JP5652116B2 - 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 this type of non-reciprocal circuit element, Patent Document 1 discloses a low-loss two-port isolator. In this two-port isolator, a first center electrode and a second center electrode that intersect with each other in an electrically insulated state are arranged on a ferrite, and a DC magnetic field is applied to an intersection of the first and second center electrodes. Yes. In order to make the impedance of the input terminal lower than 50Ω, an inductor is inserted between the input terminal and the input port (one end of the first center electrode).

  However, in the isolator, it is necessary to prepare an inductor as an additional component for impedance conversion, the insertion loss is increased by the Q value of the inductor, and the circuit element itself is hindered in size reduction.

JP 2005-102143 A

  Therefore, an object of the present invention is to provide a non-reciprocal circuit device that can achieve a reduction in input impedance without reducing insertion loss or increasing size.

The non-reciprocal circuit device according to one aspect of the present invention is
A first conductor and a second conductor provided in a state of being connected to each other at one end to the main surface of the microwave magnetic body;
A third conductor drawn from a connection point of the first conductor and the second conductor, intersecting the first conductor and the second conductor in an insulating state and wound around the microwave magnetic body;
A permanent magnet that applies a DC magnetic field to the intersection of the first conductor, the second conductor, and the third conductor;
With
The end portions of the first conductor and the second conductor are input / output ports, the end portion of the third conductor is a ground port,
A resistance element is connected between the input / output ports in parallel to the first conductor and the second conductor,
The mutual inductance between the first conductor and the third conductor is different from the mutual inductance between the second conductor and the third conductor;
It is characterized by.

  In the nonreciprocal circuit device, for example, when a high frequency current is input to the input / output port of the first conductor, a large high frequency current flows through the second conductor and the third conductor and is output from the input / output port of the second conductor. At this time, since the high-frequency current hardly flows through the resistance element, the insertion loss is reduced. On the other hand, the high-frequency current input from the input / output port of the second conductor is released as heat by the resistance element, and hardly flows through the first conductor. The first conductor, the second conductor, and the third conductor are magnetically coupled, and the mutual inductance between the first conductor and the third conductor is different from the mutual inductance between the second conductor and the third conductor. By adjusting the mutual inductance of both, the impedance on the input side is lowered.

  That is, in the non-reciprocal circuit element, the conductor provided in the microwave magnetic body has an impedance conversion function, and it is not necessary to add an inductor as a separate part, so that the insertion loss is reduced or the size is increased. A reduction in input impedance can be achieved without incurring.

  According to the present invention, it is possible to achieve a reduction in input impedance without reducing insertion loss or increasing size.

It is a disassembled perspective view which shows the nonreciprocal circuit device (2 port type isolator) which is 1st Example. In a 1st Example, it is a perspective view which shows the state which mounted the ferrite magnet assembly on the circuit board. FIG. 3 is an equivalent circuit diagram of the first embodiment. In a 1st Example, it is a perspective view which shows the ferrite which attached the conductor and the electrode. It is a disassembled perspective view which shows the ferrite magnet assembly in 1st Example. It is a graph which shows the characteristic of 1st Example. In the nonreciprocal circuit device (2 port type isolator) which is 2nd Example, it is a perspective view which shows the ferrite which attached the conductor and the electrode. It is a graph which shows the characteristic of 2nd Example. In the nonreciprocal circuit device (2 port type isolator) which is 3rd Example, it is a perspective view which shows the ferrite which attached the conductor and the electrode. It is a graph which shows the characteristic of 3rd Example.

  Embodiments of a nonreciprocal circuit device according to the present invention will be described below with reference to the accompanying drawings. In the drawings showing the respective embodiments, the same parts and portions are denoted by the same reference numerals, and redundant description is omitted.

(Refer 1st Example and FIGS. 1-6)
An exploded perspective view of the nonreciprocal circuit device according to the first embodiment is shown in FIG. This non-reciprocal circuit element is a two-port isolator, and generally includes a circuit board 20, a ferrite magnet element 30 including a microwave magnetic body 32 (hereinafter referred to as a ferrite 32), and a pair of permanent magnets 41. The flat yoke 10, the sealing resin 11, the chip-type resistance element R, and the chip-type capacitor element C are included.

  As described in detail below with reference to FIGS. 4 and 5, the ferrite 32 has a first conductor 35, a second conductor 36, and a third conductor 37 formed of a conductor film on the front and back main surfaces 32 a and 32 b. Is formed. Here, the ferrite 32 has a rectangular parallelepiped shape having a first main surface 32a and a second main surface 32b parallel to each other, an upper surface 32c, and a lower surface 32d.

  The permanent magnet 41 is opposed to the main surface 32a, 32b so as to apply a magnetic field to the ferrite 32 in a direction perpendicular to the main surface 32a, 32b, for example, via an epoxy adhesive 42, The magnet element 30 is configured. The main surface of the permanent magnet 41 has the same dimensions as the main surfaces 32a and 32b of the ferrite 32, and is disposed with the main surfaces facing each other so that their external shapes match.

  As shown in FIGS. 4 and 5, the first conductor 35 extends about 2/3 of the first main surface 32a to the left with one end connected to the electrode 35a provided to the right of the lower surface 32d. Are connected to the midpoint conductor 38. The second conductor 36 has one end connected to the electrode 36a provided on the left side of the lower surface 32d and extends to the right about the first main surface 32a by about 1/3 and is connected to the midpoint conductor 38. . The midpoint conductor 38 is connected to an electrode 37a provided on the upper surface 32c.

  The third conductor 37 is mainly composed of conductors 37b, 37f, and 37j provided on the second main surface 32b, and conductors 37d and 37h provided on the first main surface 32a via the insulating layer 43. The upper portions of the conductors 37b, 37f, and 37j are connected to the electrodes 37a, 37e, and 37i, and the lower portions are connected to the electrodes 37c, 37g, and 37k. The upper portions of the conductors 37d and 37h are connected to the electrodes 37e and 37i, and the lower portions are connected to the electrodes 37c and 37g. That is, the third conductor 37 is composed of conductors 37b, 37d, 37f, 37h, and 37j and electrodes 37a, 37c, 37e, 37g, 37i, and 37k. It intersects the two conductors 36 in an insulated state and is wound around the ferrite 32 for 2.5 turns.

  The electrodes formed on the upper and lower surfaces 32c and 32d of the ferrite 32 are formed by applying or filling electrode conductors in the recesses. 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 through holes. In the case of manufacturing by a multi-cavity technique, it may be cut in a state where a permanent magnet is also laminated on the mother ferrite substrate via an adhesive.

  As the ferrite 32, YIG ferrite or the like is used. The first, second, and third conductors 35, 36, and 37 and various electrodes can be formed by printing, transferring, photolithography, or the like as a thick film or thin film of silver or a silver alloy. As the insulating layer 43, a dielectric thick film such as glass or alumina, a resin film such as polyimide, or the like can be 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 flat yoke 10 forms a high-frequency electromagnetic circuit and has a shielding function, and is fixed to the upper surface of the ferrite / magnet element 30 via a sealing resin 11.

  The circuit board 20 has an input terminal electrode 21, an output terminal electrode 22, and a ground terminal electrode 23 formed on the surface. The ferrite / magnet element 30, the resistance element R, and the capacitor element C are mounted on the circuit board 20. The ferrite magnet element 30 is mounted on the circuit board 20 so that the main surfaces 32a and 32b of the ferrite 32 are positioned in the vertical direction. At this time, the electrode 35 a is connected to the input terminal electrode 21, the electrode 36 a is connected to the output terminal electrode 22, and the electrode 37 k is connected to the ground terminal electrode 23. Further, the resistance element R and the capacitor element C are connected to the input terminal electrode 21 and the output terminal electrode 22, respectively.

  According to the connection relationship, the two-port isolator is configured as an equivalent circuit shown in FIG. That is, the first conductor 35 and the second conductor 36 are connected by the midpoint conductor 38, the end portion (electrode 35a) of the first conductor 35 is used as the input port P1, and the end portion (electrode 36a) of the second conductor 36. Is the output port P2, and the end (electrode 37k) of the third conductor 37 is the ground port P3. Further, a resistance element R and a capacitor element C are connected in parallel to the first conductor 35 and the second conductor 36 between the input port P1 and the output port P2.

  In the two-port isolator having the above configuration, when a high frequency current is input to the input port P1, a large high frequency current flows through the second conductor 36 and the third conductor 37 and is output from the output port P2. At this time, almost no high-frequency current flows through the resistor element R and the capacitor C1, so that the insertion loss is reduced. On the other hand, the high-frequency current input from the output port P2 is attenuated by the parallel resonance circuit formed by the first conductor 35 and the capacitor C1, and is released as heat by the resistance element R.

  The first conductor 35, the second conductor 36, and the third conductor 37 are magnetically coupled as inductors L1, L2, and L3, respectively, and the mutual inductance between the first conductor 35 and the third conductor 37, and the second conductor 36. And the third conductor 37 have different mutual inductances, and the impedance on the input side is reduced by adjusting the mutual inductance of the two. That is, in the first embodiment, the coupling between the first conductor 35 (L1) and the third conductor 37 (L3) is relatively strong, and the second conductor 36 (L2) and the third conductor 37 (L3) are coupled. Coupling is adjusted relatively weakly. Such adjustment is performed by making the lengths of the first conductor 35 and the second conductor 36 different and making the degree of coupling of the third conductor 37 to the first conductor 35 and the second conductor 36 different. Thus, in the first embodiment, the conductors 35, 36, and 37 (inductors L1, L2, and L3) provided on the ferrite 32 have an impedance conversion function, and it is not necessary to add an inductor as a separate component. A reduction in input impedance can be achieved without reducing insertion loss or increasing the size.

  As in the first embodiment, the insertion loss characteristic when the third conductor 37 is wound around the ferrite 32 for 2.5 turns is shown by a curve A in FIG. 6, and the isolation characteristic is shown by a curve B in FIG. In the frequency band 1.920 to 1.980 GHz, the insertion loss is −0.452 to −0.471 dB, and the isolation is −14.265 to −15.987 dB.

  Further, in the two-port isolator, the ferrite / magnet element 30 is mechanically stable because the ferrite 32 and the pair of permanent magnets 41 are integrated by the adhesive 42, and is deformed or damaged by vibration or impact. It will not be a robust isolator.

(Refer to the second embodiment, FIGS. 7 and 8)
As shown in FIG. 7, the nonreciprocal circuit device (two-port isolator) according to the second embodiment intersects the first conductor 35 and the second conductor 36 in an insulated state by crossing the third conductor 37 to the ferrite 32. .5 turns. In FIG. 7, all the components of the third conductor 37 are not shown, but some of the components shown in FIG. 5 are omitted and wound for 1.5 turns.

  The effects of the first conductor 35, the second conductor 36, and the third conductor 37 in the second embodiment are the same as those in the first embodiment. The insertion loss characteristic is shown by the curve A in FIG. This is shown by curve B in FIG. In the frequency band of 1.920 to 1.980 GHz, the insertion loss is -0.592 dB and the isolation is -12.919 to -20.050 dB.

(Refer to the third embodiment, FIGS. 9 and 10)
As shown in FIG. 9, the nonreciprocal circuit device (two-port isolator) according to the third embodiment intersects the third conductor 37 with the first conductor 35 and the second conductor 36 in an insulated state, and the ferrite 32 .5 turns. In FIG. 9, all the components of the third conductor 37 are not shown, but each component shown in FIG. 5 is increased and is wound for 3.5 turns.

  The effects of the first conductor 35, the second conductor 36, and the third conductor 37 in the third embodiment are the same as those in the first embodiment. The insertion loss characteristic is shown by the curve A in FIG. This is shown by curve B in FIG. In the frequency band 1.920 to 1.980 GHz, the insertion loss is −0.416 to −0.390 dB, and the isolation is −11.186 to −20.286 dB.

(Relationship between number of turns and input / output impedance)
Table 1 below shows the relationship between the number of turns of the third conductor 37 with respect to the ferrite 32, the input impedance S11, and the output impedance S22. When the number of turns is 1.5 turns or more, conversion characteristics appear in the real part of the impedance between the input and output, and the impedance value itself increases. Further, in 2.5 turns, the output impedance becomes 50Ω, and has an impedance conversion function of input 25 + j20Ω and output 50 + j0Ω.

(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 41 are reversed, the input port P1 and the output port P2 are switched. The shapes of the first, second, and third conductors 35, 36, and 37 can be variously changed. For example, the first and second conductors 35, 36 may be branched into two on the main surface 32 a of the ferrite 32, and may wrap around the side surface. Further, the circuit board 20 may be a multilayer board, and the capacitor element C and the like may be constituted by internal electrodes.

  As described above, the present invention is useful for non-reciprocal circuit devices, and is particularly excellent in that a reduction in input impedance can be achieved without reducing insertion loss or increasing size.

DESCRIPTION OF SYMBOLS 20 ... Circuit board 21 ... Input terminal electrode 22 ... Output terminal electrode 23 ... Ground terminal electrode 30 ... Ferrite magnet element 32 ... Ferrite 35 ... 1st conductor 36 ... 2nd conductor 37 ... 3rd conductor 41 ... Permanent magnet P1 ... Input Port P2 ... Output port P3 ... Ground port R ... Resistance element

Claims (6)

A first conductor and a second conductor provided in a state of being connected to each other at one end to the main surface of the microwave magnetic body;
A third conductor drawn from a connection point of the first conductor and the second conductor, intersecting the first conductor and the second conductor in an insulating state and wound around the microwave magnetic body;
A permanent magnet that applies a DC magnetic field to the intersection of the first conductor, the second conductor, and the third conductor;
With
The end portions of the first conductor and the second conductor are input / output ports, the end portion of the third conductor is a ground port,
A resistance element is connected between the input / output ports in parallel to the first conductor and the second conductor,
The mutual inductance between the first conductor and the third conductor is different from the mutual inductance between the second conductor and the third conductor;
A nonreciprocal circuit device characterized by the above.   The nonreciprocal circuit device according to claim 1, wherein a capacitive element is connected in parallel to the resistance element between the input / output ports.   The nonreciprocal circuit device according to claim 1, wherein the first conductor and the second conductor have different lengths. The non- inductance according to claim 1 or 2 , wherein a mutual inductance between the first conductor and the third conductor is different from a mutual inductance between the second conductor and the third conductor. Reversible circuit element. 5. The nonreciprocal circuit device according to claim 1, wherein the first conductor and the second conductor are provided only on one main surface of the microwave magnetic body. 6. . Furthermore, a circuit board having connection terminal electrodes on its surface is provided, and the microwave magnetic body is an integral magnetic body / magnet element sandwiched between the main surfaces of the permanent magnet,
6. The magnetic body / magnet element is mounted on a surface of the circuit board so that a main surface of the microwave magnetic body is positioned in a vertical direction. The nonreciprocal circuit device according to 1.

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