JP2003197758A - Microwave integrated circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microwave integrated circuit using an interdigital capacitor having a coplanar structure, which reduces the crosstalk with external circuits, decreases the influence on the microwave integrated circuit and external circuits, and increases the charge capacity value of an interdigital capacitor. <P>SOLUTION: The interdigital capacitor 11 has a coplanar structure used for a microwave integrated circuit 10. A bridge-like ground conductor 14 is bridged above and across coplanar electrodes 12, 13 to reduce the crosstalk and the influence on the microwave integrated circuit 10 and external circuits and to increase the charge capacity value of the capacitor 11. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave integrated circuit, and more particularly to a microwave integrated circuit in which an interdigital capacitor having a coplanar structure is covered with a bridge-shaped ground conductor above the coplanar electrode.

[0002]

2. Description of the Related Art In a microwave integrated circuit, part of a microwave signal is radiated to the outside due to the transmission characteristics of microwaves. Therefore, the microwave signal radiated to the outside may cause crosstalk with an external circuit close to the microwave integrated circuit. Seen from this external circuit, the radiated microwave signal is noise. This noise may affect the circuit characteristics. On the contrary, noise from an adjacent external circuit 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 an adjacent external circuit. Generally, a shield of a metal plate such as a copper plate is provided on the entire microwave integrated circuit.

FIG. 4 shows an interdigital capacitor 1 having a coplanar structure used in a microwave integrated circuit. An equivalent circuit of this interdigital capacitor 1 is shown in FIG. Incidentally, Cc (Cc> 0) in FIG.
Indicates the combined charge capacity value.

According to FIG. 4, the interdigital capacitor 1 included in the microwave integrated circuit includes the coplanar electrodes 2 and 3 and the 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 to face each other to form a capacitor. A ground conductor 4 is present outside the coplanar electrodes 2 and 3 forming a capacitor.

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]

However, the 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 shields. 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 combined charge capacity between the coplanar electrodes 2 and 3 as well as a combined charge capacity with an external circuit component. That is, the microwave integrated circuit is easily coupled to the external circuit and crosstalk is likely to occur.

Further, the conventional interdigital type capacitor has a small charge capacity value, which narrows the degree of freedom in circuit design in micro integrated circuit design.

The present invention has been made in consideration of the above-mentioned circumstances, and reduces the crosstalk between the microwave integrated circuit and an external circuit in the vicinity thereof, and at the same time, the charge of the interdigital capacitor provided in the microwave integrated circuit. An object is to provide a microwave integrated circuit having an increased capacitance value.

[0009]

In order to solve the above problems, a microwave integrated circuit according to the present invention has a microwave provided with an interdigital capacitor having a coplanar structure as described in claim 1. In integrated circuits,
A bridge-shaped ground conductor is installed so as to extend from above between ground conductors outside the coplanar electrodes facing each other of the interdigital capacitor, and the bridge-shaped ground conductor covers the coplanar electrode.

In order to solve the above problems, in the microwave integrated circuit according to the present invention, as described in claim 2, the bridge-shaped ground conductor of the interdigital capacitor is grounded outside the opposing coplanar electrode. It is characterized in that the space between the conductors is formed by a semi-cylindrical sheet member.

In the microwave integrated circuit thus constructed, the crosstalk with the external circuit can be reduced and the charge capacity value of the interdigital type capacitor can be increased, so that the microwave integrated circuit and the external circuit can be provided. The influence given can be reduced.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a microwave integrated circuit according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is 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. Further, FIG. 2 shows a sectional view taken along the line AA of FIG.

According to FIGS. 1 and 2, the interdigital capacitor 11 includes coplanar electrodes 12 and 13 and a bridge-shaped ground conductor 14 on the upper surface of a dielectric substrate 15. On the other hand, a lower ground conductor 16 is provided on the lower surface of the dielectric substrate 15. On the upper surface of the dielectric substrate 15, the coplanar electrode 12,
13 are provided facing each other. Further, because of the interdigital capacitor 11 having the coplanar structure, the ground conductor 17 exists on the outer side where the coplanar electrodes 12 and 13 face each other. Above the coplanar electrodes 12 and 13, a bridge-like grounding conductor 14 formed from a semi-elliptical cylinder (semi-cylindrical) sheet member is provided so as to cover the coplanar electrodes 12 and 13, and electrically connected to both ground conductors 17. Connected. That is, the bridge-shaped ground conductor 14 is bridge-connected between the ground conductors 17 and 17, and is provided over the coplanar electrodes 12 and 13.

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-shaped ground conductor 14, so that the bridge-shaped ground conductor 14 has the same effect as the shield plate. This bridge ground conductor 1
Due to the shielding effect of No. 4, the interdigital capacitor 11 has almost no coupling charge capacity with the element of the external circuit which causes the crosstalk. Therefore, crosstalk can be reduced significantly.

In the microwave integrated circuit 10,
Since it is a capacitor component that can have a coupled charge capacity with an adjacent external circuit, if the interdigital capacitor 11 can suppress the coupled charge capacity with an external circuit to a small value, the crossing of the microwave integrated circuit 10 as a whole will occur. It is possible to reduce talk.

FIG. 3 shows an equivalent circuit showing the charge capacity 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, 13 and the bridge-shaped ground conductor 14 in addition to the coupling charge capacity value Cc between the coplanar electrodes 12, 13. Has a charge capacity value Cp (Cp> 0) between them, and a ground-electrode charge capacity value.

FIG. 3B shows an equivalent circuit that is a more specific version of the equivalent circuit of FIG. According to this figure, the charge capacitance value of the interdigital capacitor 11 is the charge capacitance value of a capacitor in which a capacitor having a charge capacitance value of Cc and a capacitor having two capacitors having a charge capacitance value of Cp are connected in series. 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.

According to the embodiment of the present invention, in the microwave integrated circuit 10 including the interdigital capacitor 11 in which the bridge-shaped ground conductor 14 is provided above the coplanar electrodes 12 and 13, the bridge-shaped ground conductor 14 is shielded. It greatly reduces crosstalk with external circuits,
The influence on the microwave integrated circuit 10 and the external circuit can be reduced. Further, the charge capacity value of the interdigital capacitor 11 is larger than the charge capacity value of the conventional interdigital capacitor 1, and the degree of freedom in circuit design is expanded.

In the microwave integrated circuit 10 according to this embodiment, the bridge-shaped ground conductor 14 is formed in a semi-elliptical cylinder shape, but is not limited to the semi-elliptical cylinder shape. Includes all semi-cylindrical shapes. That is, the bridge-shaped ground conductor 14 may be formed in a semicircular shape or a half-angle tubular shape.

At least one interdigital capacitor in which the bridge-shaped ground conductor 14 is provided above the coplanar electrodes 12 and 13 may be present.

Furthermore, the interdigital capacitor 1 provided in the microwave integrated circuit 10 according to the present embodiment.
Although No. 1 includes the lower ground conductor 16 on the lower surface of the dielectric substrate 15, the lower ground conductor 16 may be omitted.

[0023]

According to the microwave integrated circuit of the present invention,
In an interdigital capacitor composed of a coplanar structure used in a microwave integrated circuit, a bridge-shaped ground conductor is provided over the coplanar electrode to reduce crosstalk with an external circuit, It is possible to provide a microwave integrated circuit in which the influence on the external circuit is reduced and the charge capacity value of the interdigital capacitor is increased.

[Brief description of 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 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 showing 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]

10 Microwave integrated circuit 11 Interdigital capacitor 12,13 Coplanar electrode 14 Bridge-shaped ground conductor 15 Dielectric substrate 16 Lower ground conductor 17 Ground conductor

Claims (2)

[Claims] 1. A microwave integrated circuit including an interdigital capacitor having a coplanar structure, wherein a bridge-shaped ground conductor is formed so as to extend from above between ground conductors outside the coplanar electrodes facing each other of the interdigital capacitor. A microwave integrated circuit that is installed, and the bridge-shaped ground conductor covers the coplanar electrode. 2. The microwave according to claim 1, wherein the bridge-shaped ground conductor of the interdigital capacitor has a semi-cylindrical sheet member between the ground conductors outside the coplanar electrodes facing each other. Integrated circuit.