JPH07326908A - Irreversible circuit element - Google Patents

Abstract

PURPOSE:To improve insertion loss characteristics or the like without increasing the number of parts by forming a recessed part or a hole at a part opposite to the permanent magnet of a yoke for forming a magnetic closed circuit and impressing an uniform magnetic field to the entire ferrite. CONSTITUTION:The recessed part 1a is formed at the center part of the bottom plate inner wall of the lower yoke 1 of a circulator. The recessed part 1a formed at the center part of the bottom plate inner wall of the lower yoke 1 is formed in a shape for forming approximately a part of a sphericality. That is, it is formed so as to let the thickness of the center part of the recessed part 1a be thin and to let the thickness become closer to the thickness of a plate thickness as the peripheral part of the recessed part 1a gets closer. Magnetic force distribution at a ferrite position inside the magnetic closed circuit formed by the lower yoke and an upper yoke has flat characteristics at the part equivalent to the diameter of the ferrite and the uniform magnetic field is impressed to the entire ferrite. As a result, the insertion loss of the circulator is substantially improved more than the insertion loss of a conventional circulator indicated by a dotted line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-reciprocal circuit device, such as an isolator or a circulator, used in a communication device such as a car phone or a mobile phone.

[0002]

2. Description of the Related Art Generally, non-reciprocal circuit elements such as isolators and circulators have a function of passing signals only in the transmission direction and blocking transmission in the opposite direction, and are used in mobile telephones, mobile phones and the like. It is used in the transmitter circuit of body communication equipment.

As such a circulator, there is one having a structure as shown in FIGS. 7 and 8, for example. FIG. 7 is an exploded perspective view showing the overall configuration of the circulator.
Is an exploded perspective view showing the internal structure of the dielectric multilayer substrate,
What is shown in FIG. 7 is shown upside down. In the following drawings, various electrode (pattern) forming portions are shown by being filled with dots.

In this circulator, as shown in FIG. 7, a ground plate 2 is arranged on a bottom plate of a lower yoke 1, a ferrite 3 is arranged on the ground plate 2, and a central portion thereof is arranged so as to cover the ferrite 3. A dielectric multi-layer substrate 4 having a concave portion into which a ferrite 3 is fitted is placed on the upper yoke 6, and an upper yoke 6 having a permanent magnet 5 attached to an inner wall of a top plate is attached to the lower yoke 1 to form a magnetic closed circuit. At the same time, the permanent magnet 5 is configured to apply a DC magnetic field to the ferrite 3. The lower yoke 1 and the upper yoke 6 are made of magnetic metal, and the surfaces thereof are plated with Ag or the like. The bottom plate portion of the lower yoke 1 facing the permanent magnet 5 is formed by parallel surfaces having no unevenness.

As shown in FIG. 8, the multilayer substrate 4 has various electrodes formed on the surface of a large number of dielectric ceramic green sheets having a thickness of several tens of μm by pattern printing or the like, and the sheets are laminated. Then, the various electrodes formed on each sheet are connected to each other at predetermined places by through holes or via holes.

Specifically, the sheets 21 to 26 are provided with a ground electrode, a port electrode, a connection electrode and the like, and the multilayer substrate 4
Forming the input / output section of the.

Three capacitance electrodes are formed on the sheet 32, and a matching circuit (matching capacitance) of each port is formed by two interelectrode capacitances between these capacitance electrodes and the ground electrodes formed on the sheets 31 and 33. Are formed.

One center electrode is formed on each of the sheets 41, 42 and 43, and the center electrodes are stacked so as to form an angle of 120 degrees with each other, one end of which is a port electrode and the other end of which is grounded. It is connected to the electrode by a via hole or the like.

The circulator thus constructed is
Irreversibility is generated by applying a DC magnetic field to the ferrite 3 in a direction perpendicular to its main surface. And
A magnetic field in the vertical direction is applied to the ferrite 3 by a magnetic closed circuit formed by the permanent magnet 5 and the yoke composed of the lower yoke 1 and the upper yoke 6.

[0010]

However, in the conventional circulator shown in FIG. 7, the bottom plate portion of the yoke is formed by parallel planes having no unevenness, and the magnetic force lines are perpendicular to the ferrite central portion, but In the peripheral part of the magnetic field, the magnetic flux will pass with an inclination, and the distribution of the magnetic force at the ferrite position will have a unimodal characteristic as shown by the broken line in FIG.
A uniform magnetic field is not applied to the entire ferrite. As described above, since the magnetic field applied to each part of the ferrite is not uniform, there is a problem that characteristics such as insertion loss and isolation are deteriorated.

Therefore, an object of the present invention is to solve the problems of the conventional non-reciprocal circuit device as described above, and to form a recess or a hole in a part of a yoke forming a magnetic closed circuit to form a ferrite core. The object is to provide a high-performance nonreciprocal circuit device having good characteristics such as insertion loss by applying a uniform DC magnetic field to each part.

[0012]

To achieve the above object, the present invention provides a nonreciprocal circuit device comprising a permanent magnet, a ferrite and a plurality of center electrodes arranged in a yoke forming a magnetic closed circuit. In the yoke forming the magnetic closed circuit, a concave portion or a hole is formed in a portion facing the permanent magnet so that a uniform magnetic field is applied to the entire ferrite.

[0013]

According to the above structure, the portion of the yoke constituting the magnetic closed circuit of the nonreciprocal circuit element facing the permanent magnet is processed into a recess or a hole, so that the magnetic force distribution in the magnetic closed circuit is made uniform. Can be converted. Therefore, a uniform magnetic field is applied to each part of the ferrite, and the insertion loss and the like of the nonreciprocal circuit device can be improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments. In the following figures, the same or corresponding parts as those of the conventional example are designated by the same reference numerals.

The configuration of the circulator according to the first embodiment of the present invention is shown in FIGS. 1 and 2, and FIG. 3 and FIG. 4 show the magnetic force distribution and frequency insertion loss characteristics in the magnetic closed circuit. FIG. 1 is an exploded perspective view showing the overall configuration of the circulator.
2A is a top view of the lower yoke 1 shown in FIG. 1, and FIG. 2B is a sectional view taken along line XX of FIG.

As shown in FIGS. 1 and 2, a recess 1a is formed in the central portion of the inner wall of the bottom plate of the lower yoke 1 of the circulator of this embodiment. Other configurations are the same as those shown in FIG. 7 of the conventional example, and the description thereof will be omitted. An isolator can be made by connecting a terminating resistor between any one of the port electrodes of this circulator and the ground electrode.

As shown in FIG. 2, the recess 1a formed in the central portion of the inner wall of the bottom plate of the lower yoke 1 is formed in a shape forming a part of a substantially spherical surface. In other words, the thickness of the central portion of the concave portion 1a is small, and the thickness of the concave portion 1a is formed so as to approach the plate thickness toward the peripheral portion of the concave portion 1a. The magnetic force distribution at the ferrite position in the magnetic closed circuit formed by the lower yoke 1 and the upper yoke has a flat characteristic in the portion corresponding to the diameter of the ferrite as shown by the solid line in FIG. A strong magnetic field will be applied. As a result,
As shown by the solid line in FIG. 4, the insertion loss of this circulator is significantly improved over the insertion loss of the conventional circulator shown by the dotted line.

In the above embodiment, only the inner wall portion of the bottom plate of the lower yoke 1 is processed to form the recessed portion 1a. However, the present invention is not limited to this, and as shown in FIGS. 5 (a) and 5 (b). The recess 1a may be formed by denting the bottom plate of the lower yoke 1 into a substantially spherical shape without changing the thickness of the central part of the bottom plate, and the shape of the recess 1a is not limited to the spherical shape, but may be a cylindrical shape. Other shapes such as a polygonal shape and a conical shape may be used.

Further, instead of denting the central portion of the lower yoke, the peripheral portion of the lower yoke may be raised.

When a recess is formed in the bottom plate of the lower yoke as in each of the above-described embodiments, the magnetic force distribution in the magnetic closed circuit can be adjusted by the outer diameter and depth of the recess and the recess size. The shape and size of is appropriately set according to the shape and size of the permanent magnet, ferrite, and the like that form the circulator.

FIG. 6 shows the structure of the lower yoke according to the second embodiment of the present invention. As shown in FIGS. 6A and 6B, a plurality of holes 1b are formed in the central portion of the bottom plate of the lower yoke 1 of this embodiment. The hole 1b is formed so as to penetrate the bottom plate of the lower yoke 1, and is for uniformizing the magnetic force distribution in the magnetic closed circuit as in the concave portion of the first embodiment. In this case, the magnetic force distribution can be made uniform by the size, number, and arrangement of the holes, so that characteristics such as insertion loss and isolation can be improved.

Although the hole 1b is formed so as to penetrate the bottom plate of the lower yoke 1 in FIG. 6, it need not necessarily be formed so as to penetrate therethrough, and through holes and non-through holes may be mixed. .

In the first and second embodiments described above, either the recess or the hole is formed in the bottom plate of the lower yoke, but it goes without saying that the lower yoke may be formed with the recess and the hole in combination. . Further, in addition to the yoke of the present invention in which a recess is formed, a permanent magnet having a recess may be used together.

Further, in the above-mentioned embodiment, the center electrode, the matching circuit, etc. are formed of a multi-layer substrate in order to reduce the size.
The present invention is not limited to this, and the present invention can be applied to a structure in which each center electrode is formed of a metal conductor and a matching circuit in which a capacitor or the like is mounted on a substrate.

[0025]

As described above, according to the nonreciprocal circuit device of the present invention, a concave portion or a hole is formed in a portion of a yoke forming a magnetic closed circuit, the portion facing the permanent magnet, so that the ferrite is uniformly distributed over the entire ferrite. Since such a magnetic field is applied, characteristics such as insertion loss can be improved without increasing the number of parts.

Therefore, according to the present invention, the insertion loss,
It is possible to provide a high-performance non-reciprocal circuit device having good characteristics such as isolation.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing the overall configuration of a circulator according to a first embodiment of the present invention.

2A is a top view of a lower yoke of a circulator according to the first embodiment of the present invention, and FIG. 2B is a sectional view taken along line XX of FIG.

FIG. 3 is a diagram showing a distribution of magnetic force in a magnetic closed circuit of the circulator of the present invention and the conventional circulator.

FIG. 4 is a diagram showing frequency insertion loss characteristics of the present invention and a conventional circulator.

5A is a top view of a lower yoke of a circulator according to a modified example of the first embodiment of the present invention, and FIG. 5B is an X of FIG.
It is a X-ray sectional view.

FIG. 6 is a top view of the lower yoke of the circulator according to the second embodiment of the present invention, and FIG. 6B is a sectional view taken along line XX of FIG.

FIG. 7 is an exploded perspective view showing the overall configuration of a conventional circulator.

FIG. 8 is an exploded perspective view showing a configuration of a multilayer substrate of the present invention and a conventional circulator.

[Explanation of symbols]

 1 Lower Yoke 1a Recess 1b Hole 2 Ground Plate 3 Ferrite 4 Multilayer Substrate 5 Permanent Magnet 6 Upper Yoke

Claims (1)

[Claims] 1. A non-reciprocal circuit device having a permanent magnet, ferrite and a plurality of center electrodes arranged in a yoke forming a magnetic closed circuit, wherein the yoke forms the magnetic closed circuit, and A nonreciprocal circuit device characterized in that recesses or holes are formed in opposing portions so that a uniform magnetic field is applied to the entire ferrite.