JP3891437B2 - Three-terminal pair irreversible element and communication device using the same - Google Patents

Description

  The present invention relates to a circulator / isolator that is a non-reciprocal element for high frequency, and more particularly to the field of a three-terminal pair non-reciprocal element having a small insertion loss and a wide band characteristic.

  As a technical state of an isolator that is a current high-frequency nonreciprocal element, one terminal of a three-terminal-pair circulator is generally terminated with a matching impedance. This junction type circulator is classified into two types, that is, a distributed constant type circulator and a lumped constant type circulator. The circulator has an irreversible electrical characteristic, and its structure is based on a structure in which a magnetic field is applied perpendicularly to the ferrite thin plate and a conductor is close to the periphery of the ferrite thin plate. The former distributed constant type is selectively used when the size of the isolator element is ¼ or more of the wavelength of the high frequency transmitted through the ferrite thin plate handled, and the latter lumped constant type is used when the size is 1/8 or less. The lumped constant type is more suitable for miniaturization.

  FIG. 21 shows a schematic structure diagram and a schematic circuit diagram when an isolator is realized by connecting a matching impedance (resistive element R) to one terminal pair of a three-terminal pair lumped constant circulator currently used in a mobile phone or the like. Show. The ferrite thin plate G is made of garnet-type ferrite, and three central conductors L1, L2, and L3 are arranged on this upper surface at an angular interval of 120 degrees as shown in FIG. One end of each center conductor serves as an input / output line for the terminal pairs 1, 2, and 3, and the other end is connected to a common portion GR serving as a ground conductor. Matching capacitors C1, C2, and C3 are connected in parallel between one end of each of the central conductors L1, L2, and L3 and the common portion GR. Further, a resistance element R for absorbing energy in order to realize an isolator is attached between the terminal pair 3 and the common part GR. A permanent magnet is loaded so that a static magnetic field substantially perpendicular to the main surface of the ferrite thin plate G is applied, but it is omitted in the drawing. By carefully adjusting the direction and strength of the static magnetic field, and the sizes of the center conductors L1, L2, and L3 and the matching capacitors C1, C2, and C3, the structure of FIG. 21 has the desired frequency (hereinafter referred to as the center frequency). The high frequency input from the terminal pair 1 is transmitted to the terminal pair 2 and the high frequency input from the terminal pair 2 is transmitted to the terminal pair 3 with a small loss. When the resistance element R is connected to the terminal pair 3, most of the energy is absorbed there, and the high frequency hardly propagates from the terminal pair 2 to the terminal pair 1. That is, it is possible to realize an isolator which is an element that helps propagation in one direction and blocks it in the opposite direction.

  Conventionally, the intersection angle of the terminal pairs 1, 2, and 3 is normally set to 120 degrees, but a three-terminal pair nonreciprocal element that is set to an unequal angle has also been proposed (see, for example, Patent Documents 1 and 2).

JP-A-9-102704 Japanese Patent Laid-Open No. 10-163709

  The prior art structure of FIG. 21 is symmetrical and has the advantage of being easy to make, but has the disadvantage that the insertion loss is not very small and the bandwidth is narrow. Further, even with the structure disclosed in Patent Document 1 or Patent Document 2, the insertion loss and the bandwidth are not sufficiently improved. In addition, these conventional devices have a problem that they are not cheap in terms of cost.

  The present invention has been made in view of the above-described prior art, and an object of the present invention is to provide a three-terminal pair irreversible element with a small insertion loss and a wide bandwidth, and a communication device using the same.

According to the first aspect of the present invention, the first, second and third central conductors are arranged close to the ferrite thin plate so as to cross each other in an electrically insulated state, and the ferrite thin plate has a static magnetic field generated by a permanent magnet. One end of each of the first, second, and third central conductors is a first, second, and third input / output terminal, and the other end is connected to a common portion, and the first, second, First, second, and third matching capacitors are respectively connected between the third input / output terminal and the common portion, and any one of the first , second, and third input / output terminals is connected. A resistance element is connected between the input / output terminal and the common part, and one of the remaining two input / output terminals is an input terminal, and the other is an output terminal. The crossing angle as viewed on the input / output terminal side of the central conductor as the output terminal is 90 degrees or less. This is a three-terminal pair nonreciprocal element.

According to a second aspect of the present invention, there is provided a crossing angle of the central conductor connected to the resistance element and the central conductor serving as the input terminal on the input / output terminal side, or the center conductor serving as the output terminal and the center serving as the output terminal. The three-terminal-pair nonreciprocal element is characterized in that the crossing angle seen on the input / output terminal side of the conductor is 90 degrees or less .

According to a third aspect of the present invention , there is provided a three-terminal non-reciprocal element characterized in that an intersection angle of the central conductor serving as the input terminal and the central conductor serving as the output terminal viewed from the input / output terminal side is about 60 degrees. is there.

  According to a fourth aspect of the present invention, there is provided a three-terminal pair nonreciprocal element, wherein a central portion of at least one of the first, second and third central conductors is divided into three or more conductors. is there.

  The invention according to claim 5 is the three-terminal pair nonreciprocal element characterized in that the common part is a ground conductor.

  A sixth aspect of the present invention is a communication device comprising at least one three-terminal-pair nonreciprocal element according to any one of the first to fifth aspects of the present invention.

  The circulator / isolator, which is a three-terminal pair nonreciprocal element of the present invention, has a small insertion loss, a wide bandwidth, and can cope with cost reduction.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 shows an assembly drawing of a central conductor and a ferrite thin plate according to one embodiment of the present invention. On the disk-shaped ferrite thin plate G, the first, second, and third center conductors L1, L2, and L3 are arranged so as to intersect while maintaining an electrically insulating state. The difference from the prior art is that the intersection angle φ between the first and second center conductors is not 120 degrees but 60 degrees. The crossing angle here is an angle formed by the center line of each central conductor crossing the ferrite thin plate, and is the crossing angle seen on the input / output terminal side. Similarly, the crossing angle θ between the second and third central conductors is 60 degrees. By adopting such a configuration, the bandwidth of insertion loss has been dramatically improved. Although the electrical insulation state is not shown in the drawing, it is achieved by inserting an adhesive tape such as Teflon (registered trademark) or polyimide between the central conductors. It can also be realized by applying an insulating coating such as a resist on the surface of the central conductor.

  FIG. 2 is a circuit diagram realized as an isolator by connecting accessory parts to the central conductor and ferrite thin plate assembly of FIG. 1 which is an embodiment of the present invention. The ferrite thin plate G is applied with a static magnetic field by a permanent magnet, which is not shown in the drawing. One ends of the first, second, and third central conductors are input / output terminals 1, 2, and 3, respectively, and the other ends are connected to the common portion GR. First, second, and third matching capacitors C1, C2, and C3 are respectively attached between the input / output terminals 1, 2, and 3 and the common portion GR. A resistance element R is connected between the input / output terminal 3 and the common part GR. In this embodiment, the direction of the static magnetic field applied to the ferrite thin plate G from the outside is determined so that 1 is an input terminal and 2 is an output terminal. The effect of the present invention is not limited to this, and there is no change even if 2 is an input terminal and 1 is an output terminal.

  FIG. 3 is a diagram for explaining the effects of the present invention in comparison with the prior art. FIG. 3A shows the prior art, and FIG. 3B shows the first central conductor L1 and the second central conductor L2 of the present invention. The former crossing angle is 120 degrees and the latter is 60 degrees. In either case, the first center conductor L1 is an input, and the second center conductor L2 is an output. Although resistance elements are connected to the third central conductor L3, they are omitted in FIG. 3 because they are not directly related to the description of this effect. First, when the circulator operates ideally, the input voltage and the output voltage are in opposite phases in the conventional technique. In the embodiment using the technique of the present invention shown in FIG. 1, the input voltage and the output voltage are in phase. That is, if the voltage on the common part GR side of the center conductor is zero, the L1 and L2 end voltages on the opposite side have opposite signs in the prior art, and the signs in the technique of the present invention are the same and their absolute values are respectively equal. However, the actual central conductors L1 and L2 are two parallel lines, and there are a plurality of intersecting portions as shown in the figure. The black circles in the figure are portions where the voltage absolute values of the two central conductors are equal. A white circle is a portion where the absolute values of the voltages are different. Of course, if the shape of the center conductor is thin, not two, as shown in the figure, the two center conductors always intersect at the center of the ferrite sheet G, so the crossing portion of the center conductor does not depend on the intersection angle of the center conductor. There is almost no difference in the absolute voltage value. However, in practice, two or more central conductors are used in order to make the high frequency magnetic field inside the ferrite thin plate uniform.

As shown in FIG. 3, when two parallel lines intersect, a voltage difference is generated at the intersecting location. That is, when the intersecting angle is 120 degrees according to the prior art, the voltage difference between the two central conductors in the black circle portion is the largest and V _A + V _B ≈2V _A. On the other hand, when the intersection angle of the present invention is 60 degrees, there is no voltage difference in the black circle portion, and the voltage difference in the white circle portion is the largest and is V _C −V _D. As is apparent from the figure, V _A + V _B ≈2V _A >> V _C −V _D is satisfied. However, V _A , V _B , V _C , and V _D are absolute values of voltages at each point.
This means that in the case of the prior art, when energy propagates from the input terminal to the output terminal, the voltage difference at the intersection between the two central conductors is large and high-frequency current tends to flow through the line capacitance. Yes. Since this high frequency current does not directly contribute to the circulator operation, the insertion loss characteristic of the isolator is deteriorated. On the other hand, in the case of the technique of the present invention, the voltage difference in this portion is reduced to 1/5 to 1/10 as compared with the prior art, and the unnecessary high frequency current is greatly reduced even if the line capacitance is the same. Has a positive impact.

  FIG. 4 is a diagram for explaining another advantage of the present invention. The central conductor is generally made by punching a copper plate by photoetching or die. FIG. 4A is a developed view of the center conductor of the prior art. It spreads symmetrically in three directions and the number of central conductors per unit area of the copper plate is small. Compared to this, as shown in FIG. 4B, the development view of the center conductor of the present invention is slightly biased to the lower half, and the number of center conductors taken per unit area of the copper plate increases. This is particularly effective for mobile phone isolators that are called for cost reduction.

  FIG. 5 is an equivalent circuit diagram of an isolator used for demonstrating the effect of the present invention. A difference from FIG. 2 is that a series capacitor Cs is added between the input terminal 1 and the output terminal 2 and the isolator body. This capacitor Cs is for impedance conversion and is used when the impedance inside the isolator is high.

  FIGS. 6 (a) and 6 (b) show the results of electrical characteristics of an experiment conducted using a 6 mmφ garnet. The prior art is indicated by a dotted line, and the result of the present invention is indicated by a solid line. In the figure, the vertical axis represents the loss level, the horizontal axis represents the frequency, and the center frequency is the 650 MHz band. (A) shows the frequency characteristics of the reflection loss characteristic and insertion loss characteristic of the input terminal, and (b) shows the output terminal. Here, a particularly remarkable change appeared in the insertion loss characteristic of FIG. It has been found that the use of the present invention improves the insertion loss peak value by about 0.02 dB to 0.05 dB. The bandwidth is also wide as shown in the figure. When compared with the 20 dB ratio bandwidth of the reflection loss of the input terminal, it was 6% in the technology of the present invention compared with 6% in the conventional technology. From this, it was confirmed that the effect of the present invention was remarkable.

  FIG. 7 shows another embodiment of the present invention. The intersection angle φ between the first center conductor L1 and the second center conductor L2 is 40 degrees, and the intersection angle θ between the second center conductor L2 and the third center conductor L3 is also 40 degrees. Both cases are less than 60 degrees.

  FIG. 8 shows another embodiment of the present invention. The intersection angle φ between the first center conductor L1 and the second center conductor L2 is 40 degrees, and the intersection angle θ between the second center conductor L2 and the third center conductor L3 is 70 degrees. 70 degrees in this case was chosen as exactly half of 140 degrees, which is a complementary angle of 40 degrees. Further, the distance between the two lines of the third central conductor L3 is wide. This is a device for avoiding the overlap of the central portion with other central conductors when the third central conductor is folded and overlapped, so that the height of the isolator is not substantially increased. This naturally changes the impedance of the center conductor L3, so the value of the resistance element R connected to it must also be adjusted accordingly.

  FIG. 9 shows another embodiment of the present invention. The intersection angle φ between the first center conductor L1 and the second center conductor L2 is 80 degrees, and the intersection angle θ between the second center conductor L2 and the third center conductor L3 is also 80 degrees. Both indicate cases greater than 60 degrees.

  FIG. 10 shows another embodiment of the present invention. The intersection angle φ between the first center conductor L1 and the second center conductor L2 is 40 degrees, and the intersection angle θ between the second center conductor L2 and the third center conductor L3 is 100 degrees. The former is smaller than 90 degrees and the latter is larger than 90 degrees.

As can be seen from the above description, the points of the three-terminal-pair nonreciprocal element of the present invention are the intersection angle φ between the first central conductor L1 and the second central conductor L2, the second central conductor L2 and the third central conductor L2. This means that the crossing angle θ of the central conductor L3 does not exceed 90 degrees at the same time. However, if the angle changes while maintaining the relationship of φ = θ, φ + θ does not exceed 180 degrees. This case corresponds to FIG. 1, FIG. 7, and FIG.
As a special case, the symmetry is best when φ = θ = 60 degrees. This corresponds to the embodiment of the present invention, FIG. Φ + θ = 90 degrees is also a special condition when the central conductor L1 and the central conductor L3 are orthogonal to each other. At this time, φ = θ = 45 degrees.

  FIG. 11 shows another embodiment of φ = θ = 60 degrees of the present invention. This is the case where the shape of the central conductor is not two parallel lines but seven parallel lines. This is a device for generating a high-frequency magnetic field as uniformly as possible on the entire surface of the ferrite thin plate. However, in this case, there is a high risk that the line-to-line capacitance will increase, so care must be taken in designing the number and line width. (A) is a case where seven parallel lines are used for all three central conductors, and (b) is a case where only the third central conductor L3 is a two parallel lines.

  FIG. 12 shows another embodiment of φ = θ = 60 degrees of the present invention. This is a case where the shape of the central conductor is not two parallel lines but one line. In order to reduce the line-to-line capacity as much as possible, the central part of the line is made thinner. (A) shows a case where one of the three central conductors uses one line, and (b) shows a case where only the third central conductor L3 has two parallel lines. This is a device for avoiding the overlap of the central portion with other central conductors when the third central conductor is folded and overlapped, so that the height of the isolator is not substantially increased.

FIG. 13 is one of reference examples. A resistance element R is connected to the second central conductor L2. Input terminals and output terminals are 1 to 3. Also in this case, the central conductor shape of FIG. 4B can be used.

  FIG. 14 shows another embodiment of the present invention. A situation is shown in which an assembly of a central conductor of φ = 40 ° and θ = 70 °, a rectangular ferrite thin plate, capacitors C1, C2, C3, and a resistance element R are roughly arranged in a rectangular region. Capacitors C1 and C2 are composed of one structure, for example, electrodes provided on both surfaces of a ceramic single plate. C3 and R are provided separately. The capacitor does not need to be a ceramic single plate, and the effect is the same with a ceramic laminate.

FIG. 15 is one of reference examples. In this case, the arrangement is when the input terminal is the central conductor L1 and the output terminal is the central conductor L3. The situation where the internal capacitors C1, C2, C3 and the resistance element R corresponding to FIG. 13 of the reference example are arranged in a rectangular region is schematically shown. Each of the capacitors C1, C2, and C3 is composed of a separate structure.

FIG. 16 is one of reference examples. This shows a state in which the capacitors C1, C2, C3 and the resistance element R are formed of an integrated laminated structure CER in the example of FIG. 15 where the input terminal is the central conductor L1 and the output terminal is the central conductor L3. In this way, the laminated structure CER can be made small as a whole, which is effective for cost reduction.

  FIG. 17 is a development view of the integrally laminated structure CER of FIG. (a) is a top view, (b) is a side sectional view, and (c) is a bottom view. Capacitors C1, C2, and C3 are encapsulated in one laminated ceramic component, and a resistor R is printed and fired on the upper surface. A ground conductor electrode GR is printed and fired on the lower surface. The top and bottom GNs are connected through holes. In order to increase the capacitance of each capacitor, the counter electrode of each capacitor is connected to the upper and lower surfaces through holes.

  FIG. 18 shows another embodiment of the present invention. A situation is schematically shown in which an assembly of a central conductor of φ = 40 degrees and θ = 100 degrees and a rectangular ferrite thin plate, capacitors C1, C2, C3, and a resistance element R are arranged in a rectangular region. However, the input terminal is connected to the center conductor L1, and the output terminal is connected to the center conductor L2. The capacitors C1 and C2 are made of one structure. C3 and R are provided separately.

FIG. 19 is an example of an electric circuit block diagram of an RF portion of a mobile phone. In this example, an antenna 10, a duplexer 11 composed of a transmission filter and a reception filter, a transmission circuit 12 connected to input / output means on the transmission filter side of the duplexer, and input / output on the reception filter side of the duplexer. And a receiving circuit 13 connected to the means. An outline of the transmission circuit 12 includes a filter, a mixer, and a power amplifier from the transmission side. A transmission signal is amplified by the power amplifier, and then transmitted from the antenna 10 through the transmission filter of the duplexer 11 after passing through the isolator of the present invention. The The received signal is sent from the antenna 10 through the receiving filter of the duplexer 11 to the receiving circuit 13, amplified by a low noise amplifier in the receiving circuit, passed through the filter, and then distributed by the mixer from the voltage control transmitter VCO to the splitter. The signal is mixed with the transmitted signal from the station and converted to an intermediate frequency.
Although the configuration of such a wireless communication device is an example, a low-loss, wide-band and highly reliable communication device can be realized by using the three-terminal pair nonreciprocal element of the present invention.

It is the top view which assembled the center conductor and ferrite thin plate which show the Example of this invention. 3 is an equivalent circuit of an isolator based on a three-terminal pair nonreciprocal element according to an embodiment of the present invention. It is a figure explaining the comparison and superiority of (a) prior art and (b) this invention regarding the voltage difference of a center conductor. It is a figure explaining the comparison and superiority of (a) prior art and (b) this invention regarding a center conductor. 4 is an equivalent circuit of an isolator based on a three-terminal pair nonreciprocal element according to the present invention. It is a characteristic comparison figure of the isolator by this invention, and the isolator of a prior art. It is an assembly drawing of the center conductor and ferrite thin plate which shows one Example of this invention. It is an assembly drawing of the center conductor and ferrite thin plate which shows one Example of this invention. It is an assembly drawing of the center conductor and ferrite thin plate which shows one Example of this invention. It is an assembly drawing of the center conductor and ferrite thin plate which shows one Example of this invention. It is an assembly drawing of the center conductor and ferrite thin plate which shows one Example of this invention. It is an assembly drawing of the center conductor and ferrite thin plate which shows one Example of this invention. It is the equivalent circuit of the isolator based on the 3 terminal pair nonreciprocal element by a reference example . FIG. 3 is a layout view of a capacitor, a resistor, a central conductor, and a ferrite thin plate according to an embodiment of the present invention. It is a layout view of a capacitor, a resistor, a central conductor and a ferrite thin plate according to a reference example . It is a layout view of a capacitor, a resistor, a central conductor and a ferrite thin plate according to a reference example . 1 is an integrated assembly diagram of a capacitor and a resistor according to an embodiment of the present invention. FIG. 3 is a layout view of a capacitor, a resistor, a central conductor, and a ferrite thin plate according to an embodiment of the present invention. It is a circuit block diagram of the communication apparatus by one Example of this invention. It is an assembly drawing of a center conductor and a ferrite thin plate by a prior art. It is the equivalent circuit of the isolator based on the 3 terminal pair nonreciprocal element of a prior art.

Explanation of symbols

L1, L2, L3 ... 1st, 2nd, 3rd center conductor
G ... Ferrite thin plate
GR ... Ground conductor
C1, C2, C3 ... matching capacitors
R: Resistance element
CER: Laminated structure 1, 2, 3, integrated capacitor and resistor, input / output terminal φ: angle θ formed by first and second center conductors θ: second center conductor and third center conductor Angle

Claims (6)

The first, second, and third central conductors are arranged close to the ferrite thin plate so as to cross each other in an electrically insulated state, and the ferrite thin plate is applied with a static magnetic field by a permanent magnet. One end of each of the second and third central conductors is a first, second, and third input / output terminal, and the other end is connected to a common portion, and the first, second, and third input / output terminals are connected to each other. First, second, and third matching capacitors are connected between the common portions, and any one of the first , second, and third input / output terminals and the common portion are connected. Between the two input / output terminals, one of which is an input terminal, and the other is an output terminal. The central conductor serving as the input terminal and the central conductor serving as the output terminal A three-terminal irreversible element characterized in that the crossing angle seen at the input / output terminal side is 90 degrees or less. Child. The crossing angle seen on the input / output terminal side of the central conductor serving as the input terminal and the central conductor connecting the resistive element, or the input / output terminal side of the central conductor connecting the resistive element and the central conductor serving as the output terminal The three-terminal-pair nonreciprocal device according to claim 1 , wherein the crossing angle seen is 90 degrees or less . The three-terminal-pair nonreciprocal element according to claim 1 , wherein an intersection angle of the central conductor serving as the input terminal and the central conductor serving as the output terminal viewed from the input / output terminal side is about 60 degrees . The three-terminal pair according to any one of claims 1 to 3, wherein a central portion of at least one of the first, second, and third central conductors is divided into three or more conductors. Non-reciprocal element. The three-terminal-pair nonreciprocal device according to any one of claims 1 to 4, wherein the common portion is a ground conductor. A communication apparatus comprising at least one non-reciprocal element having a three-terminal pair according to claim 1.

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