JP2011205545A - High frequency amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high frequency amplifier capable of surely preventing abnormal oscillation caused by a spatial loop even in a high-gain amplifier.SOLUTION: A high frequency amplifier includes: a microstrip line 3 formed on a dielectric substrate 2; an amplification element 1 connected to the microstrip line 3; a metal housing 7 in which an accommodation part 7a is formed for accommodating the amplification element 1 placed on the dielectric substrate 2; a metal body 8 which is fitted to the accommodation part 7a of the metal housing 7 and with which a first groove 8b is formed at the side of a surface opposed to the amplification element 1; and a first conductive rubber 9 inserted into the first groove 8b of the metal body 8. When the metal body 8 is fitted to the accommodation part 7a of the metal housing 7, the first conductive rubber 9 presses the amplification element 1 mounted on the dielectric substrate 2, thereby shutting off a spatial loop on the amplification element 1.

Description

  The present invention relates to a high-frequency amplifier used when, for example, a microwave band signal is amplified.

  Amplifiers that amplify microwave signals are used for low noise amplification, high gain amplification, high output amplification, and the like. In general, a high frequency amplifier employs a technique of mounting an amplifying element in a groove of a metal case. However, when the amplified output signal returns to the input signal side via the space above the amplification element, a spatial loop may be formed and the amplifier may oscillate.

  Therefore, various devices have been proposed for preventing oscillation of the high-frequency amplifier.

  A high-frequency amplifier has been proposed in which an insulation wire between the amplifying element and the lid is filled with a conductive material (see, for example, Patent Document 1). This is because an insulating wire in which a conductor wire is insulated with a dielectric material is passed through a space formed between the n-stage amplifier mini-module and the lid, and an external power supply voltage is applied to one end of the penetrating insulating wire. The power supply line of the first stage amplifier mini-module side connection part is connected to the power supply line of the connection part of the last-stage amplifier mini-module side, and the insulation line in the space is filled with a conductive material.

  In addition, it has been proposed to secure input / output isolation of a microwave active element by using a wall portion formed on a lid portion constituting a shield case (see, for example, Patent Document 2). This includes a circuit pattern formed on an insulating substrate, a microwave active element mounted on the circuit pattern, a conductive main body case in which the insulating substrate is accommodated, and a conductive material fitted in the main body case. In the microwave amplifier provided with a conductive lid portion, a wall portion forming a shield room is projected on the inner side of the lid portion, and a notch portion and step portions on both sides of the notch portion are formed on the wall portion. When the lid is fitted to the main body case, the stepped portion is brought into contact with the ground electrode of the microwave active element mounted on the insulating substrate.

JP 7-94976 A JP-A-7-235846

  In the high-frequency amplifier described in Patent Document 1, an amplification element having a size that can fit within the dimensions of the cutoff waveguide may be used. However, with a wide lateral amplification element, the cutoff waveguide cannot be formed and loop oscillation occurs. Since the conductive material is filled between the lid and the amplifying element, there is a problem that the circuit adjustment and the amplifying element cannot be replaced with the lid removed.

  In addition, as described in Patent Document 2 described above, the method of attaching a metal body on an amplifying element and blocking the loop in the upper space of the amplifying element is as follows. It is valid. However, a gap due to dimensional tolerance is generated between the metal body and the amplifying element. When the amplification element has an amplification factor of several hundred times, a component leaking from this gap is generated, and there is a problem that a spatial loop is formed and oscillates.

  Accordingly, the present invention has been made in response to such a conventional situation, and an object thereof is to provide a high-frequency amplifier capable of reliably preventing abnormal oscillation caused by a spatial loop.

  According to one aspect of the present invention, a microstrip line formed on a dielectric substrate, an amplifying element connected to the microstrip line, and the amplifying element placed on the dielectric substrate are accommodated. A metal case in which a housing part is formed, a metal body that fits in the housing part of the metal housing and has a first groove formed on a surface facing the amplifying element; and A first conductive rubber inserted into the first groove, and when the metal body is fitted into the housing portion of the metal casing, the first conductive rubber is placed on the dielectric substrate. A high-frequency amplifier is provided that presses the mounted amplifying element to block a spatial loop on the amplifying element.

  In the high-frequency amplifier, the first conductive rubber has a volume resistivity of 0.1 Ω · cm or less.

  The high-frequency amplifier has a notch formed in the vertical direction near the corner of the metal body, and the notch has an outer edge protruding from the outer periphery of the metal body. A second conductive rubber having a large diameter is inserted to shut off a space loop that goes around the housing portion of the metal casing and the periphery of the metal body.

  In the high frequency amplifier, the screw hole formed in the metal body is a through hole, and a second groove is formed in the longitudinal end portion of the metal body to insert and insert a third conductive rubber. The outer edge of the conductive rubber 3 protrudes beyond the outer periphery at the end in the longitudinal direction of the metal body, and a space loop that goes around the screwed portion and the housing portion and the periphery of the metal body is blocked. It is characterized by.

  According to the present invention, it is possible to reliably prevent abnormal oscillation caused by a spatial loop even in a high gain amplifier.

It is a figure which shows the structure of the high frequency amplifier which concerns on 1st Embodiment. It is a figure which shows the structure of the modification of 1st Embodiment. It is a figure which shows the structure of the high frequency amplifier which concerns on 2nd Embodiment. It is a figure which shows the structure of the modification of 2nd Embodiment. It is a figure which shows the structure of the modification of 2nd Embodiment. It is a figure which shows the structure of the modification of 2nd Embodiment. It is a figure which shows the structure of the high frequency amplifier which concerns on 3rd Embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected about the same location and the overlapping description is abbreviate | omitted.

(First embodiment)
FIG. 1 is a diagram showing a configuration of a high-frequency amplifier according to the first embodiment of the present invention. In FIG. 1 (a), in order to make the internal structure of the high-frequency amplifier easier to understand, a part thereof is omitted. In addition, the internal space of the high-frequency amplifier is represented by the cross-sectional structures of AA ′ and BB ′. The high-frequency amplifier can be used, for example, when a ground wave is amplified and launched toward a satellite in a mobile relay vehicle. As shown in FIG. 1, the high-frequency amplifier has an amplification element 1 having a desired amplification factor placed on a dielectric substrate 2 and includes an input terminal 4 and an output terminal 5. The input / output terminals 4 and 5 and the amplifying element 1 are connected by a microstrip line 3 formed on a dielectric substrate 2. The microstrip line 3 also serves as a power supply line to the amplifying element 1. The amplification element 1 configured as described above is accommodated in a substantially concave accommodating portion 7a formed in the metal casing 7, and is covered with a concave metal body 8 from above. That is, the metal body 8 has a dimensional relationship such that the metal body 8 fits into the housing portion 7 a of the metal housing 7. The metal body 8 is screwed to the metal housing 7 with screws 10. FIG. 1B is a diagram showing the metal body 8.

  In the structure shown in FIG. 1, when a spatial loop is formed in which a part of the signal to be output is radiated from the microstrip line 3 to the space and returned to the input side, the high frequency amplifier causes abnormal oscillation. . Therefore, in order to suppress such abnormal oscillation, the space formed by the metal casing 7 and the lid 6 where the microstrip line 3 is formed is formed into a cut-off waveguide shape. As shown in the figure, a loop caused by a spatial loop inside the housing portion 7a of the metal housing 7 by adopting a waveguide shape of ½ wavelength (10 mm in the case of a high frequency signal of 15 GHz) or less. Oscillation is suppressed.

  However, a gap due to dimensional tolerance occurs between the metal body 8 and the amplifying element 1. For example, the gap is about 0.1 to 0.2 mm. In an amplifying element whose amplification factor of the high frequency amplifier is several hundred times, a component leaking from this gap is generated, and a spatial loop is formed, resulting in abnormal oscillation.

  Therefore, in the present embodiment, a groove 8b is formed on the surface 8a side of the metal body 8 facing the amplifying element 1, and a substantially kamaboko type conductive rubber 9 is inserted into the groove 8b. The groove portion 8b is formed at a plurality of places, for example, two places in parallel in the direction of the signal input / output direction. The size of the groove 8b is made slightly smaller than the outer diameter of the conductive rubber 9. Due to the elasticity of the conductive rubber 9, when the amplification element 1 is covered with the metal body 8, no gap is formed between the amplification element 1 and the metal body 8 so as to form a space loop. The conductive rubber 9 is a mixture of rubber and carbon black. In order to enhance the shielding effect, for example, a conductive rubber having a volume resistivity of 0.1 Ω · cm or less is suitable. The shape of the conductive rubber 9 is merely an example.

  With such a configuration, a gap that easily occurs between the amplifying element 1 and the metal body 8 is filled, so that a spatial loop on the amplifying element 1 can be blocked. Further, since the conductive rubbers 9 are arranged in parallel, the space loop can be cut off at two places.

  After the metal body 8 is attached, the cover 6 is covered so as to cover the accommodating portion and the upper surface of the metal casing 7. For example, the external size of the high frequency amplifier is about 30 mm × about 39 mm.

  The function of the high-frequency amplifier configured as described above will be briefly described. For example, assuming that a 15 GHz high frequency signal is amplified with a gain of 600 to 800 times as an input signal, the wavelength is about 20 mm. This input signal is input from the input terminal 4, transmitted through the microstrip line 3 patterned on the dielectric substrate 2, and input to the amplifying element 1. The signal amplified by the amplifying element 1 is transmitted to the output terminal 5 and taken out as an output signal. The output signal amplified to a gain of 600 to 800 times does not cause abnormal oscillation because there is no spatial loop above the amplification element 1. Further, the internal circuit of the high-frequency amplifier can be adjusted while the cover 6 is covered or the cover 6 is removed.

  According to the first embodiment, since the spatial loop is not formed above the amplifying element 1, loop oscillation is suppressed even when an amplifying element having an amplification factor of several hundred times is mounted. Can do.

(Modification of the first embodiment)
In FIG. 1, although the groove part 8b is formed in the metal body 8 in two places, it is not limited to this. As shown in FIG. 2, a groove 8 c may be formed in one place on the surface 8 a side of the metal body 8 facing the amplifying element 1. By inserting a conductive rubber 91 wider than the conductive rubber 9 shown in FIG. 1 into the groove 8c, the space loop can be sufficiently blocked. In this modification, there is an advantage that the processing of the groove is only required in one place.

(Second Embodiment)
FIG. 3 is a diagram showing the configuration of the high-frequency amplifier according to the second embodiment of the present invention. For example, in an amplification element having a high gain such as an amplification factor of about 1000 times, there is a possibility that abnormal oscillation cannot be suppressed only by blocking the spatial loop on the amplification element 1. That is, when the high-frequency amplifier is viewed from above, a leak component in the lateral direction that passes through the gap between the housing portion 7a of the metal housing 7 and the metal body 8 of the output signal amplified by the amplification element 1 may occur. Because there is.

  Therefore, in the second embodiment, notches 8 d are formed in the vertical direction near the four corners of the metal body 8. The cutout portion 8d may be formed in a through hole shape in which a part of a circle is cut, or may be formed in a cutout having a rectangular cross section. A substantially cylindrical conductive rubber 92 is fitted into the notch 8d. The conductive rubber 92 has an outer shape larger than that of the notch 8d, and is pushed into the notch 8d while compressing the diameter. Therefore, the outer edge of the inserted conductive rubber 92 protrudes from the outer periphery of the metal body 8.

  When the metal body 8 to which the conductive rubber 9 and the conductive rubber 92 are attached is placed on the amplification element 1 housed in the housing portion 7a of the metal housing 7, the outer edge of the conductive rubber 92 is deformed while the metal housing 8 is deformed. The gap between the housing portion 7a of the body 7 and the metal body 8 is closed. For this reason, formation of a space loop in which the amplified output signal wraps around the periphery of the housing portion 7a and the metal body 8 of the metal housing 7 can be prevented, and the space between the housing portion 7a of the metal housing 7 and the metal body 8 can be prevented. Leakage in the lateral direction through the gap is suppressed.

  According to the second embodiment, it is possible to ensure isolation of the amplifying element in the lateral method.

(Modification of the second embodiment)
In the example shown in FIG. 3, the notches 8d are formed in the metal body 8 at four locations, but the present invention is not limited to this. This is because it is only necessary to reduce the gap between the housing portion 7a of the metal casing 7 and the metal body 8 and suppress lateral leakage. For example, FIG. 4, FIG. 5, and FIG. 6 show modifications in which the notch 8d is formed in two places.

(Third embodiment)
FIG. 7 is a diagram showing a configuration of a high-frequency amplifier according to the third embodiment of the present invention. In the first embodiment and the second embodiment, the metal body 8 is fixed to the metal housing 7 by screwing with a screw 10. As shown in FIGS. 1 and 3, when the screwing position of the screw 10 is provided at the end of the metal body 8, the housing portion 7 a of the metal housing 7 and the metal body around the screwing position of the screw 10. There is a possibility that a gap will be formed between the two. When the output signal amplified by the amplifying element 1 leaks in the lateral direction passing through such a gap, abnormal oscillation occurs. In particular, in the amplifying element 1 having a high amplification factor of about 1000 times, abnormal oscillation occurs even if there are only a few spatial loops. Therefore, in the third embodiment, the screw hole 81b formed in the metal body 81 is a through hole, and two groove portions 81c are formed at the end in the longitudinal direction. For example, a kamaboko-type conductive rubber 93 is inserted into the groove 81c. The outer edge of the inserted conductive rubber 93 protrudes from the outer periphery at the end in the longitudinal direction of the metal body 81.

  In such a configuration, when the metal body 81 to which the conductive rubber 9 and the conductive rubber 93 are attached is placed on the amplification element 1 accommodated in the accommodating portion 7b of the metal housing 7, the outer edge of the conductive rubber 93 is obtained. While closing, the gap between the housing portion 7b of the metal casing 7 and the metal body 81 is closed. For this reason, it is possible to prevent the amplified output signal from forming a space loop that wraps around the periphery of the housing portion 7b of the metal casing 7 and the metal body 81 as well as around the screwed portion of the screw 10. Leakage in the lateral direction passing through the gap between the housing portion 7a of the housing 7 and the metal body 81 is suppressed.

  According to the third embodiment, it is possible to ensure isolation of the amplifying element in the lateral direction including the periphery of the fastening screw.

  According to the present embodiment, abnormal oscillation due to a spatial loop can be reliably prevented even with a high gain amplifier. In addition, the internal circuit can be adjusted regardless of the presence or absence of the lid of the metal case.

  Note that the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

1: Amplifying element 2: Dielectric substrate 3: Microstrip line 4: Input terminal 5: Output terminal 6: Lid 7: Metal casing 8, 81: Metal bodies 9, 91, 92: Conductive rubber

Claims (8)

A microstrip line formed on a dielectric substrate;
An amplifying element connected to the microstrip line;
A metal housing in which an accommodating portion for accommodating the amplifying element placed on the dielectric substrate is formed;
A metal body that fits into the housing portion of the metal casing and has a first groove formed on the surface facing the amplification element;
A first conductive rubber fitted into the first groove of the metal body,
When the metal body is fitted into the housing portion of the metal casing, the first conductive rubber presses the amplification element mounted on the dielectric substrate, and the space on the amplification element A high-frequency amplifier characterized by breaking a loop.   2. The high frequency amplifier according to claim 1, wherein the metal body is screwed to the metal casing with a screw.   3. The high-frequency amplifier according to claim 1, wherein the first groove portion of the metal body is formed in parallel at a plurality of locations in a direction in a signal input / output direction.   4. The high-frequency amplifier according to claim 1, wherein the first conductive rubber has a volume resistivity of 0.1 Ω · cm or less. 5. A notch is formed in the vertical direction in the vicinity of the corner of the metal body, and the notch has a diameter larger than that of the notch so that the outer edge protrudes from the outer periphery of the metal body. Insert 2 conductive rubber,
5. The high-frequency amplifier according to claim 1, wherein a space loop that goes around a housing portion of the metal casing and a periphery of the metal body is blocked.   6. The high-frequency amplifier according to claim 5, wherein the second conductive rubber has a volume resistivity of 0.1 Ω · cm or less. A screw hole formed in the metal body is a through hole, and a second groove is formed at a longitudinal end portion of the metal body to insert and insert a third conductive rubber.
The outer edge of the third conductive rubber protrudes from the outer periphery at the end portion in the longitudinal direction of the metal body,
The high-frequency amplifier according to any one of claims 2 to 6, wherein a space loop that wraps around a screw threaded portion and a peripheral portion of the housing portion and the metal body is cut off.   The high-frequency amplifier according to claim 7, wherein the third conductive rubber has a volume resistivity of 0.1 Ω · cm or less.

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