is a fear that pseudo-response and mode hopping will occur. It is therefore desirable to provide a magnetically responsive material made of a ferromagnetic material thin film (YIG thin film) capable of suppressing a magnetostatic mode generating an undesired pseudo response without damaging a uniform mode, which will be described later.

Fig. 8 shows the state of the internal direct-current magnetic field Hi when a DC magnetic field is applied perpendicularly to a YIG circular film having a thickness t and a diameter D (radius R). At this time, its thickness diameter ratio t/D is sufficiently small, and the distribution of the magnetic field in the thickness direction of the sample is negligible because the demagnetizing field is large in the disk type and suddenly becomes small at the outer edge portion thereof, so that the internal DC magnetic field is small near the center and starts suddenly becoming large near the outer edge. According to the above-mentioned documentAs a result of the analysis, if the ratio of R/R is § w/R at Hi § w/R, the static magnetic mode lies between 0 ≦ R/R § w, where w is the angular frequency at which the static magnetic mode resonates and γ is the gyromagnetic ratio. When the magnetic field is fixed, the resonance frequency becomes larger as the modulus N increases to gradually extend the magnetostatic mode or region to the outside as shown in FIG. 9A, and FIG. 9B shows the correspondence (1, N)₁The distribution of high-frequency magnetization components of the mode three low-order mode samples, where the absolute value indicates the amplitude of the high-frequency magnetization element and the reference numeral indicates the phase relationship of the high-frequency magnetization components, is clear from fig. 9, since the high-frequency magnetization components become less in the static magnetic mode, if this is utilized, it is possible to suppress excitation of a magnetic mode generating a pseudo response without affecting the uniform mode.

In practice, as shown in FIG. 10, the annular groove 53 may be formed on the YIG thin film magnetic resonance element 52 by, for example, a selective etching process, for example, in the case where a disk shape formed on the GGG substrate 51 provides an annular portion, the YIG thin film magnetic resonance element 52 may be made sufficiently small in its thickness, and the magnetostatic mode in this case is (1, N)₁And (5) molding.

In (1, 1)₁The mode 53 formed where the mode high-frequency magnetization component becomes 0 and the element 52 are coaxial, and the groove 53 may be constituted continuously or intermittently, and in the configuration shown in fig. 11, the area surrounded by the groove 53 may be thinner than its outer portion, in which case the demagnetizing field increases in the inner area immediately adjacent to the groove 53, and therefore the demagnetizing field will be substantially uniform in this area. In other words, as shown by the broken line in fig. 9A, the dc magnetic field is substantially uniform over a wide range in the radial direction. This can suppress excitation of the static magnetic mode other than the homogeneous mode.

The slot 53 in such a magnetic resonance element throttles the magnetization, in this case, because the slot is placed in (1, 1)₁The position where the mode high-frequency magnetization component becomes 0 does not affect the excitation (1, 1)₁The mode, on the other hand, the slot 53 is placed at a position where the high-frequency magnetization component is not 0 for the other magnetostatic mode, so that the magnetization at high speed is partially completed. As a result, the excitation of these modes isThe weak enable suppresses the spurious response without breaking the uniform mode.

Since the distribution of the high-frequency magnetization component in the YIG film (see fig. 9B) does not depend at all on the magnitude of the saturation magnetization of the sample and also does not greatly depend on the thickness radius ratio, even when the saturation magnetization and the thickness of the ferromagnetic layer 52 are different, there is no need to change the position of the groove 53 corresponding thereto.

According to the experiment, YIG thin film element with radius of 1mm and thickness of 20 μm is made of YIG thin film, and a groove 53 with depth of 2 μm and radius of 0.8mm is formed on the YIG thin film, and the ferromagnetic resonance frequency is tested by using microstrip line, and FIG. 12 shows the test result of insertion loss, and the no-load Q value is 775.

In the circular YIG thin-film resonator element, the (1, 1) mode high-frequency magnetization component is 0 at R/R of 0.8.

Consider further a YIG film element with a radius of 1mm and a thickness of 20 μm (without a slot) made of the same YIG film, using microstrip lines to test for ferromagnetic resonance. The test result of the insertion loss at that time is shown in fig. 13, and the unloaded Q value is 660. As can be readily understood from the above comparison, according to the present embodiment, in addition to (1, 1)₁The excitation of the out-of-mode magnetostatic films can be suppressed, thus suppressing the spurious response. The homogeneous mode is not impaired here, nor is the unloaded Q value impaired.

In a resonance element of a YIG thin film magnet, that is, a ferromagnetic thin film, other structures can also suppress magnetostatic mode excitation that may generate a pseudo response, and it is considered that its inner region is formed thinner than its outer region. As will be described in detail below. When a direct-current magnetic field DC is applied to a YIG circular thin film having a thickness t and a diameter D (radius R) and perpendicularly acts on the surface of the thin film, the internal DC magnetic field Hi may be expressed as Hi ═ Ho-Hd (R/R) -Ha. Where Hd is the demagnetizing field and Ha is the anisotropic magnetic field. In this case, the thickness/diameter ratio t/D is sufficiently small that the magnetic field distribution of the specimen in the thickness direction is negligible. The results of the calculation of the YIG disk demagnetizing field Hd with a thickness of 20 μm and a radius of 1mm are shown in FIG. 14. Since the demagnetizing field Hd is large in the inside of the disc and becomes suddenly small at the edge portion thereof, the internal dc magnetic field is small near the center portion and becomes suddenly large near the outer edge portion. The calculation results of the distribution of the demagnetization field when the film thickness of the same YIG film inner region with a radius of 0.8mm was reduced by 1 μm are shown in FIG. 15. It can be seen from fig. 15 that when the thickness of the inner area is slightly thinner by a little, the demagnetizing field is increased by a little near the edge portion of the area where the thickness is reduced, and the flat area of the demagnetizing field is enlarged.

As described above, when the internal area of the YIG thin-film element is reduced in thickness by a little from the thickness of its external area, the flat region of the demagnetizing field in the internal area is widened, so that the magnetostatic mode that generates a pseudo response can be suppressed. For example, as shown in fig. 16, a YIG thin film element 52 composed of a ferromagnetic material is formed on a GGG substrate 51. A concave portion 54 is formed on the upper surface of the YIG thin-film element 52 such that the thickness of the inner area is smaller than that of the outer area. While the YIG film 52 is made thin enough to make the magnetic field distribution uniform in the thickness direction when the magnetostatic mode is (1, N)₁And (5) molding.

The concave portion 54 extends all the way to a position such that the excitation of a magnetostatic mode generating a pseudo response can be effectively suppressed. Preferably in a position where (1, 1)₁The amplitude of the mode becomes 0. For example, when the YIG thin film element 52 is circular in shape, the concave portion 54 extends to 0.75-0.85 times the diameter.

According to the experiment, the ferromagnetic resonance was tested using a microstrip line on the circular concave portion 54 of radius 0.75mm and depth 1.7 μm concentrically formed on the YIG thin film magnetic resonance element of thickness 20 μm and radius 1 mm. Fig. 17 shows the test result of the insertion loss, and the no-load Q value at this time is 865.

Since the resonant frequency of a magnetically resonant element, such as a YIG thin film element, is dependent on the saturation magnetization of the element, the resonant frequency is directly influenced by the temperature characteristic of the saturation magnetization. If the resonator circuit described above uses a YIG thin-film element, the resonance frequency will be affected by, for example, the ambient temperature and malfunction will occur. To avoid this, at least one of the poles 4 and 5 of the yoke 1 is provided with a soft magnetic plate of the same material as the temperature characteristic of the YIG film element 52. The temperature dependency of the YIG thin film element itself is compensated by the dependency of the magnetic field of the magnetic plate in the magnetic gap 2, so that the YIG thin film element has a reduced temperature variation characteristic.

According to the present embodiment, the magnetic flux generated between the magnetic poles 4 and 5 can be changed according to the change of the current applied to the coil 6, thus changing an oscillation frequency. Under such conditions, the minimum frequency f of the oscillation frequency_minCan give

f_mig＝7（N_T·4 πMs+Hs）

T is the gyromagnetic ratio, N_TIs the demagnetization factor.

M₃Is the saturation magnetization, H₃Is a saturated magnetic field.

Due to N of YIG ball_TIs N_TN of YIG film (1/3)_TIs N_T< 1. The lower bound of the variation frequency of the tuned oscillator using YIG film is much lower than that of the tuned oscillator using YIG ball. If the applied DC magnetic field is gradually changed, the main magnetic film (110) and other static magnetic films may occasionally become identical in frequency and generate spurious oscillation and tuning deviation. Using the YIG thin film tunable oscillator of this example, when the DC magnetic field is varied, (1, N)₁The modes also all change equally in frequency without modes crossing each other, causing such damage. In general, if there is no mirror polishing on both sides of the YIG disk plate made of block (bulk), the unloaded Q value cannot be increased. On the other hand, the YIG film produced by the film forming process does not require mirror polishing, and a GGG substrate can be used as a substrate for a tuned oscillator.

In recent years, since a homogeneous mode of N ═ 1, that is, a main mode of a magnetostatic mode of the YIG thin film is operated, a Q value is not added and thus a high value is obtained, and Ssub (single sideband) noise can be reduced. Further, since the external Q value can be lowered, it is possible to widen the oscillation region of the changing frequency. In addition, according to the present example, the YIG film was used without the above-described disadvantages inherent in the YIG ball.

Fig. 18 to 25 respectively show other embodiments of the tuned oscillator according to the present invention. In fig. 18 to 25 elements corresponding to those in fig. 5 have been given the same reference numerals and are not described in detail again. In the embodiments presented in fig. 18 to 22, the resonator circuit uses a bipolar transistor 37 as the active element. In the embodiments shown in fig. 23 to 25, the tuned oscillator circuit uses a two-terminal element such as a gunn diode, an avalanche diode or the like as an active element.

Fig. 18 shows a modified example of fig. 5 in which the coupling strip line 33 passes through the characteristic impedance Z. Grounded, in the tuned oscillator circuit of fig. 18, when the YIG thin-film magnetic resonance element 35 is not resonant, γ ═ 0, i.e., γ is the center of the smith chart, and thus the amplitude condition to start oscillation is not satisfied. The probability of parasitic oscillations is thus very small.

Fig. 19 shows an example of a tuned oscillator in which a YIG thin-film magnetic resonance element 35 is sandwiched between two coupled microstrip lines 33 and 33a, the emitter of a transistor 37 is grounded through the microstrip line 33, and the base of the transistor 37 is grounded through the strip line 33 a. In the example of fig. 19, the YIG thin film magnetic resonant element 35 acts as a bandpass filter determined in a feedback circuit that does not act as an output loop, where positive feedback is added when the YIG thin film magnetic resonant element 35 resonates, establishing the condition | N | > 1. In particular to one of the base and emitter strip lines by a characteristic impedance Z_oAt termination, the likelihood of parasitic oscillations is reduced.

Figure 20 shows an example tuned oscillator circuit in which the emitter of transistor 37 passes through a reactance X₁Grounded, the base of transistor 37 passes through reactance circuit X₃The collector of the transistor 37 is connected in series by the microstrip line coupling of the YIG magnetic resonance element 35, and the impedance matching circuit 38 and the load 45 are grounded. In this case, the YIG thin-film magnetic resonance element is placed at the output end as a band elimination filter. At the YIG resonant frequency a part of the signal is fed back to the negative resistance circuit and such a tuned oscillator operates as a self-injection blocking type oscillator.

Fig. 21 shows an example of a tuned oscillator in which a YIG thin-film magnetic resonance element 35 is sandwiched between microstrip coupling lines 33 and 33a, the collector of a transistor 37 is grounded through the microstrip line 33a, an input-side impedance matching circuit 38 is grounded through the microstrip line 33, and the other parts of the circuit are similar to the example of fig. 20. At this time, the YIG thin-film magnetic resonance element is placed as a band pass filter at the output end, and if the YIG thin-film magnetic resonance element 35 does not resonate, the load 45 is short-circuited, and the phase condition of oscillation is not established. When the YIG thin-film magnetic resonance element resonates, the load 45 and the impedance matching circuit 38 can be regarded as passing through the YIG thin-film magnetic element 35, and thus the oscillation condition is satisfied.

Fig. 22 shows an example of a tuned oscillator circuit, wherein the tuned oscillator circuit of fig. 5 constitutes a parallel feedback oscillator. The tuned oscillator examples in figures 20 and 21 can each form a corresponding parallel feedback oscillator circuit.

Fig. 23 shows a tuned oscillator circuit in which one end of a micro stripline 33 of a YIG thin film magnetic resonance element 35 is grounded through a two-terminal active element 37a, and the other end of the micro stripline 33 is grounded through a series circuit of a microstrip impedance matching circuit 38 and a load 45, and xn and r are seen from the a terminal, respectively, and the aforementioned oscillation condition is established. At this time, the YIG thin-film magnetic resonance element 35 is placed in the output band as a band elimination filter, and a part of the signal at the YIG resonance frequency is fed back to the both-end active element 37a, so that this tuned oscillator circuit operates under a so-called self-injection blocking type oscillator.

Fig. 24 shows an example of a tuned oscillator in which one end of a microstrip coupling line 33 of a YIG thin film magneto-oscillation element 35 is grounded, and the other end of this microstrip line is grounded at a source element 37a through a 2-terminal and is grounded through a series circuit of an impedance matching circuit 38 and a load 45. In fig. 24, the negative resistance circuit 43 in fig. 4 is the 2-terminal active element 37 a.

Fig. 25 shows an example of a tuned oscillator in which a YIG thin film magnetic vibration element 35 is sandwiched between two microstrip coupling lines 33 and 33a, a two-terminal active element 37a is grounded at one end and at the other end via a microstrip line 33a, and is grounded at the input terminal of an impedance matching circuit 38 via the microstrip line 33, and the rest is similar to fig. 23. In this case, the YIG thin-film magnetic resonance element is placed as a band-pass filter at the output terminal, and if the YIG thin-film magnetic resonance element 35 does not resonate, the load 45 is short-circuited, and thus the phase condition of oscillation does not hold. If the YIG thin-film magnetic resonance element 35 resonates, the load 45 and the impedance matching circuit 38 can be considered to pass through the YIG thin-film magnetic resonance element 35, thus establishing an oscillation condition.

The oscillator circuit according to the present invention is not limited to the above-described embodiments, and other oscillator circuits can of course be used in the present invention. In the above-described embodiments, the bipolar transistor is used as a three-terminal active device, and needless to say, the field-effect active transistor may be used as a three-terminal active device. Further, it is also needless to say that the present invention is not limited to the above-described embodiments and can include various modifications and variations without departing from the scope of the present invention.

Claims (7)

1. A tuned oscillator comprising: an active element, a magnetic resonator, a microstrip line, and a DC bias magnetic field device, wherein: the magnetic resonator is composed of a magnetic crystal, the microstrip line is electromagnetically coupled to the magnetic crystal, the DC bias magnetic field device applies a DC bias magnetic field to the magnetic crystal, and the microstrip line is connected to the active element; the magnetic crystal is composed of a YIG (ytterbium, iron, and garnet) thin film formed by thin film formation technology, and the resonance is a uniform mode of magnetic resonance. 2. The tuned oscillator according to claim 1, wherein the magnetic crystal is a thin film YIG formed on a non-magnetic substrate by liquid phase epitaxial growth technology. 3. The tuned oscillator according to claim 2, wherein the non-magnetic substrate is an ytterbium gallium garnet single crystal. 4. The tuned oscillator according to claim 1, wherein the magnet crystal is a YIG thin disk having a groove on its outer periphery. 5. The tuned oscillator according to claim 1, wherein the magnet crystal is a YIG thin disk, the thickness of the central portion of which is smaller than the thickness of the peripheral portion. 6. The tuned oscillator according to claim 1, further comprising an impedance matching element connected to the active element. 7. The tuned oscillator according to claim 1, further comprising an impedance matching element connected to the magnetic crystal.

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