JP2005184245A - Coupler and high frequency module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coupler that can be downsized and to provide a high frequency module with respect to the coupler for electromagnetically coupling first and second transmission lines and the high frequency module. <P>SOLUTION: The coupler (200) for electromagnetically coupling an unbalanced transmission line and a balanced transmission line includes: a first strip line (151) connected to the unbalanced transmission line; and a second strip line (152) electromagnetically coupled to the first strip line (151) and a constant potential is applied to a midpoint of the second strip line (152). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a coupling device and a high-frequency module, and more particularly to a coupling device and a high-frequency module that electromagnetically couple a first transmission path and a second transmission path.

  2. Description of the Related Art Conventionally, in a mobile phone or a wireless communication device, when an unbalanced transmission line such as an antenna and a balanced transmission line such as a signal processing IC are coupled, a coupling element called a balun element is used for matching. Yes. In recent years, for the purpose of miniaturization, a balun element chip formed by being laminated on a dielectric layer on which a coupling line is formed has been developed (Patent Document 1).

  Such a balun element is mounted and used in a high-frequency module.

  FIG. 16 is a block diagram of a conventional high frequency module.

  The conventional high frequency module 1 includes an unbalanced-balanced conversion circuit 11, a matching circuit 12, a bias adjustment circuit 13, and a signal processing IC.

  The unbalanced-balanced conversion circuit 11 is composed of a balun element or the like, and couples an unbalanced transmission line from the antenna and a balanced transmission line. The balanced transmission line connected to the unbalanced-balanced conversion circuit 11 is connected to the matching circuit 12. The matching circuit 12 matches the impedance of the balanced transmission line with the input impedance of the signal processing IC 14.

  The bias adjustment circuit 13 includes capacitors C11 and C12 connected between the matching circuit and the signal processing IC. The capacitors C11 and C12 are constituted by chip capacitors.

  A bias voltage is supplied from the bias voltage terminals Tbias11 and Tbias12 to the connection point between the signal processing IC 14 and the capacitors C11 and C12. The signal processing IC 14 demodulates the original signal from the signal supplied from the balanced transmission line through the bias adjustment circuit 13.

JP 2002-50910 A

  However, since the conventional balun element chip is surface-mounted on the circuit board and used, a space for surface-mounting the balun element chip on the circuit board is required. For this reason, further miniaturization has been difficult.

  In addition, when a balanced transmission line is connected to a signal processing IC or the like, a bias adjustment circuit or the like is required, and a chip capacitor or the like is required, which increases the surface mounting area and makes it difficult to reduce the size.

  The present invention has been made in view of the above points, and an object thereof is to provide a coupling device and a high-frequency module that can be miniaturized.

  The present invention is a coupling device (200) for electromagnetically coupling an unbalanced transmission line and a balanced transmission line, which is connected to a first stripline (151) connected to the unbalanced transmission line and unbalanced transmission. And a second strip line (152) electromagnetically coupled to the first strip line (151), and a constant potential is applied to an intermediate point of the second strip line (151). .

  The present invention also provides a first capacitance (C2) connected in parallel to the first stripline (151) and a second capacitance (C3) connected in parallel to the second stripline (152). It is characterized by having.

  Further, according to the present invention, the first stripline (151) is formed in the intermediate layer of the laminated substrate (101) in which the substrates (110, 120, 130) of at least three layers or more are laminated, and the second stripline ( 152) is formed in the intermediate layer of the multilayer substrate (101), and is formed on the multilayer substrate (101) above the first strip line (151) and the second strip line (152). A first shield part (121b) that shields the upper portions of the first strip line (151) and the second strip line (152), and the first strip line (151) and the second strip line on the laminated substrate (101). A second sheet is formed below the strip line (152) and shields the lower portions of the first strip line (151) and the second strip line (152). Characterized in that de unit and (132a) provided.

  In addition, the first strip line (151) and the second strip line (152) are formed in the same layer of the multilayer substrate (101).

  Further, the first strip line (151) and the second strip line (152) are formed in different layers of the multilayer substrate (101).

  In the present invention, a high frequency circuit, an unbalanced transmission path, a balanced transmission path, and a coupling device (200) for electromagnetically coupling the unbalanced transmission path and the balanced transmission path are mounted on the circuit board (101). The high-frequency module (100) includes a coupling device (200) connected to the first stripline (151) connected to the unbalanced transmission line and the unbalanced transmission, and the first stripline (151). ) And a second stripline (152) electromagnetically coupled, and a constant potential is applied to an intermediate point of the second stripline (152).

  The above reference numerals are only for reference, and are not intended to limit the description of the scope of claims.

  According to the present invention, the first stripline (151) connected to the unbalanced transmission path and the second stripline (coupled to the unbalanced transmission and electromagnetically coupled to the first stripline (151) ( 152), and applying a constant potential to the intermediate point of the second strip line (151) eliminates the need to apply a constant voltage when connecting the balanced transmission line to an IC or the like. Therefore, the number of chip parts can be reduced. For this reason, it is possible to increase the density and reduce the size of the apparatus.

[First embodiment]
[High-frequency module 100]
1 is a block diagram of the first embodiment of the present invention, FIG. 2 is a perspective view of the first embodiment of the present invention, and FIG. 3 is an exploded perspective view of the first embodiment of the present invention.

The high-frequency module 100 of the present embodiment is, for example, a wireless LAN (local area
network), mounted in a wireless communication system and the like. The high-frequency module 100 has a configuration in which an electronic component 102 that constitutes a high-frequency circuit is mounted on a circuit board 101, and includes an unbalance-balance conversion circuit 103, a matching circuit 104, and a signal processing IC 105.

  The unbalanced-balanced conversion circuit 103 is a circuit for supplying a high-frequency signal from an unbalanced transmission line such as an antenna to the balanced transmission line. The matching circuit 104 is a circuit for impedance matching between the balanced transmission line and the signal processing IC 105. The signal processing IC 105 is an IC for demodulating a transmission signal from a high-frequency signal on a balanced transmission path.

  The circuit board 101 is formed by performing wiring by a silk screen method using a copper (Cu) or silver (Ag) paste on an unfired sheet-like substrate each made of glass epoxy resin or ceramic, and a plurality of the wiring substrates to which the wiring is applied. By laminating the sheets and baking them while applying pressure, the circuit board 101 in which the three substrates of the first substrate 110, the second substrate 120, and the third substrate 130 are laminated is formed.

  On the first substrate 110, an electronic component 102 is mounted and a printed wiring pattern 111 that is connected to each other is formed.

  A printed wiring pattern 121 is formed on the second substrate 120. The third substrate 130 has a printed wiring pattern 131 formed on the upper surface and a printed wiring pattern 132 formed on the lower surface.

  FIG. 4 is a plan view of the printed wiring patterns 111 and 121, and FIG. 5 is a plan view of the printed wiring patterns 131 and 132. 4A shows a printed wiring pattern 111, FIG. 4B shows a printed wiring pattern 121, FIG. 5A shows a printed wiring pattern 131, and FIG. 5B shows a plan view of the printed wiring pattern 132.

  The printed wiring pattern 111 is a pattern for mounting the electronic component 102 and connecting the electronic components 102 to each other. The printed wiring pattern 111 is connected to the other printed wiring patterns 121, 131, and 132 through the via hole 141.

  The printed wiring pattern 121 has a wiring pattern 121a and a ground pattern 121b for shielding the lower wiring through the lower portion of the printed wiring pattern 111. The printed wiring pattern 121 is connected to the other printed wiring patterns 111, 131, and 132 through the via hole 141.

  The wiring pattern 121a performs connection between the via holes 141. Wiring can be performed by crossing the lower part of the printed wiring pattern 111 by the wiring pattern 121a. The ground pattern 121b is connected to the ground, and shields the printed wiring pattern 131 on the arrow Z1 direction side.

  The printed wiring pattern 131 includes a wiring pattern 131a for connecting to the outside, a ground pattern 131b, and a coupling pattern 131c. The wiring pattern 131 a is a wiring pattern that connects the terminal pattern 131 d and the via hole 141. The ground pattern 131b is a pattern that is connected to the ground and shields the wiring pattern.

  The coupling pattern 131c is a pattern in which the first strip line 151 and the second strip line 152 are wired so as to be parallel to each other over a predetermined length, and the signal from the unbalanced transmission line such as an antenna and the antenna is IC. This is a pattern for configuring the balun element unit 200, which is a coupling device for coupling with a balanced transmission line for supplying to the circuit board 101, in the circuit board 101.

  The printed wiring pattern 132 includes a ground pattern 132a and a terminal pattern 132b. The ground pattern 132a is connected to the ground, and shields at least the arrow Z2 direction side of the coupling pattern 131c.

[Balance element 200]
The circuit board 101 includes first to third balun element units 200 that are coupling devices for coupling an unbalanced transmission line such as an antenna and a balanced transmission line for supplying a signal from the antenna to an IC or the like. It is formed over the substrates 110 to 130. The balun element unit 200 constitutes the unbalance-balance conversion circuit 103 shown in FIG.

  FIG. 6 is a perspective view of the balun element unit 200, and FIG. 7 is an equivalent circuit diagram of the balun element unit 200.

  The balun element unit 200 includes a first strip line 151, a second strip line 152, a first shield part 121b, a second shield part 132b, and capacitors C1, C2, and C3.

  The first strip line 151 is formed on the upper surface side of the third substrate 130, that is, on the arrow Z1 direction side, and is connected to the unbalanced transmission path. The second strip line 152 is formed on the lower surface side of the third substrate 130 in parallel with the first strip line 151 at a predetermined interval, and is connected to the balanced transmission line. The first strip line 151 and the second strip line 152 are electromagnetically coupled.

  The first shield portion 123 is provided on the upper surface side of the second substrate 120, that is, the surface on the arrow Z1 direction side, and the upper surface side of the first strip line 151 and the second strip line 152 on the arrow Z1 direction side. Shield. The second shield part 124 is provided on the lower surface side of the third substrate 130, that is, the surface in the direction of the arrow Z2, and the lower surface side of the first strip line 151 and the second strip line 152, that is, the arrow Z2. Shield the direction side.

  The capacitor C <b> 1 is composed of a chip capacitor and is surface-mounted on the printed wiring pattern 111 of the first substrate 110. One end of the capacitor C1 is connected to the unbalanced transmission line, and the other end is connected to one end of the first strip line 151 through the via hole 141.

  The capacitor C <b> 2 is composed of a chip capacitor and is surface-mounted on the printed wiring pattern 111 of the first substrate 110. One end of the capacitor C2 is connected to one end of the first strip line 151 through the via hole 141, and the other end is connected to the other end of the first strip line 151 through the via hole 141.

  Further, the capacitor C3 is formed of a chip capacitor and is surface-mounted on the printed wiring pattern 111 of the first substrate 110. Capacitor C3 has one end connected to one end of second strip line 152 through via hole 141 and the other end connected to the other end of second strip line 152 through via hole 141. The impedance matching of the balun element unit 200 is achieved by these capacitors C1 to C3.

  A via hole 141 is connected to the second strip line 152 at an intermediate position. The via hole 141 is connected to the printed wiring pattern 111 of the first substrate 110 and grounded. Thereby, as shown in FIG. 6, the middle point of the second strip line 152 is set to the ground potential. Therefore, the reference potential of the balanced transmission path can be set to the ground level.

〔effect〕
According to the present embodiment, the first and second strip lines 151 and 152 constituting the balun element unit 200 and the ground patterns 121b and 132a for shielding them are built in the intermediate layer of the circuit board 101. As a result, chip components such as capacitors C1 to C3 can be surface-mounted on the upper portion. Therefore, the size of the projected area can be reduced.

[Modification]
In this embodiment, the middle point of the second strip line 152 is set to the ground potential, but a predetermined bias voltage may be applied.

  FIG. 8 shows an equivalent circuit diagram of a modification of the first embodiment of the present invention.

  In this modification, a bias voltage of a predetermined level is applied from the bias voltage generation circuit 210 to the midpoint P0 of the second stripline 152 constituting the balun element unit 200. The bias voltage generation circuit 210 includes a voltage source 211, a capacitor C11, and a choke coil L, and is mounted on the circuit board 101.

  The voltage source 211 applies a predetermined level of voltage to the second strip line 152. The capacitor C11 is connected between the connection point between the voltage source 211 and the middle point of the second stripline 152 and the ground, and the fluctuation of the bias voltage applied to the middle point P0 of the second stripline 152 is changed. To absorb and stabilize. The choke coil L prevents the high frequency signal from flowing into the voltage source 211.

  The bias voltage generation circuit 210 is not necessarily mounted on the circuit board 101, and may be configured on a board on which the high frequency module 100 is mounted.

  According to this modification, by applying a bias voltage to the middle point P0 of the second strip line 152, it is not necessary to adjust the bias of the balanced transmission path, and it is necessary to apply a bias voltage at the input end of the signal processing IC. Disappear. For this reason, a circuit can be simplified.

[Second Embodiment]
FIG. 9 is a perspective view of the second embodiment of the present invention, and FIG. 10 is an exploded perspective view of the second embodiment of the present invention. In the figure, the same components as those in FIGS. 2 and 3 are denoted by the same reference numerals, and the description thereof is omitted.

  The high frequency module 300 of the present embodiment is different from the first embodiment in the configuration of the circuit board 301. In the circuit board 301 of this embodiment, wiring is applied to an unfired sheet-like substrate made of glass epoxy resin or ceramic by a silk screen method using a copper (Cu) or silver (Ag) paste. A plurality of sheets are stacked and fired while applying pressure, whereby the first substrate 310, the second substrate 320, the third substrate 330, and the fourth substrate 340 are stacked. Yes.

  In this embodiment, the balun element unit 350 is constituted by four substrates, ie, the first substrate 310, the second substrate 320, the third substrate 330, and the fourth substrate 340.

[Balance element 350]
FIG. 11 is a perspective view of the balun element unit 350. In the figure, the same components as those in FIG.

  The balun element unit 350 of the present embodiment is configured such that the first strip line 151 and the second strip line 152 are formed in different layers.

  The first strip line 151 is formed on the surface of the fourth substrate 340 in the arrow Z1 direction. The second strip line 152 is formed on the surface of the third substrate 330 in the arrow Z1 direction.

  The first strip line 151 and the second strip line 152 are shaped and arranged so as to overlap in the directions of the arrows Z1 and Z2, and at a distance d corresponding to the thickness of the third substrate 330, It is formed over a predetermined length along the surface 311. As a result, since the spread in the surface direction of the substrate and in the directions of the arrows X and Y can be reduced, the projection area can be reduced, and thus the size can be reduced.

  In the present embodiment, the first strip line 151 is formed on the surface of the fourth substrate 340 in the direction of arrow Z1, and the second strip line 152 is formed on the surface of the third substrate 330 in the direction of arrow Z1. However, the second strip line 152 is formed on the surface of the fourth substrate 340 in the direction of the arrow Z1, and the first strip line 151 is formed on the surface of the third substrate 330 in the direction of the arrow Z1. Also good.

[Third embodiment]
The capacitors C1, C2, and C3 are not limited to chip capacitors, and may be formed by a printed wiring pattern in the same manner as the balun element unit 200. By forming the chip capacitor with a printed wiring pattern, chip parts can be reduced.

  FIG. 12 is a perspective view of a third embodiment of the present invention, and FIG. 13 is an exploded perspective view of the third embodiment of the present invention. In the figure, the same components as those in FIGS. 2 and 3 are denoted by the same reference numerals, and the description thereof is omitted.

  The high-frequency module 400 of this embodiment is configured such that the capacitors C1 to C3 constituting the balun element unit 401 are formed by a printed wiring pattern of the multilayer circuit board 111.

  FIG. 14 is a perspective view of the balun element portion 401, and FIG. 15 is a cross-sectional view of the balun element portion 401. In the figure, the same components as those in FIG. 4 are denoted by the same reference numerals, and the description thereof is omitted.

  The balun element portion 401 of this embodiment has a configuration in which a first capacitor wiring pattern 411, a second capacitor wiring pattern 412 and a third capacitor wiring pattern 413 are formed on a third substrate. . The first capacitor wiring pattern 411 is formed adjacent to the first strip line 151 and connected in parallel to the first strip line 151. The second capacitor wiring pattern 412 is formed adjacent to the second strip line 152 and connected in parallel to the second strip line 152. The third capacitor wiring pattern 413 is connected to one end of the first strip line 151 and has an unbalanced transmission line connected to the other end.

  The first capacitor wiring pattern 411, the second capacitor wiring 412, and the third capacitor wiring 413 are a ground pattern 121 b formed on the second substrate 120 and a ground pattern formed on the third substrate 130. A capacitor is formed between the capacitor 132a and the capacitor 132a. The capacitor C2 shown in FIG. 6 is configured by the first capacitor wiring pattern 411 and the ground patterns 121b and 132a, and the capacitor C3 shown in FIG. 6 is configured by the second capacitor wiring pattern 412 and the ground patterns 121b and 132a. For example, the third capacitor wiring pattern 413 and the ground patterns 121b and 132a constitute the capacitor C1 shown in FIG.

  According to the present embodiment, since chip capacitors corresponding to the capacitors C1, C2, and C3 can be eliminated, other electronic components can be surface-mounted on the first substrate 110, so that further miniaturization is possible.

  In the configuration of the second embodiment, capacitors C1, C2, and C3 can be formed as printed wiring patterns on the circuit board as in the third embodiment.

It is a block block diagram of 1st Example of this invention. 1 is a perspective view of a first embodiment of the present invention. It is a disassembled perspective view of 1st Example of this invention. 2 is a plan view of printed wiring patterns 111 and 121. FIG. 3 is a plan view of printed wiring patterns 131 and 132. FIG. 3 is a perspective view of a balun element unit 200. FIG. 3 is an equivalent circuit diagram of a balun element unit 200. FIG. It is an equivalent circuit schematic of the modification of 1st Example of this invention. It is a perspective view of 2nd Example of this invention. It is a disassembled perspective view of 2nd Example of this invention. 3 is a perspective view of a balun element unit 330. FIG. It is a perspective view of 3rd Example of this invention. It is a disassembled perspective view of 3rd Example of this invention. 3 is a perspective view of a balun element unit 401. FIG. 3 is a cross-sectional view of a balun element unit 401. FIG. It is a block block diagram of the conventional high frequency module.

Explanation of symbols

100, 300, 400 High-frequency module 101 Circuit board, 102 Electronic component 103 Unbalance-balance conversion circuit, 104 Matching circuit, 105 Signal processing IC
110 1st board | substrate, 120 2nd board | substrate, 130 3rd board | substrate 111, 121, 131, 132 Printed wiring pattern 121a Printed wiring pattern, 121b Grounding pattern 131a Wiring pattern, 131b Grounding pattern, 131c Connection pattern 131d Terminal pattern 132a Ground pattern, 132b Terminal pattern 141 Via hole 151 First strip line, 152 Second strip line 200 Balun element section 210 Bias voltage generation circuit 211 Voltage source 211
301 circuit board 310 first board 320 second board 330 third board 340 fourth board 401 balun element portion 411 first capacitor wiring pattern 412 second capacitor wiring pattern 413 third Capacitor wiring patterns C1, C2, C3, C11 capacitors

Claims (6)

A coupling device for electromagnetically coupling an unbalanced transmission line and a balanced transmission line,
A first stripline connected to the unbalanced transmission line;
A second stripline connected to the unbalanced transmission and electromagnetically coupled to the first stripline;
A coupling device, wherein a constant potential is applied to an intermediate point of the second strip line. A first capacitance connected in parallel to the first stripline;
The coupling device according to claim 1, further comprising a second capacitance connected in parallel to the second stripline. The first strip line is formed in an intermediate layer of a laminated substrate in which at least three or more layers are laminated,
The second strip line is formed in an intermediate layer of the laminated substrate;
A first shield part formed on top of the first stripline and the second stripline on the multilayer substrate and shielding the top of the first stripline and the second stripline;
A second shield part formed on the laminated substrate below the first stripline and the second stripline and shielding the lower part of the first stripline and the second stripline; The coupling device according to claim 1 or 2, wherein 4. The coupling device according to claim 3, wherein the first strip line and the second strip line are formed in the same layer of the multilayer substrate. 4. The coupling device according to claim 3, wherein the first strip line and the second strip line are formed in different layers of the laminated substrate. A high-frequency module comprising a circuit board and a high-frequency circuit, an unbalanced transmission path, a balanced transmission path, and a coupling device that electromagnetically couples the unbalanced transmission path and the balanced transmission path,
The coupling device includes a first strip line connected to the unbalanced transmission line;
A second stripline connected to the unbalanced transmission and electromagnetically coupled to the first stripline;
A high-frequency module, wherein a constant potential is applied to an intermediate point of the second strip line.

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