JP5083113B2 - Non-reciprocal circuit element - Google Patents

Description

  The present invention relates to a nonreciprocal circuit device, and more particularly to a nonreciprocal circuit device such as an isolator or a circulator used in a microwave band.

  Conventionally, nonreciprocal circuit elements such as isolators and circulators have a characteristic of transmitting a signal only in a predetermined specific direction and not transmitting in a reverse direction. Utilizing this characteristic, for example, an isolator is used in a transmission circuit unit of a mobile communication device such as a car phone or a mobile phone.

  As a two-port type isolator in which the first and second center electrodes are wound around the ferrite in a non-reciprocal circuit element of this type in an insulated state, Patent Document 1 discloses that the first center electrode and A circuit board in which termination resistors connected in parallel are built in is disclosed. The termination resistor may be formed on the surface of the circuit board, or a chip-type element may be mounted on the circuit board.

By the way, the termination resistor has a problem that it generates heat when a high frequency signal is inputted from the output port side. If the termination resistor is directly connected to the ground, heat can be radiated through the ground electrode. However, since this type of termination resistor is only connected to the input / output port, heat dissipation is poor, and characteristics such as insertion loss deteriorate as temperature rises.
International Publication No. 2007/086177 Pamphlet

  SUMMARY OF THE INVENTION An object of the present invention is to provide a non-reciprocal circuit device that can improve the heat dissipation of a termination resistor and suppress deterioration of characteristics such as insertion loss.

In order to achieve the above object, a non-reciprocal circuit device according to one aspect of the present invention comprises:
With permanent magnets,
A ferrite to which a DC magnetic field is applied by the permanent magnet;
A first center electrode and a second center electrode arranged to intersect the ferrite in an electrically insulated state from each other;
A circuit board on which the permanent magnet and the ferrite are mounted;
With
The first center electrode has one end electrically connected to the input port and the other end electrically connected to the output port;
The second center electrode has one end electrically connected to the output port and the other end electrically connected to the ground port.
A first matching capacitor is electrically connected between the input port and the output port;
A second matching capacitor is electrically connected between the output port and the ground port;
A resistor is electrically connected between the input port and the output port,
Both ends of the resistor are connected to a heat dissipation electrode provided on the mounting surface of the circuit board, and the heat dissipation electrode is not connected to an element other than the resistor,
It is characterized by.

  According to the present invention, since both ends of the resistor connected between the input port and the output port are connected to the heat radiation electrode not connected to other elements, the heat dissipation of the resistor is improved. As a result, deterioration of characteristics such as insertion loss due to temperature rise can be suppressed.

  Embodiments of a nonreciprocal circuit device according to the present invention will be described below with reference to the accompanying drawings.

(Refer 1st Example and FIGS. 1-7)
FIG. 1 shows an exploded perspective view of a 2-port isolator which is a first embodiment of a nonreciprocal circuit device according to the present invention. This two-port isolator is a lumped constant isolator, and generally includes a flat-plate yoke 10, a circuit board 20, and a ferrite / magnet element 30 including a ferrite 32 and a permanent magnet 41. In FIG. 1, the hatched portion is a conductor.

  As shown in FIG. 2, the ferrite 32 is formed with a first center electrode 35 and a second center electrode 36 which are electrically insulated from each other on the front and back main surfaces 32a and 32b. Here, the ferrite 32 has a rectangular parallelepiped shape having a first main surface 32a and a second main surface 32b which are parallel to each other.

  The permanent magnet 41 is bonded to the main surfaces 32a and 32b via, for example, an epoxy adhesive 42 so as to apply a DC magnetic field to the ferrite 32 in a direction substantially perpendicular to the main surfaces 32a and 32b. (See FIG. 4), the ferrite-magnet element 30 is formed. The main surface 41a of the permanent magnet 41 has the same dimensions as the main surfaces 32a and 32b of the ferrite 32, and is arranged with the main surfaces 32a and 41a and the main surfaces 32b and 41a facing each other so that their external shapes coincide with each other. Yes.

  The first center electrode 35 is formed of a conductor film. That is, as shown in FIG. 2, the first center electrode 35 rises from the lower right on the first main surface 32a of the ferrite 32 and branches into two at the upper left at a relatively small angle with respect to the long side. It is inclined and rises to the upper left, wraps around the second main surface 32b via the relay electrode 35a on the upper surface, and branches into two so as to overlap the first main surface 32a in a transparent state on the second main surface 32b One end thereof is connected to a connection electrode 35b formed on the lower surface. The other end of the first center electrode 35 is connected to a connection electrode 35c formed on the lower surface. Thus, the first center electrode 35 is wound around the ferrite 32 for one turn. And the 1st center electrode 35 and the 2nd center electrode 36 demonstrated below cross | intersect in the state insulated by mutually forming the insulating film.

  The second center electrode 36 is formed of a conductor film. In the second center electrode 36, first, the 0.5th turn 36a is inclined at a relatively large angle with respect to the long side from the lower right to the upper left on the first main surface 32a and intersects the first center electrode 35. The first turn 36c is formed so as to intersect the first central electrode 35 substantially perpendicularly on the second main surface 32b via the relay electrode 36b on the upper surface. . The lower end portion of the first turn 36c goes around the first main surface 32a via the relay electrode 36d on the lower surface, and the 1.5th turn 36e is the first main surface 32a in parallel with the 0.5th turn 36a. It is formed so as to intersect with the center electrode 35 and wraps around the second main surface 32b via the relay electrode 36f on the upper surface. Similarly, the second turn 36g, the relay electrode 36h, the 2.5th turn 36i, the relay electrode 36j, the third turn 36k, the relay electrode 36l, the 3.5th turn 36m, the relay electrode 36n, the fourth turn The eyes 36o are formed on the surface of the ferrite 32, respectively. Further, both ends of the second center electrode 36 are connected to connection electrodes 35 c and 36 p formed on the lower surface of the ferrite 32, respectively. The connection electrode 35 c is shared as a connection electrode at each end of the first center electrode 35 and the second center electrode 36.

  That is, the second center electrode 36 is wound around the ferrite 32 in a spiral manner for four turns. Here, the number of turns is calculated by assuming that the state in which the center electrode 36 crosses the first or second main surface 32a, 32b once each is 0.5 turns. The crossing angle of the center electrodes 35 and 36 is set as necessary, and the input impedance and insertion loss are adjusted.

  Further, the connection electrodes 35b, 35c, 36p and the relay electrodes 35a, 36b, 36d, 36f, 36h, 36j, 36l, 36n are silver or silver in a recess 37 (see FIG. 3) formed on the upper and lower surfaces of the ferrite 32. It is formed by applying or filling an electrode conductor such as an alloy, copper, or copper alloy. In addition, dummy recesses 38 are formed on the upper and lower surfaces in parallel with various electrodes, and dummy electrodes 39a, 39b, and 39c are formed. This type of electrode is formed by forming a through hole in the mother ferrite substrate in advance, filling the through hole with an electrode conductor, and then cutting at a position where the through hole is divided. Various electrodes may be formed as conductor films in the recesses 37 and 38.

  As the ferrite 32, YIG ferrite or the like is used. The first and second center electrodes 35 and 36 and various electrodes can be formed as a thick film or thin film of silver or a silver alloy by a method such as printing, transfer, or photolithography. As the insulating film of the center electrodes 35 and 36, a dielectric thick film such as glass or alumina, a resin film such as polyimide, or the like can be used. These can also be formed by methods such as printing, transfer, and photolithography.

  The ferrite 32 can be integrally fired with a magnetic material including an insulating film and various electrodes. In this case, Cu, Ag, Pd, or Pd / Ag that can withstand high temperature firing of various electrodes is used.

  As the permanent magnet 41, a strontium-based, barium-based, or lanthanum-cobalt-based ferrite magnet is usually used. As the adhesive 42 for adhering the permanent magnet 41 and the ferrite 32, it is optimal to use a one-component thermosetting epoxy adhesive.

  The circuit board 20 is a laminated substrate obtained by forming predetermined electrodes on a plurality of dielectric sheets, laminating them, and sintering them. As shown in FIG. 6 and FIG. Matching capacitors C1, C2, Cs1, Cs2, Cp1, and Cp2 are incorporated, and a termination resistor R that is a chip-type element is externally attached on the circuit board 20. Terminal electrodes 25a to 25e are formed on the front surface, and external connection terminal electrodes 26, 27, and 28 and a heat radiation electrode 29 are formed on the back surface (mounting surface). The description of the multilayer structure in the circuit board 20 is omitted.

  The ferrite / magnet element 30 is placed on the circuit board 20, and various electrodes on the lower surface of the ferrite 32 are integrated by reflow soldering with the terminal electrodes 25a, 25b, and 25c on the circuit board 20, and permanently. The lower surface of the magnet 41 is integrated on the circuit board 20 with an adhesive.

  The flat yoke 10 has an electromagnetic shielding function and is disposed immediately above the ferrite / magnet element 30. As shown in FIG. 5, a resin material 61 is filled between the circuit board 20 and the yoke 10 and around the ferrite / magnet element 30. The terminal resistance R is also covered with the resin material 61. The resin material 61 is, for example, a resin in which silica, phenol resin, and epoxy resin are mixed as main components.

  The functions of the flat yoke 10 are to suppress magnetic leakage from the ferrite / magnet element 30 and high-frequency electromagnetic field, to suppress the influence of external magnetism, and to mount this isolator on the substrate 70 using a chip mounter. It is to provide a place to pick up with a vacuum nozzle. The flat yoke 10 does not necessarily need to be grounded, but may be grounded by soldering or conductive adhesive, and the effect of the high frequency shield is improved when grounded.

  The flat yoke 10 is a nickel plate plated with Ag. However, the material of the yoke 10 is not limited to nickel, and may be a soft iron steel plate, a silicon steel plate or the like, and the plating may be Cu or the like.

  The connection relationship between the matching circuit element and the first and second center electrodes 35 and 36 is, for example, as shown in FIG. 6 as a first circuit example and FIG. 7 as a second circuit example. Here, the connection relationship will be described based on the second circuit example shown in FIG.

  The external connection terminal electrode 26 formed on the back surface of the circuit board 20 is connected to the terminal electrode 25a (input port P1) via the matching capacitor Cs1, and is connected to the matching capacitor C1 and the termination resistor R. Yes. The terminal electrode 25 a is connected to one end of the first center electrode 35 through a connection electrode 35 b formed on the lower surface of the ferrite 32.

  The other end of the first center electrode 35 and one end of the second center electrode 36 are connected via a connection electrode 35c formed on the lower surface of the ferrite 32 and a terminal electrode 25b (output port P2) formed on the surface of the circuit board 20. The terminal resistor R and the capacitors C1 and C2 are connected to the external connection terminal electrode 27 formed on the back surface of the circuit board 20 via the capacitor Cs2. The end point resistor R is connected to terminal electrodes 25d and 25e formed on the surface of the circuit board 20.

  The other end of the second center electrode 36 is connected to the capacitor C2 and the circuit board 20 via the connection electrode 36p formed on the lower surface of the ferrite 32 and the terminal electrode 25c (ground port P3) formed on the surface of the circuit board 20. It is connected to an external connection terminal electrode 28 formed on the back surface.

  A grounded impedance adjusting capacitor Cp1 is connected to a connection point between the input side terminal electrode 26 and the capacitor Cs1. Similarly, a grounded impedance adjusting capacitor Cp2 is also connected to a connection point between the output terminal electrode 27 and the capacitor Cs2.

  The first circuit example shown in FIG. 6 is a basic type in which some elements (capacitors Cs1, Cs2, Cp1, and Cp2) in the second circuit example shown in FIG. 7 are omitted.

  In the above two-port isolator, the terminal electrodes 25d and 25e to which both ends of the terminating resistor R are connected are connected via a through-hole conductor 29a provided on the circuit board 20, as shown in FIGS. It is connected to a heat dissipation electrode 29 provided on the back surface (mounting surface) of the circuit board 20. The isolator is mounted on the printed wiring board 70, and at that time, the heat radiation electrode 29 is solder-connected to the heat radiation electrode 71 on the board 70.

  In the two-port isolator configured as described above, one end of the first center electrode 35 is connected to the input port P1, the other end is connected to the output port P2, and one end of the second center electrode 36 is connected to the output port P2. Since the other end is connected to the ground port P3, during operation, a large high-frequency current flows through the second center electrode 36, and almost no high-frequency current flows through the first center electrode 35. Therefore, a 2-port lumped constant isolator with low insertion loss can be obtained.

  Further, since the second center electrode 36 is wound around the ferrite 32 by two turns or more, the inductance value of the second center electrode 36 is high, and the characteristics as an isolator are improved.

  Furthermore, since both end portions of the termination resistor R are connected to the heat radiation electrode 29 that is not connected to other elements via the through-hole conductor 29a, the heat dissipation of the termination resistor R is improved, and as a result, the temperature rises. Degradation of characteristics such as insertion loss can be suppressed. The terminal resistance R also radiates heat through the resin material 61. The through-hole conductor 29a is formed by forming an electrode film such as Ag on the inner wall surface of the through-hole. The through-hole conductor 29a has a thermal conductivity higher than that of the dielectric constituting the circuit board 20, and has good heat dissipation. In particular, if the through hole conductor 29a is filled in the through hole, the thermal conductivity is further improved.

  On the other hand, since the ferrite 32 and the pair of permanent magnets 41 are integrated with the adhesive 42, the ferrite / magnet element 30 is mechanically stable and becomes a robust isolator that is not deformed or damaged by vibration or impact.

(Refer to the second embodiment, FIGS. 8 and 9)
As shown in FIG. 8, the isolator according to the second embodiment has terminal electrodes 25 d and 25 e provided on the front surface of the circuit board 20 and heat radiation electrodes 29 provided on the back surface provided at corners of the circuit board 20. The connection is made through the through-hole conductor 29a.

  As shown in FIG. 9, this type of circuit board 20 is formed in a matrix on a large-area parent board. Through holes 29b are formed in the corners of one unit of the circuit board 20, the conductors are filled in the through holes 29b, and then cut along vertical and horizontal cut lines A to cut out the circuit board 20 as a sub board.

(Refer to the third embodiment, FIG. 10)
As shown in FIG. 10, the isolator according to the third embodiment is one in which heat radiation electrodes 29 are arranged diagonally on the back surface (mounting surface) of the circuit board 20. Uniform heat dissipation can be expected by disposing the heat dissipation electrodes 29 away from each other.

(Refer to the fourth and fifth embodiments, FIGS. 11 to 13)
The terminating resistor R may be a resistor film formed on or inside the circuit board 20 in addition to externally attaching the chip-type element to the surface of the circuit board 20. Even for a termination resistor formed of such a resistor film, heat dissipation is improved by connecting to a heat dissipation electrode provided on the back surface (mounting surface) of the circuit board 20 via a through-hole conductor. Can do.

  FIG. 11 shows a circuit board 20 constituting an isolator according to the fourth embodiment. A resistor film 45 is formed as a termination resistor R on the surface of the circuit board 20. The resistor film 45 is connected to the heat radiation electrode 29 through the terminal electrodes 25d and 25e and the through-hole conductor 29a.

  FIG. 12 shows a cross section of the main part of the circuit board 20 constituting the isolator according to the fifth embodiment. A resistor film 46 is formed as a termination resistor R inside the circuit board 20. The resistor film 46 is connected to the heat radiation electrode 29 through a through-hole conductor 29a. Other matching circuit elements are also built in the circuit board 20, and the connection relationship is shown in FIG. The circuit shown in FIG. 13 corresponds to the equivalent circuit shown in FIG.

(Other examples)
The non-reciprocal circuit device according to the present invention is not limited to the above-described embodiments, and can be variously modified within the scope of the gist thereof.

  For example, if the N pole and S pole of the permanent magnet are reversed, the input port and the output port are switched. Further, the configuration of the matching circuit is arbitrary, and the configurations of the first and second center electrodes are also arbitrary.

It is a disassembled perspective view which shows the nonreciprocal circuit device (2 port type isolator) which is 1st Example. It is a perspective view which shows the ferrite with a center electrode. It is a perspective view which shows the said ferrite. It is a disassembled perspective view which shows a ferrite magnet element. It is sectional drawing of the assembled isolator. It is an equivalent circuit diagram showing a first circuit example of a 2-port isolator. It is an equivalent circuit diagram showing a second circuit example of a 2-port isolator. It is a perspective view which shows the circuit board of the nonreciprocal circuit element (2 port type isolator) which is 2nd Example. FIG. 9 is a plan view showing a parent board of the circuit board shown in FIG. 8. It is a back view which shows the circuit board of the nonreciprocal circuit element (2 port type isolator) which is 3rd Example. It is a perspective view which shows the circuit board of the nonreciprocal circuit element (2 port type isolator) which is 4th Example. It is sectional drawing which shows the principal part of the circuit board of the nonreciprocal circuit element (2 port type isolator) which is 5th Example. FIG. 13 is a circuit diagram showing a connection relationship inside the circuit board shown in FIG. 12.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Yoke 20 ... Circuit board 25d, 25e ... Terminal electrode 29 ... Radiation electrode 29a ... Through-hole conductor 30 ... Ferrite magnet element 32 ... Ferrite 35 ... 1st center electrode 36 ... 2nd center electrode 41 ... Permanent magnet 45, 46 ... Resistor film 61 ... Resin material R ... Termination resistor P1 ... Input port P2 ... Output port P3 ... Ground port

Claims (11)

With permanent magnets,
A ferrite to which a DC magnetic field is applied by the permanent magnet;
A first center electrode and a second center electrode arranged to intersect the ferrite in an electrically insulated state from each other;
A circuit board on which the permanent magnet and the ferrite are mounted;
With
The first center electrode has one end electrically connected to the input port and the other end electrically connected to the output port;
The second center electrode has one end electrically connected to the output port and the other end electrically connected to the ground port.
A first matching capacitor is electrically connected between the input port and the output port;
A second matching capacitor is electrically connected between the output port and the ground port;
A resistor is electrically connected between the input port and the output port,
Both ends of the resistor are connected to a heat dissipation electrode provided on the mounting surface of the circuit board, and the heat dissipation electrode is not connected to an element other than the resistor,
A nonreciprocal circuit device characterized by the above.   The nonreciprocal circuit device according to claim 1, wherein the resistor is a chip-type device and is mounted on a surface of the circuit board.   The nonreciprocal circuit device according to claim 1, wherein the resistor is a resistor film formed on a surface or inside of the circuit board.   4. The nonreciprocal circuit device according to claim 1, wherein the heat radiation electrode is disposed substantially diagonally on a mounting surface of the circuit board. 5.   5. The nonreciprocal circuit device according to claim 1, wherein the resistor and the heat radiation electrode are connected by a through-hole conductor provided on the circuit board.   6. The nonreciprocal circuit device according to claim 5, wherein the through-hole conductor is filled in the through-hole.   The nonreciprocal circuit device according to claim 5, wherein the through-hole conductor is provided at a corner of the circuit board.   2. The ferrite and the permanent magnet constitute a ferrite magnet element in which a permanent magnet is fixed to a main surface of the ferrite on which the first and second center electrodes are arranged. The nonreciprocal circuit device according to claim 7.   9. The nonreciprocal circuit device according to claim 8, wherein the ferrite-magnet device is mounted on the circuit board, a yoke is disposed immediately above the ferrite-magnet device, and is covered with a resin material. .   10. The nonreciprocal structure according to claim 8, wherein the ferrite-magnet element has a main surface of ferrite disposed on the circuit board in a direction perpendicular to the surface of the circuit board. Circuit element.   11. The nonreciprocal circuit device according to claim 1, wherein the second center electrode is wound around both main surfaces of the ferrite for at least two turns.

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