JP2013162197A - Non-reciprocal circuit element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a non-reciprocal circuit element compact while improving the withstand voltage characteristics in the opposite direction.SOLUTION: The non-reciprocal circuit element includes a permanent magnet, a ferrite 32 to which a DC magnetic field is applied by the permanent magnet, and a first center electrode 35 and a second center electrode 36 disposed to intersect the ferrite 32 while being insulated electrically from each other. The first center electrode 35 has one end connected with an input port P1 and the other end connected with an output port P2. The second center electrode 36 has one end connected with the output port P2 and the other end connected with a ground port P3. A first matching capacitive element C1 is connected between the input port P1 and the output port P2, a second matching capacitive element C2 is connected between the output port P2 and the ground port P3, and a termination resistive element R is connected between the input port P1 and the output port P2. The first matching capacitive element C1 has a Q-value of 20-60.

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 mobile phone.

  As this type of non-reciprocal circuit element (isolator), those described in Patent Documents 1 and 2 are known. This type of isolator is provided with an equivalent circuit shown in FIG. 9 in order to achieve a low insertion loss. That is, it is a two-port isolator in which the first and second center electrodes 135 and 136 are wound around the ferrite 132 in an insulated state, and the first matching capacitor C1 is interposed between the input port P1 and the output port P2. Is connected, the second matching capacitor C2 is connected between the output port P2 and the ground port P3, and the termination is connected in parallel with the first center electrode 135 between the input port P1 and the output port P2. A resistor R is provided. When a forward high-frequency signal is input to the input terminal IN, a large current flows through the second center electrode 136 and is transmitted to the output terminal OUT. On the other hand, the high-frequency signal in the reverse direction input to the output terminal OUT is heated and diffused (ohmic loss) by the terminating resistor R.

  As the termination resistor R, a chip element is used. As the isolator is miniaturized, the chip resistor corresponds to the miniaturization. However, when the chip resistor is reduced in size, the allowable power is reduced, and the chip resistor itself cannot withstand heat generation due to the power of the high-frequency signal input from the opposite direction, and may be destroyed. That is, the withstand voltage performance in the reverse direction as an isolator is reduced. Therefore, the chip resistor cannot be miniaturized in consideration of heat resistance, and is a restriction for miniaturization of the isolator itself.

JP 2008-323533 A JP 2010-34776 A

  A first object of the present invention is to provide a non-reciprocal circuit device that can reduce the burden of heat generated by a termination resistor, improve the reverse withstand voltage characteristics, and can be reduced in size.

  A second object of the present invention is to provide a non-reciprocal circuit device that can be reduced in size by omitting a terminating resistor.

The nonreciprocal circuit device according to the first aspect of the present invention is
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;
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 termination resistance element is electrically connected between the input port and the output port,
The Q value of the first matching capacitive element is 20 to 60;
It is characterized by.

  In the non-reciprocal circuit device according to the first embodiment, since the Q value of the first matching capacitor element is as small as 20 to 60, the resistance component generated in the first matching capacitor device is relatively small, and this resistance component is the termination resistance. Will be inserted in parallel. That is, the heat generated by the high-frequency signal in the reverse direction is distributed to the termination resistor and the resistance component of the first matching capacitive element, and the heat generation of the termination resistor is reduced. As a result, the reverse withstand voltage characteristic is improved and a small chip resistor can be used, and the nonreciprocal circuit device itself is miniaturized.

The non-reciprocal circuit element which is the second form is
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;
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;
The Q value of the first matching capacitive element is 5 to 20,
It is characterized by.

  In the non-reciprocal circuit device according to the second embodiment, since the Q value of the first matching capacitor element is as small as 5 to 20, the resistance component generated in the first matching capacitor device becomes smaller. It will be inserted in between. That is, the heat generated by the high-frequency signal in the reverse direction is carried by the resistance component of the first matching capacitance element, and the termination resistor can be omitted. Thereby, the nonreciprocal circuit element itself is reduced in size.

  According to the present invention, it is possible to improve the reverse withstand voltage characteristics and to reduce the size of the isolator, and to reduce the size of the isolator by omitting the termination resistor.

It is an equivalent circuit diagram of the nonreciprocal circuit device (2-port isolator) which is the first embodiment. It is an equivalent circuit diagram of the non-reciprocal circuit device (2-port isolator) which is the second embodiment. It is a graph which shows the insertion loss characteristic and isolation characteristic of the 2 port type isolator which is 1st Example. It is a graph which shows the insertion loss characteristic and isolation characteristic of the 2 port type isolator which is 2nd Example. It is a disassembled perspective view which shows the 2 port type isolator which is 1st Example. It is a disassembled perspective view which shows the ferrite magnet element which comprises the 2 port type isolator which is 1st Example. It is a disassembled perspective view which shows the ferrite with a center electrode. It is a perspective view which shows a ferrite. It is an equivalent circuit diagram of a conventional 2-port type isolator.

  Embodiments of a nonreciprocal circuit device according to the present invention will be described below with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the same member and part in each figure, and the overlapping description is abbreviate | omitted.

(Refer to the first embodiment, FIGS. 1 and 3)
The 2-port isolator according to the first embodiment is constituted by the equivalent circuit shown in FIG. That is, the ferrite 32 to which a DC magnetic field is applied by a permanent magnet (not shown), and the first center electrode 35 (inductance L1) and the second center electrode 36 ( Inductance L2). The first center electrode 35 has one end connected to the input port P1 and the other end connected to the output port P2. The second center electrode 36 has one end connected to the output port P2 and the other end connected to the ground port P3. A termination resistor R is connected in parallel with the first center electrode 35 between the input port P1 and the output port P2, a first matching capacitor C1 is connected between the input port P1 and the output port P2, and the output port P2 The second matching capacitor C2 is connected between the first and second ground ports P3.

  Further, a capacitor Cs1 for matching input impedance is connected between the input port P1 and the input terminal IN, and a capacitor Cs2 for matching output impedance is connected between the output port P2 and the output terminal OUT. Further, a grounded impedance adjustment capacitor CA is connected to the input port P1.

  In the two-port isolator composed of the above-described equivalent circuit, when a high-frequency current is input to the input terminal IN (forward input), a large current flows through the second center electrode 36 and is transmitted to the output terminal OUT. This transmission frequency is determined by a parallel resonance circuit formed by the inductance L2 of the second center electrode 36 and the capacitor C2. At this time, almost no high-frequency current flows through the termination resistor R and the capacitor C1, so the insertion loss is small. On the other hand, when a high-frequency current is input to the output terminal OUT (reverse direction input), it is attenuated (isolated) by the parallel resonance circuit formed by the inductance L1 of the first center electrode 35 and the capacitor C1 and the termination resistor R. .

Here, the following numerical values are used for each element.
Capacitor C1: 22 pF (Q: 30, resistance component R ₁ : 720Ω)
Capacitor C2: 5.7 pF
Capacitor Cs1: 9pF
Capacitor Cs2: 15 pF
Termination resistance R: 720Ω

The capacitor C1 has a small Q value of 30, and the resistance component R ₁ existing in the capacitor C1 and generated in parallel with the terminating resistor R is 720Ω. That is, the heat generated by the high-frequency signal in the reverse direction is distributed to the termination resistor R and the resistance component R _{1 of the} capacitor C1, and the heat generation of the termination resistor R is reduced. As a result, the reverse withstand voltage characteristic is improved, and a small chip resistor can be used as the termination resistor R, and the isolator itself is also miniaturized.

  FIG. 3 shows insertion loss characteristics and isolation characteristics in the first embodiment. In FIG. 3, the insertion loss characteristics are as shown in the curve A, and the numerical values are shown on the left vertical axis. The isolation characteristics are as shown in curve B, and the numerical values are shown on the right vertical axis.

In the first embodiment, 20 to 60 can be used as the Q value of the capacitor C1. The resistance values R ₁ and R are selected so that isolation is maximized in the combined resistance value of the equivalent parallel resistance component R _{1 of the} capacitor C1 and the termination resistor R. The ratio of heat generation between them (the interest rate of power consumption) is a value inversely proportional to the equivalent parallel resistance value R ₁ and the termination resistance value R. In the first embodiment, the combined resistance value that maximizes isolation is designed to be 100 to 500Ω. The relationship between the Q value and the capacitance value varies depending on the capacitance value and the frequency band to be used, as indicated by Q = ωCR. However, by setting the Q value of the capacitor C1 in the range of about 20 to 60, the equivalent parallelism is obtained. The resistance component R ₁ can be set to about 200 to 3000Ω, and is a value that can be compared with the termination resistance value R. As a result, the power consumption ratio of the capacitor C1 with respect to the high-frequency signal in the reverse direction can be borne by a certain amount (10% or more).

  When the Q value of the capacitor C1 is larger than 60, the power consumption rate in the capacitor C1 is small, and improvement in the withstand voltage characteristic in the reverse direction as an isolator can hardly be expected. On the other hand, when the Q value of the capacitor C1 is smaller than 20, most of the power consumption ratio is biased toward the capacitor C1, and in this case, improvement of the withstand voltage characteristic cannot be expected.

For comparison, the numerical value of each element of the conventional 2-port isolator shown in FIG. 9 is shown.
Capacitor C1: 22 pF (Q: 110, resistance component R ₁ : 1000Ω)
Capacitor C2: 5.7 pF
Capacitor Cs1: 9pF
Capacitor Cs2: 15 pF
Termination resistance R: 360Ω

  The input loss characteristic and isolation characteristic of the conventional two-port isolator having the above numerical values are almost the same as those of the first embodiment shown in FIG. In other words, the first embodiment has input loss characteristics and isolation characteristics equivalent to those of the prior art, and withstand voltage characteristics in the reverse direction are improved, and a small chip resistor can be used as the termination resistor R. Thus, the isolator itself is reduced in size.

(Refer to the second embodiment, FIGS. 2 and 4)
The two-port isolator according to the second embodiment is configured by the equivalent circuit shown in FIG. 2, and the termination resistor R is omitted as compared with the first embodiment (see FIG. 1). The equivalent parallel resistance component R ₁ of the capacitor C1 is used as the equivalent resistance. A capacitor having a Q value of 5 to 20 is used as the capacitor C1.

Specific numerical values of each element are as follows.
Capacitor C1: 22 pF (Q: 17, resistance component R ₁ : 360Ω)
Capacitor C2: 5.7 pF
Capacitor Cs1: 9pF
Capacitor Cs2: 15 pF
Termination resistor R: omitted

In the second embodiment, the capacitor C1 has a small Q value of 17, and the resistance component R ₁ generated in the capacitor C1 is 360Ω, which is substantially equal to the resistance value of the termination resistor R shown in FIG. Thus, heat generation by the high frequency signal in the reverse direction is performed by the resistance component R _{1 of the} capacitor C1. Since the termination resistor R is omitted, the isolator itself is downsized.

  FIG. 4 shows insertion loss characteristics and isolation characteristics in the second embodiment. In FIG. 4, the insertion loss characteristic is as shown in the curve A, and the numerical value is shown on the left vertical axis. The isolation characteristics are as shown in curve B, and the numerical values are shown on the right vertical axis.

In the second embodiment in which the terminating resistor R is omitted, 5 to 20 can be used as the Q value of the capacitor C1. When the Q value of the capacitor C1 is less than 5, or, if greater than 20, the equivalent parallel resistance component R ₁ of the capacitor C1 in place of the terminating resistor R shown in the first embodiment deviates from the appropriate range The necessary isolation characteristics (reverse input signal attenuation) cannot be obtained.

(Specific configuration in the first embodiment, see FIGS. 5 to 8)
Next, a specific configuration of the two-port isolator shown in the equivalent circuit in FIG. 1 will be described. The two-port type isolator is configured as a lumped constant type isolator. As shown in FIG. 5, the circuit board 20, a ferrite magnet element 30 composed of a ferrite 32 and a permanent magnet 41, and chip elements C1, C2 are schematically shown. , Cs1, Cs2, CA, R. As shown in FIG. 7, the ferrite 32 has a first center electrode 35 and a second center electrode 36 that are electrically insulated from each other on the front and back main surfaces 32 a and 32 b. 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. 6), 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. 7, the first center electrode 35 is inclined at a relatively small angle with respect to the long side at the upper left in a state where the first main surface 32 a of the ferrite 32 rises from the lower right and branches into two. Formed on 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. 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. The first central electrode 35 is formed so as to intersect with the first central electrode 35, wraps around the second main surface 32b via the relay electrode 36b on the upper surface, and the first turn 36c is substantially perpendicular to the first main electrode 35 on the second main surface 32b. It is formed in a crossed state. 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.

  The connection electrodes 35b, 35c, and 36p and the relay electrodes 35a, 36b, 36d, 36f, 36h, 36j, 36l, and 36n are silver or silver in a recess 37 (see FIG. 8) 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 board in which predetermined electrodes are formed on a plurality of dielectric sheets, laminated, and sintered. The ferrite-magnet element 30 is placed on the circuit board 20, and the connection electrodes 35b, 35c, 36p on the lower surface of the ferrite 32 are connected to terminal electrodes 25a, 25b, 25b on the circuit board 20, as shown in FIG. The bottom surface of the permanent magnet 41 is integrated on the circuit board 20 with an adhesive.

  The capacitor C1 is soldered between the terminal electrodes 26a and 26b, the capacitor C2 is soldered between the terminal electrodes 26c and 26d, the capacitor Cs1 is soldered between the terminal electrodes 26e and 26f, and the capacitor Cs2 is soldered between the terminal electrodes 26g and 26f. The capacitor CA is soldered between the terminal electrodes 26i and 26j, and the termination resistor R is soldered between the terminal electrodes 26k and 26l. The first and second center electrodes 35 and 36 and each element are electrically connected so as to form the equivalent circuit shown in FIG. 1 inside the circuit board 20 and provided on the back surface of the circuit board 20. The input terminal IN, the output terminal OUT, and the ground terminal GND are connected.

(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, shape, number of turns, etc. of the first center electrode and the second center electrode are arbitrary. The capacitor may be a single plate type in addition to the chip type, or may be formed inside a circuit board.

  As described above, the present invention is useful for non-reciprocal circuit devices, and is particularly excellent in that it can improve the withstand voltage characteristics in the reverse direction and can reduce the size of the isolator.

30 ... ferrite magnet device 32 ... ferrite 35 ... first center electrode 36 ... second center electrode 41 ... permanent magnets P1 ... input port P2 ... output port P3 ... ground port R ... terminating resistor C1, C2 ... matching capacitors R ₁ ... Equivalent parallel resistance

Claims (2)

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;
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 termination resistance element is electrically connected between the input port and the output port,
The Q value of the first matching capacitive element is 20 to 60;
A nonreciprocal circuit device characterized by the above. 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;
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;
The Q value of the first matching capacitive element is 5 to 20,
A nonreciprocal circuit device characterized by the above.

Images