JP2001102789A - High-frequency shield circuit structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-frequency shield circuit structure, capable of decreasing transmission of high frequencies emitted from a high frequency circuit part to outside a high-frequency shielding body. SOLUTION: A circuit substrate 11 is provided on a metallic base plate, and transmission paths 18a, 18b, 18c extended on the circuit substrate 11 and connected to a high frequency circuit part 14 and a low-frequency circuit part 13 are provided on this circuit substrate 11. A ground pattern 15 is provided on the substrate 11, so as to enclose the high frequency circuit part 14, and also a metallic block 16 is provided on this ground pattern 15 so as to enclose spacially the high-frequency circuit part 14. Ingress paths 15a, 15b, 15c for a transmission path eliminating the ground pattern 15 are provided on the substrate 11. Furthermore, cutouts 16a, 16b, 16c for introducing the transmission path are provided in the metallic block 16 on this ingress path. High-frequency ground circuit parts 17a, 17b, 17c, 17d, 17e, 17f connected in terms of high frequency to the transmission path are provided in fully in proximity to the ingress path and also inside and outside the metallic block.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a high-frequency shielding circuit structure for reducing high-frequency leakage, and more particularly to a high-frequency circuit for processing high-frequency signals in a microwave band, a millimeter-wave band, and the like, and this high-frequency circuit unit And a microwave circuit device having a function of preventing leakage of high frequency waves, that is, microwaves from the high frequency circuit section.

[0002]

2. Description of the Related Art Conventionally, a high-frequency circuit section and a control drive circuit section for controlling and driving the high-frequency circuit section are provided on the same substrate structure. A high-frequency cutoff structure is provided to prevent waves from leaking.

FIG. 1 schematically shows an example of a substrate structure provided with this high-frequency cutoff structure. In FIG. 1, reference numeral 51 denotes a circuit board constituting the substrate structure 50.
0 is attached to a metal base plate 52 as a ground plane. On the circuit board 51, a high-frequency circuit, for example,
A high-frequency circuit section 54 composed of a high-frequency amplifier circuit and a control drive circuit section 53 that controls a high-frequency circuit in the high-frequency circuit section 54 and generates a control drive signal for driving the same are provided. The high-frequency circuit section 54 and the control drive circuit section 53
Are transmission lines 58a, 58 provided on the substrate 51.
b, 58c, and the transmission lines 58a, 5c
The control drive signal is sent to the control drive circuit 5
3 to the high-frequency circuit unit 54. High frequency circuit section 5
A ground pattern 55, in the illustrated example, a rectangular band-shaped ground pattern 55 is provided on the circuit board 51 around the high frequency circuit unit 54. The ground pattern 55 enters a through hole (not shown) penetrating the circuit board 51 and is electrically connected to a metal base plate 52 as a ground plane of the board structure 50.

A high frequency is radiated from the high frequency circuit section 54 into free space.
A box-shaped metal block 56 is provided on the circuit board 51 to shield the circuit board 51. The box-shaped metal block 56 has a bottom surface that defines an opening thereof, and a screw, an adhesive or the like is used to fix the substrate structure 5 so that the bottom surface contacts the ground pattern 55.
Fixed to 0. Accordingly, the metal block 56 is connected to the ground pattern 55 and the base plate 52 via the ground pattern 55, and the high-frequency circuit unit 54 is formed of a shield substantially composed of the metal block 56, the ground pattern 55 and the metal base plate 52. It will be stored inside the body.

[0005] Transmission lines 58a extending on the substrate 51,
The transmission lines 58a, 58b, and 58c are naturally located on the circuit board 51 where the 58b and 58c enter the high-frequency circuit section 54.
Line entry portions 55a, 55b, 5 from which the ground pattern is removed so that the ground pattern 58c does not contact the ground pattern 55.
5c is formed, and the metal block 56 on the line entry portion 55a also corresponds to the line entry portions 55a, 55b, 55c such that the metal block 56 does not contact the transmission lines 58a, 58b, 58c. Notch holes 56a, 56b, 56c for entering the track are formed. Further, a high-frequency circuit section 54 is provided between the transmission lines 58a, 58b, and 58c via the lines 58a, 58b, and 58c.
High-frequency grounding circuits 57a, 57b, 57c for grounding the high-frequency waves leaked from the power supply. The high-frequency grounding circuits 57a, 57b, 57c
1 and terminal portions 59a, 59b, 59c and line 58 electrically connected to the metal base plate 52.
Capacitors 60a, 60b, 60c for connecting the terminals a, 58b, 58c and the terminals 59a, 59b, 59c at high frequencies are provided.

[0006]

In the structure shown in FIG. 2, the high-frequency wave transmitted through the high-frequency circuit portion 54 is sealed inside the high-frequency portion shielding metal block 56.
The device is designed so as not to leak to the transmission lines 58a, 58b, 58c. However, the transmission lines 58a, 58b,
High frequency leakage through 58c cannot be completely prevented,
Leakage may occur outside the metal block via the transmission lines 58a, 58b, 58c. In addition, the high-frequency circuit unit 5
4 is spatially coupled to the transmission lines 58a, 58b, 58c extending into the metal block 56, and the high-frequency waves radiated into the space in the metal block 56 for shielding the high-rise wave portion are spatially coupled to the transmission lines 58a, 58b, 58c. A high frequency may be transmitted to 58c. As a result, there is a possibility that high frequencies are transmitted outside the metal block 56 via the transmission lines 58a, 58b, 58c. The transmitted high frequency is grounded by the high frequency grounding circuits 57a, 57b and 57c, and is prevented from entering the control drive circuit unit 53.
8a, 58b, and 58c may be radiated to free space, and this high frequency is transmitted through the free space to the control drive circuit unit 5.
3 in some cases. Thus, the control drive circuit unit 5
For 3, an unnecessary high frequency mixed into the control drive circuit unit 53 may adversely affect the electrical performance of the microwave circuit device and the like. For example, when a power amplifier is provided in the high-frequency circuit section 54 and a drive circuit for the power amplifier is provided in the control drive circuit section 53, the high-frequency radiation radiated from the power amplifier into the high-frequency section shielding metal block 56 is applied to the metal block. It is spatially coupled to the transmission line extending into 56 and transmitted outside the same metal block. As a result, radiation from the transmission line to free space occurs, and the radiated high frequency may be mixed into the drive circuit 53 via the free space. As a result, a high-frequency closed circuit is formed between the power amplifier, the drive circuit, the transmission line, and the free space, and the power amplifier may oscillate.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a high-frequency shielding circuit structure capable of reducing transmission of high-frequency radiation emitted by a high-frequency circuit portion to outside the high-frequency shielding body. To provide.

[0008]

According to the present invention, there is provided a substrate structure comprising a metallic base plate and a circuit board provided on the base plate, and a high-frequency circuit section provided on the circuit board. A bias circuit unit provided on the circuit board, the bias circuit unit driving a high-frequency circuit having a transmission line connected to the high-frequency circuit, and the transmission circuit in an electrically non-contact state. An introduction path for a path is provided, electrically connected to the base plate, and a metallic shield that spatially surrounds the high-frequency circuit unit, and is provided in or near the introduction path. And a high-frequency grounding circuit connected to the transmission line at a high frequency and electrically connected to the base plate.

In the above invention, the shield is
A ground pattern provided on the substrate so as to surround the high-frequency circuit unit and a metal block that is in contact with the ground pattern; and the introduction path is provided in a substrate region where the ground pattern is removed and in this region. A high-frequency shielding circuit structure is provided, which is constituted by a cutout of a corresponding metal block.

Further, in the above invention, there is provided a high-frequency shield circuit structure, wherein the high-frequency grounding circuit portion is provided inside and outside the shield.

Further, in the above invention, there is provided a high-frequency shielding circuit structure, wherein the high-frequency grounding circuit section is provided in the introduction path and is constituted by a capacitor connected to the shielding body.

As described above, in the high-frequency shielding circuit structure according to the present invention, the high-frequency grounding circuit is provided in or near the introduction path of the high-frequency shielding metal shield. Therefore, even if the high frequency radiated from the high-frequency circuit into the high-frequency shielding metal shield is spatially coupled to the transmission line extending into the shield, the transmission line is grounded at a high frequency and outside the shield. Phenomena radiated into free space are reduced. Therefore, adverse effects on the electrical performance of the high-frequency circuit device and the like can be reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the high-frequency shielding structure according to the present invention will be described below with reference to the drawings.

FIG. 2 is an exploded perspective view schematically showing a circuit board structure provided with a high-frequency shielding structure for reducing high-frequency leakage according to one embodiment of the present invention. In FIG. 2, reference numeral 11 denotes a circuit board constituting the board structure 10, and the circuit board 51 has
0 is attached to a metal base plate 52 as a ground plane. On the circuit board 11, a high-frequency circuit, for example,
A high-frequency circuit section 14 composed of a high-frequency amplifier circuit and a control drive circuit section 13 as a low-frequency circuit section that generates a control drive signal for controlling and driving the high-frequency circuit in the high-frequency circuit section 14 are provided. I have. This high frequency circuit section 14
And the control drive circuit unit 13 are connected via transmission lines 18a, 18b, 18c provided on the substrate 11, and control drive signals are transmitted from the control drive circuit unit 13 via the transmission lines 18a, 18b, 18c. It is supplied to the high-frequency circuit unit 14. On the circuit board 11 around the high-frequency circuit section 14, a ground pattern 15, in the illustrated example, a rectangular band-shaped ground pattern 15 is provided so as to surround the high-frequency circuit section 14. The ground pattern 15 is electrically connected to a metal base plate 12 as a ground plane of the board structure 10 through a through hole (not shown) penetrating the circuit board 11.

The high frequency is radiated from the high frequency circuit section 14 to the free space.
A box-shaped metal block 16 is provided on the circuit board 11 for shielding the circuit board. The box-shaped metal block 16 has a bottom surface that defines the opening, and the substrate structure 1 is screwed, glued, or the like so that the bottom surface contacts the ground pattern 15.
Fixed to 0. Accordingly, the metal block 16 is connected to the ground pattern 15 and the base plate 12 via the ground pattern 15, and the high-frequency circuit section 14 is substantially formed of the metal block 16, the ground pattern 15 and the metal base plate 12. It will be stored in the body enclosure.

A transmission line 18a extending on the substrate 11,
Naturally, the transmission lines 18a, 18b, 18b, 18c enter the high-frequency circuit portion 14 on the circuit board 51.
The ground pattern is removed so that the ground pattern 18c does not make electrical contact with the ground pattern 55, and the transmission lines 18a, 18b,
In order to secure the introduction route of 18c, the track entrances 15a, 15
b, 15c are formed, and the line entrances 15a, 15c are formed.
Similarly, the metal blocks 16 on the transmission lines 18a, 18b, and 18c correspond to the line entrances 15a, 15b, and 15c so that the metal blocks 16 do not contact the transmission lines 18a, 18b, and 18c. Notch holes 16a, 16b, 16c for the introduction path are formed.

In the embodiment of the present invention, as shown in FIG. 2, on both sides of the ground pattern 15 adjacent to the line entrances 15a, 15b, 15c, the transmission lines 18a, 18
external high-frequency grounding circuits 17a and 17 for grounding high-frequency waves leaking from the high-frequency circuit portion 54 via the high-frequency circuits b and 18c.
b, 17c and internal high-frequency grounding circuits 17d, 17e, 1
7f is provided. That is, in the space inside the metal block 16, the internal high-frequency ground circuits 17d, 17e, and 17f are provided adjacent to the line entrances 15a, 15b, and 15c, and the internal high-frequency ground circuits 17d, 17e, and 17f are connected to the transmission line 18a. , 18b, 18c, and also outside the metal block 16, similarly to the line entrances 15a, 15c.
b, 15c, and external high-frequency ground circuits 17a, 17
b, 17c are provided.
a, 17b, 17c are transmission lines 18a, 18b, 18c
It is connected to the.

These high-frequency grounding circuits 17a, 17b, 1
7c, 17d, 17e, and 17f are terminal portions 19a, 19b, 19c, 19d, and 19 that penetrate the substrate 51 and are electrically connected to the metal base plate 12, respectively.
e, 19f, lines 18a, 18b, 18c and terminal 1
9a, 19b, 19c, 19d, 19e, 19f Capacitors 20a, 20b, 20c, 20 for high-frequency connection
d, 20e, and 20f. The capacitors 20a, 20b, 20c, 20d, 20e, 20
f may be composed of a dielectric material, and in some cases, may be composed of a stray capacitance between electrodes.

In the embodiment shown in FIG. 2, high-frequency radiation radiated from the high-frequency circuit section 14 in the metal block 16 is transmitted to the transmission lines 18a and 18 extending into the metal block 16.
b, 18c to be spatially coupled to the transmission lines 18a, 18c.
b, 18c, the high frequency is first transmitted to the internal high-frequency grounding circuits 17d, 17e, 17c.
f, and this internal high-frequency ground circuit 17d,
17e, 17f is not captured, the track entrance 15a, 15
b, 15c, even if a high frequency is transmitted through the transmission lines 18a, 18b, 18c.
External high-frequency grounding circuits 17d and 17 provided outside 15c
e and 17f are grounded.

Accordingly, the high-frequency waves transmitted from the high-frequency circuit section 14 to the transmission lines 18a, 18b, and 18c by radiation or directly to the transmission lines 18a, 18b, and 18c inside and outside the metal block 16, and adjacent to the metal block 16. High-frequency grounding circuits 17a, 17b, 17
c, 17d, 17e, 17f, and the transmission line 18
The transmission to the control drive circuit unit 13 via the switches a, 18b, and 18c is reduced, or the transmission is reliably prevented in some cases. As a result, deterioration of the characteristics of the circuit system such as oscillation of the circuit system due to leakage or undesired transmission of high frequency can be prevented.

In the embodiment shown in FIG. 2, the high-frequency grounding circuits 17a, 17b, 17c, 17d, 17e, 1
7f are provided inside and outside the metal block 16 adjacent to the transmission lines 18a, 18b, 18c and the metal block 16, but only inside the metal block 16 as shown in FIG. 3 according to the modified embodiment of FIG. May be provided, or
As shown in FIG. 4 according to a modified embodiment of FIG. 2, it may be provided only outside the metal block 16. Also in the embodiment shown in FIGS. 3 and 4, high-frequency waves transmitted from the high-frequency circuit unit 14 to the transmission lines 18a, 18b, and 18c by radiation or directly are transmitted through the transmission lines 18a, 18b, and 18c.
A high frequency grounding circuit 17a, 17b, 17c or 17d, 17e,
The transmission to the control drive circuit unit 13 via the transmission lines 18a, 18b, and 18c is reduced, or the transmission is reliably prevented in some cases. As a result, deterioration of the characteristics of the circuit system such as oscillation of the circuit system due to leakage or undesired transmission of high frequency can be prevented.

In FIGS. 3 and 4, the same parts or parts as those shown in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted. For the description of the structure shown in FIG. 3 and FIG. 4, refer to the description of FIG.

FIG. 5 schematically shows a circuit board structure having a high-frequency shielding structure according to another embodiment of the present invention. In the embodiment shown in FIG. 5, the high-frequency grounding circuits 17a, 17b, 17c, 17d, 17e, and 17f are not provided inside and outside the metal block 16, and the line entrance 15
A, 15b, and 15c are expanded as compared with the case shown in FIG. 2, and high-frequency ground circuits 17a, 17b, and 17c are provided in the line entrances 15a, 15b, and 15c. As the line entrances 15a, 15b, 15c are widened as compared with the case shown in FIG. 2, naturally the notch holes 16a, 16b, 16c provided in the metal block 16 for the line entrance.
Are also expanded compared to the case shown in FIG.

In the embodiment shown in FIG. 5, terminal portions 19a, 1 for high-frequency grounding circuits 17a, 17b, 17c are provided.
9b and 19c are not provided, and the high-frequency grounding circuit 17 is not provided.
a, 17b, and 17c of capacitors 20a, 20b, and 20
c is directly connected to the ground pattern 15. Therefore, in the structure shown in FIG. 5, FIGS.
The circuit configuration can be simplified as compared with the structure shown in FIG. In FIG. 5, the same parts or parts as those shown in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted. For the description of the structure shown in FIG. 5, refer to the description of FIG.

In the embodiment shown in FIG. 5, the transmission line 1 is radiated from the high-frequency circuit section 14 or directly.
The high frequencies propagated to 8a, 18b, 18c are grounded to high-frequency ground circuits 17a, 17b, 17c provided below the metal block 16 adjacent to the transmission lines 18a, 18b, 18c. Accordingly, the high frequencies are transmitted by the transmission lines 18a, 18
The transmission to the control drive circuit unit 13 via the terminals b and 18c is reduced, or the transmission is reliably prevented in some cases. As a result, deterioration of the characteristics of the circuit system such as oscillation of the circuit system due to leakage or undesired transmission of high frequency can be prevented.

[0026]

As described above, according to the present invention,
Even if the high frequency radiated from the high frequency circuit into the high frequency shielding metal block is spatially coupled to the transmission line extending into the metal block, the high frequency is grounded in the vicinity of the metal block. Accordingly, it is reduced that high frequencies are radiated to free space from the transmission line extending outside the metal block. As a result, adverse effects on the electrical performance of the high-frequency circuit device and the like can be reduced.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view schematically showing a circuit board structure provided with a conventional high-frequency shielding structure.

FIG. 2 is an exploded perspective view schematically showing a circuit board structure provided with a high-frequency shielding structure according to one embodiment of the present invention.

FIG. 3 is an exploded perspective view schematically showing a circuit board structure having a high-frequency shielding structure according to a modified embodiment of the present invention.

FIG. 4 is an exploded perspective view schematically showing a circuit board structure having a high-frequency shielding structure according to another modification of the present invention.

FIG. 5 is an exploded perspective view schematically showing a circuit board structure having a high-frequency shielding structure according to another embodiment of the present invention.

[Explanation of symbols]

11, 51: circuit board 12, 52: metal base plate 13, 53: control drive circuit 14, 54: high frequency circuit 15, 55: ground pattern 16, 56: high frequency shielding metal block 18a, 18b, 18c, 58a , 58b, 58c ... transmission lines 17a, 17b, 17c, 17d, 17e, 17f, 5
7a, 57b, 57c ... High frequency grounding circuit

Claims (5)

[Claims] A substrate structure comprising a metallic base plate and a circuit board provided on the base plate; a high-frequency circuit unit provided on the circuit board; and a high-frequency circuit unit provided on the circuit board. A bias circuit section,
A bias circuit unit for driving a high-frequency circuit having a transmission path connected to the high-frequency circuit, and an introduction path for the transmission path in an electrically non-contact state are provided and electrically connected to the base plate. A metallic shield that spatially surrounds the high-frequency circuit section; and a metal shield provided in or near the introduction path, connected to the transmission path at a high frequency, and electrically connected to the base plate. And a high-frequency grounding circuit connected to the high-frequency grounding circuit. 2. The shield comprises a ground pattern provided on the substrate so as to surround the high-frequency circuit section and a metallic block contacting the ground pattern. 2. The high-frequency shielding circuit structure according to claim 1, wherein the high-frequency shielding circuit structure is constituted by a substrate region from which is removed and a cutout portion of a metal block corresponding to this region. 3. The high-frequency shielding circuit structure according to claim 1, wherein said high-frequency grounding circuit portion is provided inside and outside said shielding body. 4. The high-frequency shielding circuit structure according to claim 1, wherein said high-frequency grounding circuit section comprises a capacitor connected to said base plate. 5. The high-frequency shield circuit structure according to claim 2, wherein said high-frequency connection circuit section comprises said ground pattern and a capacitor connected to said transmission line.