阅读说明：本技术 定向耦合器 (Directional coupler ) 是由 关健太 金良守 清水克也 于 2019-08-23 设计创作，主要内容包括：本发明提供一种在对希望的频带的高频信号高精度地进行检波的同时被小型化的定向耦合器。定向耦合器(1)具有：主线路(11),传输高频信号；副线路(12),与主线路(11)电磁耦合；终端电路(14),将副线路(12)的一端部(121)终止；可变滤波器(10),具有输入端子(101)以及输出端子(100)且输入端子(101)与副线路(12)的另一端部(122)连接,可变滤波器(10)是具有一个频带作为通带或阻带的滤波器单位电路,在该滤波器单位电路内配置有用于使该通带或阻带频移的可变无源元件。(The invention provides a directional coupler which can detect high-frequency signals of a desired frequency band with high precision and is miniaturized. A directional coupler (1) is provided with: a main line (11) that transmits a high-frequency signal; a sub-line (12) electromagnetically coupled to the main line (11); a termination circuit (14) that terminates one end (121) of the sub-line (12); a variable filter (10) has an input terminal (101) and an output terminal (100), wherein the input terminal (101) is connected to the other end (122) of a sub-line (12), and the variable filter (10) is a filter unit circuit having one frequency band as a pass band or a stop band, and a variable passive element for shifting the pass band or the stop band is disposed in the filter unit circuit.)

1. A directional coupler is provided with:

a main line transmitting a high frequency signal;

a secondary line electromagnetically coupled with the primary line;

a termination circuit terminating one end portion of the sub-line; and

a variable filter having an input terminal and an output terminal, the input terminal being connected to the other end of the sub-line,

the variable filter is a filter unit circuit having one frequency band as a pass band or a stop band,

a variable passive element for shifting the pass band or the stop band is arranged in the filter unit circuit.

2. The directional coupler of claim 1,

the variable passive element includes a switch and a passive element connected to the switch.

3. The directional coupler of claim 2, wherein,

the passive element is an inductor of the lumped constant type,

the inductor is a spiral inductor formed of a planar coil pattern.

4. The directional coupler of claim 3, wherein,

the inductor has a 1 st terminal, a 2 nd terminal, and a 3 rd terminal, a 1 st inductance value between the 1 st terminal and the 3 rd terminal, and a 2 nd inductance value different from the 1 st inductance value between the 2 nd terminal and the 3 rd terminal,

at least one of the 1 st terminal and the 2 nd terminal is connected to the switch.

5. The directional coupler as set forth in any one of claims 1 to 4,

the other end of the sub-line is not connected to a filter other than the variable filter.

6. The directional coupler as set forth in any one of claims 1 to 4,

further provided with: and a filter connected to the other end and having a passband different from a passband of the variable filter.

7. The directional coupler as set forth in any one of claims 1 to 6,

further provided with:

a 1 st switch circuit having a 1 st common terminal, a 1 st selection terminal, and a 2 nd selection terminal, and disposed between the other end portion and the variable filter; and

a 2 nd switch circuit having a 2 nd common terminal, a 3 rd selection terminal, and a 4 th selection terminal, disposed between the one end portion and the terminal circuit,

the other end portion is connected to the 1 st common terminal,

the input terminal is connected to the 1 st selection terminal and the 3 rd selection terminal,

the termination circuit is connected to the 4 th selection terminal and the 2 nd selection terminal.

8. The directional coupler as set forth in any one of claims 1 to 7,

the termination circuit has a variable element that varies a termination impedance of the termination circuit.

9. The directional coupler as set forth in any one of claims 1 to 8,

further provided with: and a 3 rd switching circuit which is disposed between the variable filter and the sub-line, and switches between a path through which the high-frequency signal transmitted through the sub-line passes through the variable filter and a path through which the high-frequency signal transmitted through the sub-line passes through the bypass line without passing through the variable filter.

10. The directional coupler as set forth in any one of claims 1 to 9,

further provided with: and a variable attenuator connected to the other end portion.

11. The directional coupler as set forth in any one of claims 1 to 10,

further provided with: and a variable matching circuit connected to the other end portion.

12. The directional coupler as set forth in any one of claims 1 to 11,

the main line and the sub-line are formed on a semiconductor substrate.

13. The directional coupler of claim 12, wherein,

at least one of the plurality of passive elements and the switch among the plurality of passive elements and the switch included in the variable filter are formed on the semiconductor substrate.

Technical Field

The present invention relates to a directional coupler.

Background

Conventionally, an electromagnetic coupler (directional coupler) in which a filter circuit including a plurality of filters and a plurality of switches is connected to one end (coupling port) of a sub-line is known (for example, see patent document 1). By connecting one of the plurality of filters to the sub-line by switching the plurality of switches, it is possible to detect a high-frequency signal of a desired frequency band without being interfered by signals of other frequency bands.

Prior art documents

Patent document

Patent document 1: specification of U.S. Pat. No. 9954564

However, in the conventional directional coupler described above, since a plurality of filters having fixed pass bands are arranged, there is a problem that the size of the directional coupler becomes large.

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made to solve the above-described problems, and an object thereof is to provide a directional coupler that is miniaturized while detecting a high-frequency signal of a desired frequency band with high accuracy.

Means for solving the problems

In order to achieve the above object, a directional coupler according to one aspect of the present invention includes: a main line transmitting a high frequency signal; a secondary line electromagnetically coupled with the primary line; a termination circuit terminating one end portion of the sub-line; and a variable filter having an input terminal and an output terminal, the input terminal being connected to the other end of the sub-line, the variable filter being a filter unit circuit having one frequency band as a pass band or a stop band, and a variable passive element for frequency-shifting the pass band or the stop band being disposed in the filter unit circuit.

Effects of the invention

According to the present invention, it is possible to provide a directional coupler that is miniaturized while detecting a high-frequency signal of a desired frequency band with high accuracy.

Drawings

Fig. 1 is a circuit diagram showing an example of a functional configuration of a directional coupler according to embodiment 1.

Fig. 2A is a circuit configuration diagram showing example 1 (variable low-pass filter) of the variable filter according to embodiment 1.

Fig. 2B is a circuit configuration diagram showing example 2 (variable high-pass filter) of the variable filter according to embodiment 1.

Fig. 2C is a circuit configuration diagram showing example 3 (variable band elimination filter) of the variable filter according to embodiment 1.

Fig. 2D is a circuit configuration diagram showing example 4 (variable band pass filter) of the variable filter according to embodiment 1.

Fig. 3 is a diagram showing a circuit configuration and a plan view structure of an inductor included in the variable filter according to embodiment 1.

Fig. 4A is a graph showing the pass characteristics in example 1 of the variable filter according to embodiment 1.

Fig. 4B is a graph showing the pass characteristics in example 2 of the variable filter according to embodiment 1.

Fig. 5A is a circuit configuration diagram showing example 5 (variable band pass filter) of the variable filter according to embodiment 1.

Fig. 5B is a circuit configuration diagram showing example 6 (variable band pass filter) of the variable filter according to embodiment 1.

Fig. 6 is a mounting configuration diagram of a directional coupler including the variable filter according to example 5 of embodiment 1.

Fig. 7A is a circuit configuration diagram showing example 7 (variable band pass filter) of the variable filter according to embodiment 1.

Fig. 7B is a circuit configuration diagram showing an 8 th example (variable band pass filter) of the variable filter according to embodiment 1.

Fig. 8 is a mounting configuration diagram of a directional coupler including the variable filter according to example 7 of embodiment 1.

Fig. 9 is a circuit diagram showing an example of a functional configuration of the directional coupler according to embodiment 2.

Fig. 10 is a circuit diagram showing an example of a functional configuration of a directional coupler according to embodiment 3.

Description of the symbols

1.2, 3 directional coupler;

10. 10A, 10B, 20, 30, 40, 50, 60, 70, 80 variable filters;

11a main line;

12 secondary lines;

14 a termination circuit;

a 14V, 16V variable termination circuit;

15A, 15B, 19A, 19B, SW11, SW12, SW13, SW14, SW21, SW22, SW53 22, SW54 22, SW55 22, SW56 22, SW57 22, SW63 22, SW64 SW22, SW65 22, SW66 22, SW 3667 22, SW22 switch;

a 17V variable matching circuit;

an 18V variable attenuator;

51. 52, 58, 59, 61, 62, 68, 69, 71, 72, 73, 74, 75, 76, 81, 82, 83, 84, 85, 86 lines;

53. 63a bandwidth adjustment circuit;

54. 55, 64, 65 impedance matching circuits;

56. 57, 66, 67 center frequency adjusting circuit;

90 a control unit;

100 output terminals;

101 an input terminal;

110 input ports;

111. 215, 311, 415 inductors;

111a, 111b, 111c terminals;

111t routing nodes;

112. 113, 114, 115, 116, 117, 211, 212, 213, 214, 216, 312, 411, 412, 413, 414, 416, 417, 531, 532, 533, 541, 542, 543, 551, 552, 553, 561, 562, 563, 571, 572, 573, 631, 632, 633, 641, 642, 643, 651, 652, 653, 661, 662, 663, 671, 672, 673 capacitors;

120 output ports;

one end portion of 121;

122, the other end;

151. 154, 191, 195 common terminal;

152. 153, 155, 156, 192, 193, 194, 196, 197, 198 selection terminals;

510. 710 a dielectric substrate;

520. 720 a semiconductor substrate;

530. 730 a terminal substrate;

540. 740 a resin member;

n71, n72, n81 and n82 connect nodes.

Detailed Description

Hereinafter, embodiments of the present invention and modifications thereof will be described in detail with reference to the accompanying drawings. The embodiments and modifications described below are all general or specific examples. The numerical values, shapes, materials, constituent elements, arrangement of constituent elements, connection methods, and the like shown in the following embodiments and modifications thereof are examples, and do not limit the present invention. Among the components in the following embodiments and modifications thereof, components not described in the independent claims are described as arbitrary components. In addition, the sizes of the components shown in the drawings and the ratio of the sizes are not necessarily strict.

(embodiment mode 1)

[1.1 Circuit Structure of Directional coupler ]

Fig. 1 is a circuit diagram showing an example of a functional configuration of a directional coupler 1 according to embodiment 1. As shown in the drawing, the directional coupler 1 includes a main line 11, a sub-line 12, a variable filter 10, a termination circuit 14, and switches 15A and 15B. As indicated by arrow M in fig. 1, the main line 11 and the sub-line 12 are electromagnetically coupled to each other.

One end and the other end of the main line 11 are connected to the input port 110(RFin) and the output port 120(RFout), respectively.

One end 121 of the sub-line 12 is connected to the switch 15B, and the other end 122 is connected to the switch 15A.

The termination circuit 14 is connected to the switches 15A and 15B.

The switch 15A is a 1 st switch circuit having a common terminal 151 (1 st common terminal), a selection terminal 152 (1 st selection terminal), and a selection terminal 153 (2 nd selection terminal) and disposed between the other end 122 and the variable filter 10. The switch 15B is a 2 nd switch circuit having a common terminal 154 (2 nd common terminal), a selection terminal 155 (3 rd selection terminal), and a selection terminal 156 (4 th selection terminal) and disposed between the one end portion 121 and the terminal circuit 14. More specifically, the other end 122 is connected to the common terminal 151, the one end 121 is connected to the common terminal 154, the input terminal 101 of the variable filter 10 is connected to the selection terminals 152 and 155, and the termination circuit 14 is connected to the selection terminals 153 and 156.

That is, the terminal circuit 14 is connected to the other end 122 via the switch 15A and to the one end 121 via the switch 15B. The variable filter 10 is connected to the other end 122 via a switch 15A, and is connected to the one end 121 via a switch 15B.

In fig. 1, the terminal circuit is only one terminal circuit 14, but the terminal circuit may include a plurality of terminal circuits connected to the switches 15A and 15B, respectively.

According to the above configuration, in order to detect the high-frequency signal transmitted from the input port 110 to the output port 120 in the main line 11 by the sub-line 12, the common terminal 154 and the selection terminal 156 are brought into a conductive state, the common terminal 154 and the selection terminal 155 are brought into a non-conductive state, the common terminal 151 and the selection terminal 152 are brought into a conductive state, and the common terminal 151 and the selection terminal 153 are brought into a non-conductive state. On the other hand, in order to detect the high-frequency signal transmitted from the output port 120 to the input port 110 in the main line 11 by the sub-line 12, the common terminal 151 and the selection terminal 153 are brought into a conductive state, the common terminal 151 and the selection terminal 152 are brought into a non-conductive state, the common terminal 154 and the selection terminal 155 are brought into a conductive state, and the common terminal 154 and the selection terminal 156 are brought into a non-conductive state. That is, by switching the switches 15A and 15B, the high-frequency signals transmitted in both directions of the main line 11 can be detected by the sub-line 12 with high accuracy.

Switches 15A and 15B may not be provided. In this case, when the high-frequency signal transmitted from the input port 110 to the output port 120 in the main line 11 is detected by the sub-line 12, the directional coupler according to the present invention has a configuration in which the other end 122 is connected to the variable filter 10 without a switch and the one end 121 is connected to the terminal circuit 14 without a switch. When the high-frequency signal transmitted from the output port 120 to the input port 110 in the main line 11 is detected by the sub-line 12, the other end 122 is connected to the terminal circuit 14 without a switch, and the one end 121 is connected to the variable filter 10 without a switch.

The variable filter 10 is a filter unit circuit having a passband or a stopband defined by one continuous band, and a variable passive element for shifting the passband is disposed in the filter unit circuit. In addition, the variable passive element refers to a passive element in which a circuit constant value of the element is variable, for example, a variable inductor in which an inductance value is variable and a variable capacitor in which a capacitance value is variable.

In this embodiment, the variable passive element includes a switch and a passive element connected to the switch.

The filter unit circuit is a filter circuit having one continuous band as a pass band or a stop band as described above, and the following filter circuits are not preferable. That is, a filter circuit including a 1 st circuit having one band as a pass band or a stop band, a 2 nd circuit having another band as a pass band or a stop band and including circuit elements different from the circuit elements constituting the 1 st circuit, and a switch circuit for switching the states (conductive state and non-conductive state) of the 1 st circuit and the 2 nd circuit does not correspond to the filter unit circuit. In this case, the 1 st circuit and the 2 nd circuit correspond to a filter unit circuit, respectively.

This allows the pass band or the stop band of the variable filter 10 to be shifted by the variable passive element provided in the filter unit circuit. In other words, one continuous frequency band defined as a pass band or a stop band of the variable filter may be changed according to circumstances. Therefore, it is possible to remove other frequency components from the high-frequency signal of a desired frequency band of the high-frequency signal transmitted through the main line 11 and to detect the high-frequency signal from the one end 121 or the other end 122 of the sub-line 12 via the variable filter 10 at the output terminal 100 with high accuracy.

In recent years, in mobile communication devices such as mobile phones using directional couplers, the frequency bands to be handled have increased rapidly due to multi-band and globalization, and power amplifiers and duplexers mounted in the mobile communication devices have become complicated and large-sized. Therefore, the demand for miniaturization of the directional coupler becomes strong. Therefore, the filter built in the directional coupler needs to be miniaturized as much as possible.

In order to cope with the multiband and globalization, when a filter circuit in which a plurality of filters (filter unit circuits) each having one fixed passband or stopband is disposed is provided on the side of the sub-line of the directional coupler as in the conventional directional coupler, mutual interference between the filters (filter unit circuits) occurs. As a result, in the functions required for the filter (filter unit circuit), a ripple is generated in a desired pass band and/or an unnecessary spurious response is generated in a desired stop band. The larger the number of filters (filter unit circuits), the stronger and more complicated the mutual interference between such filters.

Examples of the mutual interference between filters (filter unit circuits) include (1) interference due to the limit of isolation of a switch when the switch of the filter (filter unit circuit) is used, (2) interference due to inductive coupling in a filter having an inductor, (3) interference due to vibration propagation in a piezoelectric filter such as a Surface Acoustic Wave (SAW) filter or a BAW (Bulk Acoustic Wave) filter, and interference due to electric field coupling in a filter using a dielectric resonator and each of the above filters.

In order to suppress the above-described mutual interference, measures such as reinforcement of electromagnetic shielding and isolation, and division of the piezoelectric substrate and the elastic wave resonator may be taken, but this has the disadvantage of being complicated and large in size.

In contrast, according to the configuration of the directional coupler 1 according to the present embodiment, the pass band or the stop band of the variable filter 10, which is a filter unit circuit, can be shifted in frequency by the variable passive element disposed in the filter unit circuit, and therefore, it is not necessary to dispose a plurality of filters having pass bands corresponding to the bands to be detected. Therefore, the directional coupler 1 can be miniaturized while detecting a high-frequency signal of a desired frequency band with high accuracy.

In the directional coupler 1 according to the present embodiment, filters other than the variable filter 10 are not connected to the one end 121 and the other end 122 of the sub-line 12. That is, a filter having a pass band corresponding to the band to be detected is not disposed except for the variable filter 10. Therefore, the directional coupler 1 can be downsized, and the detection accuracy can be improved by suppressing ripples in the pass band and spurious waves in the stop band due to mutual interference between filters generated when a plurality of filters are arranged.

The directional coupler according to the present invention is not limited to the configuration in which only the variable filter 10 is provided as a filter connected to the sub-line 12 as in the directional coupler 1 according to the present embodiment. For example, a plurality of filters including the variable filter 10 may be connected to the sub-line 12 as in the directional coupler 3 according to embodiment 3 described later.

[1.2 Circuit Structure and pass characteristic of variable Filter ]

Fig. 2A is a circuit configuration diagram showing the variable filter 10 (1 st example of the variable filter: variable low-pass filter) according to embodiment 1. As shown in the figure, the variable filter 10 has an input terminal 101, an output terminal 100, an inductor 111, capacitors 112, 113, 114, 115, 116, and 117, and switches SW11, SW12, SW13, and SW 14. The variable filter 10 is composed of an inductor and a capacitor as lumped constant type passive elements.

A series arm circuit having an inductor 111, switches SW11, SW12, SW13, capacitors 112 and 113 is connected between the input terminal 101 and the output terminal 100. A parallel arm circuit including capacitors 114, 115, 116, and 117 and switch SW14 is connected between a path connecting input terminal 101 and output terminal 100 and the ground.

With the above connection structure, the variable filter 10 has an inductance component in the series arm connecting the input terminal 101 and the output terminal 100, and a capacitance component in the parallel arm connecting the series arm and the ground, thereby constituting a filter unit circuit (low-pass filter) having one continuous frequency band as a pass band or a stop band. Here, the inductance values of the inductors 111 can be made different by switching the switches SW11 and SW 12. Further, the combined capacitance values of the capacitors 112 and 113 can be made different by switching the switch SW 13. Further, the combined capacitance values of the capacitors 114 to 117 can be made different by switching the switch SW 14. In other words, switches SW11 to SW14 for frequency shifting the pass band or the stop band are disposed inside the variable filter 10. Further, by switching the inductor and the capacitor by the plurality of switches SW11 to SW14, it is possible to generate an inductance value and a capacitance value that can be changed in a wide range.

According to the configuration of the variable filter 10, since the pass band or the stop band is shifted by the switches SW11 to SW14 arranged in the filter unit circuit, it is not necessary to arrange a plurality of filters having pass bands corresponding to the frequency bands to be detected, and it is possible to provide the directional coupler 1 which is miniaturized while accurately detecting high-frequency signals of desired frequency bands.

Fig. 3 is a diagram showing a circuit configuration and a plan view structure of the inductor 111 included in the variable filter 10 according to embodiment 1. Fig. 3 (a) shows a circuit configuration diagram of the inductor 111, and fig. 3 (b) shows a plan configuration diagram of the inductor 111.

As shown in fig. 3 (a), the inductor 111 has a terminal 111a (3 rd terminal), a terminal 111b (1 st terminal), and a terminal 111c (2 nd terminal), and has a 1 st inductance value between the terminal 111b and the terminal 111a, and a 2 nd inductance value different from the 1 st inductance value between the terminal 111c and the terminal 111 a. As a configuration having such a 1 st inductance value and a 2 nd inductance value that are different from each other, for example, as shown in fig. 3 (b), the inductor 111 is a spiral inductor formed of a planar coil pattern. In the spiral wiring formed on the same plane, the terminal 111a is connected to the outer peripheral end portion, the terminal 111c is connected to the lead wire from the inner peripheral end portion, and the terminal 111b is connected to the lead wire from the wiring node 111t between the outer peripheral end portion and the inner peripheral end portion.

The spiral inductor 111 formed of a planar coil pattern can trap magnetic flux in a short distance from the center of the inductor 111 by suppressing the distribution of magnetic flux to be small as compared with a solenoid-type inductor. Further, since two different inductance values are generated by one spiral inductor 111, magnetic flux can be trapped in a smaller area than a structure in which two spiral inductors are arranged. Therefore, unnecessary inductive coupling of the inductor 111 with the main line 11 and the sub-line 12 can be suppressed, and thus, deterioration of the characteristics of the directional coupler 1 can be suppressed. Further, since the distance between the inductor 111 and the main line 11 and the sub-line 12 can be reduced by reducing the distance and the area of the trapped magnetic flux, the directional coupler 1 can be downsized.

As shown in fig. 2A and 3, the terminal 111b is connected to the switch SW11, and the terminal 111c is connected to the switch SW 12. The inductor 111 has the 1 st inductance value by setting the switch SW11 to the conductive state and the switch SW12 to the non-conductive state, and the inductor 111 has the 2 nd inductance value by setting the switch SW11 to the non-conductive state and the switch SW12 to the conductive state. That is, by switching the switches SW11 and SW12, a plurality of inductance values can be selectively provided by one inductor 111, and thus the variable filter 10 can be downsized.

The inductor 111 constituting the variable filter 10 may be not only a spiral inductor constituted by a 1-layer planar coil pattern but also a multilayer planar coil pattern. The multilayer planar coil pattern may not be a spiral pattern, but may be a single-wound coil pattern.

The inductor 111 is not limited to an inductor having only 3 terminals, and may be an inductor having 3 or more terminals, such as 4 terminals or 5 terminals.

The inductor 111 constituting the variable filter 10 may not be constituted by one inductor, and may be constituted by two independent inductors having different inductance values and connected to the switches SW11 and SW12, respectively.

The inductor 111 may be an MEMS (Micro Electro Mechanical Systems) type inductor having a mechanism for continuously changing an inductance value by continuously changing a magnetic circuit or the like, or may be a chip component. By using the MEMS inductor having a continuously variable inductance value, the electrical characteristics of the filter can be continuously changed, and precise adjustment can be achieved.

The switches SW11 to SW14 may be, for example, FET (Field Effect Transistor) switches or diode switches made of GaAs or CMOS (Complementary Metal oxide semiconductor).

The capacitors 112 to 117 may be capacitors having an MIM (Metal Insulator Metal) structure, capacitors including opposing comb electrodes, or chip components. Further, the capacitor may be a MEMS type capacitor having a mechanism for continuously changing the overlapping area of the opposing electrodes. By using the MEMS-type inductor whose inductance value is continuously variable and the MEMS-type capacitor whose capacitance value is continuously variable, the electrical characteristics of the filter can be continuously changed, and the pass band and the stop band can be finely adjusted. Further, by using a capacitor having an MIM structure, a relatively large capacitance value can be realized even in a small capacitor, and since leakage of an electric field can be suppressed, unnecessary capacitive coupling with the main line 11 and the sub-line 12 can be suppressed. Further, by using the capacitor constituted by the comb-teeth electrodes, the manufacturing process can be simplified. Further, by using the chip component, a large capacitance and a high Q value can be realized.

The variable filter 10 included in the directional coupler 1 may be the variable filter 20 shown in fig. 2B.

Fig. 2B is a circuit configuration diagram showing the variable filter 20 according to embodiment 1 (2 nd example of the variable filter: variable high-pass filter). As shown in the figure, the variable filter 20 has an input terminal 101, an output terminal 100, an inductor 215, capacitors 211, 212, 213, 214, and 216, and switches SW21, SW22, SW23, and SW 24. The variable filter 20 is constituted by a lumped constant type inductor and a capacitor.

A 1 st series arm circuit having capacitors 211, 212 and a switch SW21 and a 2 nd series arm circuit having capacitors 213, 214 and a switch SW22 are connected in series between the input terminal 101 and the output terminal 100. Further, a parallel arm circuit having an inductor 215, a capacitor 216, and switches SW23 and SW24 is connected between the connection point of the 1 st series arm circuit and the 2 nd series arm circuit and the ground.

With the above connection structure, the variable filter 20 has a capacitance component in the series arm connecting the input terminal 101 and the output terminal 100, and an inductance component in the parallel arm connecting the series arm and the ground, thereby constituting a filter unit circuit (high-pass filter) having one continuous frequency band as a pass band or a stop band. Here, the inductance values of the inductors 215 can be made different by switching the switches SW23 and SW 24. Further, the combined capacitance values of the capacitors 211 and 212 can be made different by switching the switch SW 21. Further, the combined capacitance values of the capacitors 213 and 214 can be made different by switching the switch SW 22. In other words, switches SW21 to SW24 for frequency shifting the pass band or the stop band are disposed inside the variable filter 20. Further, by switching the inductor and the capacitor by the plurality of switches SW21 to SW24, it is possible to generate an inductance value and a capacitance value that can be changed in a wide range.

According to the configuration of the variable filter 20, since the pass band or the stop band is shifted by the switches SW21 to SW24 arranged in the filter unit circuit, it is not necessary to arrange a plurality of filters having pass bands corresponding to the frequency bands to be detected, and it is possible to provide the directional coupler 1 which is miniaturized while accurately detecting high-frequency signals of desired frequency bands.

The structure of the inductor 215 is the same as that of the inductor 111 of the variable filter 10. This can suppress unnecessary inductive coupling of the inductor 215 to the main line 11 and the sub-line 12, and thus can suppress deterioration of the characteristics of the directional coupler 1. Further, by switching the switches SW23 and SW24, a plurality of inductance values can be selectively provided by one inductor 215, and hence the variable filter 20 can be downsized.

The variable filter 10 included in the directional coupler 1 may be the variable filter 30 shown in fig. 2C.

Fig. 2C is a circuit configuration diagram showing the variable filter 30 (example 3 of the variable filter: variable band elimination filter) according to embodiment 1. As shown in the figure, the variable filter 30 has an input terminal 101, an output terminal 100, an inductor 311, a capacitor 312, and switches SW31 and SW 32. The variable filter 30 is composed of a lumped constant type inductor and a capacitor.

A parallel arm circuit including an inductor 311, a capacitor 312, switches SW31 and SW32 is connected between the series arm connecting the input terminal 101 and the output terminal 100 and the ground.

With the above connection structure, the variable filter 30 has a band rejection filter including a filter unit circuit having an LC series resonant circuit in a parallel arm connecting the series arm and the ground, and having a stopband corresponding to one continuous frequency band. Here, the inductance values of the inductor 311 can be made different by switching the switches SW31 and SW 32. In other words, switches SW31 to SW32 for frequency shifting the stop band are disposed inside the variable filter 30.

According to the configuration of the variable filter 30, since the stop band is shifted by the switches SW31 to SW32 disposed in the filter unit circuit, it is not necessary to dispose a plurality of filters having pass bands corresponding to the bands to be detected, and it is possible to provide the directional coupler 1 which is miniaturized while accurately detecting high-frequency signals of a desired band.

The configuration of the inductor 311 is the same as that of the inductor 111 of the variable filter 10. This can suppress unnecessary inductive coupling of the inductor 311 with the main line 11 and the sub-line 12, and thus can suppress deterioration of the characteristics of the directional coupler 1. Further, by switching the switches SW31 and SW32, a plurality of inductance values can be selectively provided by one inductor 311, and thus the variable filter 30 can be downsized.

The variable filter 10 included in the directional coupler 1 may be the variable filter 40 shown in fig. 2D.

Fig. 2D is a circuit configuration diagram showing the variable filter 40 according to embodiment 1 (4 th example of the variable filter: variable band pass filter). As shown in the figure, the variable filter 40 has an input terminal 101, an output terminal 100, an inductor 415, capacitors 411, 412, 413, 414, 416, and 417, and switches SW41, SW42, SW43, SW44, and SW 45. The variable filter 40 is constituted by a lumped constant type inductor and a capacitor.

A 1 st series arm circuit having capacitors 411, 412 and a switch SW41 and a 2 nd series arm circuit having capacitors 413, 414 and a switch SW42 are connected in series between the input terminal 101 and the output terminal 100. Further, a parallel arm circuit including an inductor 415, capacitors 416 and 417, switches SW43, SW44, and SW45 is connected between the connection point of the 1 st series arm circuit and the 2 nd series arm circuit and the ground.

With the above connection configuration, the variable filter 40 has a capacitance component in the series arm connecting the input terminal 101 and the output terminal 100, and an LC parallel resonant circuit in the parallel arm connecting the series arm and the ground, thereby constituting a filter unit circuit (band-pass filter) having one continuous frequency band as a pass band or a stop band. Here, the inductance values of the inductors 415 can be made different by switching the switches SW43 and SW 44. Further, the combined capacitance values of the capacitors 411 and 412 can be made different by switching the switch SW 41. Further, the combined capacitance values of the capacitors 413 and 414 can be made different by switching the switch SW 42. Further, the combined capacitance values of the capacitors 416 and 417 can be made different by switching the switch SW 45. In other words, switches SW41 to SW45 for frequency shifting the pass band or the stop band are disposed inside the variable filter 40.

According to the configuration of the variable filter 40, since the pass band or the stop band is shifted by the switches SW41 to SW45 arranged in the filter unit circuit, it is not necessary to arrange a plurality of filters having pass bands corresponding to the frequency bands to be detected, and it is possible to provide the directional coupler 1 which is miniaturized while accurately detecting high-frequency signals of desired frequency bands.

The structure of the inductor 415 is the same as the structure of the inductor 111 of the variable filter 10. This can suppress unnecessary inductive coupling of the inductor 415 with the main line 11 and the sub-line 12, and thus can suppress deterioration of the characteristics of the directional coupler 1. Further, by switching the switches SW43 and SW44, a plurality of inductance values can be selectively provided by one inductor 415, and therefore, the variable filter 40 can be downsized.

Fig. 4A is a graph showing the pass characteristics in the variable filter 10 (example 1) according to embodiment 1. As shown in the drawing, in the variable filter 10, for example, by setting the switch SW11 to a non-conducting state (Off) and setting the switches SW12, SW13, and SW14 to a conducting state (On), a band On a lower frequency side than 1.5GHz becomes a pass band, and a band On a higher frequency side than 1.5GHz becomes a stop band. For example, by turning the switch SW11 into the on state and turning the switches SW12, SW13 and SW14 into the off state, the band at the lower frequency side than 3.5GHz becomes the pass band and the band at the higher frequency side than 3.5GHz becomes the stop band.

According to the above-described pass characteristic of the variable filter 10, when a high-frequency signal of a desired frequency band (1.5GHz or less or 3.5GHz or less) is detected, for example, a high-frequency signal from which harmonics of the high-frequency signal are removed can be detected with high accuracy.

Fig. 4B is a graph showing the pass characteristics in the variable filter 20 (example 2) according to embodiment 1. As shown in the drawing, in the variable filter 20, for example, by turning on the switches SW21, SW22, and SW23 and turning off the switch SW24, a band at a higher frequency side than 1.5GHz becomes a pass band and a band at a lower frequency side than 1.5GHz becomes a stop band. For example, by turning the switches SW21, SW22, and SW23 into a non-conductive state and turning the switch SW24 into a conductive state, a frequency band on the higher frequency side than 2.0GHz becomes a pass band, and a frequency band on the lower frequency side than 2.0GHz becomes a stop band.

According to the above-described pass characteristic of variable filter 20, when a high-frequency signal of a desired frequency band (1.5GHz or more or 2.0GHz or more) is detected, for example, a high-frequency signal from which spurious signals or the like appearing on the low-frequency side of the high-frequency signal are removed can be detected with high accuracy.

The variable filter 10 included in the directional coupler 1 may be the variable filter 50 shown in fig. 5A.

Fig. 5A is a circuit configuration diagram showing a variable filter 50 (example 5 of a variable filter: variable bandpass filter) according to embodiment 1. As shown in the drawing, the variable filter 50 includes an input terminal 101, an output terminal 100, distributed constant lines 51, 52, 58, and 59 formed of, for example, microstrip lines or the like, a bandwidth adjusting circuit 53, impedance matching circuits 54 and 55, center frequency adjusting circuits 56 and 57, and switches SW51, SW52, SW56, SW57, SW58, and SW 59. The variable filter 50 is composed of a lumped-constant bandwidth adjustment circuit 53, impedance matching circuits 54 and 55, center frequency adjustment circuits 56 and 57, and distributed-constant lines (passive elements) 51, 52, 58, and 59.

A TEM (Transverse ElectroMagnetic) mode resonator (main resonator) is formed, for example, by the lines 51 and 52. The length of each of the lines 51 and 52 in the longitudinal direction is shorter by a predetermined length than the (1/2) wavelength of a frequency higher than the center frequency of the 1 st band by a predetermined frequency.

The distributed constant lines 58 and 59 form, for example, a TEM mode resonator (tuning resonator). The lines 58 and 59 are connected to the lines 51 and 52 via the switches SW51 and SW52, whereby a resonator corresponding to a different frequency band from the main resonator can be formed. The length in the longitudinal direction of each of the length (the added value of the length of the line 51 and the length of the line 58) after the lines 51 and 58 are connected via the switch SW51 and the length (the added value of the length of the line 52 and the length of the line 59) after the lines 52 and 59 are connected via the switch SW52 is shorter by a predetermined length than the (1/2) wavelength of a frequency higher by a predetermined frequency than the center frequency of the 2 nd band different from the 1 st band.

The bandwidth adjusting circuit 53 is a 1 st circuit having capacitors 531, 532, 533, switches SW53a, and SW53b, and adjusts the pass band width of the variable filter 50 by adjusting the coupling between the resonators 51 and 52 and the coupling between the resonators 58 and 59.

The impedance matching circuit 54 is a 2 nd circuit having capacitors 541, 542, and 543, a switch SW54a, and a switch SW54b, and adjusts impedance matching on the input terminal 101 side. The impedance matching circuit 55 is a 3 rd circuit having capacitors 551, 552, 553, switches SW55a, and SW55b, and adjusts impedance matching on the output terminal 100 side.

The center frequency adjusting circuit 56 is a 4 th circuit including capacitors 561, 562, and 563, a switch SW56a, and a switch SW56b, and sets a center frequency by adjusting a resonance frequency of a resonator including at least two or more of the distributed constant lines 51, 52, 58, and 59. The center frequency adjusting circuit 57 is a 5 th circuit having capacitors 571, 572, 573, switches SW57a, and SW57b, and sets a center frequency by adjusting a resonance frequency of a resonator including at least two or more of the distributed constant lines 51, 52, 58, and 59.

The impedance matching circuit 54, the bandwidth adjusting circuit 53, and the impedance matching circuit 55 are connected in series to a path connecting the input terminal 101 and the output terminal 100.

One end of the line 51 is connected to the bandwidth adjustment circuit 53 and the impedance matching circuit 54, and the other end of the line 51 is connected to one end of the line 58 via the switch SW51 and to the center frequency adjustment circuit 56 via the switch SW 56. The other end of the line 58 is connected to the center frequency adjusting circuit 56 via a switch SW 58.

One end of the line 52 is connected to the bandwidth adjustment circuit 53 and the impedance matching circuit 55, and the other end of the resonator 52 is connected to one end of the line 59 via the switch SW52 and to the center frequency adjustment circuit 57 via the switch SW 57. The other end of the line 59 is connected to the center frequency adjusting circuit 57 via a switch SW 59.

With the above-described configuration of the variable filter 50, the pass band or the stop band can be shifted by switching the switches SW51 to SW52, SW56 to SW59, SW53a, SW53b, SW54a, SW54b, SW55a, SW55b, SW56a, SW56b, SW57a, and SW57b arranged in the filter unit circuit. Therefore, it is not necessary to arrange a plurality of filters having pass bands corresponding to the frequency bands to be detected, and it is possible to provide the directional coupler 1 which is miniaturized while detecting high-frequency signals of a desired frequency band with high accuracy.

Fig. 5B is a circuit configuration diagram showing the variable filter 60 (example 6 of the variable filter: variable bandpass filter) according to embodiment 1. As shown in the drawing, the variable filter 60 includes an input terminal 101, an output terminal 100, resonators 61, 62, 68, and 69, a bandwidth adjustment circuit 63, impedance matching circuits 64 and 65, center frequency adjustment circuits 66 and 67, and switches SW68 and SW 69. The variable filter 60 is composed of a lumped constant type bandwidth adjusting circuit 63, impedance matching circuits 64 and 65, center frequency adjusting circuits 66 and 67, and distributed constant type lines 61, 62, 68, and 69.

By the distributed constant type lines 61 and 62, for example, a TEM mode resonator (main resonator) is formed. The length of each of the lines 61 and 62 in the longitudinal direction is shorter by a predetermined length than the (1/4) wavelength of a frequency higher than the center frequency of the 1 st band by a predetermined frequency.

For example, a TEM mode resonator (tuning resonator) is formed by the distributed constant lines 68 and 69. The lines 68 and 69 are connected to the lines 61 and 62 by opening the switches SW68 and SW 69. This enables formation of a resonator corresponding to a different frequency band from the main resonator. The length in the longitudinal direction of each of the length (the sum of the length of the line 61 and the length of the line 68) after the lines 61 and 68 are connected to each other and the length (the sum of the length of the line 62 and the length of the line 69) after the lines 62 and 69 are connected to each other is shorter by a predetermined length than the (1/4) wavelength of a frequency higher by a predetermined frequency than the center frequency of the 2 nd band different from the 1 st band.

The bandwidth adjusting circuit 63 is the 1 st circuit having capacitors 631, 632, 633, switches SW63a, and SW63b, and adjusts the pass band width of the variable filter 60 by adjusting the coupling between the resonators 61 and 62 and the coupling between the resonators 68 and 69.

The impedance matching circuit 64 is a 2 nd circuit having capacitors 641, 642, 643, switches SW64a, and SW64b, and adjusts impedance matching on the input terminal 101 side. The impedance matching circuit 65 is a 3 rd circuit having capacitors 651, 652, 653, switches SW65a, and SW65b, and adjusts impedance matching on the output terminal 100 side.

The center frequency adjusting circuit 66 is a 4 th circuit having capacitors 661, 662, 663, switches SW66a, and SW66b, and sets the center frequency by adjusting the resonance frequency of a resonator including at least two or more of the distributed constant lines 61, 62, 68, and 69. The center frequency adjusting circuit 67 is a 5 th circuit having capacitors 671, 672, 673, switches SW67a, and SW67b, and sets a center frequency by adjusting a resonance frequency of a resonator including at least two or more lines among the distributed constant lines 61, 62, 68, and 69.

The bandwidth adjustment circuit 63 is connected in series to a path connecting the input terminal 101 and the output terminal 100. The impedance matching circuit 64 is connected to the input terminal 101, and the impedance matching circuit 65 is connected to the output terminal 100.

One end of the line 61 is connected to the impedance matching circuit 64 and the center frequency adjusting circuit 66, and the other end of the line 61 is connected to one end of the line 68 and the switch SW 68. One end of the line 62 is connected to the impedance matching circuit 65 and the center frequency adjusting circuit 67, and the other end of the line 62 is connected to one end of the line 69 and the switch SW 69. The other end of the line 68 and the other end of the line 69 are connected to ground.

According to the above configuration of the variable filter 60, the pass band or the stop band can be shifted by switching the switches SW68 to SW69, SW63a, SW63b, SW64a, SW64b, SW65a, SW65b, SW66a, SW66b, SW67a, and SW67b arranged in the filter unit circuit. Therefore, it is not necessary to arrange a plurality of filters having pass bands corresponding to the frequency bands to be detected, and it is possible to provide the directional coupler 1 which is miniaturized while detecting high-frequency signals of a desired frequency band with high accuracy.

Fig. 6 is a mounting configuration diagram of the directional coupler 1 including the variable filter 50 according to embodiment 1. Fig. 6 (a) shows a plan view structural diagram of directional coupler 1 (viewed from the z-axis positive direction), fig. 6 (b) shows a 1 st side view structural diagram of directional coupler 1 (viewed from the y-axis negative direction), and fig. 6 (c) shows a 2 nd side view structural diagram of directional coupler 1 (viewed from the x-axis positive direction).

A dielectric substrate 510 and a semiconductor substrate 520 using a material such as ceramic are disposed on the terminal substrate 530. The directional coupler 1 is mounted on a dielectric substrate 510 and a semiconductor substrate 520. As shown in fig. 6 (a), distributed constant lines 51, 52, 58, and 59 are formed on a dielectric substrate 510. The semiconductor substrate 520 is provided with the main line 11, the sub-line 12, switches, a control unit, a bandwidth adjusting circuit 53, impedance matching circuits 54 and 55, center frequency adjusting circuits 56 and 57, and the like. As shown in fig. 6 (b) and (c), the dielectric substrate 510 and the semiconductor substrate 520 are connected to the terminal substrate 530 through, for example, bump electrodes. A resin member 540 is formed on the main surface of the terminal substrate 530 on which the dielectric substrate 510 and the semiconductor substrate 520 are mounted so as to cover the dielectric substrate 510 and the semiconductor substrate 520.

In the dielectric substrate 510, the resonators 51, 52, 58, and 59 can be made smaller and lower in loss by selecting a substrate material having low loss and high dielectric constant, and therefore the variable filter 50 can be made smaller and lower in loss.

Further, by appropriately selecting the dielectric constant of the semiconductor substrate 520, the electrical lengths of the main line 11 and the sub-line 12 can be optimized, and microfabrication of the main line 11 and the sub-line 12 can be achieved with high accuracy. Therefore, the characteristic variation of the directional coupler 1 can be suppressed.

On the other hand, while each of the lumped constant passive elements constituting the variable filter 50 tends to have a relatively low Q value by being formed on the semiconductor substrate 520, and each of the switches formed on the semiconductor substrate 520 tends to have a high on-resistance, the passive elements and the switches can be connected to the sub-line 12 instead of the main line 11, and therefore, the influence of the low Q value and the high on-resistance can be suppressed.

In a general high-frequency circuit, it is not preferable to dispose an inductor having a low Q value and a switch having a high on-resistance on a transmission line in order to secure a low loss factor of the high-frequency circuit. On the other hand, since the sub-line 12 of the directional coupler 1 according to the present embodiment has a coupling ratio of about-20 to-30 dB with respect to the main line 11, for example, the loss of about several dB due to the low-Q inductor and the high-on-resistance switch does not affect the detection accuracy of the high-frequency signal. From this viewpoint, the influence of the low Q value and the high on-resistance can be eliminated by connecting the passive element and the switch to the sub-line 12.

The distributed constant lines 51, 52, 58, and 59 may be formed on the semiconductor substrate 520 instead of the dielectric substrate 510. In this case, a Silicon substrate having a relatively high resistance is preferably used as the semiconductor substrate 520, and by adopting an SOI (Silicon On Insulator) structure provided with an Insulator layer, the Q value of each line can be increased, and the loss of the variable filter 50 can be reduced. Further, connection to each switch and capacitor formed on the semiconductor substrate 520 is facilitated, and reliability is improved.

The distributed constant lines 51, 52, 58, and 59 may be formed directly on the terminal substrate 530 instead of the dielectric substrate 510. In this case, a resin substrate or a dielectric ceramic substrate with relatively low loss is preferably used as the terminal substrate 530. In this case, by lowering the dielectric constant of the terminal board 530, the conductor loss of the distributed constant line can be reduced without excessively lowering the impedance of the resonator, and the loss of the variable filter 50 can be reduced. Further, by increasing the dielectric constant of the terminal substrate 530, the distributed constant type line can be miniaturized, and the variable filter 50 can be miniaturized.

Fig. 7A is a circuit configuration diagram showing a variable filter 70 (example 7 of a variable filter: variable bandpass filter) according to embodiment 1. As shown in the figure, the variable filter 70 includes an input terminal 101, an output terminal 100, distributed constant type lines (e.g., strip lines) 71, 72, 73, 74, 75, and 76, and switches SW71 and SW 72. The variable filter 70 is composed of distributed constant type lines 71 to 76.

Each of the lines 71, 72, 75, and 76 is a strip line having one end in an open state, and functions as an open stub. One end of the line 73 is connected to the other end of the line 71, and the other end of the line 73 is connected to the other end of the line 75 via a switch SW 71. One end of the line 74 is connected to the other end of the line 72, and the other end of the line 74 is connected to the other end of the line 76 via a switch SW 72.

The input terminal 101 is connected to the connection node n71 of the lines 71 and 73, and the output terminal 100 is connected to the connection node n72 of the lines 72 and 74.

Lines 71 and 72 are electromagnetically coupled, lines 73 and 74 are electromagnetically coupled, and lines 75 and 76 are electromagnetically coupled.

The sum of the electrical length of the line 71 and the electrical length of the line 73 and the sum of the electrical length of the line 72 and the electrical length of the line 74 is approximately (1/2) wavelength of the center frequency of the 2 nd band. The sum of the electrical length of the line 71, the electrical length of the line 73, and the electrical length of the line 75, and the sum of the electrical length of the line 72, the electrical length of the line 74, and the electrical length of the line 76 has, for example, a wavelength of approximately (1/2) at the center frequency of the 1 st band f1, and the 1 st band is a band lower than the 2 nd band f 2.

In the above configuration of the variable filter 70, for example, the 1 st band f1 becomes the passband by turning on the switches SW71 and SW 72. For example, the 2 nd band f2 becomes a pass band by turning the switches SW71 and SW72 into a non-conductive state. By the above-described pass characteristic of the variable filter 70, when the high-frequency signal of the 1 st band f1 or the 2 nd band f2 is detected, the high-frequency signal from which harmonics, spurious, and the like of the high-frequency signal are removed can be detected with high accuracy.

Fig. 7B is a circuit configuration diagram showing a variable filter 80 (example 8 of the variable filter: variable bandpass filter) according to embodiment 1. As shown in the figure, the variable filter 80 includes an input terminal 101, an output terminal 100, distributed constant lines (for example, strip lines) 81, 82, 83, 84, 85, and 86, and switches SW81 and SW 82. The variable filter 80 is composed of distributed constant type lines 81 to 86.

The lines 81 and 82 are, for example, strip lines having one ends in an open state, and function as open stubs. One end of the line 83 is connected to the other end of the line 81 via a switch SW81, and the other end of the line 83 is connected to one end of the line 85. One end of the line 84 is connected to the other end of the line 82 via a switch SW82, and the other end of the line 84 is connected to one end of the line 86. The other end of the line 85 and the other end of the line 86 are connected to ground.

The input terminal 101 is connected to the connection node n81 of the lines 83 and 85, and the output terminal 100 is connected to the connection node n82 of the lines 84 and 86.

Lines 81 and 82 are electromagnetically coupled, lines 83 and 84 are electromagnetically coupled, and lines 85 and 86 are electromagnetically coupled.

The sum of the electrical length of the line 83 and the electrical length of the line 85 and the sum of the electrical length of the line 84 and the electrical length of the line 86 is approximately (1/4) wavelength of the center frequency of the 2 nd band f 2. The sum of the electrical length of the line 81, the electrical length of the line 83, and the electrical length of the line 85, and the sum of the electrical length of the line 82, the electrical length of the line 84, and the electrical length of the line 86 is, for example, approximately (1/4) wavelength of the center frequency of the 1 st band f1, and the 1 st band is a band lower than the 2 nd band.

In the above configuration of the variable filter 80, for example, the 1 st band f1 becomes the passband by turning on the switches SW81 and SW 82. For example, the 2 nd band f2 becomes a pass band by turning the switches SW81 and SW82 into a non-conductive state. By the above-described pass characteristic of the variable filter 80, when the high-frequency signal of the 1 st band f1 or the 2 nd band f2 is detected, the high-frequency signal from which harmonics, spurious, and the like of the high-frequency signal are removed can be detected with high accuracy.

Fig. 8 is a mounting configuration diagram of the directional coupler 1 including the variable filter 70 according to embodiment 1. Fig. 8 (a) shows a plan view structural diagram of directional coupler 1 (viewed from the z-axis positive direction), fig. 8 (b) shows a 1 st side view structural diagram of directional coupler 1 (viewed from the y-axis negative direction), and fig. 8 (c) shows a 2 nd side view structural diagram of directional coupler 1 (viewed from the x-axis positive direction).

A dielectric substrate 710 and a semiconductor substrate 720 made of a material such as ceramic are disposed on the terminal substrate 730. The directional coupler 1 is mounted on the dielectric substrate 710 and the semiconductor substrate 720. As shown in fig. 8 (a), distributed constant lines 71, 72, 73, 74, 75, and 76 are formed on a dielectric substrate 710. The semiconductor substrate 720 is provided with a main line 11, a sub-line 12, switches, and a control unit. As shown in fig. 8 (b) and (c), the dielectric substrate 710 and the semiconductor substrate 720 are connected to the terminal substrate 730 by, for example, bump electrodes. A resin member 740 is formed on the main surface of the terminal substrate 730 on which the dielectric substrate 710 and the semiconductor substrate 720 are mounted so as to cover the dielectric substrate 710 and the semiconductor substrate 720.

The dielectric substrate 710 can be made smaller and lower in loss by selecting a substrate material having low loss and high dielectric constant, and hence the variable filter 70 can be made smaller and lower in loss because the distributed constant type lines 71 to 76 can be made smaller and lower in loss.

Further, by appropriately selecting the dielectric constant of the semiconductor substrate 720, the electrical lengths of the main line 11 and the sub-line 12 can be optimized, and microfabrication of the main line 11 and the sub-line 12 can be achieved with high accuracy. Therefore, the characteristic variation of the directional coupler 1 can be suppressed.

On the other hand, each switch formed on the semiconductor substrate 720 tends to have a high on-resistance, but since each switch can be connected to the sub-line 12 instead of the main line 11, the influence of the high on-resistance can be suppressed.

In addition, the lines 71-76 can be formed on the semiconductor substrate 720 instead of the dielectric substrate 710. In this case, it is preferable to use a silicon substrate having a high resistance as the semiconductor substrate 720, and by adopting an SOI structure provided with an insulator layer, the Q value of each line can be increased, and the loss of the variable filter 70 can be reduced. Further, connection to each switch formed on the semiconductor substrate 720 is facilitated, and reliability is improved.

In addition, the distributed constant lines 71 to 76 may be formed on the terminal substrate 730 instead of the dielectric substrate 710. In this case, a resin substrate or a dielectric ceramic substrate having a relatively low loss is preferably used as the terminal substrate 730. In this case, by lowering the dielectric constant of the terminal substrate 730, the conductor loss of the distributed constant line can be reduced without excessively lowering the impedance of the resonator, and the loss of the variable filter 70 can be reduced. Further, by increasing the dielectric constant of the terminal substrate 730, the distributed constant type line can be miniaturized, and the variable filter 70 can be miniaturized.

(embodiment mode 2)

In this embodiment, a configuration of a directional coupler 2 in which a variable termination circuit, a variable matching circuit, and a variable attenuator are further added to the directional coupler 1 according to embodiment 1 is shown.

[2.1 Circuit Structure of Directional coupler ]

Fig. 9 is a circuit diagram showing an example of a functional configuration of the directional coupler 2 according to embodiment 2. As shown in the figure, the directional coupler 2 includes a main line 11, a sub-line 12, a variable filter 10, variable termination circuits 14V and 16V, switches 15A and 15B, a variable matching circuit 17V, a variable attenuator 18V, and a control unit 90. As shown by an arrow M in fig. 9, the main line 11 and the sub-line 12 are electromagnetically coupled to each other. The directional coupler 2 according to the present embodiment is different from the directional coupler 1 according to embodiment 1 in that variable termination circuits 14V and 16V are added instead of the termination circuit 14, and further, a variable matching circuit 17V, a variable attenuator 18V, and a control unit 90 are added. Hereinafter, the directional coupler 2 according to the present embodiment will be described centering on a different configuration, with the same configuration as the directional coupler 1 according to embodiment 1 omitted from description.

The variable terminal circuits 14V and 16V are connected to the switches 15A and 15B, respectively. The variable terminal circuit 14V is connected to the other end 122 via a switch 15A, and is connected to the one end 121 via a switch 15B. The variable terminal circuit 16V is connected to the other end 122 via the switch 15A and to the one end 121 via the switch 15B. The variable termination circuits 14V and 16V constitute termination circuits of the directional coupler 2.

The variable termination circuit 14V has a variable resistance element that varies the termination impedance of the termination circuit. The variable termination circuit 16V includes a variable capacitance element for varying the termination impedance of the termination circuit.

According to the configuration of the variable termination circuits 14V and 16V, the resistance value of the variable resistance element and the capacitance value of the variable capacitance element can be changed in accordance with the frequency band of the high-frequency signal to be detected, and therefore, the directivity and the isolation appropriate for the frequency band can be optimized. The filter characteristics of the variable filter 10 can be adjusted in accordance with the termination impedance adjusted by the termination circuit. Therefore, the influence on the filter characteristics of the variable filter 10 due to the connection of the variable termination circuits 14V and 16V can be eliminated.

The variable resistive element of the variable termination circuit 14V is composed of, for example, a plurality of resistive elements and switches. The plurality of resistance elements may be formed on a semiconductor substrate or may be mounted separately as a chip component.

The variable capacitance element of the variable termination circuit 16V is formed of, for example, a plurality of capacitors connected in parallel. The plurality of capacitors may be MIM capacitors formed on the semiconductor substrate or capacitors formed by opposing comb-shaped electrodes, or may be mounted separately as chip components. The variable capacitance element may be a MEMS-type capacitor having a mechanism for continuously changing the overlapping area of the opposing electrodes.

The variable matching circuit 17V is disposed between the sub-line 12 and the variable filter 10. In the present embodiment, the variable matching circuit 17V has an input terminal connected to the selection terminals 152 and 155, and an output terminal connected to the variable filter 10 via the variable attenuator 18B. The variable matching circuit 17V is composed of passive elements such as an inductor and a capacitor, and a switch. The variable matching circuit 17V can match the impedance of the sub-line 12 viewed from the variable matching circuit 17V with the input impedance of the variable filter 10 by varying the impedance, phase, and the like according to the frequency band to be detected.

Accordingly, it is possible to realize the directivity and isolation suitable for the frequency band of the high frequency signal to be detected. The filter characteristic of the variable filter 10 can be adjusted in accordance with the impedance adjusted by the variable matching circuit 17V. Therefore, the influence on the filter characteristics of the variable filter 10 due to the connection of the variable matching circuit 17V can be eliminated.

The variable matching circuit 17V may be connected to the other end 122 via the switch 15A and to the one end 121 via the switch 15B. For example, the output terminal 100 of the variable filter 10 may be connected thereto. In this case, the variable matching circuit 17V can match the impedance of the side of the sub-line 12 viewed from the variable matching circuit 17V and the impedance of the side of the output terminal 100 viewed from the variable matching circuit 17V.

The variable attenuator 18V is connected between the variable matching circuit 17V and the variable filter 10. By adjusting the attenuation factor of the variable attenuator 18V, the insertion loss of the variable filter 10, which varies depending on the band of the detection target, can be compensated, the magnitude of the detection signal at the output terminal 100 can be equalized, and the detection accuracy can be stabilized.

The variable attenuator 18V may be connected to the other end 122 via the switch 15A and connected to the one end 121 via the switch 15B. For example, the output terminal 100 of the variable filter 10 may be connected thereto.

The control unit 90 controls each switch included in the variable filter 10 so as to move the pass band or the stop band of the variable filter 10. The control unit 90 controls the switches 15A and 15B so as to select the detection terminal (coupling port) in the sub-line 12. The control unit 90 sets the resistance value of the variable resistive element of the variable termination circuit 14V and the capacitance value of the variable capacitive element of the variable termination circuit 16V according to the frequency band of the detection target. The control unit 90 sets the impedance and phase of the variable matching circuit 17V according to the frequency band of the detection target. The control unit 90 sets the attenuation factor of the variable attenuator according to the frequency band to be detected.

The control unit 90 is configured by, for example, a level shifter for opening and closing each switch based on selection information of a frequency band to be detected, an interface unit for performing serial communication or GPIO (General Purpose Input/Output) communication with the outside, a memory unit for storing information, a logic unit or a processor unit for processing signals and information, and a power supply unit for driving the switches or each unit.

According to the above configuration of the control unit 90, it is possible to selectively output a high-frequency signal of a desired frequency band from a high-frequency signal having a plurality of frequency bands transmitted through the main line 11 to the output terminal 100.

The directional coupler 2 may not have the control unit 90, and an external circuit connected to the directional coupler 2 may have the control unit 90. The control unit 90 may be incorporated in a high frequency signal processing circuit (RFIC), for example.

(embodiment mode 3)

In this embodiment, a directional coupler 2 having a plurality of variable filters and a structure for bypassing the variable filters, compared to the directional coupler 1 according to embodiment 1, will be described.

[3.1 Circuit Structure of Directional coupler ]

Fig. 10 is a circuit diagram showing an example of a functional configuration of the directional coupler 3 according to embodiment 3. As shown in the drawing, the directional coupler 3 includes a main line 11, a sub-line 12, variable filters 10A and 10B, variable termination circuits 14V and 16V, switches 15A, 15B, 19A, and 19B, and a control unit 90. As shown by an arrow M in fig. 10, the main line 11 and the sub-line 12 are electromagnetically coupled to each other. The directional coupler 3 according to the present embodiment is different from the directional coupler 1 according to embodiment 1 in that variable termination circuits 14V and 16V are added instead of the termination circuit 14, a plurality of variable filters are arranged, a configuration for bypassing the variable filters is added, and a control unit 90 is added. Hereinafter, the directional coupler 3 according to the present embodiment will be described centering on a different configuration, with the same configuration as the directional coupler 1 according to embodiment 1 omitted from description.

The variable termination circuits 14V and 16V have the same configuration as the variable termination circuits 14V and 16V included in the directional coupler 2 according to embodiment 2, and therefore, the description thereof is omitted.

The switch 19A is a 3 rd switch circuit having a common terminal 191 and selection terminals 192, 193, and 194 and disposed between the variable filters 10A and 10B and the sub-line 12. The switch 19B has a common terminal 195, selection terminals 196, 197, and 198, and is disposed between the switches 15A and 15B and the output terminal 100.

Each of the variable filters 10A and 10B has the same configuration as the variable filter 10 according to embodiment 1, and is a filter unit circuit having a passband or a stopband defined by one continuous frequency band, and a switch for shifting the passband is disposed in the filter unit circuit. The variable filter 10A has a pass band or stop band different from that of the variable filter 10B. In other words, the pass band (or stop band) of the variable filter 10A does not simultaneously contain the frequency band contained in the pass band (or stop band) of the variable filter 10B. For example, when the pass band of the variable filter 10A is set to the band a, the pass band of the variable filter 10B is set to the band B, which is a different band from the band a. However, when the passband of the variable filter 10B is moved to the frequency band a, or when the passband of the variable filter 10B is moved to the frequency band C different from the frequency band a or the frequency band B, the passband of the variable filter 10A is moved to the frequency band B.

A specific connection configuration is, for example, such that the common terminal 191 is connected to the selection terminals 152 and 155, the selection terminal 192 is connected to the input terminal of the variable filter 10A, and the selection terminal 194 is connected to the input terminal of the variable filter 10B. The common terminal 195 is connected to the output terminal 100, the selection terminal 196 is connected to the output terminal of the variable filter 10A, and the selection terminal 198 is connected to the output terminal of the variable filter 10B. Further, the selection terminal 193 and the selection terminal 197 are directly connected.

According to the above configuration, the switches 19A and 19B switch between (1) a path through the variable filter 10A, (2) a path through the variable filter 10B, and (3) a path through which the high-frequency signal transmitted through the sub-line 12 passes through the bypass line without passing through the variable filters 10A and 10B. Thus, by selecting (3) a path that is passed through the bypass line without passing through the variable filters 10A and 10B, (1) the insertion loss in the path that passes through the variable filter 10A and (2) the path that passes through the variable filter 10B, and (3) the insertion loss in the path that passes through the bypass line without passing through the variable filters 10A and 10B, the insertion loss of the variable filters 10A and 10B can be monitored, and the high-frequency signal can be detected without loss.

Further, by arranging a plurality of filters including the variable filter 10A, the detection accuracy of the high frequency signal can be improved over a wide frequency band. Further, since at least one variable filter 10A is provided, the directional coupler 3 can be miniaturized, as compared with a directional coupler constituted only by a filter having a fixed passband.

In addition, in the directional coupler 3 according to the present embodiment, a configuration having two variable filters is adopted, but in this respect, it is only necessary to have at least one variable filter, and in this respect, a filter having fixed pass band and stop band may be disposed instead of the variable filter 10B.

In addition, the switch 19B may not be provided, and in this case, a plurality of output terminals may be provided.

In addition, a duplexer, for example, may be disposed instead of the switches 19A and 19B.

Further, a plurality of filters including a variable filter may be arranged in series instead of in parallel.

The control unit 90 has the same configuration as the control unit 90 according to embodiment 2, but controls the switches 19A and 19B in accordance with the frequency band to be detected, compared to the control unit 90 according to embodiment 2.

(other embodiment, etc.)

The directional coupler according to the present embodiment has been described above by referring to the embodiment and the modified examples, but the directional coupler according to the present invention is not limited to the embodiment and the modified examples. Another embodiment in which arbitrary constituent elements in the above-described embodiment and modification are combined, a modification in which various modifications that may occur to those skilled in the art are applied to the above-described embodiment and modification without departing from the spirit of the present invention, and various devices in which the above-described directional coupler is built are also included in the present invention.

For example, in the directional coupler according to the above-described embodiment and the modifications thereof, another circuit element, wiring, or the like may be inserted between the circuit elements and the paths connecting the signal paths disclosed in the drawings.

Industrial applicability

The present invention can be widely used as a directional coupler.