JP4650996B2 - Lumped constant nonreciprocal circuit device and mobile communication device using the same - Google Patents

Description

  The present invention relates to a lumped-constant non-reciprocal circuit device such as an isolator and a circulator used in a microwave communication device and a mobile communication device using the same.

  In general, non-reciprocal circuit elements such as isolators and circulators have a function that hardly attenuates in the signal transmission direction and increases in the reverse direction. For example, they are used in the microwave band and the UHF band. It is used in a transmission / reception circuit unit of mobile communication devices such as mobile phones and automobile phones.

  FIG. 4 shows an exploded perspective view of a conventional lumped constant isolator. In this conventional example, a ground plate 30 is disposed on a lower case 21, and a ceramic substrate 40 is disposed thereon. The ceramic substrate 40 is formed with electrode patterns 43, 44, and 45 constituting a capacitive element, and has a through hole 41 in the center. One of the capacitive element electrode patterns 45 is connected to a dummy resistor 46, and the dummy resistor 46 is further connected to a ground electrode 47. The ground electrode 47 is connected to the ground plate 30 through a through hole 49. A central conductor portion is disposed in the through hole 41 of the ceramic substrate 40. The central conductor portion is composed of central conductors 56, 57, and 58 folded so as to enclose a ferrite disk (ferrimagnetic material) 50, and the central conductors are insulated from each other. The upper case 61 to which the permanent magnet 60 is bonded is fitted to the lower case 21 and configured. The center conductors 57 and 58 are drawn to the outside from the space 62 between the upper case 61 and the lower case 21 to constitute an input / output terminal.

  There is a strong demand for miniaturization and thinning of microwave communication devices such as cellular phones in which this lumped constant nonreciprocal circuit element is used, and there is a strong demand for a low cost, small and thin lumped constant nonreciprocal circuit element. Yes. Of course, it is necessary to satisfy the characteristics as a non-reciprocal circuit device. For this reason, various configurations, such as a surface mount type, a chip capacitor, and a flat plate capacitor, have been studied.

  In addition, a conventional permanent magnet is generally a ferrite magnet (SrO.nFe2O3) and has compatibility with garnet ferrite used as a ferrimagnetic material, and other magnets have not been studied much.

  In view of the above, an object of the present invention is to provide a lumped-constant non-reciprocal circuit element that can be reduced in size and thickness and a mobile communication device using the same.

In a lumped-constant non-reciprocal circuit device including a plurality of central conductors arranged close to a ferrimagnetic body and including a permanent magnet that applies a DC magnetic field to the ferrimagnetic body,
The permanent magnet has a magnetoplumbite type crystal structure in which a part of Sr and / or Ba is substituted with an R element (R element is La ) and a part of Fe is substituted with an M element (M element is Co ). In addition, a ferrite magnet in which the concentration of the R element is higher in the grain boundary than in the magnetoplumbite type crystal grain, the residual magnetic flux density Br exceeds 0.41 T, and the coercive force bHc exceeds 294 kA / m is used. It is a lumped constant type nonreciprocal circuit device characterized by
In the present invention, the coercive force iHc of the ferrite magnet further exceeds 322 kA / m, and the maximum energy product BHmax. Is over 31.6 kJ / m ³ . The second invention is a mobile communication device using the lumped constant nonreciprocal circuit device of the first invention .

  Compared to conventional ferrite magnets, it has a higher magnetic force, making it possible to reduce the size and thickness of lumped-constant nonreciprocal circuit elements, and to obtain lumped-constant nonreciprocal circuit elements that can handle high frequencies of 2 GHz or higher. Thus, it can be used for mobile communication devices.

In the present invention, it has been found that the use of a permanent magnet as described below as a permanent magnet for applying a DC magnetic field to a ferrimagnetic material enables reduction in size and thickness. _{(A 1-x R x)} O · n [(Fe 1-y M y) 2 O 3] ( atomic ratio) (A is Sr and / or Ba, R is at least one rare earth element including Y , M is at least one selected from the group consisting of Co, Mn, Ni and Zn), 0.01 ≦ x ≦ 0.4, [x / (2.6n)] ≦ y ≦ [x / (1 .6n)] is a ferrite magnet having a basic composition represented by 5 ≦ n ≦ 6 and substantially having a magnetoplumbite type crystal structure.

  In the permanent magnet, it is preferable that the R element and / or the M element are added in a pulverization step after calcination in a compound state. In addition, it is preferable that the R element and / or the M element are added in the mixing step before calcination in the state of a compound and also added in the pulverization step after calcination.

  In any case, it is preferable that the concentration of the R element is higher in the grain boundary than in the magnetoplumbite type crystal grains. When the R element is La and the M element is Co, or when the R element is La and the M element is Co, Mn and / or Zn, particularly excellent magnetic properties can be obtained.

When the n value exceeds 6, a different phase other than the magnetoplumbite phase (for example, α-Fe ₂ O ₃ ) is generated, and the magnetic characteristics are greatly deteriorated. When the n value is less than 5, Br decreases greatly. If the x value is less than 0.01, the effect of post-addition or pre- / post-addition is insufficient, and if it exceeds 0.4, the magnetic properties are conversely reduced. The M element is preferably Co alone, or Co and Mn and / or Ni.

  According to the magnet of the present invention, compared with the conventional ferrite magnet, it has a high magnetic force and has good compatibility with the ferrimagnetic material, and the lumped constant type nonreciprocal circuit device can be reduced in size and thickness. Can do.

  Further, the frequency used in the conventional lumped constant nonreciprocal circuit element is in the vicinity of 1 MHz to 2 GHz. For a high frequency exceeding 2 GHz, a lumped constant nonreciprocal circuit element capable of obtaining satisfactory characteristics is formed. I couldn't. For this reason, distributed constant type nonreciprocal circuit elements are used at such high frequencies. According to the present invention, by using the above-described permanent magnet, a lumped constant type nonreciprocal circuit device that can be used in a frequency band exceeding 2 GHz can be obtained, and the device can be made compact.

  An exploded perspective view of an embodiment according to the present invention is shown in FIG. In this embodiment, a conductive plate having a structure in which three central conductors 4, 5, and 6 project radially from a disk-shaped shield plate is prepared, and a ferrite disk 3 (ferrimagnetic) is formed on the disk-shaped portion of the conductive plate. Body). Then, the three central conductors 4, 5, 6 are folded and overlapped. At this time, the central conductors 4, 5, and 6 are insulated and overlapped. In this way, the central conductor portion is configured.

  Next, the resin case 7 has a circular concave portion 13a for the central conductor portion at the center, and has concave portions 13b, 13c, and 13d for the capacitive elements around it. A ground electrode 14a is formed at the bottom of the recesses 13a, 13b, 13c, and 13d. The ground electrode 14a is formed of an integral conductor plate, exposed on the bottom surface side, and constitutes ground external terminals (15a, 15b, etc.) among the external terminals on the side surface. Terminal electrode portions 16a, 16b, and 16c to which the central conductor is connected are formed. The terminal electrode portions 16a, 16b and 16c are electrically connected to external terminals (15c and the like) on the side surfaces. Further, a through recess 17 for arranging the resistance element is formed.

  Then, the resin case 7 is disposed on the lower case 12. At this time, the lower case 12 and the ground electrode 14a of the resin case 7 are electrically connected. The ground electrode 14a and the lower case 12 are opposed to each other with a wide installation area, and a sufficient ground can be obtained. The lower case 12 has a structure that matches the recess 18 at the bottom of the resin case 7. Thereby, surface mounting by the external terminal of the resin case 7 is enabled.

  Capacitance elements 8, 9, and 10 are inserted into the capacitor element recesses 13b, 13c, and 13d of the resin case 7, respectively. The capacitive element is a flat plate capacitor having electrodes formed on the upper and lower surfaces thereof, and the electrode on the lower surface and the ground electrode 14a formed on the bottom of the recess are connected by soldering. Further, the resistance element 11 is disposed in the through hole 17 for the resistance element, and one electrode of the resistance element 11 is disposed on the lower case 12 below the through recess 17 and is soldered.

  Next, the above-described center conductor portion is disposed in the circular recess 13 a for the center conductor portion at the center of the resin case 7. At this time, the disc-shaped shield plate of the central conductor portion is soldered to the ground electrode 14a. Thus, one end of the center conductor is grounded.

  One end of the center conductor 4 is connected to the electrode on the upper surface of the capacitive element 8 and one terminal electrode 25 of the resistance element 11. One end of the center conductor 5 is connected to the electrode on the upper surface of the capacitive element 9 and the terminal electrode portion 16b. One end of the center conductor 6 is connected to the electrode on the upper surface of the capacitive element 10 and the terminal electrode portion 16c. At this time, the heights of the terminal electrode portions 16b and 16c are configured to coincide with the heights of the electrodes on the upper surfaces of the capacitive elements 9 and 10, so that the connectivity of the center conductor is improved.

  And the permanent magnet 2 which applies a direct-current magnetic field to the ferrite disc 3 was positioned in the upper case 1, and the upper case 1 and the lower case 12 were joined, and the isolator was comprised.

  In the present embodiment, the permanent magnet 2 has a rectangular shape, is positioned on the inner surface of the upper case 1, and the periphery of the side surface of the permanent magnet 2 and the inner surface of the upper case are arranged in a close contact state. By making the permanent magnet into a rectangular shape and being in close contact with the upper case, the permanent magnet can be disposed throughout the case, which is advantageous for downsizing.

The permanent magnet 2 of this embodiment will be described below. SrCO ₃ and Fe ₂ O ₃ were blended so as to have a basic composition of SrO · nFe ₂ O ₃ (n = 5.9), wet-mixed, and then calcined at 1250 ° C. for 2 hours in the air. The calcined powder was dry pulverized with a roller mill to obtain coarse powder. Thereafter, wet pulverization was performed with an attritor to obtain a slurry containing fine powder having an average particle diameter of about 0.8 μm. At the beginning of the coarse powder pulverization step, 2.5 wt% La ₂ O ₃ and 1.2 wt% Co ₃ O ₄ are added based on the weight of the coarse powder, and 2-8 wt% Fe ₃ O ₄ (magnetite) was added. Furthermore, at the initial stage of the coarse pulverization step, 0.1% by weight of SrCO ₃ , 1.0% by weight of CaCO ₃ and 0.3% by weight of SiO ₂ are used as sintering aids based on the weight of the coarse powder. Added. Each obtained fine powder slurry was wet-molded in a magnetic field of 10 kOe, and the obtained molded body was sintered at 1210 to 1230 ° C. for 2 hours. The basic composition of the obtained sintered body substantially corresponds to the following composition formula.
(Sr _1-x La _x ) O · n [(Fe _1-y Co _y ) ₂ O ₃ ]
x = 0.15, y = x / 2n, n = 5.32 to 5.67 Table 1 shows the magnetic characteristics of the obtained example magnet and the conventional magnet.

  Thus, the permanent magnet used for this invention has a magnetic characteristic higher than before.

  According to this example, a very small and thin lumped constant type nonreciprocal circuit device of 5 mm × 5 mm × height 2 mm could be obtained. Further, FIG. 2 shows an insertion loss characteristic of the embodiment, and FIG. 3 shows an isolation characteristic. According to the present example, the 2.4 GHz band lumped constant type nonreciprocal circuit device could be configured to be very small, such as 5 mm × 5 mm × height 2 mm. In addition, the present invention is effective even at a frequency of 2 GHz or less. In particular, according to the present invention, it is a technique effective for achieving a thin lumped constant type nonreciprocal circuit device having a height of 2 mm or less.

  Although the above embodiment has been described with an isolator, it is needless to say that the circulator can be configured with the same technique. Further, if the permanent magnet of the present invention satisfies the basic composition described above, a lumped-constant nonreciprocal circuit device having desired characteristics can be obtained as in the above embodiment. Of course, the permanent magnet may be disk-shaped.

  According to the present invention, a lumped-constant nonreciprocal circuit element can be reduced in size and thickness, and a lumped-constant nonreciprocal circuit element corresponding to a high frequency of 2 GHz or more can be obtained for a mobile communication device. It can be used.

It is an exploded perspective view of one example concerning the present invention. It is an insertion loss characteristic of the Example which concerns on this invention. It is an isolation characteristic of the Example which concerns on this invention. It is a disassembled perspective view of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Upper case 2 Permanent magnet 3 Ferrite disc 4, 5, 6 Center conductor 7 Resin cases 8, 9, 10 Capacitance element 11 Resistance element
12 Lower case 13a Center conductor recess 13b, 13c, 13d Capacitor recess 14a Ground electrodes 15a, 15b, 15c External terminals 16a, 16b, 16c Terminal electrode 17 Resistance element through recess 18 Recess

Claims (4)

In a lumped-constant non-reciprocal circuit device that includes a plurality of central conductors arranged close to a ferrimagnetic body and a permanent magnet that applies a DC magnetic field to the ferrimagnetic body,
The permanent magnet has a magnetoplumbite type crystal structure in which a part of Sr and / or Ba is substituted with an R element (R element is La ) and a part of Fe is substituted with an M element (M element is Co ). In addition, a ferrite magnet in which the concentration of the R element is higher in the grain boundary than in the magnetoplumbite type crystal grain, the residual magnetic flux density Br exceeds 0.41 T, and the coercive force bHc exceeds 294 kA / m is used. A lumped-constant type nonreciprocal circuit device characterized by that. The lumped-constant nonreciprocal circuit device according to claim 1, wherein a coercive force iHc of the ferrite magnet exceeds 322 kA / m . The maximum energy product BHmax before Symbol ferrite magnet. The lumped-constant nonreciprocal circuit device according to claim 2, wherein is more than 31.6 kJ / m ³ . A mobile communication device using the lumped constant nonreciprocal circuit device according to claim 1.

Images