WO2014115595A1

WO2014115595A1 - Irreversible circuit element

Info

Publication number: WO2014115595A1
Application number: PCT/JP2014/050417
Authority: WO
Inventors: 田口　義規
Original assignee: 株式会社村田製作所
Priority date: 2013-01-23
Filing date: 2014-01-14
Publication date: 2014-07-31

Abstract

The present invention obtains good isolation characteristics across a wide bandwidth, and allows adjustment of impedance. An irreversible circuit element provided with a first center electrode (35) and a second center electrode (36) that are disposed intersecting in a mutually insulated state with a ferrite (32) to which a direct-current magnetic field is applied by a permanent magnet. The first center electrode (35) is connected at one end to an input port (P1), and at the other end to an output port (P2). The second center electrode (36) is connected at one end to the port (P2) or the port (P1), and at the other end to a ground. A capacitor (C1) is connected between the port (P1) and the port (P2), and a capacitor (C2) is connected between the port (P2) and the ground. A resistor (R) is connected between the port (P1) and the port (P2). A capacitor (C3) and an inductor (L3) are connected serially to the resistor (R). A capacitor (Cg) and an inductor (Lg) are connected serially between the other end of the second center electrode (36) and the ground. A capacitor (Ca) is connected between the port (P1) and the ground. At least one of the capacitor (C2) and the capacitor (Ca) has variable capacitance.

Description

Non-reciprocal circuit element

The present invention relates to non-reciprocal circuit elements, and more particularly to non-reciprocal circuit elements such as isolators and circulators used in the 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 a non-reciprocal circuit device of this type, as a two-port type isolator, as described in Patent Document 1, the first center electrode and the second center electrode are arranged on the surface of the ferrite so as to cross each other in an insulated state. A resistor is connected between one end of the first center electrode connected to the output port and one end of the second center electrode connected to the output port, and an inductor and a capacitor are connected in series with the resistor. It has been. According to this isolator, it is possible to improve the isolation characteristic while maintaining the insertion loss characteristic by connecting a series resonance circuit including an inductor and a capacitor to the resistor.

Patent Document 2 describes a two-port isolator in which a parallel resonant circuit composed of an inductor and a capacitor is connected between the other end of the second center electrode and the ground. The band can be widened.

Patent Document 3 describes a three-port isolator in which the end portions of three center electrodes are connected to the ground via a series resonance circuit composed of an inductor and a capacitor, respectively, and operates in a wide band by providing this series resonance circuit. Is possible.

Patent Document 4 describes a two-port isolator in which the value of the other capacitor connected in parallel with the capacitor provided between the input port and the output port (in parallel with the first center electrode) is variable. By making the value of one capacitance variable, it is possible to accurately shift (adjust) the center frequency of isolation to a predetermined band.

However, the isolator described in Patent Document 1 has a limit in widening the bandwidth. With the isolator described in Patent Document 2, isolation cannot be made in a wide band. The isolator described in Patent Document 3 is a three-port type, and is difficult to apply to a two-port type because the insertion loss increases and the input reflection characteristic becomes narrow. The isolator described in Patent Document 4 cannot adjust the impedance.

Japanese Patent No. 4155342 JP 2006-50543 A JP 2011-55222 A International Publication No. 2012/20613

An object of the present invention is to provide a non-reciprocal circuit device capable of obtaining good isolation characteristics over a wide band and capable of adjusting impedance.

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, which are arranged to intersect the ferrite in an insulated state;
With
The first center electrode has one end connected to the input port and the other end connected to the output port.
The second center electrode has one end connected to the output port or the input port, the other end connected to the ground,
A first capacitor is connected between the input port and the output port;
A second capacitor is connected between the output port and ground;
A resistor is connected between the input port and the output port, and a third capacitor and a first inductor are connected in series with the resistor,
A fourth capacitor and a second inductor are connected in series between the other end of the second center electrode and the ground,
A fifth capacitor is connected between the input port and the ground;
A capacitance value of at least one of the second capacitor and the fifth capacitor is variable;
It is characterized by.

The non-reciprocal circuit device according to the second 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, which are arranged to intersect the ferrite in an insulated state;
With
The first center electrode has one end connected to the input port and the other end connected to the output port.
The second center electrode has one end connected to the output port or the input port, the other end connected to the ground,
A first capacitor is connected between the input port and the output port;
A second capacitor is connected between the output port and ground;
A resistor is connected between the input port and the output port, and a third capacitor and a first inductor are connected in series with the resistor,
A fifth capacitor is connected between the input port and the ground;
A capacitance value of at least one of the second capacitor and the fifth capacitor is variable;
It is characterized by.

In the nonreciprocal circuit device, a third capacitor and a first inductor are connected in series with a resistor inserted between the input port and the output port, and the other end of the second center electrode and the ground Since the fourth capacitor and the second inductor are connected in series between them, a good isolation characteristic can be obtained over a wide band. Furthermore, the input impedance and / or the output impedance can be adjusted by changing the capacitance value of at least one of the second capacitor and the fifth capacitor.

According to the present invention, good isolation characteristics can be obtained over a wide band, and the impedance can be adjusted.

1 is an equivalent circuit diagram showing a first embodiment (2-port isolator) of a non-reciprocal circuit device. FIG. It is a perspective view which shows the ferrite magnet assembly which comprises 1st Example. It is a graph which shows the 1st characteristic in 1st Example. It is a graph which shows the 2nd characteristic in 1st Example. It is a graph which shows the 3rd characteristic in 1st Example. It is a Smith chart which shows the said 3rd characteristic. It is a graph which shows the 4th characteristic in the 1st example. It is a Smith chart which shows the said 4th characteristic. It is an equivalent circuit diagram which shows 2nd Example (2 port type isolator) of a nonreciprocal circuit device. It is an equivalent circuit diagram showing a third embodiment (2-port isolator) of a non-reciprocal circuit device. It is a perspective view which shows the ferrite magnet assembly which comprises 3rd Example. It is an equivalent circuit schematic which shows 4th Example of a nonreciprocal circuit device. It is a graph which shows the 1st characteristic in 4th Example. It is a Smith chart which shows the said 1st characteristic. It is a graph which shows the 2nd characteristic in 4th Example. It is a Smith chart which shows the said 2nd characteristic. It is a graph which shows the 3rd characteristic in 4th Example. It is a Smith chart which shows the said 3rd characteristic. It is a block diagram which shows an example of the transmission circuit provided with the 2 port type isolator.

Hereinafter, embodiments of the non-reciprocal circuit device according to the present invention will be described 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 to 8)
FIG. 1 shows an equivalent circuit of the nonreciprocal circuit device (2-port isolator) according to the first embodiment. The two-port isolator 1A is a lumped constant isolator, and is arranged on a ferrite 32 such that a first center electrode 35 constituting the inductor L1 and a second center electrode 36 constituting the inductor L2 are crossed in an insulated state. It is a thing.

One end (port P1) of the first center electrode 35 is connected to the input terminal 51 via a matching capacitor Cs1. The other end (port P2) of the first center electrode 35 and one end (port P2) of the second center electrode 36 are connected to the output terminal 52 via a matching capacitor Cs2, and the other end (port P3) of the second center electrode 36. ) Is connected to ground. In the first embodiment, a capacitor Cg and an inductor Lg are connected in series between the other end of the second center electrode 36 and the ground.

A matching capacitor C1 is connected in parallel with the first center electrode 35 between the port P1 and the port P2, and a matching capacitor C2 is connected in parallel with the second center electrode 36 between the port P2 and the ground. ing. A resistor R and an LC series resonance circuit (comprising an inductor L3 and a capacitor C3) are connected in parallel with the first center electrode 35 between the port P1 and the port P2. Further, an impedance adjustment capacitor Ca connected to the ground is connected to one end of the first center electrode 35.

In the 2-port isolator 1A having the above circuit configuration, when a high-frequency current is input from the terminal 51 to the port P1, a large high-frequency current flows through the second center electrode 36, and almost all the high-frequency current flows through the first center electrode 35. Does not flow, insertion loss is small, and it operates in a wide band. During this operation, almost no high-frequency current flows through the resistor R or the LC series resonance circuit (inductor L3 and capacitor C3). Therefore, the loss due to the LC series resonance circuit can be ignored and the insertion loss does not increase. Further, a capacitor C3 and an inductor L3 are connected in series with the resistor R inserted between the port P1 and the port P2, and a capacitor Cg and an inductor Lg are connected in series between the port P3 and the ground. Therefore, good isolation characteristics can be obtained over a wide band.

On the other hand, when a high-frequency current is input from the terminal 52 to the port P2, it is matched in a wide band by the impedance characteristics of the resistor R and the LC series resonance circuit, and the isolation characteristics are improved. Such isolation and insertion loss characteristics will be described later with reference to FIGS.

Furthermore, in the first embodiment, the capacitors Ca and C2 are variable capacitance capacitors. The input impedance and the output impedance can be adjusted by appropriately changing the capacitance values of the capacitors Ca and C2. Note that at least one of the capacitors Ca and C2 may be a variable capacitance capacitor.

Here, the configuration of the main part of the 2-port isolator 1A will be described with reference to FIG. The lumped constant type two-port isolator 1A includes a ferrite magnet assembly 30 in which permanent magnets 41 are bonded to the front and back surfaces of a ferrite 32 via an adhesive 42, respectively. The first center electrode 35 is wound around the front and back surfaces of the ferrite 32 by one turn, and one end electrode 35a is a port P1 and the other end electrode 35b is a port P2. The second center electrode 36 is wound four turns on the front and back surfaces of the ferrite 32 so as to intersect with the first center electrode 35 while maintaining an insulating state at a predetermined angle. The number of windings is arbitrary. One end of the second center electrode 36 is common to the electrode 35b (port P2), and the other end electrode 36a is the port P3. In FIG. 2, the illustration of the electrode on the back side of the ferrite 32 is omitted to avoid complication.

FIG. 3 shows the first characteristic of the 2-port isolator 1A by a solid line. (A) is an input reflection characteristic, (B) is an isolation characteristic, (C) is an insertion loss characteristic, and (D) is an output reflection characteristic. In FIG. 3, the characteristics of the 2-port isolator described in Patent Document 1 are indicated by a dotted line for reference. This first characteristic is simulation data in the following specifications.

Capacitor C1: 16 pF
Capacitor C2: 3.8 pF
Capacitor C3: 4.6 pF
Inductor L3: 8.2 nH
Resistance R: 30Ω
Capacitor Ca: 1.2 pF
Capacitor Cs1: 10 pF
Capacitor Cs2: 9pF
Capacitor Cg: 18pF
Inductor Lg: 1.5 nH

In the first embodiment, the capacitor C3 and the inductor L3 connected in series with the resistor R inserted between the port P1 and the port P2, and the other end of the second center electrode 36 and the ground. Isolation of 7 dB or more can be secured over a wide band of 699 to 915 MHz (relative band 26%) by the capacitor Cg and the inductor Lg connected in series therebetween.

FIG. 4 shows the second characteristic of the 2-port isolator 1A by a solid line. (A) is an input reflection characteristic, (B) is an isolation characteristic, (C) is an insertion loss characteristic, and (D) is an output reflection characteristic. In FIG. 4 as well, the characteristics of the 2-port isolator described in Patent Document 1 are indicated by dotted lines for reference. The second characteristic is that the capacitance of the capacitor Cg is changed to 12 pF and the isolation is set to 9 dB.

FIG. 5 shows the third characteristic of the 2-port isolator 1A by a solid line. (A) is an input reflection characteristic, (B) is an isolation characteristic, (C) is an insertion loss characteristic, and (D) is an output reflection characteristic. In the third characteristic, the isolation is substantially the same as in the first example, and only the input impedance is adjusted to the use frequency band. The input impedance can be adjusted to 50 ± 5Ω from Band 12 to Band 8, and the capacitance of the capacitors Ca and C2 is adjusted to be adjusted to Band 8 (880 to 915 MHz). In FIG. 6, the impedance characteristics are shown by solid lines, where (A) is the input impedance and (B) is the output impedance. In FIGS. 5 and 6, the characteristics when adjusted to Band 5 (824 to 849 MHz) are shown by dotted lines for reference.

FIG. 7 shows the fourth characteristic of the 2-port isolator 1A by a solid line. (A) is an input reflection characteristic, (B) is an isolation characteristic, (C) is an insertion loss characteristic, and (D) is an output reflection characteristic. In the fourth characteristic, the isolation is substantially the same as in the first example, and the capacitances of the capacitors Ca and C2 are adjusted to be adjusted to Band 12 (699 to 716 MHz). FIG. 8 shows the impedance characteristics with solid lines, where (A) is the input impedance and (B) is the output impedance. 7 and 8 also show the characteristics when adjusted to Band 5 (824 to 849 MHz) for reference.

(Refer to the second embodiment, FIG. 9)
FIG. 9 shows an equivalent circuit of the nonreciprocal circuit device (2-port isolator) according to the second embodiment. The two-port isolator 1B includes capacitors Caa, Cab, Cac and capacitors C2a. C2b and C2c are arranged in parallel, and the capacitors Cab and Cac and the capacitors C2b and C2c are switched (including the neutral position) by the switching

elements

55 and 56, respectively. Capacitors Caa and C2a constitute reference capacitances, respectively, and capacitors Cab and Cac and capacitors C2b and C2c perform adjustment functions for adding capacitance.

The operational effects of the 2-port isolator 1B are basically the same as those of the 2-port isolator 1A.

(Refer to the third embodiment, FIGS. 10 and 11)
FIG. 10 shows an equivalent circuit of the nonreciprocal circuit device (2-port isolator) according to the third embodiment. In this 2-port isolator 1C, one end of the second center electrode 36 is connected to one end (port P1) of the first center electrode 35, and an inductor L4 is added between the capacitor Cs1 and the input terminal 51. The other configuration is the same as that of the two-port isolator 1B according to the second embodiment.

As shown in FIG. 11, in the ferrite / magnet assembly 30, the first center electrode 35 is wound around the front and back surfaces of the ferrite 32 by one turn, the one end electrode 35a is the port P1, and the other end electrode 35b is the port. P2. The second center electrode 36 is wound four turns on the front and back surfaces of the ferrite 32 so as to intersect with the first center electrode 35 while maintaining an insulating state at a predetermined angle. The number of windings is arbitrary. One end of the second center electrode 36 is common (port P1) with the electrode 35a, and the other end electrode 36a is the port P3. In FIG. 11, the illustration of the electrode on the back side of the ferrite 32 is omitted to avoid complication.

In the two-port isolator 1C, by setting the inductance of the second center electrode 36 to be larger than the inductance of the first center electrode 35, when a high frequency current is input from the terminal 51 to the port P1, the second center electrode 36 36 and resistor R hardly flow current, current flows through the first center electrode 35, insertion loss is small, and the device operates in a wide band. During this operation, almost no high-frequency current flows through the resistor R or the LC series resonance circuit (inductor L3 and capacitor C3). Therefore, the loss due to the LC series resonance circuit can be ignored and the insertion loss does not increase. Further, a capacitor C3 and an inductor L3 are connected in series with the resistor R inserted between the port P1 and the port P2, and a capacitor Cg and an inductor Lg are connected in series between the port P3 and the ground. Therefore, good isolation characteristics can be obtained over a wide band.

The first center electrode 35 and the second center electrode 36 are magnetically coupled, and the impedance on the input side (P1) is reduced by adjusting the mutual inductance. 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. On the other hand, when a high-frequency current is input from the terminal 52 to the port P2, it is matched in a wide band by the impedance characteristics of the resistor R and the LC series resonance circuit, and the isolation characteristics are improved.

(Refer to the fourth embodiment, FIGS. 12 to 18)
FIG. 12 shows an equivalent circuit of the nonreciprocal circuit device (2-port isolator) according to the fourth embodiment. This 2-port isolator 1D is a series resonant circuit (capacitor Cg and inductor Lg) connected between the other end (port P3) of the second center electrode 36 and the ground in the 2-port isolator 1A of the first embodiment. ) Is omitted. Therefore, the operation and effect of the two-port isolator 1D are basically the same as those of the two-port isolator 1A, and the capacitor C3 is connected in series with the resistor R inserted between the ports P1 and P2. And the inductor L3 are connected, a good isolation characteristic can be obtained over a wide band.

FIG. 13 shows the first characteristic of the 2-port isolator 1D by a solid line. (A) is an input reflection characteristic, (B) is an isolation characteristic, (C) is an insertion loss characteristic, and (D) is an output reflection characteristic. FIG. 14 shows the impedance characteristics with a solid line, where (A) is the input impedance and (B) is the output impedance. This first characteristic is simulation data in the following specifications.

Capacitor C1: 16 pF
Capacitor C2: 2.2 pF
Capacitor C3: 16pF
Inductor L3: 4.6 nH
Resistance R: 25Ω
Capacitor Ca: 0.3 pF
Capacitor Cs1: 6pF
Capacitor Cs2: 6pF

In the fourth embodiment, a capacitor C3 and an inductor L3 connected in series with a resistor R inserted between the port P1 and the port P2 are used to provide a band 5 (isolation of 5 dB or more over a wide band of 824 to 849 MHz). The impedance is 57.5−j2.8Ω in Band 8 and 33.7 + j2.7Ω in Band 12, which is not 50Ω.

FIG. 15 shows the second characteristic of the 2-port isolator 1D by a solid line. (A) is an input reflection characteristic, (B) is an isolation characteristic, (C) is an insertion loss characteristic, and (D) is an output reflection characteristic. In FIG. 16, the impedance characteristics are shown by solid lines, where (A) is the input impedance and (B) is the output impedance. The second characteristic is adjusted to be compatible with Band 8 by changing the capacitances of the capacitors Ca and C2 to 0.1 and 1.6 pF, respectively. In Band 8, it can be adjusted to about 50Ω. Isolation has hardly changed.

FIG. 17 shows the third characteristic of the 2-port isolator 1D by a solid line. (A) is an input reflection characteristic, (B) is an isolation characteristic, (C) is an insertion loss characteristic, and (D) is an output reflection characteristic. FIG. 18 shows the impedance characteristics with solid lines, where (A) is the input impedance and (B) is the output impedance. The third characteristic is adjusted to be compatible with Band 12 by changing the capacitances of the capacitors Ca and C2 to 0.8 and 3.4 pF, respectively. In Band 8, it can be adjusted to about 50Ω. Isolation has hardly changed.

(Example of transmission circuit, see FIG. 19)
The two-port isolator 1 (1A, 1B, 1C, 1D) is mounted on, for example, a transmission circuit shown in FIG. In this transmission circuit, a two-port isolator 1 is inserted between a power amplifier 62 connected to a high frequency IC 61 and a duplexer 64 connected to an antenna 65. The output side of the power amplifier 62 is connected to the terminal 51, and the input side of the duplexer 64 is connected to the terminal 52.

(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. In this case, the input / output impedance can be lowered. The shapes of the first and

second center electrodes

35 and 36 are arbitrary.

As described above, the present invention is useful for non-reciprocal circuit devices, and is particularly excellent in that good isolation characteristics can be obtained over a wide band and impedance can be adjusted.

1A to 1D ... 2 port type isolator 32 ... Ferrite 35 ... First center electrode 36 ... Second center electrode 41 ...

Permanent magnet

55, 56 ... Switching elements P1, P2, P3 ... Ports C1, C2, C3, Ca, Cg ... Capacitors L3, Lg ... Inductors

Claims

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, which are arranged to intersect the ferrite in an insulated state;
With
The first center electrode has one end connected to the input port and the other end connected to the output port.
The second center electrode has one end connected to the output port or the input port, the other end connected to the ground,
A first capacitor is connected between the input port and the output port;
A second capacitor is connected between the output port and ground;
A resistor is connected between the input port and the output port, and a third capacitor and a first inductor are connected in series with the resistor,
A fourth capacitor and a second inductor are connected in series between the other end of the second center electrode and the ground,
A fifth capacitor is connected between the input port and the ground;
A capacitance value of at least one of the second capacitor and the fifth capacitor is variable;
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, which are arranged to intersect the ferrite in an insulated state;
With
The first center electrode has one end connected to the input port and the other end connected to the output port.
The second center electrode has one end connected to the output port or the input port, the other end connected to the ground,
A first capacitor is connected between the input port and the output port;
A second capacitor is connected between the output port and ground;
A resistor is connected between the input port and the output port, and a third capacitor and a first inductor are connected in series with the resistor,
A fifth capacitor is connected between the input port and the ground;
A capacitance value of at least one of the second capacitor and the fifth capacitor is variable;
A nonreciprocal circuit device characterized by the above.
3. The nonreciprocal circuit device according to claim 1, wherein at least one of the second capacitor and the fifth capacitor includes a plurality of capacitors, and the operation of the capacitors is switched by a switching device.