JPH0864923A - Pattern inductor and radio communication equipment - Google Patents

Abstract

PURPOSE: To provide a pattern inductor wherein stray capacitance can be reduced when an inductor and a ground conductor layer are three-dimensionally arranged on the surface and the back by using a double-sided board, and the electrostatic breakdown voltage characteristics of a surface acoustic wave filter can be improved. CONSTITUTION: This pattern inductor 20 is provided with a belt-shaped conductor which is formed on one conductor layer of the facing conductor layers of a printed board 21 having at least two conductor layers via an insulating layer, so as to be turned into an inductor, and a ground conductor layer 23 formed on the other conductor layer. A ground conductor in a part facing an inductor of the ground conductor layer 23 is eliminated. A radio communication equipment which is used by inserting the pattern inductor 20, in series, in the input part of a surface acoustic wave filter is also provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print type inductor, and more particularly to a pattern inductor having a ground conductor layer and a strip conductor via an insulating layer to reduce stray capacitance and improve electrostatic breakdown voltage.

[0002]

2. Description of the Related Art Conventionally, a surface acoustic wave filter having a small insertion loss and a large strip band attenuation has been widely used as a reception carrier passing band pass filter of a wireless communication device such as a cordless telephone. However, this surface acoustic wave filter has drawbacks such as a large ripple in the pass band and a low electrostatic breakdown voltage. Therefore, in order to eliminate these drawbacks, as shown in FIG. 4, an inductor 4 having a ground conductor layer 3 is provided in series with the input portion of the surface acoustic wave filter 2 to which the reception signal captured by the antenna 1 is input. Connected. The inductor 4 reduces ripples, and the ground conductor layer 3 shields the inductor 4. In addition, by disposing the ground conductor layer 3 close to the inductor 4, a discharge gap is formed as an electrostatic discharge path to improve the electrostatic breakdown voltage characteristic of the surface acoustic wave filter.

As such an inductor, a printed board having conductor layers on both sides with an insulating layer in between, a so-called double-sided board 5, is used to form a strip-shaped conductor pattern on the surface as shown in FIG. As shown, the pattern inductor 6 having the ground conductor layer 3 on the back surface is used. The input terminal portion 7 and the ground terminal portion 8 of the inductor 4 are formed with conductor patterns on the front and back surfaces of the double-sided substrate 5 so that they can be soldered to each other through through holes 9 and 10 for insertion of external leads (not shown). Has been done. The output terminal portion 11 is also formed with a conductor pattern on the front and back sides of the double-sided substrate 5 so that leads such as a capacitor (not shown) can be inserted into the through holes 12 and soldered.

However, the patterned inductor 6 having the above-described structure has a stray capacitance because it is opposed to the ground conductor layer 3 via the insulating layer such as glass epoxy of the double-sided substrate 5. This stray capacitance increases as the insulating layer of the double-sided substrate 5 becomes thinner due to the recent tendency toward lightness, thinness, shortness, and miniaturization.
When it is used in a high frequency circuit such as a wireless communication device, in particular, the insertion loss of the input signal is increased and the reception sensitivity is deteriorated. Therefore, in order to reduce the stray capacitance, as shown in FIG. 7, the inductor 13 and the ground conductor layer 14 around the inductor 13 are planarly arranged on the dielectric substrate, and the input / output of the inductor 13 is reduced. There is disclosed a pattern inductor having a structure in which a portion is provided so as to straddle the ground conductor layer 14 (see JP-A-2-163913).

[0005]

Since the above-described patterned inductor having the ground conductor layer arranged in a plane is formed on the dielectric substrate, there is a problem that the substrate material is limited. Further, since the ground conductor layer is arranged in a plane, there is a problem that the configuration area becomes large and the shield effect of the inductor by the ground conductor layer becomes insufficient. Therefore, the present invention has been proposed in order to solve the above-mentioned problems, and an object of the present invention is to provide a pattern inductor having a small stray capacitance and improving discharge voltage by forming a discharge gap as an electrostatic discharge path. And

[0006]

In a pattern inductor in which a strip conductor and a ground conductor layer are formed with an insulating layer sandwiched therebetween, the ground conductor layer has a configuration in which the ground conductor layer at a position facing the strip conductor is removed. To do. Also provided is a wireless communication device that uses a surface acoustic wave filter as a bandpass filter for a reception band, and that is used as an inductor that is inserted in series with the input portion of the surface acoustic wave filter.

[0007]

According to the above structure, since the strip conductor and the ground conductor of the inductor are not arranged to face each other, the stray capacitance between the inductor and the ground conductor can be reduced, and
Since the discharge gap is disposed in close proximity as an electrostatic discharge path between the inductor and the ground conductor layer, the electrostatic breakdown voltage characteristic of the surface acoustic wave filter can be improved. In addition, since the inductor and the ground conductor layer are three-dimensionally arranged via the insulating layer of the printed circuit board, the area of the structure can be reduced as compared with the case where the inductor and the ground conductor layer are formed on the same plane, and the ground conductor is eliminated. Since the part is only the part facing the inductor, it is very small with respect to the area of the entire ground conductor layer, so that the practical shield effect is not impaired.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In the figure, the same parts as those in the conventional example are designated by the same reference numerals and the description thereof will be omitted. The pattern inductor of the present invention is characterized by the pattern configuration of the ground conductor layer. That is, in the patterned inductor 20 of the present invention, as shown in FIG. 2, a strip-shaped conductor pattern inductor 22 is formed on the conductor layer on the surface of the double-sided substrate 21. And FIG.
As shown in FIG. 5, the ground conductor layer 23 on the back surface has a configuration in which the ground conductor at a position facing the pattern of the inductor 22 on the front conductor layer is removed. Then, similar to the conventional example, the conductor patterns of the input terminal portion 7, the ground terminal portion 8 and the output terminal portion 11 of the inductor 22 are formed on the front and back surfaces of the double-sided substrate 21 through the external leads (not shown) through the holes 9. 1
It is formed so that solder connection can be made via 0 and 12.

With this structure, as shown in FIG. 3, since the ground conductor does not exist on the back surface facing the inductor 22, the inductor 22 and the ground conductor do not face each other, and the stray capacitance is very large. In addition, the inductor 22 and the ground conductor layer 23 are made smaller, and
Since they are arranged close to each other around 4 (for example, a portion indicated by an arrow in FIG. 3), a discharge gap is formed as an electrostatic discharge path, and the electrostatic breakdown voltage characteristic of the surface acoustic wave filter can be improved. Therefore, reduce the thickness of the double-sided substrate 21,
Even if it is made light, thin, short, and small, stray capacitance of a size that poses a practical problem does not occur. In addition, since the removed portion 24 of the ground conductor is very small in only the portion facing the inductor 22 with respect to the area of the entire ground conductor layer 23, the shield effect does not decrease.

The example of the pattern inductor using the double-sided board and connected in series to the input section of the surface acoustic wave filter of the cordless phone has been described above, but the present invention is not limited to this, and for example, a three-layer printed circuit board. The first layer and the second layer are configured as described above, and the third layer is entirely used as a ground conductor layer to further improve the shield effect, and a four-layer printed circuit board is used. 3rd layer and 4
Each of the layers has the configuration of the present invention, and the pattern inductors of two circuits are three-dimensionally arranged, whereby the reception input circuit of the wireless communication device having the two circuits of the surface acoustic wave filter for bandpass can be downsized. Various uses such as possible are possible.

[0011]

According to the pattern inductor of the present invention,
Since the conductor layer of the inductor and the ground conductor are not arranged so as to face each other, the stray capacitance between the inductor and the ground conductor can be reduced, and a discharge gap can be formed close to the inductor and the ground conductor layer. Therefore, the electrostatic breakdown voltage characteristic of the surface acoustic wave filter can be improved. Further, since the inductor and the ground conductor layer are three-dimensionally arranged via the insulating layer of the printed board, the construction area can be reduced and the shielding effect is not impaired.

[Brief description of drawings]

FIG. 1 is a plan view of an essential part of a back surface of a patterned inductor according to an embodiment of the present invention.

FIG. 2 is a plan view of a main portion of a surface of a pattern inductor according to an embodiment of the present invention.

FIG. 3 is a sectional view of an essential part of a pattern inductor according to an embodiment of the present invention.

FIG. 4 is a configuration diagram of a reception input unit of a wireless communication device.

FIG. 5 is a plan view of a main part of a surface of a conventional pattern inductor.

FIG. 6 is a plan view of the main part of the back surface of a conventional pattern inductor.

FIG. 7 is a perspective view of another conventional pattern inductor.

[Explanation of symbols]

 20 Pattern Inductor 21 Double-sided Board (Printed Circuit Board) 22 Inductor 23 Grounding Conductor Layer 24 Deleted Part of Grounding Conductor

Claims (2)

[Claims] 1. A pattern inductor in which a strip conductor and a ground conductor layer are formed with an insulating layer sandwiched therebetween, wherein the ground conductor layer has a ground conductor layer at a position facing the strip conductor removed. Pattern inductor. 2. A radio communication device comprising a surface acoustic wave filter as a band pass filter for a reception band and the pattern inductor according to claim 1, which is inserted in series with an input portion of the surface acoustic wave filter. .