JP2002299127A - Laminated balun transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated balun transformer in which the adjustment of the electromagnetic coupling of a transmission path can be performed easily, and which can be made compact in size. SOLUTION: This laminated balun transformer, where the stack having a dielectric layer and a conductor layer is equipped with a first transmission path, a second transmission path to be electromagnetically coupled with that first transmission path, and a third transmission path, and for the first transmission path, one end is connected to an unbalanced terminal and the other end becomes an open end, and for the second transmission path, one end is grounded and the other end is connected with a first balanced terminal, and for the third transmission path, one end is grounded and the other end is connected with a second balanced terminal, and here the first, second, and third transmission paths are constituted severally by electrically connecting a plurality of conductor layers divided into the plural dielectric layers, and this possesses a first laminating region which is constituted by laminating a plurality of dielectric layers, where a pair of conductor layers constituting the first and second transmission paths and a second laminating region which is constituted by laminating a plurality of dielectric layers where a pair of conductor layers constituting the above first and second transmission paths are made, and is equipped with a grounding electrode which is made of a conductor layer having a spread, between the first laminating region and the second stacking region.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer balun transformer used in a mobile communication device such as a cellular phone, for connecting a balanced circuit and an unbalanced circuit, and also used as an impedance converter. It is.

[0002]

2. Description of the Related Art A balun transformer, which is a balanced-unbalanced conversion element, has an unbalanced terminal in a first transmission line and two balanced terminals in a second and third transmission lines, as shown in FIG. An unbalanced transmission line is connected to an unbalanced terminal, and two balanced transmission lines are respectively connected to two balanced terminals.
Used by connecting two signal lines. Then, the unbalanced signal input from the unbalanced terminal of the first transmission line is converted and output from the two balanced terminals of the second and third transmission lines, and the balanced signal is output based on the phase difference. Or, on the contrary, the balanced signal from the balanced terminal is converted into an unbalanced signal and output from the unbalanced terminal. Japanese Patent Application Laid-Open No. Hei 8-191016 discloses that an equivalent circuit shown in FIG. 4 and two spiral inductors are arranged side by side on a dielectric layer as shown in a laminated view in FIG. A multilayer balun transformer configured to constitute a balanced line is disclosed.

[0003]

In the above conventional example, since the two spiral inductors L2 and L3 constituting the second and third transmission lines are provided in parallel on the same dielectric layer, they are mounted on a circuit board. In this case, there is a problem that the mounting area is large. In addition, when adjusting electrical characteristics such as impedance characteristics, frequency characteristics, and band characteristics, the first transmission line and the second and third transmission lines are changed by changing the thickness of the dielectric layer and the line width of the transmission line. Adjust the electromagnetic coupling of
Since the thickness of the dielectric layer between the first transmission line and the second and third transmission lines is constant, the spiral inductor L1a forming the first transmission line and the spiral inductor forming the second transmission line L2, and between the spiral inductor L1b constituting the first transmission line and the spiral inductor L3 constituting the third transmission line, the only way to adjust each independently is to change the line width. In this method, only a slight adjustment can be performed, and adjustment of the electromagnetic coupling between the first, second, and third transmission lines is not easy. Accordingly, an object of the present invention is to provide a multilayer balun transformer that can easily adjust the electromagnetic coupling of the first, second, and third transmission lines and can reduce the size.

[0004]

According to the present invention, a first transmission line, a second transmission line electromagnetically coupled to the first transmission line, and a third transmission line are formed on a laminate having a dielectric layer and a conductor layer. One end of the first transmission line is connected to the unbalanced terminal and the other end is open; the second transmission line is grounded at one end and connected to the first balanced terminal at the other end; Is a laminated balun transformer having one end grounded and the other end connected to a second balanced terminal, wherein each of the first, second, and third transmission lines is divided into the plurality of dielectric layers. A plurality of dielectric layers in which a pair of conductor layers forming the first and second transmission lines are electrically connected to each other, and A second laminated area formed by laminating a plurality of dielectric layers on each of which a pair of conductor layers forming first and third transmission lines are formed Comprising a, between the first layered region and the second stack region, a laminated balun transformer comprising a ground electrode formed of a conductor layer having a spread. In the present invention, the first balanced terminal and the second balanced terminal
A capacitor electrode formed of a conductive layer having an extension connected to the first balanced terminal,
It is preferable to connect a capacitor constituted by a capacitor electrode formed of a conductor layer having a spread and connected to the second balanced terminal.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 is a perspective view showing the external appearance of a laminated balun transformer.
FIG. 3 is a developed view showing the configuration of each layer of the multilayer body constituting the multilayer balun transformer of FIG. This composite is made of a ceramic dielectric material that can be fired at a low temperature and has a thickness of 10 mm.
A desired electrode pattern is formed by printing a green sheet of μm to 200 μm, a plurality of green sheets having the electrode pattern are laminated, integrated, and fired integrally. The internal structure of the laminate will be described in the order of lamination. First, the lower green sheet 1 has a substantially half-turn line electrode La1 forming a part of the first transmission line and a substantially half-turn line electrode Lb1 forming a part of the second transmission line. The line electrode La1 is provided with a connection portion for connection to the unbalanced terminal In of the laminate, and the line electrode Lb1 is provided with a connection portion for connection to the ground terminal G of the laminate. I have. Next, a line electrode La2 constituting a part of the first transmission line and a line electrode L constituting a part of the second transmission line
b2, a green sheet 2 on which a line electrode La3 forming a part of the first transmission line and a line electrode Lb3 forming a part of the second transmission line are formed, A green sheet 4 on which a line electrode La4 forming a part of the first transmission line and a line electrode Lb4 forming a part of the second transmission line, and a line electrode La5 forming a part of the first transmission line A green sheet 5 on which a first transmission line and a line electrode Lb5 constituting a part of the second transmission line are formed;
A green sheet 6 including a line electrode La6 forming a part of the first transmission line and a line electrode La7 forming a part of the first transmission line. Are sequentially laminated, and the line electrodes formed on the green sheets 1 to 7 are connected appropriately through holes (indicated by black circles in the drawing).
A part L1a of one transmission line and a second transmission line L2 are formed, and a first stacked region is formed by the green sheets 1 to 7. The line electrode Lb6 formed on the green sheet 6 is provided with a connection portion connected to the unbalanced terminal OUT1, and the line electrode La7 formed on the green sheet 7 is provided with a connection portion connected to the connection terminal NC. I have. On the green sheet 7, a ground electrode E1 formed of a conductor layer having a spread is formed. A green sheet 9 on which a line electrode La9 forming a part of the first transmission line and a line electrode Lb9 forming a part of the third transmission line are formed. Line electrodes L that make up the part
a10 and a line electrode Lb10 forming a part of the third transmission line
A green sheet 11 formed with a line electrode La11 forming a part of the first transmission line and a line electrode Lb11 forming a part of the third transmission line. Line electrode La1 that forms part of the transmission line
A green sheet 12 on which a line electrode Lb12 forming a part of the second and third transmission lines is formed, a line electrode La13 forming a part of the first transmission line, and a part of the third transmission line Green sheet 13 on which a line electrode Lb13 is formed, and a line electrode La14 constituting a part of the first transmission line.
And a green sheet 14 on which a line electrode Lb14 forming a part of the third transmission line is formed, and a green sheet 15 on which a line electrode La15 forming a part of the first transmission line are formed, The line electrodes formed on the green sheets 9 to 15 are appropriately connected by through holes (indicated by black circles in the figure) to form a part L1b of the first transmission line and a third transmission line L3. 9 to 15 form a second stacked region. The line electrode La9 formed on the green sheet 9 is provided with a connection portion for connecting to the connection terminal NC of the laminate, and the line electrode Lb9 is connected for connection to the unbalanced terminal OUT2 of the laminate. Part is provided. The line electrode Lb14 formed on the green sheet 14 is provided with a connection portion for connecting to the ground terminal G of the laminate. A part of the first transmission line L1a and L1b are connected by a connection electrode NC to form a first transmission line L1. Here, part L1a, L1b of the first transmission line
Although the connection terminals NC formed on the outer surface of the laminate are used for the connection of the green sheets 9, the green sheets 9 may be provided with through holes and connected to each other.

[0006] A laminated body was formed as described above, and a laminated balun transformer shown as an equivalent circuit in FIG. 1 was obtained. With the above-described configuration, the magnetic coupling between the first transmission line L1a and the second transmission line L2, and the first transmission line L1b and the third transmission line L3 can be reduced by a conventional multilayer balun. And the first transmission line L
1a and the second transmission line L2, and the first transmission line L1b and the third transmission line L3, the line width and length can be changed, and the thickness and material (dielectric constant) of the dielectric layer can be changed. Etc.) can be selected as appropriate, and the respective magnetic coupling and capacitive coupling can be changed, and desired characteristics can be easily obtained.

[0007] Further, a first laminated region in which the first transmission line L1a and the second transmission line L2 are formed, and the first transmission line L1b and the third transmission line L3 are formed. Since the second stacked region is magnetically separated from the second stacked region by the ground electrode E1 formed by a conductor layer having a spread, the two stacked regions do not interfere with each other. Since the first stacked region and the second stacked region are configured to overlap, a mounting area when mounted on a circuit board can be reduced.

When the transmission line of the balun transformer is built in a limited laminated body, the required length of the transmission line cannot be formed, and the second and third transmission lines L2 constituting the turns ratio and the balanced side cannot be formed. , L3 in some cases. Therefore, in the present invention, it is possible to connect a capacitor C1 between the balanced terminals OUT1 and OUT2 to adjust so as to obtain a desired input / output impedance, phase balance, and power balance (Amplitude Balance). And since the said capacitor is built in the laminated body, it can be comprised small.

[0009]

According to the present invention, the electromagnetic coupling of the first, second, and third transmission lines constituting the multilayer balun transformer can be easily adjusted, and the multilayer balun transformer can be reduced in size. Can be provided.

[Brief description of the drawings]

FIG. 1 is an equivalent circuit diagram showing a multilayer balun transformer according to one embodiment of the present invention.

FIG. 2 is an external perspective view showing a laminated balun transformer according to one embodiment of the present invention.

FIG. 3 is a development view showing a laminated structure of the laminated balun transformer according to one embodiment of the present invention.

FIG. 4 is an equivalent circuit diagram showing a conventional laminated balun transformer.

FIG. 5 is a development view showing a laminated structure of a conventional laminated balun transformer.

Claims (2)

[Claims] 1. A first laminated body having a dielectric layer and a conductor layer
A transmission line, a second transmission line electromagnetically coupled to the first transmission line, and a third transmission line, one end of the first transmission line is connected to an unbalanced terminal and the other end is an open end, The second transmission line has one end grounded and the other end connected to the first balanced terminal. The third transmission line has one end grounded and the other end connected to the second balanced terminal.
Wherein the first, second, and third transmission lines electrically connect a plurality of conductor layers divided into the plurality of dielectric layers, respectively. A first laminated region formed by laminating a plurality of dielectric layers each having a pair of conductor layers forming the first and second transmission lines, and a pair of conductors forming the first and third transmission lines. A second laminated region formed by laminating a plurality of dielectric layers each having a layer formed thereon, wherein a conductive layer having a spread is formed between the first laminated region and the second laminated region. A stacked balun transformer, comprising: a ground electrode; 2. A capacitor electrode formed between a first balanced terminal and a second balanced terminal, the capacitor electrode being formed of an expanded conductor layer connected to the first balanced terminal, and the second balanced terminal. 2. The multilayer balun transformer according to claim 1, wherein a capacitor constituted by a capacitor electrode formed of a conductor layer having a spread connected to the terminal is connected.