JP2009290835A - Integratable non-reciprocal circuit element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an integratable non-reciprocal circuit element (isolator/circulator) which is formed on a surface of a circuit board on which another electronic element is arranged. <P>SOLUTION: The non-reciprocal circuit element is provided with: a microstrip line 1 having a Y-shaped center junction part 8 on a surface; a dielectric substrate 2 forming a ground conductor 6 on a rear; and a metal cap 3 formed on the surface side of the dielectric substrate 2 to cover at least the center junction part. The non-reciprocal circuit element is further provided with a gyromagnetic area generation member (planar ferrite 4 and planar dielectric 5) for generating a gyromagnetic area for non-reciprocally setting a signal transmission direction of the microstrip line 1 on an area surrounded by the metal cap 3 and the microstrip line 1. The ground conductor 6 formed on the rear of the dielectric substrate 2 is provided with a non-conductor portion on at least a part of a portion opposed to the area covered with the metal cap 3 on the surface of the dielectric substrate 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a nonreciprocal circuit device such as an isolator / circulator using a gyromagnetic effect, and particularly enables integration with a small, other electronic device using a microstrip line.

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, and other electronic components Is relatively large compared to
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. In the microwave integrated circuit isolator disclosed in Patent Document 1, a ferrite disk is embedded in a ceramic substrate, and a microstrip conductor and a ground conductor are formed over the front and back surfaces thereof.

Further, Patent Document 2 discloses a technology of a front and back mounting type isolator as a non-reciprocal circuit element aimed at further miniaturization. In this case, hexagonal ferrite that does not require a magnet is fired into a cylindrical shape, embedded in a ceramic substrate, the grounding conductor is entirely on one side of the ceramic substrate, and the branching junction and joining surface of the isolator are on the other side. Forming. However, these non-reciprocal circuit elements according to the prior art surround the entire element with a yoke, and therefore the isolator / circulator is manufactured as one component because the transmission line cannot be formed on the same substrate as other electronic elements. There is a problem that it is difficult to integrate. In other words, conventional non-reciprocal circuit elements such as isolators / circulators have a structure in which a transmission line is formed on a ferrite surface and surrounded by a yoke or a ground, so that a non-reciprocal circuit element cannot be formed on a circuit board. It was difficult.
Patent Document 3 describes a nonreciprocal circuit device in which a ferrite magnetic material is placed on a micro slip line. However, Patent Document 3 does not describe or suggest a metal cap and a non-conductor portion on the back side of the dielectric substrate.
Japanese Patent Laid-Open No. 10-173409 Japanese Patent Laid-Open No. 11-17408 Japanese Patent Application Laid-Open No. 2001-102813

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 circuit device for microwaves that utilizes the gyromagnetic effect. Since the lumped constant type isolator / circulator having a conventional structure is manufactured as individual components, it cannot be integrated with other electronic elements on the circuit board.
SUMMARY OF THE INVENTION An object of the present invention is to provide an irreversible circuit element (isolator / circulator) that can be integrated on a circuit board and can be formed on a surface on which other electronic elements are arranged. To do.

In order to achieve the above object, the present invention has the following configuration.
A dielectric substrate provided with a microstrip line having a Y-shaped center junction on the front surface and a ground conductor on the back surface;
A metal cap that is provided on the surface side of the dielectric substrate and covers at least the central joint;
A non-reciprocal circuit device having
A gyromagnetic region generating member for generating a gyromagnetic region for irreversibly setting a signal transmission direction on the microstrip line in a region surrounded by the metal cap and the microslip line;
The ground conductor provided on the back surface of the dielectric substrate is characterized in that a non-conductor portion is provided on at least a part of a portion facing the region covered with the metal cap on the surface of the dielectric substrate. A nonreciprocal circuit device.

Moreover, there may exist the following as a preferable embodiment.
The gyro magnetic region generating member is composed of a flat plate dielectric and a flat plate ferrite arranged in a stacked manner.
The gyro magnetic region generating member further has flat plate-shaped permanent magnets arranged in a stacked manner.
The metal cap and the ground conductor of the dielectric substrate are electrically connected.
The metal cap is made of a soft magnetic material.
The flat dielectric, the flat ferrite, and the flat permanent magnet may be laminated in any order, but the flat dielectric is laminated on the micro slip line, and the flat dielectric is placed on the flat dielectric. It is preferable to laminate a plate-like ferrite and laminate the plate-like permanent magnet on the plate-like ferrite. The flat permanent magnet may not be provided.
When a flat permanent magnet is not used, the flat ferrite is preferably hard magnetic ferrite.

According to the configuration of the present invention, the nonreciprocal circuit element can be reduced in size, and a gyromagnetic region can be generated on the microstrip line on the surface of the dielectric substrate forming the transmission region. Further, by using the circuit board as a dielectric substrate, a gyro magnetic region can be provided on the same surface as the substrate surface on which other electronic elements are installed, and integration with other electronic elements becomes possible.
In particular, a Y-shaped microstrip line is formed on the surface of a dielectric substrate, and a flat dielectric, flat ferrite, and metal cap to be a gyromagnetic region are installed on the surface, thereby making a nonreciprocal circuit device extremely Can be downsized.
Furthermore, by providing a non-conductor part with the ground conductor deleted on the back side of the dielectric substrate, the electric and magnetic fields of electromagnetic waves for obtaining irreversible transmission characteristics are further transferred from the input side transmission region to the gyro magnetic region. It is possible to efficiently guide from the magnetic region to the output side transmission region.
Similarly, electrically connecting the metal cap in the gyro magnetic region and the ground conductor existing on the back surface of the dielectric substrate, or arranging a plate-like permanent magnet in the gyro magnetic region is also an efficient and irreversible. It contributes to efficient transmission.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<Embodiment 1>
FIG. 1 is a diagram showing an example of the structure of a non-reciprocal circuit device according to Embodiment 1 of the present invention. FIG. 1A is a perspective view of the non-reciprocal circuit element from the upper surface, and FIG. 1B is a cross-sectional view taken along the alternate long and short dash line ACB in FIG. In the nonreciprocal circuit device of this embodiment, the microstrip line 1 is formed on the first substrate surface (front surface) of the dielectric substrate 2, and the ground conductor 6 is formed on the second substrate surface (back surface). A flat dielectric 5 and a flat ferrite 4 are arranged above the center joint 8 on the surface of the dielectric substrate 2. Further, the metal cap 3 is disposed so as to cover the center joint 8, the flat dielectric 5, and the flat ferrite 4. Although the ground conductor 6 is formed on the second substrate surface of the dielectric substrate 2, at least a part of the portion facing the center joint 8 is not covered (deleted) by the ground conductor 6. The structure has a conductor portion 9.

  FIG. 2 is an explanatory diagram of the transmission region 11 and the gyro magnetic region 12 in the nonreciprocal circuit device according to the first embodiment of the present invention. 2 (a) and 2 (b) correspond to FIGS. 1 (a) and 1 (b), respectively, and schematically show the transmission region and the gyro magnetic region. That is, the AD and EB broken line portions indicate the transmission region 11, and the DCE mesh portion indicates the gyro magnetic region 12. Most of the electric field of the electromagnetic wave traveling from the A direction toward the C direction is distributed in the transmission region 11 between the microstrip line and the ground conductor, but by providing a portion not covered by the ground conductor, The electric field is strongly distributed in the gyromagnetic region 12, the traveling direction of the electromagnetic wave is bent, and the electric field of the electromagnetic wave directed from C to B again propagates while being distributed in the transmission region 11. By providing the non-conductor portion 9 in the mesh portion of the DCE as described above, the electric field and magnetic field of the electromagnetic wave distributed in the dielectric substrate are reduced in the broken line portion of the AD, compared to the case where the non-conductor portion is not provided. In the shape portion, the gyromagnetic region on the metal cap side can be more efficiently induced. Further, in the broken line portion of the EB, an electric field and a magnetic field of electromagnetic waves can be induced in the dielectric substrate.

  FIG. 3 is a diagram showing an example of the structure of the nonreciprocal circuit device according to the first embodiment of the present invention. FIG. 3A is a perspective view of the non-reciprocal circuit device of the present invention, and FIG. 3B is a diagram showing the structure. The nonreciprocal circuit device 100 shown in FIG. 3 includes a microstrip line 1 having a center junction 8, a dielectric substrate 2, a metal cap 3, a plate-like ferrite 4, a plate-like dielectric 5, and a ground conductor 6. The microstrip line 1 and the ground conductor 6 can be formed on the surface of the dielectric substrate 2 by plating or the like. A non-conductor portion 9 is provided on a part of the substrate surface on which the ground conductor 6 facing the center joint portion 8 of the microstrip line 1 is formed. In order to avoid electrical contact between the metal cap 3 and the microstrip line 1, it is desirable to make a cut at the edge of the metal cap 3. Although not shown in FIG. 1, it is desirable that the metal cap 3 is electrically connected to the ground conductor 6 by providing a through hole in the dielectric substrate 2 and filling a material having high electrical conductivity. Thereby, the electric potentials of the ground conductor 6 and the metal cap 3 become equal, and the electric field and magnetic field of electromagnetic waves can be efficiently induced from the transmission region to the gyromagnetic region, and the operation of the nonreciprocal circuit element can be stabilized. The gyromagnetic effect is generated by applying a magnetic field of electromagnetic waves to the tabular ferrite 4 magnetized substantially perpendicular to the flat plate surface substantially perpendicular to the magnetization direction. In the case where the material of the tabular ferrite 4 has an easy magnetization axis in a direction substantially perpendicular to the plate surface, for example, a hard magnetic hexagonal ferrite, a magnetic field is applied from the outside of the tabular ferrite 4 The gyromagnetic effect can be generated without the need. When the material of the flat ferrite 4 is soft magnetic, it is necessary to apply a magnetic field from the outside of the flat ferrite 4. A specific form in which a magnetic field is applied from the outside will be described in a second embodiment described later. In the present embodiment shown in FIG. 1, a space for arranging a permanent magnet for applying a magnetic field to the flat ferrite 4 is provided above the flat ferrite 4.

  By making the structure of the nonreciprocal circuit element as shown in FIG. 3, the gyro magnetic region 12 can be arranged on the same surface as the substrate surface to which other electronic elements are mounted. Integration is possible. If a hard magnetic hexagonal ferrite is used as the plate-like ferrite 4, a permanent magnet for excitation becomes unnecessary and the space between the metal cap 3 and the plate-like ferrite 4 shown in FIG. The irreversible rotating element 100 can be reduced in height. In the nonreciprocal circuit device of the present invention shown in FIG. 1, the positions of the flat ferrite 4 and the flat dielectric 5 may be reversed.

  The material of the microstrip line 1 and the ground conductor 6 is preferably a material having high electrical conductivity such as Au, Ag, Cu, and Al. In addition, a printed circuit board is generally used as the dielectric substrate 2, but a ceramic substrate or the like may be used. A ceramic plate can be used for the flat dielectric 5. The flat ferrite 4 is a hard magnetic material, such as barium ferrite, strontium ferrite, or soft magnetic material, such as yttrium iron garnet (YIG ferrite) having a small magnetic resonance half width, but is an iron oxide material exhibiting ferromagnetism. I just need it. The metal cap 3 has a role as a ground conductor and an electrical / magnetic shielding effect, and at the same time it is desirable to form a magnetic circuit. Therefore, the metal cap 3 has a ferromagnetic property and has a high electrical conductivity. In order to prevent oxidation of the iron surface, iron whose surface is plated with gold or silver is most preferable.

<Embodiment 2>
FIG. 4 is a diagram showing the structure of the nonreciprocal circuit device according to the second embodiment of the present invention. FIG. 4A is a perspective view of the non-reciprocal circuit device of this embodiment, and FIG. 4B is a diagram showing the structure. The nonreciprocal circuit device 200 shown in FIG. 4 includes a microstrip line 1 including a central junction 8, a dielectric substrate 2, a metal cap 3, a flat ferrite 4, a flat dielectric 5, a ground conductor 6, and a permanent magnet 7. Composed. The difference from the first embodiment is that a permanent magnet 7 for applying a magnetic field to the flat ferrite 4 is arranged. When the flat ferrite 4 is a soft magnetic ferrite such as YIG ferrite, it is necessary to apply a magnetic field substantially perpendicular to the plate surface of the flat ferrite 4 in order to operate as a nonreciprocal circuit element. In the nonreciprocal circuit element 200 shown in FIG. 4, the metal cap 3 covers the flat dielectric 5, the flat ferrite 4, and the permanent magnet 7 for applying a magnetic field to the flat ferrite 4. The permanent magnet 7 is preferably an SmCo-based material or an NdFeB-based material having a large maximum energy product, but hard magnetic ferrite can also be used.
Since the structure of the nonreciprocal circuit element is the same as that of the second embodiment, the gyro magnetic region 12 can be arranged on the same surface as the substrate surface to which other electronic elements are attached. Integration is possible, and high-efficiency YIG ferrite that has already been developed can be used. In the nonreciprocal circuit device 200 of the present invention shown in FIG. 4, the positions of the flat ferrite 4 and the flat dielectric 5 may be reversed.

<Embodiment 3>
FIG. 5 is a diagram showing the structure of the nonreciprocal circuit device according to the third embodiment of the present invention. FIG. 5A is a perspective view of the non-reciprocal circuit device of this embodiment, and FIG. 5B is a diagram showing the structure. The nonreciprocal circuit element 300 includes a microstrip line 1, a dielectric substrate 2, a metal cap 3, a flat ferrite 4, a flat dielectric 5, a ground conductor 6, and a permanent magnet 7. A non-conductor portion 9 is provided on a part of the substrate surface on which the ground conductor 6 facing the center joint portion 8 of the microstrip line 1 is formed. The nonreciprocal circuit element 300 has a structure in which the metal cap 3 covers the flat dielectric 5, the flat ferrite 4, and the permanent magnet 7 for applying a bias magnetic field to the flat ferrite 4. The diameter of the flat ferrite 4 is substantially equal to the diameter of the non-conductor portion 9, and the diameter of the flat dielectric 5 is larger than the diameter of the flat ferrite 4 and substantially equal to the inner diameter of the metal cap 3.
Of course, these magnitudes may be reversed.
Since the structure of the nonreciprocal circuit element is the same as that of the third embodiment, the gyro magnetic region 12 can be arranged on the same surface as the substrate surface to which another electronic element or the like is attached. Integration is possible, and high-efficiency YIG ferrite that has already been developed can be used. In addition, when the electromagnetic field and the magnetic field are propagated from the transmission region to the gyromagnetic region and from the gyromagnetic region to the transmission region, the distribution of the electromagnetic field and the magnetic field can be more efficiently changed. In the nonreciprocal circuit element 300, the positions of the flat ferrite 4 and the flat dielectric 5 may be reversed.

<Embodiment 4>
FIG. 6 is a diagram showing the structure of the nonreciprocal circuit device according to the fourth embodiment of the present invention. FIG. 6A is a perspective view of the non-reciprocal circuit element 400 from the top surface, and FIG. 6B is a cross-sectional view of FIG. In the nonreciprocal circuit device 400 of the present embodiment, the microstrip line 1 including the center joint portion 8 is formed on the first substrate surface (front surface) of the dielectric substrate 2, and the ground conductor is formed on the second substrate surface (back surface). 6 is formed. A flat dielectric 5 and a flat ferrite 4 are arranged above the center joint 8 on the surface of the dielectric substrate 2. Further, the metal cap 3 is disposed so as to cover the center joint 8, the flat dielectric 5, and the flat ferrite 4. A structure in which a ground conductor 6 is formed on the second substrate surface of the dielectric substrate 2, but at least a part of a portion facing the center joint portion 8 has a non-conductor portion 9 that is not covered with the ground conductor 6. It has become. The diameter of the flat ferrite 4 is equal to the diameter of the non-conductor portion 9, and the diameter of the flat dielectric 5 is equal to the outer diameter of the metal cap 3. The reason why the width of the microstrip line 1 in the transmission region is different from that of the microstrip line 1 in the gyromagnetic region is that impedance matching is performed in order to efficiently transmit electromagnetic waves.

A simulation was performed for the following specific numerical values.
Dielectric substrate 2: Ceramic substrate having a thickness of 0.1 mm and a dielectric constant of 20.0 Flat plate dielectric 5: Ceramic having a thickness of 0.1 mm and a dielectric constant of 20.0 Flat plate ferrite 4 (YIG ferrite single crystal): 4πMs = 850G, ΔH = 2 Oe, thickness 0.1mm
FIG. 7 shows the result of calculation of the nonreciprocal transmission characteristics of the nonreciprocal circuit element 400 by the finite element method using a metal cap 3: 0.1 mm thick iron microstrip line 1 and a ground conductor 6: copper. The power of the electromagnetic wave incident from the Port 1 to the non-reciprocal circuit element 400 is P 1. Among the electromagnetic waves incident from the Port 1 to the non-reciprocal circuit element 400, the power of the electromagnetic wave reflected and returned to the Port 1 is P ′, and the non-reciprocal circuit element 400 from Port 1. P2 is the power of the electromagnetic wave transmitted to Port 2, and the power of the electromagnetic wave transmitted to Port 3 is P3 from the electromagnetic wave incident from the Port 1 to the nonreciprocal circuit element 400. Isolation and reflection loss are expressed by equations (1), (2), and (3), respectively.

(Reflection loss) = 10 log (P1 ′ / P1) (1)
(Insertion loss) = 10 log (P2 / P1) (2)
(Isolation) = 10 log (P3 / P1) (3)

As the nonreciprocal circuit element, it is preferable that the insertion loss has a small absolute value and the reflection loss and isolation have a large absolute value.
In the structure of the fourth embodiment shown in FIG. 6, as shown in FIG. 7, a result of good transmission characteristics of an insertion loss of 0.77 dB and an isolation of 16.75 dB was obtained in the vicinity of 1.97 GHz.

  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.

1 is a structural diagram of a nonreciprocal circuit device according to a first embodiment of the present invention. Explanatory drawing of a transmission area | region and a gyromagnetic area | region. 1 is a structural diagram of a nonreciprocal circuit device according to a first embodiment of the present invention. FIG. 6 is a structural diagram of a nonreciprocal circuit device according to a second embodiment of the present invention. FIG. 6 is a structural diagram of a nonreciprocal circuit device according to a third embodiment of the present invention. FIG. 6 is a structural diagram of a nonreciprocal circuit device according to a fourth embodiment of the present invention. Graph showing transmission characteristics.

Explanation of symbols

1: Microstrip line, 2: Dielectric substrate, 3: Metal cap, 4: Flat ferrite (YIG ferrite single crystal), 5: Flat dielectric, 6: Ground conductor, 7: Permanent magnet, 8: Center Junction, 9: Non-conductor portion, 11: Transmission region, 12: Gyromagnetic region, 100: Non-reciprocal circuit device, 200: Non-reciprocal circuit device, 300: Non-reciprocal circuit device, 400: Non-reciprocal circuit device

Claims (5)

A dielectric substrate provided with a microstrip line having a Y-shaped center junction on the front surface and a ground conductor on the back surface;
A metal cap that is provided on the surface side of the dielectric substrate and covers at least the central joint;
A non-reciprocal circuit device having
A gyromagnetic region generating member for generating a gyromagnetic region for irreversibly setting a signal transmission direction on the microstrip line in a region surrounded by the metal cap and the microslip line;
The ground conductor provided on the back surface of the dielectric substrate is characterized in that a non-conductor portion is provided on at least a part of a portion facing the region covered with the metal cap on the surface of the dielectric substrate. A nonreciprocal circuit device.   2. The nonreciprocal circuit device according to claim 1, wherein the gyro magnetic region generating member is composed of a flat dielectric and a flat ferrite arranged in a stacked manner.   3. The nonreciprocal circuit device according to claim 2, wherein the gyro magnetic region generating member further includes flat permanent magnets arranged in a stacked manner.   The nonreciprocal circuit device according to claim 1, wherein the metal cap and a ground conductor of the dielectric substrate are electrically connected.   The nonreciprocal circuit device according to claim 1, wherein the metal cap is made of a soft magnetic material.

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