JPH0641362Y2 - Magnetostatic wave delay device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a magnetostatic wave delay device, more specifically, a device for stabilizing an input loss and a delay time of a signal caused by a change in temperature or magnetic field. Is.

<Prior Art> First, a magnetostatic wave delay element will be briefly described. When two transducers made of a metal conductor and a magnetic material are placed close to each other in a uniform magnetic field, and a high-frequency current is passed through one of the two transducers, spins in the magnetic material near the transducer fluctuate. The fluctuations propagate as magnetostatic waves and propagate, and a high-frequency induced current due to spin fluctuations flows in the other transducer. Since the propagation speed of spin fluctuations changes according to the strength of the magnetic field, the device has a variable delay time.

FIG. 2 is a perspective view showing an example of a conventional magnetostatic wave delay element. In the figure, 1 is a first substrate made of, for example, GGG (gadolinium-gallium-garnet), and 2 is a YIG (yttrium-iron-garnet) thin film formed on the front surface (back surface in the figure) of this substrate. Reference numeral 3 is a second substrate made of, for example, alumina, and 4a and 4b are input / output transducers made of a conductor (thin film) formed on one surface of the substrate at a predetermined distance. These two substrates are fixed by contacting the YIG thin film 2 and the side on which the transducers 4a, 4b are formed. Reference numeral 5 is a ground film formed on the other surface of the second substrate. In the figure, the arrow indicated by Ho indicates the direction of the applied magnetic field, and the waveform arrow indicates the traveling direction of the magnetostatic wave. In addition, by moving the position of the substrate and setting the direction of the magnetic field applied to the magnetostatic wave delay element to X or Y, the magnetostatic surface wave (MS
SW ... Y direction) or volume backward wave (MSBVW ... X direction) can be obtained.

When a DC magnetic field is applied from the Z (Ho) direction to the magnetostatic wave delay element having the above configuration and a microwave is applied to the input transducer, the volume forward wave travels toward the output transducer side.

<Problems to be Solved by the Invention> In the magnetostatic wave delay element having the above-described configuration, due to a change in the magnetic field or a change in the ambient temperature caused by the resistance value of the coil used in the magnetic field applying means or the voltage change of the power supply, There was a problem that input loss and delay time changed. The change in the input loss and the delay time is, for example, when the input signal is 2 GHz, the loss was 5 dB and the delay time was 80 ns.
Loss and delay time cannot be precisely controlled because the loss changes to 10 dB and the delay time changes to 20 ns due to changes in the magnetic field, and the loss changes to 8 dB and the delay time increases to 50 ns due to changes in temperature. FIG. 3 shows the loss (L) when the magnetic field is changed and the temperature is changed.
It is a figure which shows the degree of change of a figure, delay time ((tau)) ... c figure. That is, the solid line shows the value at a certain standard temperature and magnetic field, and the thin line shows the value when the magnetic field and temperature change. The figure shows that the loss, phase, and delay time change due to these factors. In particular, the higher the frequency (f), the greater the degree of change in the phase and delay time. In FIG. 7c, τg is the desired delay time for the target frequency f ₁ to be delayed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the prior art, and provides a magnetostatic wave delay device which stabilizes the change of the input loss and the change of the delay time caused by the change of the magnetic field or the change of the temperature. To aim.

<Means for Solving the Problems> The structure of the present invention for solving the above problems is a substrate on which a YIG thin film is formed, an input transducer for inputting an input signal, an output transducer for outputting an output signal, and a magnetic field application. In a magnetostatic wave delay device including means, means for superposing a probe signal higher than the input signal on the input signal, and a high-pass filter for passing only the probe signal among the output signals from the output transducer. And a phase comparator that compares the phase of the probe signal with the signal from the high-pass filter, and the magnetic field of the magnetic field applying means is changed based on the signal from the phase comparator. It is what

<Operation> The higher the frequency of the signal input to the magnetostatic wave delay device, the greater the change in phase and delay time with respect to magnetic field and temperature changes. Therefore, when detecting the phase difference with the phase comparator, it is advantageous to compare at a high frequency. By changing the applied magnetic field based on the output from the phase comparator, a stable output can be obtained even when there is a change in the magnetic field or a temperature change.

<Embodiment> FIG. 1 is a block diagram showing an embodiment of a magnetostatic wave delay device of the present invention. In the figure, 1 is an input terminal to which a signal having a frequency f ₁ for obtaining a desired delay time is connected, 2 is a magnetostatic wave delay element as shown in FIG. 3, 3 is a coupler, 4 is a bandpass filter, and 5 is High-pass filter, 7 is a phase comparator, 8 is a probe signal source with a frequency f ₂ higher than the input frequency, and 9 is a frequency f ₁
It is an adder that superimposes the signal of f ₂ . Although not shown in the figure, the signal from the phase comparator 7 is input to the magnetic field applying means.

In the above configuration, the input signal f ₁ (eg, 2 GHz) and the probe signal source f ₂ (eg, 2.5 GHz) are superposed by an adder, and the desired delay is performed via the input transducer and output transducer (not shown) of the magnetostatic wave delay element. Is input to the bandpass filter 4 via the coupler 3, and the signal f ₁ is output. On the other hand, for the signal branched by the coupler 3, only f ₂ is selected by the high-pass filter 5 and input to one terminal of the phase comparator 7. The output from the probe signal source is input to the other terminal of this phase comparator, and the phases of the signals are compared. In this case, there is a delay time obtained at a certain standard temperature and magnetic field strength, and a phase shift occurs at the time of input loss, but here the shift amount is zero.
Then, the deviation of the phase from zero when the standard temperature and the strength of the magnetic field are changed is detected as an output (a phase comparator such as this is known). This output is fed back to the coil of the magnetic field applying means to control the phase shift (the shift amount from a certain standard shift) to zero.

In this embodiment, a bandpass filter is provided after the coupler, but this filter is not necessary if f ₂ can be output. Further, it is possible to precisely set the value of τg while monitoring the phase of the phase φ and the delay time τg of the relationship in advance know Oke If the output of the large f ₂ at f ₁ at f _2.

<Effects of the Invention> As described above, according to the present invention, a means for superimposing a probe signal higher than the input signal on an input signal, and a high-pass for passing only the probe signal of the output signals from the output transducers. A filter and a phase comparator for comparing the phase of the signal from the high-pass filter with the phase of the probe signal are provided, and the magnetic field of the magnetic field applying means is changed based on the signal from the phase comparator. A magnetostatic wave delay device with a stable delay time can be realized, and the value of τg can be precisely set while monitoring a large phase of f ₂ .

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a magnetostatic wave delay device according to the present invention, FIG. 2 is a diagram showing the relationship between frequency and input loss, phase, and delay time when the magnetic field and temperature change, and FIG. The figure is a perspective view of an essential part of a magnetostatic wave delay element. 1 ... Input terminal, 2 ... Magnetostatic wave delay element, 3 ... Coupler, 4 ...
… Band pass filter, 5 …… High pass filter, 7 …… Phase comparator, 8 …… Probe signal source, 9 …… Adder.

Claims (1)

[Scope of utility model registration request] 1. A magnetostatic wave delay device comprising a substrate on which a YIG thin film is formed, an input transducer for inputting an input signal, an output transducer for outputting an output signal, and a magnetic field applying means. A means for superimposing a probe signal higher than the input signal, a high-pass filter that passes only the probe signal of the output signals from the output transducer, and a phase of the signal from the high-pass filter and the probe signal are compared. A magnetostatic wave delay device comprising: a phase comparator, and configured to change the magnetic field of the magnetic field applying means based on a signal from the phase comparator.