Directional coupler

Abstract

To provide a directional coupler in which a coupling characteristic is made even flatter. There are included an input terminal, an output terminal, a coupling terminal, a termination terminal, ground terminals, a main line, a first sub line, and a second sub line. The main line is electromagnetically coupled to sub lines (first sub line, second sub line). A phase conversion unit (low pass filter) is connected between the first sub line and the second sub line. Between a point between the coupling terminal and the termination terminal, and the ground terminals, a resonant circuit is connected in which an inductor, a capacitor, and a resistor are connected in series.

Description

BACKGROUND ART

Technical Field

The present disclosure relates to a directional coupler.

Patent Document 1 (Japanese Unexamined Patent Application Publication No. 8-237012) discloses a directional coupler. In the directional coupler, a main line is provided between an input terminal and an output terminal, a sub line is provided between a coupling terminal and a termination terminal, and the main line and the sub line are electromagnetically coupled to each other. In the directional coupler disclosed in Patent Document 1, when a signal is input to the input terminal, a coupling signal having a certain ratio of power to the power of the signal is output from the coupling terminal.

In the directional coupler disclosed in Patent Document 1, there is an issue of an increase in the degree of coupling between the main line and the sub line with increasing frequency of a signal input from the input terminal. In other words, in the directional coupler disclosed in Patent Document 1, an amplitude characteristic (coupling characteristic) of the coupling signal is not flat.

A directional coupler that mitigates this issue is disclosed in Patent Document 2 (Japanese Unexamined Patent Application Publication No. 2013-5076). In the directional coupler disclosed in Patent Document 2, a sub line is divided into a first sub line and a second sub line, and a low pass filter is connected, as a phase conversion unit, between the first sub line and the second sub line. In the directional coupler disclosed in Patent Document 2, the low pass filter is designed to cause a phase shift to be produced in a signal passing therethrough in such a manner that the absolute value of the phase shift monotonically increases within a range from 0 to 180 degrees inclusive as a frequency increases in a frequency band that is used.

Thus, in the directional coupler disclosed in Patent Document 2, a coupling characteristic is flat to some degree.

Patent Document 1: Japanese Unexamined Patent Application Publication No. 8-237012

Patent Document 2: Japanese Unexamined Patent Application Publication No. 2013-5076

BRIEF SUMMARY

In the directional coupler disclosed in Patent Document 2, the phase conversion unit (low pass filter) has a frequency characteristic, and thus the coupling characteristic is not completely flat but is undulating.

For this reason, in the directional coupler disclosed in Patent Document 2, when the frequency band that is used is relatively narrow, a good coupling characteristic is exhibited. However, when the frequency band that is used is wide, there is an issue of an increase in the amplitude of an undulation, causing an error to occur in a coupling signal output from a coupling terminal.

Thus, the present disclosure provides a directional coupler in which a coupling characteristic is flat.

To solve the above-described existing issue, a non-reciprocal circuit device according to an embodiment of the present disclosure includes an input terminal, an output terminal, a coupling terminal, a termination terminal, a ground terminal, a main line connected between the input terminal and the output terminal, and a sub line connected between the coupling terminal and the termination terminal. The main line and the sub line are electromagnetically coupled to each other. The sub line includes at least a first sub line and at least a second sub line that are connected to each other. A phase conversion unit is connected between the first sub line and the second sub line. Between a point between the coupling terminal and the termination terminal, and the ground terminal, a resonant circuit is connected in which an inductor, a capacitor, and a resistor are connected in series. Incidentally, in the resonant circuit, as the order in which the inductor, the capacitor, and the resistor are connected, any order can be selected.

Since, in the directional coupler according to the present disclosure, the resonant circuit is provided in which the inductor, the capacitor, and the resistor are connected in series, the coupling characteristic is flat.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an equivalent circuit diagram of a directional coupler according to a first embodiment of the present disclosure.

FIG. 2 is an exploded perspective view of the directional coupler according to the first embodiment of the present disclosure.

FIG. 3 illustrates the directional coupler according to the first embodiment of the present disclosure.

FIGS. 4A and 4B include graphs illustrating a coupling characteristic of the directional coupler according to the first embodiment of the present disclosure and that of a comparative example.

FIG. 5A includes a graph illustrating a phase characteristic of a sub line of the directional coupler according to the first embodiment of the present disclosure, and FIG. 5C includes a graph illustrating a bandpass characteristic of a sub line of the directional coupler according to the first embodiment of the present disclosure. FIG. 5B includes a graph illustrating a phase characteristic of a subline of the comparative example, and FIG. 5D includes a graph illustrating a bandpass characteristic of a sub line of the comparative example.

FIG. 6 is an equivalent circuit diagram of a directional coupler according to a second embodiment of the present disclosure.

FIG. 7 is an equivalent circuit diagram of a directional coupler according to a third embodiment of the present disclosure.

FIG. 8 is an equivalent circuit diagram of a directional coupler according to a fourth embodiment of the present disclosure.

FIG. 9 illustrates a directional coupler according to a fifth embodiment of the present disclosure.

DETAILED DESCRIPTION

Embodiments for implementing the present disclosure will be described below with reference to the drawings.

The embodiments for implementing the present disclosure are exemplified by the following embodiments, and the present disclosure is not limited to details of the embodiments. Furthermore, the present disclosure can be implemented by a combination of details described in different embodiments, and details implemented in this case are also included in the present disclosure. Furthermore, the drawings aid in understanding the description, and, in some cases, figures are schematically drawn. In some cases, a dimensional ratio of a drawn component or between drawn components does not coincide with a dimensional ratio of that or between those described in the description. Furthermore, in some cases, in a drawing, for example, a component described in the description is omitted, or components described in the description are drawn with the number of the components being reduced.

First Embodiment

FIGS. 1 to 3 illustrate a directional coupler 100 according to a first embodiment of the present disclosure. However, FIG. 1 is an equivalent circuit diagram of the directional coupler 100. FIG. 2 is an exploded perspective view of the directional coupler 100. FIG. 3 illustrates the directional coupler 100.

As illustrated in FIG. 1, the directional coupler 100 includes an input terminal T1, an output terminal T2, a coupling terminal T3, a termination terminal T4, and ground terminals T5 and T6.

A main line M is connected between the input terminal T1 and the output terminal T2.

A first sub line S1, a low pass filter 10, which is a phase conversion unit, and a second sub line S2 are connected in this order between the coupling terminal T3 and the termination terminal T4.

In the directional coupler 100, when a signal is input to the input terminal T1, the main line M is electromagnetically coupled to the first sub line S1 and the second sub line S2.

The low pass filter 10 is an LC-based π-type filter. Specifically, in the low pass filter 10, an inductor L1 and an inductor L2 are connected in this order between the first sub line S1 and the second sub line S2. A capacitor C1 is connected between a connection point between the first sub line S1 and the inductor L1, and the ground terminals T5 and T6. A capacitor C2 is connected between a connection point between the inductor L1 and the inductor L2, and the ground terminals T5 and T6. A capacitor C3 is connected between a connection point between the inductor L2 and the second sub line S2, and the ground terminals T5 and T6.

In the directional coupler 100, a resonant circuit 20 is connected between the connection point between the first sub line S1 and the inductor L1, and the ground terminals T5 and T6. The resonant circuit 20 is a resonant circuit in which an inductor L11, a capacitor C11, and a resistor R11 are connected in series. Incidentally, in the resonant circuit 20, the order in which the inductor L11, the capacitor C11, and the resistor R11 are connected is any order. This order is not limited to the order illustrated in FIG. 1 and can be changed to any order.

Incidentally, the resistor R11 of the resonant circuit 20 is connected to moderate attenuation of a signal passing through the sub lines due to series resonance.

In this embodiment, as illustrated in FIG. 2, the directional coupler 100 is formed as a multilayer body 1 including insulator layers 1a to 1t that are laminated. The multilayer body 1 has a rectangular parallelepiped shape.

As a material of the insulator layers 1a to 1t constituting the multilayer body 1, ceramic is used. Each of the insulator layers 1a to 1t is a dielectric layer with a dielectric constant. However, the material of the insulator layers 1a to 1t (multilayer body 1) is any material, and, for example, a resin may be used in place of ceramic.

On a bottom surface of the insulator layer 1a (multilayer body 1), the input terminal T1, the output terminal T2, the coupling terminal T3, the termination terminal T4, and the ground terminals T5 and T6 are provided. The input terminal T1, the output terminal T2, the coupling terminal T3, the termination terminal T4, and the ground terminals T5 and T6 are made of metal containing, as a main component, for example, Ag, Cu, or an alloy of Ag and Cu. On their surfaces, one plated layer or a plurality of plated layers containing, as a main component, for example, Ni, Sn, or Au can be provided.

Via electrodes 2a to 2f are provided so as to extend between upper and lower main faces of the insulator layer 1a.

A ground electrode 3a, and relay electrodes 4a to 4d are provided on the upper main face of the insulator layer 1a.

Via electrodes 2g to 2l are provided so as to extend between upper and lower main faces of the insulator layer 1b.

Line electrodes 5a and 5b are provided on the upper main face of the insulator layer 1b.

The above-described via electrodes 2i to 2l, and via electrodes 2m and 2n are provided so as to extend between upper and lower main faces of the insulator layer 1c.

A line electrode 5c is provided on the upper main face of the insulator layer 1c.

The above-described via electrodes 2i to 2l are provided so as to extend between upper and lower main faces of the insulator layer 1d.

A line electrode 5d is provided on the upper main face of the insulator layer 1d.

The above-described via electrodes 2i, 2k, and 2l, and a via electrode 2o are provided so as to extend between upper and lower main faces of the insulator layer 1e.

A line electrode 5e is provided on the upper main face of the insulator layer 1e.

The above-described via electrode 2k, 21, and 2o, and a via electrode 2p are provided so as to extend between upper and lower main faces of the insulator layer 1f.

A ground electrode 3b is provided on the upper main face of the insulator layer 1f.

The above-described via electrodes 2o and 2p, and via electrodes 2q and 2r are provided so as to extend between upper and lower main faces of the insulator layer 1g.

Capacitor electrodes 6a and 6b are provided on the upper main face of the insulator layer 1g.

The above-described via electrodes 2q and 2r, and via electrodes 2s and 2t are provided so as to extend between upper and lower main faces of the insulator layer 1h.

A ground electrode 3c is provided on the upper main face of the insulator layer 1h.

The above-described via electrodes 2s and 2t, and a via electrode 2u are provided so as to extend between upper and lower main faces of the insulator layer 1i.

A line electrode 5f is provided on the upper main face of the insulator layer 1i.

The above-described via electrodes 2t and 2u, and via electrodes 2v and 2w are provided so as to extend between upper and lower main faces of the insulator layer 1j.

Line electrodes 5g to 5i are provided on the upper main face of the insulator layer 1j.

The above-described via electrode 2u, and via electrodes 2x to 2z are provided so as to extend between upper and lower main faces of the insulator layer 1k.

Line electrodes 5j to 5l are provided on the upper main face of the insulator layer 1k.

The above-described via electrode 2u, and via electrodes 2aa to 2ac are provided so as to extend between upper and lower main faces of the insulator layer 1l.

Line electrodes 5m and 5n are provided on the upper main face of the insulator layer 1l.

The above-described via electrodes 2u and 2ac, and via electrodes 2ad and 2ae are provided so as to extend between upper and lower main faces of the insulator layer 1m.

Line electrodes 5o and 5p, and a capacitor electrode 6c are provided on the upper main face of the insulator layer 1m.

The above-described via electrode 2u, and via electrodes 2af and 2ag are provided so as to extend between upper and lower main faces of the insulator layer 1n.

A capacitor electrode 6d is provided on the upper main face of the insulator layer 1n.

The above-described via electrodes 2u, 2af, and 2ag, and a via electrode 2ah are provided so as to extend between upper and lower main faces of the insulator layer 1o.

Capacitor electrodes 6e and 6f are provided on the upper main face of the insulator layer 1o.

The above-described via electrodes 2u and 2ah, and a via electrode 2ai are provided so as to extend between upper and lower main faces of the insulator layer 1p.

A capacitor electrode 6g is provided on the upper main face of the insulator layer 1p.

The above-described via electrode 2u and 2ai, and a via electrode 2aj are provided so as to extend between upper and lower main faces of the insulator layer 1q.

A ground electrode 3d and a capacitor electrode 6h are provided on the upper main face of the insulator layer 1q.

The above-described via electrode 2aj and a via electrode 2ak are provided so as to extend between upper and lower main faces of the insulator layer 1r.

A capacitor electrode 6i is provided on the upper main face of the insulator layer 1r.

The above-described via electrode 2ak and a via electrode 2al are provided so as to extend between upper and lower main faces of the insulator layer 1s.

A resistor 7 is provided on the upper main face of the insulator layer 1s.

The insulator layer 1t is a protective layer.

As a material of the via electrodes 2a to 2al, the ground electrodes 3a to 3d, the relay electrodes 4a to 4d, the line electrodes 5a to 5p, and the capacitor electrodes 6a to 6i, metal containing, as a main component, for example, Ag, Cu, or an alloy of Ag and Cu can be used. Furthermore, as a material of the resistor 7, a resistance element made of non-precious metal, such as a nickel-chromium alloy or ruthenium oxide, can be used.

Next, connection relationships among the input terminal T1, the output terminal T2, the coupling terminal T3, the termination terminal T4, the via electrodes 2a to 2al, the ground electrodes 3a to 3d, the relay electrodes 4a to 4d, the line electrodes 5a to 5p, the capacitor electrodes 6a to 6i, and the resistor 7 will be described.

The input terminal T1 and the relay electrode 4a are connected by the via electrode 2a. The output terminal T2 and the relay electrode 4b are connected by the via electrode 2b. The coupling terminal T3 and the relay electrode 4c are connected by the via electrode 2c. The termination terminal T4 and the relay electrode 4d are connected by the via electrode 2d. The ground terminal T5 and the ground electrode 3a are connected by the via electrode 2e. The ground terminal T6 and the ground electrode 3a are connected by the via electrode 2f.

The relay electrode 4a and one end of the line electrode 5a are connected by the via electrode 2g. The relay electrode 4b and one end of the line electrode 5b are connected by the via electrode 2h. The relay electrode 4c and one end of the line electrode 5e are connected by the via electrode 2i. The relay electrode 4d and one end of the line electrode 5d are connected by the via electrode 2j. The ground electrode 3a and the ground electrode 3b are connected by the via electrodes 2k and 2l.

The other end of the line electrode 5a and one end of the line electrode 5c are connected by the via electrode 2m. The other end of the line electrode 5b and the other end of the line electrode 5c are connected by the via electrode 2n.

The other end of the line electrode 5d and the capacitor electrode 6b are connected by the via electrode 2o.

The other end of the line electrode 5e and the capacitor electrode 6a are connected by the via electrode 2p.

The ground electrode 3b and the ground electrode 3c are connected by the via electrodes 2q and 2r.

The capacitor electrode 6a and one end of the line electrode 5f are connected by the via electrode 2s.

The capacitor electrode 6b and one end of the line electrode 5h are connected by the via electrode 2t.

The ground electrode 3c and the ground electrode 3d are connected by the via electrode 2u.

The one end of the line electrode 5f and one end of the line electrode 5g are connected by the via electrode 2v.

The other end of the line electrode 5f and one end of the line electrode 5i are connected by the via electrode 2w.

The other end of the line electrode 5g and one end of the line electrode 5j are connected by the via electrode 2x.

The other end of the line electrode 5h and one end of the line electrode 5k are connected by the via electrode 2y.

The other end of the line electrode 5i and one end of the line electrode 5l are connected by the via electrode 2z.

The other end of the line electrode 5j and one end of the line electrode 5m are connected by the via electrode 2aa.

The other end of the line electrode 5k and one end of the line electrode 5n are connected by the via electrode 2ab.

The other end of the line electrode 5l and the capacitor electrode 6c are connected by the via electrode 2ac.

The other end of the line electrode 5m and one end of the line electrode 5o are connected by the via electrode 2ad.

The other end of the line electrode 5n and one end of the line electrode 5p are connected by the via electrode 2ae.

The other end of the line electrode 5o and the other end of the line electrode 5p are connected to each other. A connection point between the line electrode 5o and the line electrode 5p, and the capacitor electrode 6e are connected by the via electrode 2af.

The capacitor electrode 6c and the capacitor electrode 6f are connected by the via electrode 2ag.

The capacitor electrode 6d and the capacitor electrode 6g are connected by the via electrode 2ah.

The capacitor electrode 6f and the capacitor electrode 6h are connected by the via electrode 2ai.

The capacitor electrode 6g and the capacitor electrode 6i are connected by the via electrode 2aj.

The ground electrode 3d and one end of the resistor 7 are connected by the via electrode 2ak.

The capacitor electrode 6i and the other end of the resistor 7 are connected by the via electrode 2al.

Next, relationships between the equivalent circuit of the directional coupler 100 illustrated in FIG. 1, and the above-described input terminal T1, output terminal T2, coupling terminal T3, termination terminal T4, via electrodes 2a to 2al, ground electrodes 3a to 3d, relay electrodes 4a to 4d, line electrodes 5a to 5p, capacitor electrodes 6a to 6i, and resistor 7 will be described.

The main line M is formed by a conductive path starting from the input terminal T1, passing through the via electrode 2a, the relay electrode 4a, the via electrode 2g, the line electrode 5a, the via electrode 2m, the line electrode 5c, the via electrode 2n, the line electrode 5b, the via electrode 2h, the relay electrode 4b, and the via electrode 2b, and ending at the output terminal T2.

The first sub line S1 is formed by a conductive path starting from the coupling terminal T3, passing through the via electrode 2c, the relay electrode 4c, the via electrode 2i, and the line electrode 5e, and ending at the other end of the line electrode 5e.

The second sub line S2 is formed by a conductive path starting from the other end of the line electrode 5d, passing through the line electrode 5d, the via electrode 2j, the relay electrode 4d, and the via electrode 2d, and ending at the termination terminal T4.

The inductor L1 of the low pass filter 10 is formed by a conductive path starting from the other end of the line electrode 5e, passing through the via electrode 2p, 2s, and 2v, the line electrode 5g, the via electrode 2x, the line electrode 5j, the via electrode 2aa, the line electrode 5m, the via electrode 2ad, and the line electrode 5o, and ending at the connection point between the line electrode 5o and the line electrode 5p.

The inductor L2 of the low pass filter 10 is formed by a conductive path starting from the connection point between the line electrode 5o and the line electrode 5p, passing through the line electrode 5p, the via electrode 2ae, the line electrode 5n, the via electrode 2ab, the line electrode 5k, the via electrode 2y, the line electrode 5h, and the via electrodes 2t and 2o, and ending at the other end of the line electrode 5d.

The capacitor C1 of the low pass filter 10 is formed by capacitances between the capacitor electrode 6a, and the ground electrodes 3b and 3c.

The capacitor C2 of the low pass filter 10 is formed by a capacitance between the capacitor electrode 6e and the ground electrode 3d.

The capacitor C3 of the low pass filter 10 is formed by capacitances between the capacitor electrode 6b, and the ground electrodes 3b and 3c.

The inductor L11 of the resonant circuit 20 is formed by a conductive path starting from the one end of the line electrode 5f, passing through the line electrode 5f, the via electrode 2w, the line electrode 5i, the via electrode 2z, the line electrode 5l, and the via electrode 2ac, and ending at the capacitor electrode 6c.

The capacitor C11 of the resonant circuit 20 is formed by capacitances between the capacitor electrodes 6c, 6f, and 6h, and the capacitor electrodes 6d, 6g, and 6i.

The resistor R11 of the resonant circuit 20 is formed by the resistor 7.

The directional coupler 100 with the above structure can be manufactured by a typical manufacturing method for manufacturing a directional coupler including a multilayer body including insulator layers that are laminated.

As illustrated in FIG. 3, in the directional coupler 100, a coupler section including the main line M and a plurality of sub lines (first sub line S1, second sub line S2) is disposed in a lower portion 8 of the multilayer body 1, and the phase conversion unit (low pass filter 10) and the resonant circuit 20 are disposed in an upper portion 9 of the multilayer body 1. For the directional coupler 100, when such a disposition structure is employed, electronic components are efficiently disposed within the multilayer body 1.

Furthermore, in the directional coupler 100, the ground electrode 3c is provided in an interlayer space of the multilayer body 1, which is a space between the lower portion 8 and the upper portion 9. Hence, in the directional coupler 100, interference between the coupler section, and the phase conversion unit (low pass filter 10) and the resonant circuit 20 is suppressed by the ground electrode 3c.

FIG. 4A illustrates a coupling characteristic of S(3, 2) of the directional coupler 100. Furthermore, for comparison purposes, FIG. 4B illustrates a coupling characteristic of S(3, 2) of a comparative example in which the resonant circuit 20 is removed from the directional coupler 100.

Furthermore, FIG. 5A illustrates a phase characteristic of S(3, 4) of the directional coupler 100. For comparison purposes, FIG. 5B illustrates a phase characteristic of S(3, 4) of the comparative example in which the resonant circuit 20 is removed from the directional coupler 100.

Furthermore, FIG. 5C illustrates a bandpass characteristic of S(3, 4) of the directional coupler 100. For comparison purposes, FIG. 5D illustrates a bandpass characteristic of S(3, 4) of the comparative example in which the resonant circuit 20 is removed from the directional coupler 100.

Incidentally, these characteristics are measured assuming that the output terminal T2 is a first terminal, the input terminal T1 is a second terminal, the coupling terminal T3 is a third terminal, and the termination terminal T4 is a fourth terminal.

As seen from FIG. 5B, in the comparative example, the phase changes linearly and reaches a peak of 180 degrees at about 4.3 GHz to return back. Thus, in the comparative example, when a frequency band that is used in the directional coupler is wide, it is difficult to achieve a flat coupling characteristic. On the other hand, as seen from FIG. 5A, in the directional coupler 100, the phase does not return back even at 5.0 GHz.

Furthermore, as seen from FIG. 5D, in the comparative example, the bandpass characteristic of S(3, 4) is flat. As seen from FIG. 5C, however, the bandpass characteristic of S(3, 4) of the directional coupler 100 is curved. This is because it is conceivable that, in the directional coupler 100, an attenuation characteristic due to series resonance of the resonant circuit 20 is added to a frequency characteristic of the low pass filter 10, which is the phase conversion unit.

As a result, as illustrated in FIGS. 4(A) and 4(B), the coupling characteristic of the directional coupler 100 is flatter than the coupling characteristic of the comparative example. In the directional coupler 100, the attenuation characteristic due to series resonance of the resonant circuit 20 is added to the frequency characteristic of the low pass filter 10, which is the phase conversion unit, and thus the coupling characteristic is flatter.

As described above, it has been ascertained that, in the directional coupler 100, the provision of the resonant circuit 20 makes the coupling characteristic even flatter.

Second Embodiment

FIG. 6 illustrates a directional coupler 200 according to a second embodiment of the present disclosure. However, FIG. 6 is an equivalent circuit diagram of the directional coupler 200.

The directional coupler 200 according to the second embodiment differs from the directional coupler 100 according to the first embodiment in a partial configuration. Specifically, in the directional coupler 100, the resonant circuit 20 is connected between a connection point between the first sub line S1 and the phase conversion unit (low pass filter 10), and the ground terminals T5 and T6. In the directional coupler 200, the resonant circuit 20 is connected between a connection point between the coupling terminal T3 and the first sub line S1, and the ground terminals T5 and T6. Except for the above, the configuration of the directional coupler 200 is the same as that of the directional coupler 100.

In the directional coupler 200 as well, the provision of the resonant circuit 20 makes the coupling characteristic even flatter.

Third Embodiment

FIG. 7 illustrates a directional coupler 300 according to a third embodiment of the present disclosure. However, FIG. 7 is an equivalent circuit diagram of the directional coupler 300.

The directional coupler 300 according to the third embodiment differs from the directional coupler 100 according to the first embodiment in a partial configuration. Specifically, in the directional coupler 100, the resonant circuit 20 is connected between the connection point between the first sub line S1 and the phase conversion unit (low pass filter 10), and the ground terminals T5 and T6. In the directional coupler 300, the resonant circuit 20 is connected between a connection point between the phase conversion unit (low pass filter 10) and the second sub line S2, and the ground terminals T5 and T6. Except for the above, the configuration of the directional coupler 300 is the same as that of the directional coupler 100.

In the directional coupler 300 as well, the provision of the resonant circuit 20 makes the coupling characteristic even flatter.

Fourth Embodiment

FIG. 8 illustrates a directional coupler 400 according to a fourth embodiment of the present disclosure. However, FIG. 8 is an equivalent circuit diagram of the directional coupler 400.

The directional coupler 400 according to the fourth embodiment differs from the directional coupler 100 according to the first embodiment in a partial configuration. Specifically, in the directional coupler 100, the resonant circuit 20 is connected between the connection point between the first sub line S1 and the phase conversion unit (low pass filter 10), and the ground terminals T5 and T6. In the directional coupler 400, the resonant circuit 20 is connected between a connection point between the second sub line S2 and the termination terminal T4, and the ground terminals T5 and T6. Except for the above, the configuration of the directional coupler 400 is the same as that of the directional coupler 100.

In the directional coupler 400 as well, the provision of the resonant circuit 20 makes the coupling characteristic even flatter.

Fifth Embodiment

FIG. 9 illustrates a directional coupler 500 according to a fifth embodiment of the present disclosure. However, FIG. 9 illustrates the directional coupler 500.

The directional coupler 500 according to the fifth embodiment differs from the directional coupler 100 according to the first embodiment in a partial configuration. Specifically, as illustrated in FIG. 3, in the directional coupler 100, the coupler section including the main line M and the plurality of sub lines (first sub line S1, second sub line S2) is disposed in the lower portion 8 of the multilayer body 1, and the phase conversion unit (low pass filter 10) and the resonant circuit 20 are disposed in the upper portion 9 of the multilayer body 1. In the directional coupler 500, a first portion 58, which is the coupler section including the main line M and the plurality of sub lines (first sub line S1, second sub line S2), is disposed laterally next to a second portion 59, which includes the phase conversion unit (low pass filter 10) and the resonant circuit 20, in a multilayer body 51.

The directional coupler 500 is lower in profile than the directional coupler 100.

The directional couplers 100, 200, 300, 400, and 500 according to the first to fifth embodiments have been described above. However, the present disclosure is not limited to these descriptions, and various modifications can be made in accordance with the gist of the disclosure.

For example, although, in the directional couplers 100, 200, 300, 400, and 500, the low pass filter 10 is included as a phase conversion unit, the phase conversion unit is not limited to a low pass filter. For example, in place of the low pass filter, an open stub provided between a sub line and a ground may serve as a phase conversion unit.

A directional coupler according to an embodiment of the present disclosure is as described in the “Solution to Problem” section.

In this directional coupler, the phase conversion unit can be a low pass filter. Furthermore, the low pass filter can be a π-type filter. In this case, a good phase shift can be caused to be produced in a signal passing through the sub line.

Furthermore, the resonant circuit can be connected between a connection point between the first sub line and the phase conversion unit, and the ground terminal. Alternatively, the resonant circuit can be connected between a connection point between the coupling terminal and the first sub line, and the ground terminal. Alternatively, the resonant circuit can be connected between a connection point between the phase conversion unit and the second sub line, and the ground terminal. Alternatively, the resonant circuit can be connected between a connection point between the second sub line and the termination terminal, and the ground terminal. In these cases, the coupling characteristic can be made even flatter by the resonant circuit.

Furthermore, there can be included a multilayer body including a plurality of insulator layers that are laminated, a ground electrode provided on an insulator layer, a line electrode provided on an insulator layer, a capacitor electrode provided on an insulator layer, and a resistor provided on an insulator layer. In this case, the directional coupler according to the present disclosure can be readily constructed.

Furthermore, the input terminal, the output terminal, the coupling terminal, the termination terminal, and the ground terminal can be provided on one surface of the multilayer body, a coupler section including the main line and the sub line can be mostly disposed in a one-side portion in a lamination direction of the multilayer body, and the phase conversion unit and the resonant circuit can be mostly disposed in an other-side portion in the lamination direction of the multilayer body. In this case, electronic components can be efficiently disposed within the multilayer body. Furthermore, in this case, the ground electrode can be provided in an interlayer space of the multilayer body, which is a space between the one-side portion in the lamination direction of the multilayer body and the other-side portion in the lamination direction of the multilayer body. In this case, interference between the coupler section, and the phase conversion unit and the resonant circuit can be suppressed by the ground electrode.

Alternatively, the input terminal, the output terminal, the coupling terminal, the termination terminal, and the ground terminal can be provided on one surface of the multilayer body, and a coupler section including the main line and the sub line can be disposed laterally next to the phase conversion unit and the resonant circuit in the multilayer body. In this case, the directional coupler can be reduced in profile.

REFERENCE SIGNS LIST

• • 1 multilayer body
  • 1 a to 1t insulator layer
  • 2 a to 2al via electrode
  • 3 a to 3d ground electrode
  • 4 a to 4d relay electrode
  • 5 a to 5p line electrode
  • 6 a to 6i capacitor electrode
  • 7 resistor
  • 10 low pass filter (phase conversion unit)
  • 20 resonant circuit
  • T1 input terminal
  • T2 output terminal
  • T3 coupling terminal
  • T4 termination terminal
  • T5, T6 ground terminal (ground)
  • M main line
  • S1 first sub line
  • S2 second sub line

Claims

1. A directional coupler comprising: an input terminal;an output terminal;a coupling terminal;a termination terminal;a ground terminal;a main line connected between the input terminal and the output terminal; anda sub line connected between the coupling terminal and the termination terminal,wherein the main line and the sub line are electromagnetically coupled to each other,wherein the sub line comprises a first sub line and a second sub line that are connected to each other,wherein a phase conversion circuit is connected between the first sub line and the second sub line,wherein a resonant circuit is connected between the ground terminal and a point between the coupling terminal and the termination terminal, andwherein the resonant circuit comprises an inductor, a capacitor, and a resistor connected in series.

2. The directional coupler according to claim 1, wherein the phase conversion circuit is a low pass filter.

3. The directional coupler according to claim 2, wherein the low pass filter is a π-type filter.

4. The directional coupler according to claim 1, wherein the resonant circuit is connected between the ground terminal and a connection point between the first sub line and the phase conversion circuit.

5. The directional coupler according to claim 1, wherein the resonant circuit is connected between the ground terminal and a connection point between the coupling terminal and the first sub line.

6. The directional coupler according to claim 1, wherein the resonant circuit is connected between the ground terminal and a connection point between the phase conversion circuit and the second sub line.

7. The directional coupler according to claim 2, wherein the resonant circuit is connected between the ground terminal and a connection point between the phase conversion circuit and the second sub line.

8. The directional coupler according to claim 3, wherein the resonant circuit is connected between the ground terminal and a connection point between the phase conversion circuit and the second sub line.

9. The directional coupler according to claim 1, wherein the resonant circuit is connected between the ground terminal and a connection point between the second sub line and the termination terminal.

10. The directional coupler according to claim 1, further comprising: a multilayer body comprising a plurality of insulator layers that are laminated;a ground electrode on the laminated insulator layers;a line electrode on the laminated insulator layers;a capacitor electrode on the laminated insulator layers; anda resistor on the laminated insulator layers.

11. The directional coupler according to claim 10, wherein the input terminal, the output terminal, the coupling terminal, the termination terminal, and the ground terminal are on one surface of the multilayer body,wherein more than half of a coupler section including the main line and the sub line is disposed in a first half portion of the multilayer body in a lamination direction, andwherein the phase conversion circuit and the resonant circuit are more than half disposed in a second half portion of the multilayer body in the lamination direction, the first half portion and the second half portion being in different halves of the multilayer body.

12. The directional coupler according to claim 11, wherein the ground electrode is between the first half portion of the multilayer body and the second half portion of the multilayer body.

13. The directional coupler according to claim 10, wherein the input terminal, the output terminal, the coupling terminal, the termination terminal, and the ground terminal are on one surface of the multilayer body, andwherein a coupler section comprising the main line and the sub line is laterally next to the phase conversion circuit and the resonant circuit in the multilayer body.