JP3869131B2 - NRD guide gun oscillator - Google Patents

Description

BACKGROUND OF THE INVENTION
The present invention relates to an NRD guide gun oscillator configured by combining an NRD guide (non-radiative dielectric waveguide) circuit and a Gunn diode.
[0001]
[Prior art]
NRD guide circuits are attracting attention as transmission lines in the microwave, especially in the millimeter wave band of 30 GHz or higher, because they have lower propagation loss than microstrip lines and are easier to produce propagation paths than waveguides. ing. This NRD guide circuit has a structure in which a dielectric strip line through which an electromagnetic wave propagates is sandwiched between two parallel flat plates of conductive metal. The facing distance between the parallel flat plates is set to ½ or less of the operating frequency wavelength. Therefore, the electromagnetic wave is blocked at a place other than the dielectric strip line and its emission is suppressed, so that the electromagnetic wave can be propagated along the dielectric strip line with low loss. Oscillators of 35 GHz band and 60 GHz band configured by combining this NRD guide circuit and a Gunn diode have been developed, and an oscillation output comparable to a waveguide is obtained.
[0002]
FIG. 5A is a diagram showing a configuration of a conventional NRD guide gun oscillator. In this structure, a mount 120 on which a Gunn diode 110 is mounted together with a dielectric strip line 3 is installed in a space between parallel plates 1 and 2, and a high-frequency output oscillated by the Gunn diode 110 passes through a resonator 130. Then, it is led out to the dielectric strip line 3. In FIG. 5 (a), a part of the parallel plate 1 is notched for the understanding of the drawing.
[0003]
FIG. 5B is a diagram showing a typical example of the resonator 130, which includes a copper foil portion 131 obtained by patterning a copper foil of a Teflon copper-clad ridge layer substrate by etching. The oscillation frequency can be adjusted by adjusting the width and length of the copper foil portion 131. FIG. 6 is a diagram showing the configuration of the mount 120. The Gunn diode 110 is housed in a cylindrical part 121, and a bias voltage is applied via a bias choke 140 connected next to the cylindrical part 121. The bias choke 140 is obtained by patterning a Teflon copper-clad laminate by etching, and further cutting off the laminate so that the copper foil portion that becomes the connection portion lid 141 in the cylindrical portion 121 remains. The Gunn diode 110 has its cathode electrode brazed to the heat dissipation base 122 of the mount 120. The heat radiating base 122 is insulated and separated from the lid 141 by a cylindrical ceramic 142, and the lid 141 is connected to the anode electrode of the Gunn diode 110 by a ribbon 143.
[0004]
[Problems to be solved by the invention]
However, the above-described NRD guide gun oscillator is difficult to manufacture because it uses a special mount 120. In particular, the bias choke 140 has to scrape the substrate to expose the lid 141. There was a very bad problem. In addition, since the anode electrode of the Gunn diode 110 and the lid 141 are connected by the ribbon 143, there is a problem that parasitic inductance occurs and characteristics vary. An object of the present invention is to provide an NRD guide gun oscillator in which the above problems are solved.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, parallel plates made of two metal plates are arranged at intervals of 1/2 or less of the wavelength of the operating frequency, and a dielectric strip line is sandwiched between the parallel plates. In the NRD guide gun oscillator, an insulating or semi-insulating flat substrate having two signal electrodes connected to both ends of a signal line and a ground electrode insulated from each signal electrode formed on the surface, and a semiconductor A first contact layer, an active layer, a second contact layer, and a metal layer are sequentially laminated on the upper surface of the substrate, and the metal layer is partitioned by a recess, and an anode electrode and a cathode electrode are formed on the same plane. The bumps formed on one of the two electrodes are directly connected to the signal electrode of the flat substrate and the bump formed on the other electrode is directly connected to the ground electrode. An upper Gunn diode and a heat sink supporting the back surface of the flat substrate with respect to the parallel plate, and configured to electromagnetically couple substantially the center of the signal line of the flat substrate to the dielectric strip line did.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram showing the structure of an NRD guide gun oscillator according to an embodiment of the present invention. The NRD guide circuit has a structure in which a dielectric strip line 3 is sandwiched between two metal parallel plates 1 and 2 and is the same as the conventional example. In the present embodiment, two Gunn diodes 20 are mounted on the line substrate 10, and these are supported with respect to the parallel plate 2 through grounding, heat dissipation, and a heat sink 30.
[0012]
As shown in FIGS. 2A and 2B, the line substrate 10 is semi-insulating or insulating (for example, AlN having a specific resistance of about 10 ⁶ Ωcm or more and a thermal conductivity of about 140 W / mK or more, (SiC , diamond, etc.) on the surface of a flat substrate 11, a signal line 12, a choke portion 13 for applying a DC bias to the signal line 12, two signal electrodes 14 connected to both ends of the signal line 12, two signals Two pairs of surface ground electrodes 15 arranged so as to sandwich the electrode 14 are formed, a ground electrode 16 is formed on the back surface, and the surface ground electrode 15 is connected to the ground electrode 16 by a via hole 17. This line substrate 10 has no ground electrode on the back surface of the signal line 12 and forms a suspended line.
[0013]
As shown in FIGS. 3A and 3B, the Gunn diode 20 is formed by laminating a first contact layer 22, an active layer 23, a second contact layer 24, and a metal layer 25 on the upper surface of the semiconductor substrate 21. Then, by forming a circular recess 26 at the center so as to reach the first contact layer 22 from the metal layer 25, the metal layer 25 is divided into an anode electrode 25A and a cathode electrode 25K, and the anode electrode The Au bumps 27 that are easy to be thermocompression bonded on the 25A, and the same Au bumps 28 are formed on the cathode electrode 25K so as to have the same level of height. The bumps 27 and 28 are also equivalent to the anode electrode 25A and the cathode electrode 25K. As an example, the semiconductor substrate 21 is made of n-type gallium arsenide with an impurity concentration of 1 to 2 × 10 ¹⁸ atoms / cm ³ , and the first contact layer 22 has an impurity concentration of 2 × 10 ¹⁸ atoms / cm ³ and a thickness of 1 The active Katsura layer 23 is made of n-type gallium arsenide having an impurity concentration of 1.2 × 10 ¹⁶ atoms / cm ³ and a thickness of 1.6 μm, and the second contact layer 24 is made of impurities. It is made of n-type gallium arsenide having a concentration of 1 × 10 ¹⁸ atoms / cm ³ and a thickness of 0.3 μm. Instead of gallium arsenide, other compound semiconductors such as indium phosphide can be used. The Gunn diode 20 is set such that the area of the active layer in the partition corresponding to the anode electrode 25A is the area (cross-sectional area) in which a predetermined operating current of the Gunn diode can be obtained.
[0014]
Further, the area of the active layer corresponding to the cathode electrode 25K is set to be 10 times or more of the area of the active layer corresponding to the anode electrode 25A, and the electric resistance of the semiconductor stacked portion under the cathode electrode 25K is that of the anode electrode 25A. By setting it to 1/10 or less, the portion does not function as a Gunn diode but functions as a low resistance substantially.
[0015]
As shown in FIG. 3C, the Gunn diode 20 has a structure in which the second contact layer 24 and the active layer 23 under the cathode electrode 25K in FIG. 3B are removed. replaced with 'bumps 27 and the upper surface of the first contact layer 22 directly cathode electrode 25K deposited on the bump 28 anode electrode 25A may be those provided in the level of height the same.
[0016]
When mounting the Gunn diode 20 on the flat substrate 11 of the line substrate 10, the bump 27 of the anode electrode 25 </ b> A is connected to the signal electrode 14, and the pair of bumps 28 of the cathode electrode 25 </ b> K is connected to the pair of surface ground electrodes 15. Perform thermocompression bonding so that they are connected. Then, the portion of the ground electrode 16 of the line substrate 10 is connected to the heat sink 30 so as to be grounded to the flat plate 2 through the heat sink 30. The same applies to the other Gunn diode.
[0017]
As shown in FIG. 1, the line substrate 10 is mounted on the NRD guide circuit so that the flat substrate 11 of the line substrate 10 is perpendicular to the parallel plates 1 and 2, and the central portion of the signal line 12 is the dielectric strip line 3. It approaches so that it may approach from the perpendicular direction with respect to the base of this. When a voltage is applied to the choke portion 13, the Gunn diode 20 closer to the choke 13 is connected from the signal electrode 14, and the far Gunn diode 20 is connected from the signal electrode 14 via the signal line 12 to the via hole 17, Current flows through the path of the ground electrode 16, the heat sink 30, and the flat plate 2, and electromagnetic waves (microwaves) are generated by the two Gunn diodes 20. The generated electromagnetic wave resonates in the signal line 12, and a part thereof is coupled with the dielectric strip line 3 and propagates.
[0018]
In the present embodiment, since the choke portion 13 is formed on the flat substrate 11, it can be formed by etching simultaneously with the signal line 12, the signal electrode 14, and the surface ground electrode 15, so that it is not necessary to remove the substrate and assemble it. Is easy and its working efficiency is improved.
[0019]
In addition, since the Gunn diode 20 is directly mounted on the flat substrate 11 in a face-down posture, no parasitic inductance that causes a problem when using a ribbon is generated.
[0020]
Further, since the heat generated by the Gunn diode 20 is transmitted to the heat sink 30 via the bumps 27 and 28 and the flat substrate 11 having good thermal conductivity, the heat dissipation effect is enhanced. Further, since the Gunn diode 20 is supported by the bumps 28 of the cathode electrodes 25K on both sides, it is possible to prevent an excessive load from being applied to the central semiconductor laminated portion that substantially functions as the Gunn diode.
[0021]
In the above description, the signal line 12 of the line substrate 10 is a suspended line. However, if the ground electrode 16 is provided on the entire back surface of the flat substrate 11, a microstrip line is obtained. The line may be a coplanar line in which a signal line is provided in the center of the upper surface of the flat substrate 11 and a pair of ground electrodes are provided on the same surface so as to sandwich the signal line. In this case, the Gunn diode 20 may connect the bump 27 of the anode electrode 25A to the central signal line and connect the bumps 28 on both sides of the cathode electrode 25K to the ground electrode.
[0022]
Furthermore, the anode electrode 25A and the cathode electrode 25K of the Gunn diode 20 may be reversed depending on the concentration gradient of the active layer. In this case, the polarity of the voltage applied to the choke portion 13 may be selected as appropriate.
[0023]
In FIG. 4, the line substrate 10 is mounted so as to be perpendicular to the parallel plates 1 and 2.
[0024]
【The invention's effect】
As described above, according to the present invention, the connection between the choke for applying the bias and the Gunn diode is simplified, the assembly is facilitated, and the working efficiency is improved.
[0025]
Moreover, no ribbon is required for mounting the Gunn diode, and no parasitic inductance is generated.
[Brief description of the drawings]
FIG. 1 is a perspective view of an NRD guide gun oscillator according to an embodiment of the present invention.
2A is a plan view of a line substrate, and FIG. 2B is a back view.
3A is a plan view of a Gunn diode, FIG. 3B is a cross-sectional view, and FIG. 3C is a cross-sectional view of a modified Gunn diode.
FIG. 4 is a perspective view of an NRD guide gun oscillator according to another embodiment of the present invention.
5A is a perspective view of a conventional NRD guide gun oscillator, and FIG. 5B is a perspective view of a resonator.
6A is a perspective view of the mount of the NRD guide gun oscillator shown in FIG. 6, and FIG. 6B is a sectional view taken along line BB in FIG.
[Explanation of symbols]
1, 2: Metal parallel plate, 3: Dielectric strip line, 10: Line substrate, 11: Flat substrate, 12: Signal line, 13: Choke part, 14: Signal electrode, 15: Surface ground electrode, 16: Ground Electrode, 17: Via hole, 20: Gunn diode, 21: Semiconductor substrate, 22: First contact layer, 23: Active layer, 24: Second contact layer, 25: Metal layer, 25A: Anode electrode, 25K: Cathode electrode, 26: recess, 27, 28: bump, 30: heat sink, 110: conventional Gunn diode, 120: mount, 121: cylindrical portion of mount, 122: heat dissipation base, 130: resonator, 131: resonance Copper foil part of the vessel, 140: bias choke, 141: lid, 142: cylindrical ceramic, 143: ribbon.

Claims (1)

In an NRD guide gun oscillator in which parallel plates made of two metal plates are arranged at intervals of 1/2 or less of the wavelength of the operating frequency, and a dielectric strip line is sandwiched between the parallel plates,
An insulative or semi-insulating flat substrate having two signal electrodes connected to both ends of the signal line and a ground electrode insulated from each signal electrode formed on the surface;
A first contact layer, an active layer, a second contact layer, and a metal layer are sequentially stacked on the upper surface of the semiconductor substrate, and the metal layer is partitioned by a recess, and an anode electrode and a cathode electrode are formed on the same plane. And two or more bumps formed on one electrode of the two electrodes are directly connected to the signal electrode of the flat substrate and the bump formed on the other electrode is directly connected to the ground electrode. Gunn diode,
An NRD guide comprising: a heat sink for supporting a back surface of the flat substrate with respect to the parallel plate; and an electromagnetic wave coupling of a substantially center of the signal line of the flat substrate to the dielectric strip line. Gun oscillator.

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