JPH0645829A - Magnetostatic wave oscillator - Google Patents

Abstract

(57) [Abstract] [Purpose] To realize a magnetostatic wave oscillator with improved phase noise characteristics and an expanded oscillation band. [Structure] A second magnetostatic wave delay having the same saturation characteristic as the first magnetostatic wave delay line 10a is detected by detecting the saturation level of the first magnetostatic wave delay line 10a from the oscillation output of the first magnetostatic wave oscillator circuit. Line 10
By controlling the saturation level of the oscillating amplifier 7b connected to b to be slightly lower than the saturation level of the first magnetostatic wave delay line 10a, the second magnetostatic wave oscillator circuit can constantly operate the magnetostatic wave delay line 10b at each set frequency. It oscillates with the maximum signal level within the range where saturation does not occur.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of phase noise characteristics of a magnetostatic wave oscillator and expansion of an oscillation band.

[0002]

2. Description of the Related Art FIG. 3 is a diagram showing a basic configuration of a conventional magnetostatic wave oscillator. 1 is a magnetostatic wave propagation medium made of YIG (yttrium-iron-garnet) thin film, 2 and 3 are input and output transducers, 4 is a transducer for extracting oscillation output, and 5 and 6 are static. Magnetostatic wave absorbers provided at both ends of the magnetic wave propagation medium. These are magnetostatic wave delay lines 1.
Configure 0. Reference numeral 7 is an oscillating amplifier which is connected between the input / output transducers 2 and 3 and constitutes an oscillating loop together with the magnetostatic wave delay line 10. When a microwave is applied to the input transducer 2 by the amplifier 7, a magnetostatic wave (MSW) propagates through the YIG film 1 as shown by arrow a. This magnetostatic wave is converted into an electric signal by the transducer 3 and input to the amplifier 7. The oscillation frequency of this magnetostatic wave oscillator changes when the magnitude of the static magnetic field applied to the YIG film 1 changes in response to the control input.

[0003]

In the above magnetostatic wave oscillator, the signal level in the oscillation loop connecting the amplifier 7 and the magnetostatic wave delay line 10 is as high as possible, the better the S / N ratio and the better the phase noise. The characteristics can be obtained. However, the saturation level of the magnetostatic wave delay line 10 has frequency characteristics as shown in FIG. 4 and sharply decreases below 3 GHz. When saturation occurs at these saturation levels due to excessive input from the amplifier 7, the intrinsic phase noise generated by the magnetostatic wave delay line 10 itself sharply increases from a in the unsaturated state to b in the saturated state, as shown in FIG. However, the phase noise characteristic deteriorates. Here, the horizontal axis frequency is based on the carrier frequency that is the center of oscillation. For this reason, when oscillating at a frequency of 3 GHz or less, the oscillation rule depends on the saturation level.
The signal level in the loop must be reduced. For example, when oscillating from 1 GHz, it is necessary to lower the oscillation level by about 15 dB as compared with the case of oscillating from 3 GHz. Further, as shown in FIG. 6, the saturation level of the amplifier 7 becomes smaller as it goes to higher frequencies along with the gain, so that the S / N ratio deteriorates and the band becomes narrower on the high frequency side. That is, conventionally, it was not possible to maintain a good phase noise characteristic in a high band and at the same time to extend the band to a low frequency of 3 GHz or lower.

The present invention has been made to solve the above problems, and an object thereof is to realize a magnetostatic wave oscillator having an improved phase noise characteristic and an expanded oscillation band.

[0005]

The present invention relates to a magnetostatic wave oscillator in which a magnetostatic wave delay line and an amplifier form an oscillation loop, and the oscillation frequency thereof is changed by a static magnetic field corresponding to a control input. The feature is that the first magnetostatic wave delay line and the first oscillation loop are connected to the first magnetostatic wave delay line.
Of the first magnetostatic wave oscillation circuit and a first amplifier having a saturation level higher than the saturation level of the first magnetostatic wave delay line, and the output of the first magnetostatic wave oscillation circuit is detected. A detection circuit, a second amplifier whose saturation level is controlled in accordance with the output of the detection circuit, and a second amplifier having the same saturation characteristic as the first magnetostatic wave delay line are connected to the second amplifier. And a second magnetostatic wave delay circuit comprising a second magnetostatic wave delay line forming a second oscillation loop, wherein the saturation level of the second amplifier is higher than that of the first magnetostatic wave delay line. The point is that it is configured to be small.

[0006]

Since the output amplitude of the first magnetostatic wave oscillation circuit is determined by the saturation level of the first magnetostatic wave delay line, this saturation level can be detected by the detection circuit, and the second output based on this detection output. The saturation level of the amplifier is controlled to be smaller than the saturation level of the first magnetostatic wave delay line. First and second
Since the magnetostatic wave delay line of 1 has the same saturation characteristic, the second magnetostatic wave delay line always operates in a non-saturated state.

[0007]

The present invention will be described in detail below with reference to the drawings.
FIG. 1 is a configuration block diagram showing an embodiment of a magnetostatic wave oscillator according to the present invention. The configuration of the magnetostatic wave delay lines 10a and 10b is the same as in the case of FIG. Reference numeral 11 is a coil drive circuit for generating a drive output corresponding to the frequency setting control input V _c ,
Two magnetostatic wave oscillators 12 and 13 are arranged (usually side by side in a plane) in an air gap formed between them.
The pole pieces, 14 provided so as to face each other are wound around the pole piece 12, and an exciting coil driven by the output of the coil driving circuit 11 is denoted by 10a and a first magnetostatic wave delay line is designated by 7a. Is the input / output transformer of the magnetostatic wave delay line 10a.
The first amplifier for oscillation having a saturation level sufficiently higher than the saturation level of the magnetostatic wave delay line 10a by connecting between the first and the second magnetostatic wave oscillation circuits, and + V is a power supply for supplying the power supply current of the amplifier 7a. Voltage, 15 is a detection circuit that detects the output of the first magnetostatic wave oscillation circuit, 16 is a variable constant current circuit that outputs a current corresponding to the output of the detection circuit 15, and 7b is a power supply supplied from the variable constant current circuit 16. The second oscillator 10b for oscillation whose saturation level is controlled by the current has the same saturation characteristic as the magnetostatic wave delay line 10a, and the amplifier 7b is connected between the input and output transducers of the second oscillator 10b. It is a second magnetostatic wave delay line forming a loop, and the amplifier 7b and the magnetostatic wave delay line 10b form a second magnetostatic wave oscillation circuit.
Here, in order to make the saturation characteristics of the magnetostatic wave delay lines 10a and 10b the same, for example, the compositions and the film thicknesses may be made the same. Figure 2
Shows a concrete example of the amplifier 7b, which constitutes a high-frequency amplifier with a transistor. T ₁ is a transistor, R _{1 to} R
Reference numeral ₄ is a bias resistor, and C ₁ and C ₂ are coupling capacitors. The output of the variable constant current source 16 is applied to one end of the resistor R ₁ .

The operation of the magnetostatic wave oscillator having the above configuration will be described below. The excitation output of the coil drive circuit 11 corresponding to the control input V _c causes the exciting coil 14 to generate a static magnetic field of a predetermined strength, and the static magnetic fields cause the first and second magnetostatic wave oscillators to oscillate at a predetermined frequency. To do. Since the amplifier 7a has a saturation level sufficiently higher than the saturation level of the magnetostatic wave delay line 10a, the oscillation output level of the first magnetostatic wave delay line 10a is determined by the saturation level of the magnetostatic wave delay line 10a. The detection circuit 15 detects the saturation level of the magnetostatic wave delay line 10a by detecting this oscillation output. The variable constant current circuit 16 flows into the power input terminal of the amplifier 7b a current such that the saturation level of the amplifier 7b becomes slightly smaller than the saturation level of the magnetostatic wave delay line 10a corresponding to the output of the detection circuit 15. Since the magnetostatic wave delay lines 10a and 10b have the same saturation characteristics, the second magnetostatic wave oscillator circuit is always below the saturation level of the magnetostatic wave delay line 10b at each set frequency, that is, within the range where the magnetostatic wave delay line 10b is not saturated. It oscillates with the maximum signal level.

According to the magnetostatic wave oscillator having such a structure,
Oscillation in which the saturation level of the first magnetostatic wave delay line is detected from the oscillation output of the first magnetostatic wave oscillator circuit and is connected to the second magnetostatic wave delay line having the same saturation characteristics as the first magnetostatic wave delay line. By controlling the saturation level of the amplifier for use to be slightly lower than the saturation level of the first magnetostatic wave delay line, the second magnetostatic wave oscillator circuit is always in the range where saturation does not occur in the magnetostatic wave delay line 10b at each set frequency. It oscillates with the maximum signal level. Therefore, the oscillation band can be extended to the low range without deteriorating the high-frequency phase noise characteristic and the oscillation upper limit frequency characteristic. Even when using YIG films with different characteristics, or when the YIG film has complicated saturation characteristics, the YIG film that is always used can be used without measuring the saturation characteristics accurately or using an approximation circuit of the saturation characteristics. It is possible to obtain the best possible phase noise characteristic and sweep frequency range.

As the first amplifier 7a, an ordinary amplifier may be used as long as an output sufficient for saturating the delay line 10b is output. As with 7b, an amplifier for controlling the saturation level by the power supply current is used. May be. In addition, the second amplifier 7b
However, the variable limiter circuit is not limited to the one in which the saturation level is controlled by the power supply current, and a variable limiter circuit may be provided on the output side of an ordinary amplifier and the variable limiter circuit may be controlled in accordance with the output of the detector 15.

[0011]

As described above, according to the present invention, it is possible to realize a magnetostatic wave oscillator having improved phase noise characteristics and an expanded oscillation band with a simple structure.

[Brief description of drawings]

FIG. 1 is a configuration block diagram showing an embodiment of a magnetostatic wave oscillator according to the present invention.

FIG. 2 is a configuration circuit diagram showing a specific example of an oscillation amplifier 7b of the circuit shown in FIG.

FIG. 3 is a configuration block diagram showing a basic configuration of a conventional magnetostatic wave oscillator.

4 is a diagram showing frequency characteristics of a saturation level of a magnetostatic wave delay line in the circuit of FIG.

5 is a diagram showing frequency characteristics of intrinsic phase noise of the magnetostatic wave delay line in the circuit of FIG.

6 is a diagram showing a frequency characteristic of a saturation level of an oscillation amplifier 7 in the circuit of FIG.

[Explanation of symbols]

7a first amplifier 7b second amplifier 10a first magnetostatic wave delay line 10b second magnetostatic wave delay line 15 detection circuit 16 variable constant current circuit V _c control input

Claims (1)

[Claims] 1. A magnetostatic wave delay line and an amplifier form an oscillation loop, wherein the oscillation frequency is changed by a magnetostatic field corresponding to a control input. A first magnetostatic wave oscillation comprising a first amplifier connected to one magnetostatic wave delay line to form a first oscillation loop and having a saturation level higher than the saturation level of the first magnetostatic wave delay line. A circuit, a detection circuit for detecting the output of the first magnetostatic wave oscillation circuit, a second amplifier whose saturation level is controlled according to the output of the detection circuit, and the first magnetostatic wave delay line. The second oscillator has the same saturation characteristics and is connected to the second amplifier.
And a second magnetostatic wave oscillation circuit including a second magnetostatic wave delay line that forms a loop, and the saturation level of the second amplifier is lower than the saturation level of the first magnetostatic wave delay line. A magnetostatic wave oscillator characterized in that.