JPH07106856A - Phase modulation circuit - Google Patents

Abstract

PURPOSE:To simplify phase modulation by supplying an AC current to a ferro magnetic line, generating an induced AC voltage due to a change in magnetic flux between both ends of the line, detecting the voltage and superimposing an AC current onto the detected voltage thereby changing a magnetic field. CONSTITUTION:A basic circuit of the phase modulation circuit is constituted of a ferromagnetic line 2, an AC coupling capacitive element 4 with respect to an induced voltage, an AC power supply 6 and a signal power supply 6. A current from the AC power supply 6 is supplied to both ends of the thin and long ferromagnetic line 2, and simultaneously, a control signal, that is, a modulation signal is applied from the signal power supply 8 to the both ends of the thin and long ferromagnetic line 2 thereby extracting the induced voltage produced in the ferromagnetic line 2 via the capacitive element 4. When the frequency of the AC current in use is lower, since a voltage across the resistance of the ferromagnetic line 2 is increased more than the induced voltage, the voltage across the resistance of the ferromagnetic line 2 is cancelled by using a resistance bridge circuit (not shown) to extract the induced voltage only. Thus, the cost of the modulation circuit is reduced without use of any active element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a phase modulation circuit that changes the phase of a carrier wave in accordance with the amplitude of an input signal.

[0002]

2. Description of the Related Art Amplitude modulation circuits and frequency modulation circuits are widely known as modulation circuits at present, and these are mainly used in the field of communication. Amplitude modulation is a method of changing the amplitude of a carrier wave in accordance with the amplitude of an input signal, while frequency modulation is a method of changing the frequency of a carrier wave in accordance with the amplitude of an input signal. These are A
Widely used in M radio and FM radio. In the modulation circuit, a phase modulation circuit exists in addition to the above amplitude modulation circuit and frequency modulation circuit. Phase modulation is a method of changing the phase of a carrier wave in accordance with the amplitude of an input signal. The phase modulation circuit can be widely used in the fields of communication and information such as signal generation devices in the field of communication, especially in a noisy environment such as wireless communication and factory communication, and in the field of security.

These modulation circuits have the number of constituent elements,
There are advantages and disadvantages in circuit complexity, signal-to-noise ratio, occupied bandwidth, etc. The amplitude modulation circuit has a simple circuit configuration, as represented by a reactance transistor circuit, and the demodulation circuit also uses a rectifier circuit to extract an output proportional to the envelope of the amplitude-modulated signal. The original modulation signal can be taken out, and the configuration is very simple. Further, it has an advantage that the occupied bandwidth can be reduced by the single sideband communication system (SSB) or the like. However, there is a drawback that the signal-to-noise ratio (S / N) is very bad because most of the noise affects the amplitude. On the other hand, frequency modulation is a method of reading the instantaneous frequency of the received frequency or the deviation of the frequency from the carrier,
It has little effect on noise and has a very good S / N ratio compared to the amplitude modulation wave. However, the occupied bandwidth needs to be 4 to 5 times as large as the amplitude modulated wave is about 9 kHz. Further, the frequency modulation circuit has a simple circuit configuration as represented by a reactance transistor circuit, but has a drawback that adjustment is troublesome so that the demodulation circuit is represented by a Foster-Sealey type circuit. Further, in both the amplitude modulation circuit and the frequency modulation circuit, transistors and FETs are part of the circuit constituent elements, so that the environment resistance
In particular, there were problems in temperature and humidity resistance change and impact resistance. Furthermore, it could not be used in outer space or radioactively contaminated space where ultraviolet rays pose a problem.

[0004]

On the other hand, the conventional phase modulation circuit has a very excellent S / N ratio as compared with the frequency modulation circuit as compared with the amplitude modulation circuit. However, the configuration of the phase modulation circuit is very complicated as in the Armstrong circuit which is a typical phase modulation circuit. Therefore, the phase modulation circuit has the same performance as the frequency modulation circuit, but has not been widely used in general. Figure 1
[Fig. 3] shows a configuration diagram of an Armstrong modulation circuit. In this circuit, the output of the carrier wave oscillation circuit is divided into two. One is input to the mixing circuit through the amplifier circuit. The other is
It is applied to the balanced modulation circuit together with the other input modulation signal, and the amplitude modulated wave of only the double sideband is obtained as the output of the balanced modulation circuit. The phase is shifted by 90 ° by the phase shift circuit and amplified by the amplifier circuit. Next, the output of the amplifier circuit is combined with the carrier wave in the mixing circuit to obtain the phase modulation output. As described above, the circuit configuration is complicated. As the phase modulated wave, the original signal wave can be easily extracted by comparing the time difference between the fundamental wave and the modulated wave in the phase demodulation circuit. Therefore, it is considered that the simplification of the configuration of the phase modulation circuit greatly contributes to the spread of the phase modulation circuit.

An object of the present invention is to provide a phase modulation circuit having a simple circuit structure.

[0006]

A phase modulation circuit according to the present invention uses a ferromagnetic wire as a phase modulation element. The AC power supply supplies an AC current across the ferromagnetic wires. The frequency of this alternating current is higher than the frequency of the control current. An induced AC voltage is generated in the ferromagnetic wire by applying an alternating current to the ferromagnetic wire. On the other hand, the signal supply circuit supplies a control current (modulation signal) across the ferromagnetic wire. An induced AC voltage is generated in the ferromagnetic material by the control current and the AC current. This induced AC voltage is extracted and output as a phase modulation output signal. (In the embodiment, the induced AC voltage is taken out by the capacitor.) As a result, the phase of the induced AC voltage shifts in correspondence with the magnitude of the control current flowing through the ferromagnetic wire, and the phase is modulated by the control current. Preferably, the AC power supply supplies a triangular wave AC current.
Thereby, the linearity with respect to the control current of the phase control is obtained. Preferably, the AC power supply supplies an AC current having a DC bias. This enables use of the phase modulation characteristic in an arbitrary phase range. Preferably, the ferromagnetic wire has a material or shape that has magnetic properties that allow it to generate a sufficient induced voltage. Therefore, as the ferromagnetic wire, a wire made of a ferromagnetic material having a substantially circular cross section and a high circumferential magnetic permeability is desirable. An example is an amorphous magnetic wire, especially an amorphous magnetic wire having a negative or zero magnetostriction. Further, in order to satisfy the characteristics of the phase modulation element depending on the desired phase modulation range or the desired magnitude of the control current, the amorphous magnetic wire subjected to the tension annealing treatment can be used. Furthermore, high permeability Fe composed of permalloy, sendust magnetic wire, and fine crystal grains
Alloy wire or the like can also be used.

[0007]

[Function] When an alternating current is applied to the ferromagnetic wire by an alternating current power source,
An induced voltage corresponding to the temporal change of the magnetic flux in the circumferential direction of the ferromagnetic material is generated between both ends of the ferromagnetic wire. In particular, in the case of an amorphous ferromagnet in which a change in magnetic flux in the circumferential direction suddenly occurs within a narrow magnetic field range when the magnetic field is increased, the induced voltage generated is large. The phase of the induced voltage (AC) is constant without the control current. In this state, when a control current is further supplied to the ferromagnetic wire by the control power supply, a DC magnetic field is generated in the circumferential direction of the ferromagnetic wire, and this DC magnetic field becomes a bias magnetic field, and the phase of the induced voltage changes. That is, the phase of the induced voltage generated between both ends of the ferromagnetic wire is modulated by the control current. This phase modulation circuit has an extremely simple structure. Further, since it has no active element, it has high reliability.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described by way of embodiments with reference to the accompanying drawings. When an alternating current is applied to the ferromagnetic wire, an induced voltage is generated with the change of the magnetic flux with time. here,
An elongated wire having a circular cross section is used as the ferromagnetic wire, and the time t
At the same time, a triangular wave alternating current whose phase φ increases linearly is passed between both ends of the ferromagnetic wire to excite the ferromagnetic wire. The sum of the magnetic field (HΔ) generated by AC excitation and the magnetic field (H _s ) generated by the control current (modulation signal) (HΔ + H _s ) is the reverse magnetic domain formation limit magnetic field (H ^* ). Is equal to. As shown in FIG. 2, as the magnetic field increases, the magnetic flux changes in the circumferential direction in a very narrow magnetic field range, and a pulsed AC voltage is generated as an induced voltage waveform. Here, the magnitude of the positive induced voltage wave is defined as eL ₊ , and the magnitude of the negative induced voltage wave is defined as eL ₋ . FIG. 3 shows a case where the control current I _c is further applied to the ferromagnetic wire. In this case as well, the magnetic flux change in the circumferential direction with an increase in the magnetic field occurs in an extremely narrow magnetic field range, and the induced voltage waveform is pulse-shaped. AC voltage is generated.
However, the value of the magnetic field in which the magnetic flux changes in the circumferential direction changes due to the control current.

Now, the magnetic field (excitation wave) generated by an alternating current can be expressed by the following mathematical formula.

[Number 1] _{HΔ = 2 · H m · ω} · t / π = 2 · H m · φ / π ...... (1) to here, to here -π / 2 ≦ φ ≦ π / 2, H m is the magnetic field Represents the maximum value of, and ω represents the frequency. The maximum magnetic field _Hm is greater than the magnetic field H ^* required to cause a circumferential magnetic flux change in the magnetic wire. The phase φ is set to 0 at the intersection of the excitation wave and the ground line. in this case,
The conditions under which the induced voltage waves eL ₊ and eL ₋ are generated are as follows.

2 ^* H _m ^* φ / π = H ^* (2) Therefore, the induced wave voltage eL when the control current is 0
The phase φ ₀ of ₊ and eL ₋ is determined by Expression (3).

[Formula 3] φ ₀ = (π / (2 · H _m )) · H ^* …… (3)

On the other hand, the circumferential magnetic field H _c generated by the control current I _c can be expressed by the following equation, where the magnetic wire radius is a.

H _c = I _c / (2 · π · a) (4) Here, the frequency ω of the excitation wave is sufficiently higher than the frequency of the control current I _c . Therefore, the control current I _c is handled as a DC. The conditions under which the induced voltage wave eL ₊ is generated when the control current I _c is superimposed on the excitation triangular wave (FIG. 3) are as follows.

[Equation 5] 2 · H _m · φ + / π + I _c / (2 · π · a) = H ^* (5) Here, the intersection of the exciting wave portion having a positive slope and the ground line is used as a reference. The phase φ of the nearest positive induced voltage wave is φ
Define as ₊ . In this case, the phase φ of the induced voltage wave eL _+
+ Is represented by the following formula.

[Equation 6] φ ₊ = π / (2 · H _m ) · (H ^* − (I _c / (2 · π · a))) (6) = φ ₀ − (1 / (4 · H _m · a)) · I _c Therefore, the inclination phi ₊ / I _c of the phase (phi ₊₎ versus the control current (I _c) in the case of the triangular wave excitation is expressed by equation (7).

[Equation 7] φ ₊ / I _c = -1 / (4 · H _m · a) (7)

Similarly, the phase φ ₋ of the induced voltage wave eL ₋ generated by the excitation wave having a negative slope can be expressed by the following equation.
Here, the phase φ to the nearest negative induced voltage wave is based on the intersection of the excitation wave part with a negative slope and the ground line.
The φ _- to be defined.

[Equation 8] φ ₋ = φ ₀ + (1 / (4 · H _m · a)) · I _s (8) Therefore,

Equation 9] _{φ - / I c = 1 /} (4 · H m · a) ...... (9) Therefore, the magnetic properties of the ferromagnetic wire, the shape and the applied AC current amplitude H _m, the above equation (3 ), (6) to (9)
A phase modulation circuit having a desired control current vs. phase characteristic can be constructed by selecting using.

Here, the alternating current applied to the ferromagnetic wire is a triangular wave. Accordingly, the phase change due to the control current applied is proportional to the control current I _c, it is possible to improve the linearity of the phase modulation characteristics. Further, in order to enable the use of the phase modulation characteristic in an arbitrary phase range, an alternating current having a direct current bias can be used as the alternating current.
In this case, the magnetic field (excitation wave) generated by the alternating current is expressed by the following mathematical formula.

HΔ = H ₀ + 2 · H _m · ω · t / π = H ₀ + 2 · H _m · φ / π (10) where −π / 2 ≦ φ ≦ π / 2 H ₀ represents a DC bias. Therefore, the phase when there is no control current deviates from the case of Expression (3).

[Formula 11] φ ₀ = (π / (2 · H _m )) · (H ^* −H ₀ ) ... (11)

As shown in FIG. 4, the basic circuit configuration of the phase modulation circuit of this embodiment is only a ferromagnetic wire 2, a capacitor element 4 for AC coupling of an induced voltage 4, an AC power supply 6 and a signal power supply 8. . An electric current is supplied from an AC power supply 6 to both ends of the elongated ferromagnetic wire. In this embodiment, the excitation frequency is 1
It is 0 kHz. At the same time, a control current (modulation signal) is supplied from the signal power supply 8 to both ends of the ferromagnetic wire. At this time, the induced voltage generated in the ferromagnetic wire 2 is taken out via the capacitor element 4. The ferromagnetic wire 2 is a wire made of a ferromagnetic conductor, and it is desirable that the reversal of the magnetic flux in the circumferential direction occurs within a narrow magnetic field range in order to obtain a large induced voltage.
The magnetic properties and shape of the ferromagnetic conductor are determined according to the desired phase modulation properties. As described later, it does not change the magnitude of the induced voltage in the range of the control current I _c. Therefore, the amplitude limiting circuit With control current I _c in this range is unnecessary.

However, when the frequency of the alternating current used is low, the voltage due to the resistance of the ferromagnetic wire becomes larger than the induced voltage. Therefore, in order to act as a phase modulation circuit, only the induced voltage is taken out. Ingenuity is required.
The phase of the induced voltage differs from the phase of the current by 90 °. Therefore, this problem can be easily solved by using a resistance bridge circuit that cancels the voltage resistance due to the magnetic wire resistance. Therefore, in the phase modulation circuit shown in FIG. 5, a resistance bridge circuit is added. This resistance bridge circuit
In addition to the ferromagnetic wire 2, three resistance elements 10, 12, 14 are added. That is, the variable resistor 10 is connected between the grounded end of the ferromagnetic wire 2 and the AC power source 6, and the resistor 12 is connected between the variable terminal of the variable resistor 10 and the capacitor element 4.
Further, a resistor 14 is connected between the side of the resistor 12 connected to the capacitor element 4 and the side of the ferromagnetic wire 2 not grounded. In the circuit used in this example, the resistance of the two resistance elements is 1 kΩ, and the resistance value of the variable resistance element is 0 to 300 Ω. At this time, the equilibrium condition of the resistance bridge is as follows.

[Mathematical formula-see original document] r _m / r ₁₀ = r ₁₄ / r ₁₂ (12) where r _m is the resistance value of the ferromagnetic wire 2 and r ₁₀ is the resistance value of the variable portion of the variable resistor 10. Yes, r ₁₂ and r ₁₄ are
These are the resistance values of the resistors 12 and 14, respectively. Variable resistance 10
Only the induced voltage can be taken out through the capacitor element 4 by adjusting the resistance value r ₁₀ of the above to realize the balanced condition.

As described above, by using the ferromagnetic wire, the phase modulation circuit having a simple structure is realized. As is clear from comparison between the phase modulation circuit shown in FIG. 4 and the conventional example (Armstrong phase modulation system) shown in FIG. 1, the phase modulation circuit of the present embodiment has an extremely simple circuit configuration, Satisfy the purpose of. Moreover, this phase modulation circuit covers a wide range of frequencies. In addition, since it is possible to use a circuit configuration that does not use any active elements such as transistors, it has extremely excellent environmental resistance compared to any of the amplitude modulation circuit, frequency modulation circuit, and conventional phase modulation circuit. High reliability can be realized.

As the material of the ferromagnetic wire 2, a material having a high circumferential magnetic permeability is desirable in order to generate a sufficient induced voltage. An example is an amorphous ferromagnetic wire, especially an amorphous ferromagnetic wire having a negative or zero magnetostriction.
Also, the desired phase modulation range or the desired control current I _c
In order to satisfy the characteristics of the phase modulation element that depends on the size, the amorphous ferromagnetic wire subjected to the tension annealing treatment can be used. Hereinafter, the present invention will be described in more detail with reference to two examples. Table 1 shows Example 1 and Example 2 described later.
The magnetic materials used in step 1 and the processing conditions thereof are shown below. The magnetic material, an amorphous ferromagnetic material which has been subjected to tension annealing treatment, its composition _{is, (Fe 0.06 Co 0 .94)} 72.5 Si 12.5
It is B ₁₅ . Example 1 and Example 2 are different in wire diameter and annealing time.

[Table 1]

Example 1 In Example 1, as the ferromagnetic wire 2, an amorphous wire drawn to a diameter of 124 μm, which was heat-treated under the conditions shown in Table 1, was used. Figure 6
Shows the phase versus control current characteristics of the induced voltage wave. When performing the phase modulation, the ferromagnetic wire 2 is excited by the current supplied to the magnetic wire 2 by the AC power supply 6, and the ferromagnetic wire 2 is excited.
AC induced voltage is induced at both ends of. This AC induced voltage is a voltage due to the resistance of the ferromagnetic wire 2 and a voltage generated due to a change in the circumferential magnetic flux of the ferromagnetic wire 2 due to the action of the current supplied to the ferromagnetic wire 2 by the AC power supply 6. Only the latter is taken out by using the resistive bridge circuit described above. The excitation wave has a frequency of 10 kHz
A triangular wave of z was used. The induced voltage taken out by the resistance bridge circuit showed a very sharp pulse-like waveform, and the half width thereof was 2 microseconds or less. The phase of this pulsed induced voltage is controlled by the control current I _c generated by the signal power source 8 side directly connected to the ferromagnetic wire.

From the result of FIG. 6, a minute alternating current (± 30
It is apparent that the induced voltage phases φ ₊ and φ ₋ can be linearly controlled by mA). That is, the phase of the induced AC voltage across the ferromagnetic wire, which is obtained by passing an alternating current through the ferromagnetic wire, changes with the control current I _c flowing through the ferromagnetic wire 2. In the example of FIG. 6, the phase is −0.1π to 0.5π.
It can be controlled in the range of. FIG. 7 shows changes in the absolute value of the pulse height (induction voltage amplitude) due to the control current I _c . The control current characteristic shows that the scope of the magnitude of the induced voltage in the range of the control current I _c is not changed is present. By using this range, the amplitude limiting circuit, which was necessary in the final stage of the conventional phase modulation circuit, becomes unnecessary, and the phase modulation circuit can be further simplified.

Example 2 In Example 2, as the ferromagnetic wire 2, an amorphous wire drawn to a diameter of 30 μm and heat-treated under the conditions shown in Table 1 was used. Figure 8
Shows the phase versus control current characteristics of the induced voltage wave. As the excitation wave, a triangular wave with a frequency of 10 kHz was used as in Example 1.
As shown in the result of FIG. 8, the phase of the induced voltage is -0.1π with an alternating current (± 15 mA) which is smaller than that of the first example.
It was possible to control linearly in the range of ~ 0.5π. FIG. 9 shows the control current characteristic of the induced voltage amplitude (absolute value).
Similar to the result shown in Example 1, there is a range in which the magnitude of the induced voltage does not change in a certain range of the control current I _c . By using this range, the phase modulation circuit can be further simplified. Example 1 and as is evident from Example 2, by varying the like shape of the ferromagnetic wire 2, it is possible to change the phase control range for the control current I _c. This makes it possible to meet the demand for a phase modulation circuit configuration having desired characteristics.

[0020]

The phase modulation circuit according to the present invention has an extremely simple circuit configuration and can control the phase with a minute current. Further, by selecting magnetic materials having different ferromagnetic wire shapes or magnetic characteristics, the phase control range or the variable range of the control current can be changed, and various characteristics can be met. Moreover, the elements constituting the phase modulation circuit of the present invention are inexpensive and easily obtained. Further, the reliability is extremely high because no active element is used.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an example of a conventional phase modulation circuit.

FIG. 2 is a diagram illustrating an induced voltage wave generated by using a triangular excitation wave.

FIG. 3 is a diagram illustrating an induced voltage wave generated when a control current is superimposed on a triangular excitation wave.

FIG. 4 is a circuit diagram showing a basic configuration of a phase modulation circuit of the present invention.

5 is a circuit diagram of a circuit used in Examples 1 and 2. FIG.

6 is a diagram showing characteristics of control current versus phase obtained in Example 1. FIG.

7 is a diagram showing characteristics of control current vs. induced voltage obtained in Example 1. FIG.

8 is a diagram showing characteristics of control current versus phase obtained in Example 2. FIG.

9 is a diagram showing characteristics of control current vs. induced voltage obtained in Example 2. FIG.

[Explanation of symbols]

2 ... Ferromagnetic wire, 4 ... Capacitor elements 4, 6 ... AC power supply, 8 ... Signal power supply.

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[Procedure amendment]

[Submission date] January 11, 1994

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 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenichi Bushida, Kenji Bushida 23, Uji Kozakura, Uji City, Kyoto Prefecture Unitika Central Co., Ltd. (72) Inventor, Isamu Ogasawara 23, Uji Kozakura, Uji City, Kyoto Unitika Co., Ltd. Central In the laboratory

Claims (7)

[Claims] 1. A ferromagnetic wire, a signal supply circuit for supplying a control current between both ends of the ferromagnetic wire, and an AC power supply for supplying an alternating current having a frequency higher than that of the control current between both ends of the ferromagnetic wire. A phase modulation circuit comprising an output circuit for outputting an induced alternating voltage generated by a ferromagnetic material by the control current and the alternating current. 2. The phase modulation circuit according to claim 1, wherein the AC power supply supplies a triangular wave AC current. 3. The phase modulation circuit according to claim 1, wherein the AC power supply supplies an AC current having a DC bias. 4. The phase modulation circuit according to claim 1, wherein the ferromagnetic wire is made of a ferromagnetic material having a high circumferential magnetic permeability. 5. The phase modulation circuit according to claim 4, wherein the ferromagnetic wire is made of an amorphous ferromagnetic material. 6. The phase modulation circuit according to claim 5, wherein the ferromagnetic wire is made of an amorphous ferromagnetic material having a negative or zero magnetostriction. 7. The phase modulation circuit according to claim 6, wherein the ferromagnetic wire is a ferromagnetic wire subjected to tension annealing treatment.