JP2008244680A - Non-reciprocal circuit element which can be integrated - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-reciprocal circuit element (isolator/circulator), which can be formed on a dielectric substrate, especially on a circuit board, and can be integrated. <P>SOLUTION: The non-reciprocal circuit element comprises a dielectric substrate 1 having a transmission line 2 on one surface and a ground plane 3 on the opposite surface, a flat plate ferrite 4 arranged at the ground plane side of the dielectric substrate, a flat plate permanent magnet 5 arranged at a surface opposite to the dielectric substrate of the flat plate ferrite, and a yoke 6 arranged at a surface opposite to the flat plate ferrite of the flat permanent magnet so as to enclose the flat plate ferrite and the flat permanent magnet. Wherein, at least a part of the yoke 6 is connected to the ground plane of the dielectric substrate, while at least the dielectric substrate side surface of the york is open. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention can sufficiently induce a microwave even when a transmission line is formed on a dielectric substrate in a ferrite part of an isolator / circulator that is a non-reciprocal circuit element using a gyromagnetic effect, and further efficiently applies a bias magnetic field. The present invention relates to the structure of a yoke to be applied to ferrite and the integration of an isolator / circulator that can be realized by applying the structure.

In recent years, portable electronic devices are required to be miniaturized, and accordingly, electronic components mounted thereon are also required to be small and thin. Non-reciprocal circuit elements (isolators / circulators), which are one of the electronic components, are gradually becoming smaller and thinner, but the whole is surrounded by a yoke in order to apply a sufficient bias magnetic field, Is relatively large compared to Further, the structure is not such that elements are formed and integrated on a circuit board.
Conventional isolators / circulators have a structure in which ferrite is sandwiched between a transmission line and a ground plane in order to obtain good irreversible operating characteristics, and generally a transmission line is formed on the surface of the ferrite. Further, in order to apply a strong bias magnetic field to the ferrite portion, the magnetic circuit is formed by surrounding the entire element with a yoke such as iron. However, since the entire element is surrounded by a yoke, the transmission line cannot be formed on the same substrate as the other electric elements, so that there is a problem that the isolator / circulator is a single chip and is difficult to integrate. In other words, the conventional non-reciprocal circuit element (isolator / circulator) has a structure in which the transmission line is formed on the ferrite surface and surrounded by the yoke or the ground, and therefore, the non-reciprocal circuit element cannot be formed on the circuit board. It was difficult. FIG. 4 is an example of a conventional non-reciprocal circuit device.

The following are mentioned as a prior art.
Patent Document 1 describes a non-reciprocal circuit device in which a transmission line is provided on a substrate made of SiO ₂ , flat ferrite is disposed on the substrate, and the substrate and the flat ferrite are surrounded by a ground conductor. . However, Patent Document 1 does not consider the formation of a nonreciprocal circuit element on a circuit board.
Patent Document 2 describes a nonreciprocal circuit element that includes a nonreciprocal circuit element body 10, a permanent magnet 20, and a yoke 30, and at least one surface of the yoke 30 is open. The nonreciprocal circuit element body 10 has a transmission line embedded therein and does not form the transmission line on a dielectric substrate. In the configuration of Patent Document 2, it is considered that the performance as a non-reciprocal circuit element cannot actually be exhibited sufficiently.
JP 2006-262260 A JP-A-8-78911

When an electromagnetic wave travels through the ferrite applied so that the bias magnetic field is perpendicular to both the traveling direction of the electromagnetic wave and the amplitude direction of the electromagnetic field, the propagation direction of the electromagnetic wave is rotated by the gyromagnetic effect. The isolator / circulator is a non-reciprocal rotating element for microwaves that uses this gyromagnetic effect, and its frequency characteristics greatly depend on the bias magnetic field applied to the ferrite. In general, a bias magnetic field of about 300 Oe or more is required to operate an isolator / circulator at a frequency of GHz or more. Considering the demagnetizing factor of the ferrite plate, it is usually necessary to apply a magnetic field of 1000 Oe or more to the ferrite. However, with a small permanent magnet (mm size) built in a conventional small isolator / circulator, it is difficult to apply such a large magnetic field unless the magnetic circuit is configured by covering the entire element with a yoke. There was a problem.
An object of the present invention is to solve the above problems and to provide an irreversible circuit element (isolator / circulator) that can be integrated on a dielectric substrate, particularly on a circuit substrate.

In order to achieve the above object, the present invention has the following configuration.
A dielectric substrate having a transmission line on one side and a ground plane on the other side;
A flat ferrite disposed on the ground plane side of the dielectric substrate;
A flat permanent magnet disposed on a surface of the flat ferrite opposite to the dielectric substrate;
A yoke disposed on the surface of the flat permanent magnet opposite to the flat ferrite and disposed so as to surround the flat permanent magnet and the flat ferrite;
The yoke is at least partially connected to the ground plane of the dielectric substrate,
A non-reciprocal circuit device, wherein at least a surface of the yoke on the dielectric substrate side is open.
A circuit board forming step of forming a transmission line on one side of the circuit board and a ground plane on the opposite side;
A yoke mounting step of mounting a flat ferrite and a flat permanent magnet, and mounting the yoke disposed so as to surround the flat permanent magnet and the flat ferrite on the ground surface side of the circuit board;
Connecting the yoke to a ground conductor of the ground plane, and
The ground conductor is removed from a part of the ground surface, and the flat ferrite is disposed in a portion of the circuit board from which the ground conductor is removed in the yoke mounting step. Circuit element mounting method.

Moreover, it has the following embodiments.
The dielectric substrate is a circuit board, and the transmission line and the ground plane are formed on the circuit board.
The flat ferrite is a YIG single crystal. The flat ferrite is not particularly limited as long as it has ferrite characteristics, but a YIG single crystal is particularly preferable.

  Since the present invention adopts the above configuration, the magnetic field and electric field of electromagnetic waves can be concentrated on the substrate and the ferrite magnet located between the transmission line and the ground plane, so that the ferrite surface can be used like a conventional isolator / circulator. It is not necessary to form a transmission line directly. Therefore, the transmission line can be arranged on the side opposite to the ferrite on the circuit board (dielectric substrate), and the degree of freedom in designing the circuit board is increased. In addition, in order to uniformly apply a bias magnetic field to a ferrite magnet, a conventional isolator / circulator forms a closed magnetic circuit in a form in which the entire element is covered with a yoke. However, a yoke is formed only on the upper or lower surface of a ferrite magnet. A bias magnetic field with sufficient strength can be obtained even by arranging them. Therefore, by adopting such a structure, it can be arranged on a circuit board and can be integrated.

Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.
1 and 2 are diagrams showing an example of the structure of the non-reciprocal circuit device of the present invention. The left figure of FIG. 1 is a perspective view, and the right figure is a perspective view and a side view from above. FIG. 2 is a diagram illustrating the relationship between the dielectric substrate, the yoke, and the ground plane. The nonreciprocal circuit device includes a dielectric substrate 1 having a transmission line 2 on one side and a ground plane (ground conductor) 3 on the opposite side, and a flat ferrite 4 disposed on the ground plane 3 side of the dielectric substrate 1. And a flat permanent magnet 5 disposed on the surface of the flat ferrite 4 opposite to the dielectric substrate 1, and a flat permanent magnet 5 disposed on the surface opposite to the flat ferrite 4; And a yoke 6 arranged so as to surround the flat permanent magnet 5 and the flat ferrite 4. The dielectric substrate 1 is, for example, a printed circuit board, but is not limited to a printed circuit board. Further, the flat ferrite 4 is, for example, a YIG single crystal, but is not limited thereto, and may be anything as long as it has ferrite properties. The yoke 6 is at least partially connected to the ground plane 3 of the dielectric substrate 1 and at least the surface of the yoke 6 on the dielectric substrate 1 side is open.

With such a structure, the magnetic field and electric field of electromagnetic waves can be concentrated on the substrate and the ferrite magnet located between the transmission line and the ground plane. There is no need to form a transmission line. In addition, in order to apply a bias magnetic field uniformly to a ferrite magnet, a conventional isolator / circulator forms a closed magnetic circuit in such a manner that the entire element is covered with a yoke. A bias magnetic field with sufficient strength can be obtained even by arranging them. Furthermore, integration is possible by using such a structure.
With this nonreciprocal circuit element configuration, a part of the ground plane opposite to the transmission line coupling portion formed on the circuit board is removed, and a ferrite single crystal, a permanent magnet for bias and a yoke are arranged there. Only, irreversible operating characteristics can be obtained. As a result, it is possible to realize miniaturization and integration of an isolator / circulator that has been difficult to integrate with other electrical elements. This nonreciprocal rotating element is basically based on the operating principle of a small nonreciprocal element (Patent Document 1), but can also be applied to a general distributed constant type nonreciprocal element.

Examples are shown below.
Dielectric substrate: Gallium arsenide (GaAs) with a thickness of 0.1mm and dielectric constant of 12.9
Ferrite (YIG single crystal): 4πMs = 850G, ΔH = 2 Oe, thickness 0.15mm
Permanent magnet: SmCo
Yoke: Fig. 3 shows the results of transmission characteristics calculated by the finite element method using iron with a thickness of 0.15 mm.
Good transmission characteristics of insertion loss of 0.88dB and isolation of 24.04dB were obtained near 1.92GHz.

Although an example of the embodiment of the present invention has been described above, the present invention is not limited to this, and it goes without saying that various modifications can be made within the scope of the technical idea described in the claims. Yes.

It is a structural diagram of the nonreciprocal circuit device of the present invention. It is a figure showing the relationship between the dielectric substrate of the nonreciprocal circuit device of this invention, a yoke, and a ground plane. It is a graph showing a transmission characteristic. It is a figure of the conventional nonreciprocal circuit device.

Explanation of symbols

1 Dielectric substrate (circuit board)
2 Transmission line 3 Ground plane (ground conductor)
4 Flat ferrite (YIG single crystal)
5 Flat permanent magnet 6 Yoke

Claims (4)

A dielectric substrate having a transmission line on one side and a ground plane on the other side;
A flat ferrite disposed on the ground plane side of the dielectric substrate;
A flat permanent magnet disposed on a surface of the flat ferrite opposite to the dielectric substrate;
A yoke disposed on the surface of the flat permanent magnet opposite to the flat ferrite and disposed so as to surround the flat permanent magnet and the flat ferrite;
The yoke is at least partially connected to the ground plane of the dielectric substrate,
A non-reciprocal circuit device, wherein at least a surface of the yoke on the dielectric substrate side is open.   The nonreciprocal circuit device according to claim 1, wherein the dielectric substrate is a circuit substrate, and the transmission line and the ground plane are formed on the circuit substrate.   The non-reciprocal circuit device according to claim 1, wherein the flat ferrite is a YIG single crystal. A circuit board forming step of forming a transmission line on one side of the circuit board and a ground plane on the opposite side;
A yoke mounting step of mounting a flat ferrite and a flat permanent magnet, and mounting the yoke disposed so as to surround the flat permanent magnet and the flat ferrite on the ground surface side of the circuit board;
Connecting the yoke to a ground conductor of the ground plane, and
The ground conductor is removed from a part of the ground surface, and the flat ferrite is disposed in a portion of the circuit board from which the ground conductor is removed in the yoke mounting step. Circuit element mounting method.