JP2001267810A - Lumped parameter type non-reciprocal circuit element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a miniaturized non-reciprocal circuit element. SOLUTION: In the non-reciprocal circuit element provided with a ferrimagnetic material obtained by arranging plural center conductors and plural permanent magnets for impressing DC magnetic fields to the ferrimagnetic material, two or more kinds of permanent magnets having respectively different temperature coefficients are used as the permanent magnets.

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 having an irreversible transmission characteristic with respect to a high-frequency signal, and more particularly to a non-reciprocal circuit device used in a mobile communication system such as a mobile phone. The present invention relates to a non-reciprocal circuit device called a curator.

[0002]

2. Description of the Related Art Hitherto, non-reciprocal circuit devices such as isolators and circulators have been known as one of transmission / reception circuit components used in a microwave band and a UHF band for mobile phones, automobile phones and the like. In general, isolators and circulators are used for the purpose of preventing breakage of an amplifier, and have a function of reducing insertion loss in a signal transmission direction and increasing reverse loss in a reverse direction. Hereinafter, in the specification of the present application, an isolator among non-reciprocal circuit devices will be described as an example.

FIG. 2 is an exploded perspective view showing an example of an isolator. This isolator includes an upper case 1, a magnet 2, an assembly 20, plate capacitors 8, 9, and 10, a dummy resistor 1
1, a resin case 7, and a lower case 12.
The assembly 20 prepares a conductive plate having a structure in which three center conductors 4, 5, and 6 project radially from a disk-shaped shield plate,
A ferrite disk (ferrimagnetic material) 3 is arranged on the disk-shaped portion of the conductive plate. And three central conductors 4, 5, 6
Fold and stack. At this time, each of the center conductors 4, 5, 6
Are insulated and stacked.

The resin case 7 has a circular concave portion 13a for an assembly at the center, and concave portions 13b, 13c, and 13d for capacitive elements around the concave portion 13a. Connection electrodes are formed at the bottom of the concave portion for the capacitor and the concave portion 13a for the assembly. And this connection electrode is formed as an integrated 0.
It is composed of a conductor plate of about 1 mm, is exposed on the bottom side, and constitutes an external terminal on the side surface. Capacitors 8, 9,
10 is inserted. This capacitive element is a flat plate capacitor having electrodes formed on the upper and lower surfaces thereof, and is connected by soldering to electrodes on the lower surface and connection electrodes formed on the bottom of the concave portion. Also,
The resistance element 11 is arranged, and one electrode of the resistance element 11 is connected to the connection electrode by soldering. Next, the resin case 7
In the circular recess 13a for the assembly of
0 is placed. One end of the center conductor 5 is connected to the electrode on the upper surface of the capacitor 9 and one terminal electrode of the resistor 11.
One end of the center conductor 4 is connected to an electrode on the upper surface of the capacitive element 8. One end of the center conductor 6 is connected to the capacitive element 10.
Is connected to the electrode on the upper surface of. Then, the resin case 7 is disposed on the lower case 12. Then, the permanent magnet 2 for applying a DC magnetic field to the magnetic body 3 is positioned in the upper case 1, and the upper case 1 and the lower case 12 are fitted to each other to form an isolator.

[0005]

In recent years, with the miniaturization of passive components such as semiconductor elements such as ICs and transistors, multilayer chip capacitors, multilayer chip inductors, and chip resistors, the size of microwave devices having these mounted on the surface has been reduced.・ Thinning is progressing rapidly. In such a movement, lumped-constant type circulator isolators, which are very important non-reciprocal circuit elements in configuring a microwave device, are also required to be reduced in size and thickness. As a method of reducing the size of the non-reciprocal circuit elements such as the isolator and the circulator, a method of reducing the size of the magnet while maintaining a necessary magnetic force using a high-performance magnet can be considered. Conventionally,
Since the temperature characteristic of the saturation magnetization of the garnet ferrite used as the ferrimagnetic material 3 is as large as −0.4 to −0.2% / ° C., an Sr ferrite magnet having a large temperature characteristic of the residual magnetic flux density Br is used as the permanent magnet 2. In general, the Sr ferrite magnet has a residual magnetic flux density of about 0.45 T and a (BH) max.
Is about 40 KJ / m ³ , so there is naturally a limit to miniaturization. Magnets having a stronger magnetic force than the Sr ferrite magnet include RCo ₅ type, R ₂ Co ₁₇ type, and RF
There are eB-based magnets, R-Fe-N-based magnets (R is one or more of rare earth elements including Y), magnets, etc., but these magnets have flatter temperature characteristics than Sr ferrite magnets. In addition, the temperature characteristics of the ferrimagnetic material cannot be eliminated, and it has been difficult to satisfy the temperature characteristics of the entire isolator and circulator element. Accordingly, an object of the present invention is to provide a miniaturized non-reciprocal circuit device while maintaining the temperature characteristics at a level where there is no practical problem.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a non-reciprocal circuit device comprising a ferrimagnetic body having a plurality of center conductors disposed therein, and a permanent magnet for applying a DC magnetic field to the ferrimagnetic body. This is a lumped constant type non-reciprocal circuit device using two or more permanent magnets having different temperature coefficients. In the present invention, at least one of the two or more permanent magnets is
Sr ferrite magnet, and other permanent magnets are RCo ₅ system, R ₂ Co ₁₇ system, R-Fe-B system, RF
e-N type (R is one of rare earth elements including Y or 2
Or more rare earth magnets.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A non-reciprocal circuit device according to an embodiment of the present invention will be described with reference to an exploded perspective view of FIG. This non-reciprocal circuit device has many parts similar to those of the conventional non-reciprocal circuit device, and different portions will be described below. In the non-reciprocal circuit device of the present invention, a permanent magnet for applying a DC magnetic field to a ferrimagnetic material is configured using two or more types of permanent magnets 2a and 2b having different temperature coefficients. Here, the two or more types of permanent magnets having different temperature coefficients may be appropriately selected from Sr ferrite magnets and rare earth magnets shown in Table 1. The shape of the permanent magnet is preferably plate-like for ease of processing, for example, Nd-Fe
-If the magnet is a B-based magnet, a dry powder or a mixture of a dry powder and an organic solvent, a mineral oil or a synthetic oil is prepared as a raw material powder,
Powder is fed into the mold cavity and formed into a plate in a magnetic field.
The obtained molded body can be dried, sintered, and heat-treated as necessary. Further, the Sr ferrite magnet can be obtained by preparing a dry powder or a mixture of dry powder and water as a raw material powder, forming it into a plate shape in a magnetic field, and drying and sintering the obtained formed body as necessary. I can do it.

[0008]

[Table 1]

The Sr ferrite magnet 2b thus obtained
And the Nd-Fe-B-based magnet 2a were bonded using a heat-resistant adhesive to form an integral permanent magnet. The upper and lower yokes 1 and 2 are applied to the permanent magnet so that a DC magnetic field is applied to the ferrimagnetic material.
The non-reciprocal circuit device of the present invention was arranged between the two. With such a configuration, the magnetic force obtained by the Sr ferrite magnet alone can be easily obtained even when the total thickness is made thinner than before, and the temperature characteristic of the residual magnetic flux density Br is also rare earth element. It can be made larger than when only magnets are used,
As a result, it was possible to obtain a miniaturized non-reciprocal circuit device while maintaining the temperature characteristics to such an extent that there is no practical problem.

[0010]

As described above, according to the present invention, it is possible to obtain a miniaturized nonreciprocal circuit device while maintaining the temperature characteristics at a level where there is no practical problem.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a non-reciprocal circuit device according to one embodiment of the present invention.

FIG. 2 is an exploded perspective view of a conventional non-reciprocal circuit device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper case 2, 2a, 2b Permanent magnet 3 Ferrimagnetic body 12 Lower yoke

Claims (3)

[Claims] 1. A non-reciprocal circuit device comprising: a ferrimagnetic body having a plurality of center conductors disposed therein; and a permanent magnet for applying a DC magnetic field to the ferrimagnetic body, wherein the permanent magnet has two different temperature coefficients. A lumped constant type non-reciprocal circuit device characterized by using the above permanent magnet. 2. At least one of the two or more permanent magnets
One is Sr · F₂O ₃A system magnet
A lumped constant type non-reciprocal circuit device according to claim 1. 3. At least one of the two or more permanent magnets is an RCo ₅ system, an R ₂ Co ₁₇ system, an R—Fe—B system,
3. The lumped-constant type nonreciprocal circuit device according to claim 2, wherein the lumped element type non-reciprocal circuit device is an R-Fe-N-based (R is one or two or more rare earth elements including Y) rare earth magnet.