JP2004140856A - Oscillator and radio apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oscillator which is small in sized, facilitates the adjustment of resonant frequency, improves mass-productivity, sufficiently suppresses a fundamental wave and reduces a loss, and a radio apparatus using the same. <P>SOLUTION: A line 7 and a gun diode 6 are provided on a dielectric substrate 3 to constitute an oscillation circuit, a dielectric strip 5 is located between upper and lower conductor plates 1 and 2 to comprise an NRD guide as an output transmission line, and the line 7 and the NRD guide are coupled. A cutoff frequency of the NRD guide is determined to cut off the fundamental wave component of a signal oscillated by the oscillation circuit and to propagate a higher harmonic component. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a microwave band or millimeter wave band oscillator provided with an oscillation circuit using a Gunn diode or the like, and an output transmission line for outputting an oscillation signal, and a radio apparatus using the oscillator.

Conventionally, Patent Documents 1 and 2 disclose oscillators in a microwave band or a millimeter wave band using a negative resistance element such as a Gunn diode which are caused to perform multiple oscillation.

By using such an oscillation circuit that performs multiplied oscillation, it is possible to easily configure an oscillator in a millimeter wave band exceeding the 60 GHz band, for example, which cannot be directly oscillated by a Gunn diode or the like.
Japanese Patent Publication No. 6-105851 Japanese Patent Publication No. 6-22289

However, in the oscillator disclosed in Patent Literature 1, cavity resonance is performed using a waveguide. Therefore, the resonance frequency is determined by a space volume, and it is difficult to adjust the resonance frequency. Is not suitable and costs are high. Moreover, there is a problem that the size becomes large.

Further, in the oscillator disclosed in Patent Document 2, since only the fundamental wave is blocked by the microstrip pattern, it is difficult to sufficiently suppress the fundamental wave, and the microstrip pattern for blocking the fundamental wave is: There is a problem that the signal of the harmonic to be used is also attenuated, and the loss increases.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and to provide a small-sized oscillator that facilitates adjustment of a resonance frequency and that can be manufactured at low cost and that is suitable for mass production, and a wireless device using the same. .

Another object of the present invention is to provide an oscillator capable of sufficiently suppressing a fundamental wave and reducing a loss, and a wireless device using the same.

An oscillator according to the present invention includes an oscillation circuit formed on a dielectric substrate, and an output transmission line for transmitting an oscillation output signal of the oscillation circuit, wherein the output transmission line is provided between two substantially parallel conductor plates. And a cut-off frequency of the dielectric line that cuts off a fundamental wave component or a fundamental wave component and a low-order harmonic component of an oscillating signal by the oscillation circuit. A wave component is determined to propagate, a slot is formed in one of the conductor plates constituting the dielectric line, and the dielectric substrate is disposed outside the conductor plate, and the line of the oscillation circuit and the dielectric line are disposed. And is combined.

In the oscillator according to the present invention, a negative resistance element is mounted near a short position of a line having an integral multiple of a half wavelength and having at least one end opened, and the line of the oscillation circuit is coupled to the output line. It is characterized by having made it.

In the oscillator according to the present invention, the impedance obtained when the bias power supply is viewed from a connection point of the negative resistance element to the bias line for supplying a bias voltage to the negative resistance element has a frequency of the fundamental wave and a frequency of the harmonic wave. It is characterized by providing a stub so as to have a high impedance.

The oscillator according to the present invention is characterized in that a variable reactance element is connected to the line of the oscillation circuit, and a line for supplying a control voltage to the variable reactance element is provided.

The oscillator according to the present invention is characterized in that a terminal for weak coupling is provided on the line of the oscillation circuit.

無線 The wireless device of the present invention is characterized by using an oscillator having any of these structures.

According to the present invention, a high-frequency signal that is difficult to oscillate directly can be easily obtained. In addition, since an oscillation circuit is configured using a dielectric substrate and an output transmission line including a dielectric material portion is used between two substantially parallel conductor surfaces, it differs from the case where a cavity waveguide is used. In addition, the circuit pattern can be easily formed, the size can be easily adjusted, and the resonance frequency can be easily adjusted, which is suitable for mass production and cost reduction. In addition, since the fundamental wave component or low-order harmonic is reliably cut off by the output transmission line and only the harmonic component to be used is transmitted, the signal of the harmonic to be used is not attenuated. No loss occurs. Further, since a return signal from the dielectric line to the oscillation circuit is suppressed, and a fundamental frequency signal does not return, stable oscillation characteristics can be obtained.

Further, according to the present invention, a negative resistance element is mounted in the oscillation circuit near a short position of a line having an integer multiple of a half wavelength with at least one end opened, and the line of the oscillation circuit is Since the output line is coupled, a low impedance negative resistance element such as a Gunn diode can be easily impedance-matched to the line, and the output power can be increased.

Further, according to the present invention, the impedance of the bias line that supplies the bias voltage to the negative resistance element, as viewed from the connection point of the negative resistance element to the bias power supply, is the frequency of the fundamental wave and the harmonics. By providing the stub so as to have a high impedance under the frequency, the oscillation signal does not leak to the bias line, and the modulation characteristics and the oscillation efficiency are improved.

Further, according to the present invention, a variable reactance element is connected to the line of the oscillation circuit, and a line for supplying a control voltage to the variable reactance element is provided, so that the oscillation frequency is made variable by the control voltage. And can be used as a voltage controlled oscillator.

According to the present invention, by providing a terminal for weak coupling to the line of the oscillation circuit, it is possible to monitor a fundamental frequency signal lower than the frequency to be used without adversely affecting the oscillation circuit, Low cost measuring instruments can be used.

According to the present invention, by using an oscillator having any of these structures, a small-sized, low-loss, high-gain millimeter-wave radar can be obtained as a whole.

The configuration of the oscillator according to the first embodiment will be described with reference to FIGS.
FIG. 1A is a plan view of an oscillator having upper and lower conductor plates with an upper conductor plate removed, and FIGS. 1B and 1C are views of FIG. 1A with an upper conductor plate provided. It is sectional drawing of a BB part and a CC part. In FIG. 1, reference numeral 1 denotes a lower conductor plate, and 2 denotes an upper conductor plate, which constitutes an oscillator in a space sandwiched between the upper and lower conductor plates. Reference numerals 3 and 4 in the figure denote dielectric substrates, respectively. A line 7 for an oscillation circuit is provided on the upper surface of the dielectric substrate 3, and a Gunn diode 6 is connected to a predetermined position. The gun diode 6 is a pill package type, is mounted on the lower conductor plate 1, and its protruding electrode is inserted into a hole formed in the dielectric substrate 3, and the electrode of the gun diode is soldered to the line 7. Electrically connected.

A bias line 8 for supplying a bias voltage to the Gunn diode 6 is formed on the upper surface of the dielectric substrate 3, and stubs 9 and 10 are provided at predetermined positions. A variable reactance element 12 is mounted on the upper surface of the dielectric substrate 3 between the line 7 and the stub 11 for the variable reactance element.

線路 A line 13 for supplying a control voltage to the variable reactance element 12 is formed on the upper surface of the dielectric substrate 4, and stubs 14 and 15 are formed at predetermined positions.

In FIG. 1, reference numeral 5 denotes a dielectric strip. A groove having the width of the dielectric strip 5 is formed at a predetermined position on the upper and lower conductor plates 1 and 2, and the dielectric strip 5 is arranged along the groove. ing. The dielectric strip 5 and the upper and lower conductor plates 1 and 2 constitute a non-radiative dielectric line (hereinafter referred to as “NRD guide”). In particular, in this example, the distance between the upper and lower conductor plates in the spaces on both sides of the dielectric strip 5 is made narrower than the distance between the upper and lower conductor plates of the dielectric strip 5 to prevent the LSE01 mode from propagating, and the single LSM01 mode It acts as a non-radiative dielectric line adapted to propagate modes.

The dielectric substrate 3 has a portion near the end of the line 7 provided on the upper surface thereof oriented in a direction perpendicular to the axial direction of the dielectric strip 5 and parallel to the upper and lower conductor plates, and the open end thereof has a width of the dielectric strip 5. It is arranged to be located at the center in the direction. As a result, the mode of the suspended line formed by the line 7 and the upper and lower conductor plates is magnetically coupled to the LSM01 mode of the dielectric line.

FIG. 2 is a circuit diagram showing the configuration of the oscillation circuit portion shown in FIG. When one wavelength on the line 7 is represented by λg, in this example, the line 7 has a length of N × λg / 2, and both ends are opened. Here, N is an integer of 1 or more. Since the impedance of the Gunn diode 6 is as low as about several ohms, the Gunn diode 6 is connected to a position of λg / 4 from one open end of the line, that is, a position of a substantially short-circuit point equivalently to achieve impedance matching. The variable reactance element 12 is connected to a predetermined position between the connection position of the gun diode 6 and the other open end. Since the variable reactance element stub 11 has a length of λg / 4 and has an open end, the variable reactance element 12 is connected between the connection point of the variable reactance element 12 to the line 7 and an equivalent ground. The configuration is connected.

With the above configuration, the oscillation signal from the Gunn diode 6 passes through the line 7, is coupled to the dielectric line, and transmitted through the dielectric line.

The NRD guide has a frequency cutoff characteristic, and the cutoff frequency of the dielectric strip 5 is set higher than the fundamental oscillation frequency of the Gunn diode 6 and lower than the frequency of the second harmonic (second harmonic). The relative permittivity, the size, and the size of the space between the upper and lower conductor plates are determined. Therefore, only the harmonic components of the oscillation signal are transmitted to the NRD guide. For example, when the fundamental oscillation frequency of the Gunn diode 6 is 38 GHz, its second harmonic, 76 GHz, is transmitted to the NRD guide.

Incidentally, higher-order harmonics higher than the third-order harmonic are also transmitted. However, the higher the order, the smaller the output power, and the effect is negligible compared to the fundamental wave.

Since the oscillation frequency of the gun diode 6 varies depending on the reactance of the variable reactance element 12 loaded on the line 7, the oscillation frequency can be adjusted or modulated by the control voltage for the variable reactance element 12. Further, since the ratio of the change in the oscillation frequency to the change in the control voltage changes depending on the connection position of the variable reactance element 12 to the line 7, the frequency adjustment width or the modulation width is determined by the connection position of the variable reactance element.

FIG. 3 is a diagram showing the configuration of the bias line portion shown in FIG. The stub 9 is provided at a position (1) away from the position of the gun diode 6, and the length from the connection point to the bias line 8 to the open end is (2). The stub 10 is provided at a position (3) away from the position of the gun diode 6, and the length from the connection point to the bias line 8 to the open end is (4). In the above (1), the wavelength of the second harmonic on the bias line is substantially 1/4 wavelength from the connection position of the Gunn diode, that is, the position of the substantially short-circuit point. (2) is the wavelength of the second harmonic, which is approximately 1/4 wavelength. In the above (3), the wavelength of the fundamental wave on the bias line is approximately 1/4 wavelength from the connection position of the Gunn diode, that is, the position of the equivalent short circuit point. (4) is the wavelength of the fundamental wave, which is approximately 1/4 wavelength. However, the length (3) from the short-circuit point to the connection position of the stub 10 takes into account the influence of the stub 9 (lengths of (1) and (2) above).

Therefore, the impedance Z viewed from the bias power supply side from A becomes a high impedance (ideally the point of infinite impedance on the Smith chart) at the fundamental frequency and the frequency of the second harmonic, and the stub 9 is the second harmonic. The component trap, stub 10, acts as a trap for the fundamental component. Thus, the oscillation signal does not leak to the bias power supply side via the bias line, and the modulation characteristics and the oscillation efficiency are improved.

ス Stubs similar to the above two stubs are also provided on the control voltage supply line 13 as shown in FIG. The stub 14 is connected to a position １ ／ wavelength away from the equivalent short-circuit point of the variable reactance element stub 11 at the wavelength of the second harmonic, and the length from the connection point to the open end is the wavelength of the second harmonic. Is 1/4 wavelength. The stub 15 is connected to a position １ ／ wavelength away from the equivalent short-circuit point of the variable reactance element stub 11 at the wavelength of the fundamental wave, and the length from the connection point to the open end is 1 at the wavelength of the fundamental wave. / 4 wavelength. Therefore, the oscillation characteristic does not leak to the control voltage supply line 13 side, and the modulation characteristics and the oscillation efficiency are improved.

Next, FIG. 4 shows the configuration of the oscillator according to the second embodiment. FIG. 4 is a plan view with the upper conductor plate removed. Unlike the example shown in FIG. 1, an electrode 21 and an adjustment terminal 20 connected to the electrode 21 are provided on the dielectric substrate 3. Further, in this example, no structure for varying the frequency by voltage control is provided.

(4) In FIG. 4, the electrode 21 is weakly coupled to the line 7, and the oscillation signal can be monitored by connecting a spectrum analyzer or the like to the adjustment terminal 20. For example, in the case of adjusting the oscillation frequency, one open end T of the line 7 is trimmed so that the fundamental frequency becomes a half of the actually used second harmonic frequency.

As described above, since the electrode 21 is only weakly coupled to the line 7, there is no other adverse effect. In addition, since the fundamental wave component is weakly coupled to the unblocked line 7 and the oscillation signal is monitored, the frequency of the fundamental wave which is lower than the oscillation frequency output to the NRD guide can be measured. It is possible to use a spectrum analyzer.

As described in the first embodiment, a variable reactance element is provided so that the oscillation frequency can be voltage-controlled, and the oscillation frequency is detected from the signal taken out by the adjustment terminal so that the oscillation frequency becomes a specified frequency. Alternatively, feedback may be applied to the control voltage to stabilize the oscillation frequency.

Next, the configuration of the oscillator according to the third embodiment will be described with reference to FIG.
In the first and second embodiments, the dielectric substrate 3 is provided in the space between the upper and lower conductor plates, but in the third embodiment, the dielectric substrate 3 is arranged outside the upper and lower conductor plates. I do. That is, a slot 22 is formed in the upper conductor plate 2 along the longitudinal direction of the dielectric strip 5, and the dielectric substrate 3 is arranged so that the line 7 of the oscillation circuit is orthogonal to the slot 22. The configuration of the dielectric substrate 3 is basically the same as that shown in FIG. 1 or FIG. However, the mode of the microstrip line (substantially TEM mode) propagating on the line 7 of the oscillation circuit and the LSM mode of the dielectric line are magnetically coupled via the slot 22. At this time, the TEM mode magnetic field spreads through the slot 22, whereas the LSM mode magnetic field hardly leaks from the slot 22 to the dielectric substrate 3 side. Therefore, one-way coupling is performed from the line 7 to the NRD guide. According to such a configuration, even if the reflected wave at the discontinuous portion of the NRD guide returns to the Gunn diode side, the signal level is suppressed and the NRD guide does not propagate the fundamental wave component. The signal returning to the side 6 does not include a fundamental wave component. Therefore, the influence on the oscillation characteristics is extremely small.

Next, a configuration of an oscillator according to a fourth embodiment will be described with reference to FIG.
FIG. 6A is a plan view of the oscillation circuit portion in a state where the upper conductor plate is removed, and FIG. 6B is a cross-sectional view in a plane perpendicular to the bias line in a state where the upper conductor plate is provided. In this example, the bias line 8 is formed with a repetitive pattern of a portion w having a large line width and a portion n having a small line width, thereby giving a low-pass filter characteristic of blocking an oscillation signal component. A concave spring 23 is provided in a narrow path portion indicated by n. The concave spring 23 is provided in a space between the dielectric substrate 3 and the upper conductor plate 2 in a state where the dielectric substrate 3 is disposed in a space formed between the upper and lower conductor plates 1 and 2. The dielectric substrate 3 is pressed against the lower conductor plate 1 side. Therefore, even if the dielectric substrate 3 is slightly warped, the dielectric substrate 3 is securely fixed in the space formed by the upper and lower conductor plates, and stable frequency characteristics can be obtained.

Since the concave spring is provided in the narrow path portion of the bias line, the concave spring does not conduct to the bias line, and since this portion is a portion where the bias line equivalently acts as an inductor, the bias line Has almost no effect on

Next, an example in which a planar dielectric line is used as an output transmission line will be described with reference to FIG.
FIG. 7 is a perspective view showing a configuration of a main part of an oscillator including an oscillation circuit and an output transmission line. In FIG. 7, reference numeral 30 denotes a dielectric substrate, on which electrodes 31a and 31b are provided, and a slot is formed in a region sandwiched between the two electrodes 31a and 31b. Electrodes 32a and 32b are also provided on the lower surface of the dielectric substrate 30, and a slot is formed in a region between the two electrodes 32a and 32b. With this structure, a planar dielectric line (PDTL) mainly having a region in the dielectric substrate sandwiched between the upper and lower two slots as a propagation path is configured. In the figure, broken arrows indicate magnetic field vectors, and solid arrows indicate electric field vectors. In FIG. 1, reference numeral 3 denotes a dielectric substrate, which forms a microstrip line by forming a line 7. Both are arranged so that the surface of the line 7 is substantially at the height of the center surface of the planar dielectric line, and the line 7 is perpendicular to the electromagnetic wave propagation direction of the planar dielectric line. The configuration of the other parts is the same as that shown in FIG.
With this configuration, the planar dielectric line and the microstrip line are magnetically coupled, and an oscillator using the planar dielectric line as an output transmission line is obtained.

Next, a configuration example of a millimeter wave radar will be described as an embodiment of a wireless device with reference to FIG.
In FIG. 8, VCO is the oscillator shown in the first embodiment. This VCO frequency-modulates, for example, a triangular wave signal provided from a signal processing circuit, and outputs an oscillation signal. This oscillation output signal is transmitted to the primary radiator via the isolator → coupler → circulator. Accordingly, the primary radiator transmits a millimeter wave signal with a predetermined beam width via a dielectric lens or the like. The coupler provides a part of the transmission signal to the mixer as a local signal. When the reflected wave from the object enters the primary radiator, the received signal is provided to the mixer via the circulator. The mixer mixes the received signal from the circulator and the local signal to generate an intermediate frequency signal. The IF amplifier amplifies this intermediate frequency signal and provides it to the signal processing circuit. The signal processing circuit detects the distance to the object and the relative speed of the object from the modulated signal and the IF signal given to the VCO.

In the embodiment, the pill type gun diode is used, but a surface mount type gun diode may be mounted on the dielectric substrate. Further, a three-terminal element such as an FET may be used as the negative resistance element in addition to the Gunn diode. For example, when a MOS-FET is used, a line for coupling to the NRD guide is connected to the drain, a resonance line is connected to the source, and a bias line is connected to the gate.

In the embodiment, a Gunn diode whose fundamental wave is a 38 GHz band is used to obtain an oscillation signal in the 76 GHz band, which is the second harmonic, but higher harmonics higher than the third harmonic depending on the purpose. The cutoff frequency may be determined between the second harmonic and the third harmonic so that the component is transmitted to the output transmission line.

Furthermore, in the embodiment, the line 7 of the oscillation circuit provided on the dielectric substrate 3 is brought close to the end of the dielectric strip 5 so that the coupling between the lines is achieved. May be divided into upper and lower parts by a plane parallel to the above, and a dielectric substrate may be arranged between the dielectric strips on the upper and lower sides to couple the line of the oscillation circuit and the NRD guide.

FIG. 2 is a diagram illustrating a configuration of an oscillator according to the first embodiment. Diagram showing the relationship between the line of the oscillation circuit and the connection position of the Gunn diode etc. in the same oscillator The figure which shows the structure of the bias line of the oscillation circuit in the same oscillator FIG. 3 is a diagram illustrating a configuration of an oscillator according to a second embodiment. FIG. 4 is a diagram illustrating a configuration of an oscillator according to a third embodiment. FIG. 7 is a diagram illustrating a configuration of an oscillator according to a fourth embodiment. FIG. 14 is a partial perspective view illustrating the configuration of an oscillator according to a fifth embodiment. FIG. 14 is a block diagram illustrating a configuration of a millimeter wave radar according to a sixth embodiment.

Explanation of reference numerals

1-Lower conductor plate 2-Upper conductor plate 3,4-Dielectric substrate 5-Dielectric strip 6-Gun diode 7-Line 8-Bias line 9-Stub for harmonics 10-Stub for fundamental wave 11-Variable reactance element Stub 12-variable reactance element 13-control voltage supply line 14-harmonic stub 15-fundamental stub 20-adjustment terminal 21-electrode 22-slot 23-concave spring 30-dielectric substrate 31,32- electrode

Claims (6)

An oscillator including an oscillation circuit formed on a dielectric substrate and an output transmission line for transmitting an oscillation output signal of the oscillation circuit,
The output transmission line is a dielectric line in which a dielectric strip is disposed between two substantially parallel conductor plates,
The cut-off frequency of the dielectric line is determined so as to cut off a fundamental wave component or a fundamental wave component and a lower harmonic component of an oscillation signal of the oscillation circuit, and propagate a higher harmonic component therefrom.
A slot is formed in one conductor plate constituting the dielectric line, the dielectric substrate is arranged outside the conductor plate, and the line of the oscillation circuit and the dielectric line are coupled. Oscillator. The oscillation circuit has a negative resistance element mounted near a short position of a line having an integral multiple of a half wavelength and having at least one end opened, and the line and the output transmission line are coupled. The oscillator according to claim 1, wherein: A bias line that supplies a bias voltage to the negative resistance element, the impedance when viewing the bias power supply from the connection point of the negative resistance element has a high impedance under the fundamental frequency and the harmonic frequency. 3. The oscillator according to claim 2, wherein a stub is provided. 4. The oscillator according to claim 2, wherein a variable reactance element is connected to a line of the oscillation circuit, and a line for supplying a control voltage to the variable reactance element is provided. (5) The oscillator according to any one of (2) to (4), wherein a terminal for weak coupling is provided on a line of the oscillation circuit. A wireless device using the oscillator according to any one of claims 1 to 5.

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