JP3934417B2 - Microwave integrated circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a microwave integrated circuit, and more particularly to a microwave integrated circuit in which an upper portion of a coplanar electrode is covered with a bridge-like ground conductor in an interdigital capacitor having a coplanar structure.
[0002]
[Prior art]
In the microwave integrated circuit, a part of the microwave signal is radiated to the outside due to the transmission characteristics of the microwave. For this reason, the microwave signal radiated to the outside may cause crosstalk with an external circuit adjacent to the microwave integrated circuit. From the viewpoint of this external circuit, the emitted microwave signal is noise. This noise may affect circuit characteristics. On the contrary, noise from an external circuit that is close may affect the circuit characteristics of the microwave integrated circuit. Therefore, measures are taken so that a part of the microwave signal does not crosstalk with the adjacent external circuit. Generally, a shield made of a metal plate such as a copper plate is provided on the entire microwave integrated circuit.
[0003]
FIG. 4 shows an interdigital capacitor 1 having a coplanar structure used in a microwave integrated circuit. An equivalent circuit of the interdigital capacitor 1 is shown in FIG. Note that Cc (Cc> 0) in FIG. 5 indicates a combined charge capacity value.
[0004]
According to FIG. 4, the interdigital capacitor 1 provided in the microwave integrated circuit includes coplanar electrodes 2 and 3 and a ground conductor 4 on the upper surface of the dielectric substrate 5. A lower ground conductor 6 is provided on the lower surface of the dielectric substrate 5. The coplanar electrodes 2 and 3 of the interdigital capacitor 1 are provided facing each other to form a capacitor. A ground conductor 4 exists outside the coplanar electrodes 2 and 3 forming a capacitor.
[0005]
On the other hand, according to FIG. 5, the charge capacity value of the interdigital capacitor 1 is determined only by Cc between the coplanar electrode 2 and the coplanar electrode 3, that is, the combined charge capacity value.
[0006]
[Problems to be solved by the invention]
However, miniaturization and integration of microwave integrated circuits have progressed, and there are situations in which microwave integrated circuits and external circuits are not necessarily shielded by a shield. In this case, in the interdigital capacitor 1 used in the microwave integrated circuit, the coplanar electrodes 2 and 3 of the interdigital capacitor 1 and the external circuit are close to each other without shielding. Therefore, the interdigital capacitor 1 can have a coupled charge capacity between components of the external circuit in addition to the coupled charge capacity between the coplanar electrodes 2 and 3. That is, the microwave integrated circuit is easily coupled with an external circuit, and is likely to cause crosstalk.
[0007]
In addition, the conventional interdigital capacitor has a small charge capacity value, and the degree of freedom in circuit design in micro integrated circuit design is narrowed.
[0008]
The present invention has been made in consideration of the above-described circumstances. The present invention reduces crosstalk between a microwave integrated circuit and an external circuit adjacent thereto, and reduces the charge capacity value of an interdigital capacitor provided in the microwave integrated circuit. An object is to provide an increased microwave integrated circuit.
[0009]
[Means for Solving the Problems]
In order to solve the above-described problem, a microwave integrated circuit according to the present invention includes, as described in claim 1, a microwave integrated circuit including an interdigital capacitor having a coplanar structure. A bridge-shaped ground conductor is provided between the ground conductors outside the coplanar electrodes facing each other, and the coplanar electrode is covered with the bridge-shaped ground conductor.
[0010]
In order to solve the above-described problem, according to the microwave integrated circuit of the present invention, as described in claim 2, the bridge-shaped ground conductor included in the interdigital capacitor is between ground conductors outside the coplanar electrodes facing each other. Is formed in a semi-cylindrical shape .
[0011]
In the microwave integrated circuit configured as described above, the crosstalk with the external circuit can be reduced and the charge capacity value of the interdigital capacitor can be increased, which has an influence on the microwave integrated circuit and the external circuit. It can be made smaller.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a microwave integrated circuit according to the present invention will be described below with reference to the accompanying drawings.
[0013]
FIG. 1 shows a perspective view of an interdigital capacitor 11 having a coplanar structure used in a microwave integrated circuit 10 showing an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line AA in FIG.
[0014]
According to FIGS. 1 and 2, the interdigital capacitor 11 includes coplanar electrodes 12 and 13 and a bridge-like ground conductor 14 on the upper surface of the dielectric substrate 15. On the other hand, a lower ground conductor 16 is provided on the lower surface of the dielectric substrate 15. Coplanar electrodes 12 and 13 are provided on the upper surface of the dielectric substrate 15 so as to face each other. Further, because of the interdigital capacitor 11 having a coplanar structure, a ground conductor 17 exists outside the coplanar electrodes 12 and 13 facing each other. Above the coplanar electrodes 12 and 13, bridging the ground conductor 14 formed by a semi-elliptic cylinder (semi-cylindrical) shape of the sheet member is straddled to cover the coplanar electrodes 12 and 13, both the ground conductor 17 and the electrically Connected. That is, the bridge-shaped ground conductor 14 bridges the ground conductors 17 and 17 and straddles the coplanar electrodes 12 and 13.
[0015]
In the interdigital capacitor 11, the bridge-shaped ground conductor 14 is provided above the coplanar electrodes 12 and 13 so as to bridge the bridge, so that the bridge-shaped ground conductor 14 has the same effect as the shield plate. Due to the shielding effect of the bridge-like ground conductor 14, the interdigital capacitor 11 has almost no coupling charge capacity with an element of an external circuit that causes crosstalk. Therefore, crosstalk can be greatly reduced.
[0016]
Further, in the microwave integrated circuit 10, since it is a capacitor component that can have a coupled charge capacity between adjacent external circuits, if the coupled charge capacity with the external circuit can be kept small in the interdigital capacitor 11, Crosstalk reduction as a whole of the microwave integrated circuit 10 can be achieved.
[0017]
FIG. 3 shows an equivalent circuit representing the charge capacitance value of the interdigital capacitor 11 provided in the microwave integrated circuit 10 of the present invention. The charge capacity value of the conventional interdigital capacitor 1 shown in FIG. 5 is determined only by the combined charge capacity value between the coplanar electrode 2 and the coplanar electrode 3, that is, Cc. However, according to FIG. 3A, the interdigital capacitor 11 includes the coplanar electrodes 12 and 13 and the bridge-like ground conductor 14 in addition to the coupled charge capacitance value Cc between the coplanar electrodes 12 and 13. Charge capacitance value Cp (Cp> 0) and ground-electrode charge capacitance value.
[0018]
FIG. 3B is an equivalent circuit that more specifically embodies the equivalent circuit of FIG. According to this figure, the charge capacity value of the interdigital capacitor 11 is the charge capacity value of a capacitor in which a capacitor having a Cc charge capacity value and a capacitor in which two capacitors having a Cp charge capacity value are connected in series are connected in parallel. Is equal to Therefore, the charge capacity value of the interdigital capacitor 11 is larger than the charge capacity value of the conventional interdigital capacitor 1.
[0019]
According to the embodiment of the present invention, the microwave integrated circuit 10 including the interdigital capacitor 11 in which the bridge-shaped ground conductor 14 is straddled above the coplanar electrodes 12 and 13 has the bridge-shaped ground conductor 14 serving as a shield. Therefore, the crosstalk with the external circuit can be greatly reduced, and the influence on the microwave integrated circuit 10 and the external circuit can be reduced. In addition, the charge capacity value of the interdigital capacitor 11 becomes larger than the charge capacity value of the conventional interdigital capacitor 1, and the degree of freedom in circuit design is expanded.
[0020]
In the microwave integrated circuit 10 according to the present embodiment, the bridge-shaped ground conductor 14 is formed in a semi-elliptical cylinder shape, but is not limited to a semi-elliptical cylinder shape. Includes any semi-cylindrical shape. That is, the bridge-like ground conductor 14 may be formed in a semicircular shape, or may be formed in a half-square tube shape.
[0021]
The number of interdigital capacitors in which the bridge-shaped grounding conductor 14 is disposed above the coplanar electrodes 12 and 13 may be at least one.
[0022]
Furthermore, although the interdigital capacitor 11 provided in the microwave integrated circuit 10 according to the present embodiment includes the lower ground conductor 16 on the lower surface of the dielectric substrate 15, the lower ground conductor 16 may be omitted.
[0023]
【The invention's effect】
In the microwave integrated circuit according to the present invention, in an interdigital capacitor having a coplanar structure used in a microwave integrated circuit, a bridge-like ground conductor is straddled above the coplanar electrode, thereby crossing with an external circuit. It is possible to provide a microwave integrated circuit in which the talk is reduced, the influence on the microwave integrated circuit and the external circuit is reduced, and the charge capacity value of the interdigital capacitor is increased.
[Brief description of the drawings]
FIG. 1 is a perspective view of an interdigital capacitor provided in a microwave integrated circuit according to the present invention.
FIG. 2 is a cross-sectional view taken along line AA in the perspective view of the interdigital capacitor provided in the microwave integrated circuit according to the present invention.
FIG. 3 is an equivalent circuit representing a charge capacity value of an interdigital capacitor provided in the microwave integrated circuit according to the present invention.
FIG. 4 is a schematic configuration diagram of an interdigital capacitor provided in a conventional microwave integrated circuit.
FIG. 5 is an equivalent circuit showing a charge capacity value of an interdigital capacitor provided in a conventional microwave integrated circuit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Microwave integrated circuit 11 Interdigital capacitor 12, 13 Coplanar electrode 14 Bridge-like ground conductor 15 Dielectric board | substrate 16 Lower ground conductor 17 Ground conductor

Claims (2)

In a microwave integrated circuit including an interdigital capacitor configured in a coplanar structure, a bridge-shaped ground conductor straddling the coplanar electrode is installed between ground conductors outside the coplanar electrode facing the interdigital capacitor, A microwave integrated circuit characterized in that the coplanar electrode is covered with the bridge-like ground conductor. 2. The microwave integrated circuit according to claim 1, wherein the bridge-shaped ground conductors of the interdigital capacitors are formed in a semi-cylindrical shape between the ground conductors outside the opposing coplanar electrodes.

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