JPH05102710A - High frequency transmission circuit - Google Patents

Abstract

PURPOSE:To easily form a bypass capacitor or a coupling capacitor coping with high density mount. CONSTITUTION:A strip conductor 3 is provided in a dielectric body 2 of a multi-layer board and an interval between ground planes 1a and 1b opposite to the strip conductor 3 is changed and the area of the strip conductor 3 is changed to form a capacitor with a prescribed static capacitance between the strip conductor 3 and the ground planes 1a, 1b. One terminal of the strip conductor 3 is connected to a power line of the high frequency circuit with a throughhole to act the capacitor like a bypass capacitor. Moreover, a surface mount component is connected by the strip conductor 3 and the ground planes 1a, 1b with a throughhole to act the capacitor like a coupling capacitor and other component is mounted between the components on the surface to attain high density mount.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a wireless communication device,
The present invention relates to a high frequency transmission circuit used for a high frequency circuit using a multilayer circuit board.

[0002]

2. Description of the Related Art Conventionally, a high-frequency transmission circuit using this type of multilayer circuit board uses an inner layer conductor portion as a connection line for performing high-frequency transmission between surface-mounted high-frequency components.
In addition to this, it is also used as a ground plane for a shield that blocks coupling between high-frequency components. Further, it is also used as a coaxial line having a predetermined impedance, a so-called strip line.

[0003]

However, this conventional high-frequency transmission circuit only performs high-frequency transmission and shielding, and is not used as a component itself. It cannot meet the demand for high-density mounting. For this reason, there is a drawback that it cannot contribute to cost reduction, weight reduction, and size reduction of high-frequency equipment.

As described above, the present invention solves the conventional problems and is an excellent high-frequency transmission circuit in which a bypass capacitor for high-frequency removal or a coupling capacitor for high-frequency transmission that can contribute to high-density mounting can be easily constructed. The purpose is to provide.

[0005]

In order to achieve this object, a high frequency transmission circuit of the present invention includes a strip conductor provided in an inner layer portion of a multilayer circuit board and connected to the high frequency circuit, and facing the strip conductor. And a conductor layer connected to the high-frequency circuit, the distance between the strip conductor and the conductor layer is changed, and the area of the strip conductor is changed to change the area between the strip conductor and the conductor layer. Is operated as a capacitor having a predetermined electrostatic capacity.

[0006]

Therefore, according to the high frequency transmission circuit of the present invention, since the strip conductor and the conductor layer facing the strip conductor are formed into a capacitor having a predetermined capacitance and are connected to the high frequency circuit, A bypass capacitor for high frequency removal corresponding to the high density mounting or a coupling capacitor for high frequency transmission can be easily configured.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a high frequency transmission circuit on a multi-layer substrate according to the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention.
In FIG. 1, 1a and 1b are ground planes in the multilayer substrate, 2 is a dielectric provided between the ground planes 1a and 1b, and 3 is a strip conductor provided in the dielectric 2.

The operation of this configuration will be described below.
Impedance Z of the strip conductor 3 in this configuration
₀ is approximately

[0010]

[Equation 1]

Can be expressed as As can be understood from this (Equation 1), the distance between the ground planes 1a and 1b and the strip conductor 3, that is, the ground plane 1
The impedance of the strip conductor 3 can be lowered by reducing the distance h between a and 1b and increasing the width w of the strip conductor 3.

FIGS. 2 and 3 show the results of analysis of the equation (1) using microwave simulation (MDS).
FIG. 2 shows the capacitance (0 to 100 PF) with respect to the area (AREA) of the strip conductor 3 as M1, M2, M3, M4, and M5.
And M6. The condition in this case is that the frequency is 800 to 1000 MHz, and the strip conductor 3
Has a width w of 1 mm, a length of 34 mm and a thickness t of 0.0
The distance between the ground planes 1a and 1b and the strip conductor 3 is 0.4 mm.

FIG. 3 shows impedances at M1, M2, M3, and M4. In this case, the condition is 90 frequency.
0 MHz, the distance between each of the ground planes 1a and 1b and the strip conductor 3 is 0.4 mm, the width w of the strip conductor 3 is 1 mm, and the thickness t is 0.035 mm.

This result also demonstrates that the strip conductor 3 can be used as a capacitance having a low impedance, that is, as a condenser forming a high frequency circuit. Since the capacitor operates as a capacitor having a low impedance as described above, the gap between the strip conductor 3 and the ground planes 1a and 1b facing each other is changed, and the area of the strip conductor 3 is changed to obtain a predetermined static capacitance. The capacitance can be used as a bypass capacitor for high frequency removal forming a high frequency circuit or a coupling capacitor for high frequency transmission.

In the bypass capacitor in this case, a strip conductor 3 is provided in the dielectric 2 between the ground planes 1a and 1b on the surface layer of the multilayer circuit board, and one end of this is connected to the power supply line of a high frequency circuit (not shown) by a through hole. The surface mounting area is not reduced.

Also in the case of a coupling capacitor, it suffices to connect a surface-mounted component (not shown) to one or both of the strip conductor 3 and the ground planes 1a and 1b arranged in the dielectric 2 by through holes. Also, since it is not necessary to provide a coupling capacitor on the surface layer, high density mounting becomes possible. Therefore, in each case, high-density mounting can be easily performed, and as a result, it is possible to contribute to the cost reduction, weight reduction and size reduction of the high frequency device.

[0017]

As is apparent from the above description, in the high frequency transmission circuit of the present invention, a strip conductor and a conductor layer facing the strip conductor are formed into a capacitor having a predetermined electrostatic capacitance to form a high frequency circuit. Since they are connected, there is an effect that a bypass capacitor for high frequency removal corresponding to high density mounting or a coupling capacitor for high frequency transmission can be easily configured.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of an embodiment of a high frequency transmission circuit of the present invention.

FIG. 2 is a characteristic diagram showing capacitance with respect to a change in area of a strip conductor by MDS.

FIG. 3 is an impedance characteristic diagram showing changes in impedance due to MDS.

[Explanation of symbols]

 1a, 1b Ground plane 2 Dielectric 3 Strip conductor

Claims (1)

[Claims] 1. A strip conductor provided on an inner layer portion of a multilayer circuit board and connected to a high frequency circuit; and a conductor layer provided on the multilayer circuit board facing the strip conductor and connected to a high frequency circuit. By changing the distance between the strip conductor and the conductor layer, and changing the area of the strip conductor so that the space between the strip conductor and the conductor layer operates as a capacitor having a predetermined capacitance. A high-frequency transmission circuit characterized in that