JP4069431B2 - Multilayer directional coupler - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a directional coupler used for microwave communication equipment and the like.
[0002]
[Prior art]
A conventional directional coupler using a plurality of strip lines is shown in FIG. This conventional example shows a case of the same plane type in which the main line and the sub line are produced on the same substrate. In this case, two strip lines 53 and 54 are arranged in parallel at a distance S on the surface of a dielectric substrate 51 having a planar ground conductor 52 formed on the back surface. The parallel lengths of the strip lines 53 and 54 are configured to be a quarter wavelength of the wavelength of the electromagnetic wave propagating in the dielectric substrate.
[0003]
The high frequency power input from the port P1 passes through the strip line 53, which is the main line, and is output to the port P2. At this time, due to the coupling of the strip line 53 as the main line and the strip line 54 as the sub line, a part of the electric power passing through the strip line 53 flows to the strip line 54 and is output to the port P3. At this time, no output appears at the port P4. Next, when power flows in the opposite direction of the strip line 53 as the main line, that is, from the port P2 toward the port P1, a part of the power appears at the port P4 and does not appear at the port P3. In other words, by adopting such a configuration, a part of the forward power and the reverse power flowing through the strip line 53 of the main line are separated and taken out to the output ports P3 and P4 terminals of the strip line 54 of the sub line, respectively. be able to. This is the basic operation of the directional coupler.
[0004]
The coupling from the main line 53 to the sub line 54 is possible by adjusting the interval S between the parallel portions of the two strip lines.
In the description of the conventional example of FIG. 4, the main line and the sub line are the strip lines 53 and 54. However, as apparent from the symmetrical structure of FIG. In addition, the basic operation of the directional coupler can be realized.
[0005]
Thus, the directional coupler having a function of separating a part of the high-frequency power with directivity is used for controlling the transmission power of a transmitter of, for example, a cellular phone in microwave communication. FIG. 5 shows a block diagram of the application example. The ports P1 and P2 of the main line 72 of the directional coupler 71 are arranged between the transmission power amplifier and the antenna 74, and one port P3 of the sub line 73 is connected to the automatic gain control circuit and connected to the other port P4. A resistance element 75 that absorbs power is connected. In this way, only a part of the output of the transmission power amplifier appears at the port P3 and is led to the automatic gain control circuit. Part of the high-frequency power flowing backward from the antenna 74 appears at the port P4 and is absorbed by the resistance element 75. The signal output of the automatic gain control circuit is sent to a transmission power amplifier capable of gain control, and high frequency output can be controlled according to the purpose.
[0006]
Japanese Patent Application Laid-Open No. 7-131211 discloses an example in which this directional coupler has a laminated structure. This shows a laminated directional coupler having a structure in which two strip lines wound one or more times are sandwiched between two ground conductors.
[0007]
[Problems to be solved by the invention]
However, miniaturization is an important issue for mobile phones and other devices that have made remarkable progress in the field of microwave communications. In addition to the miniaturization of single elements, multiple functions are combined into one element. Is now required.
In view of the above, an object of the present invention is to provide a laminated directional coupler with a built-in low-pass filter function, and to reduce the size of the laminated directional coupler with a built-in low-pass filter function. And
[0008]
[Means for Solving the Problems]
The present invention is a laminated type directivity having a low-pass filter function in which a coil electrode forming a main line and a coil electrode forming a sub line are formed in different dielectric layers and a grounding capacitor is connected to both ends of the main line. A coupler, wherein at least the main line is a coil in which coil electrodes formed on a plurality of dielectric layers are connected by through holes and wound one or more times, and the first ground electrode and the second ground electrode The main line and the sub line are arranged opposite to each other in a region sandwiched between the first and second capacitance forming electrodes, and a region sandwiched between the second ground electrode and the third ground electrode. The first capacitor forming electrode and the second capacitor forming electrode are formed in different dielectric layers and overlapped in the stacking direction, and are connected in parallel with the main line. Condensate To the formation of the a multilayer directional coupler according to claim.
[0009]
In the present invention, the length of the main line and the sub line is set to 1/15 wavelength to 1/8 wavelength .
[0010]
In the present invention, the sub-line has a coil structure wound one or more times.
[0011]
According to the present invention, the sub-line has a coil structure wound less than once.
[0012]
In the present invention, the capacitance forming electrode has a structure facing one side of the ground electrode and the other surface facing another capacitance forming electrode.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the main line and the sub line are formed in a region sandwiched between the first and second ground electrodes to constitute a directional coupler. A capacitance forming electrode is formed in a region sandwiched between the second earth electrode and the third earth electrode, and a capacitor constituted thereby is connected to the main line to constitute a low-pass filter. In other words, by using the main line as the main line of the directional coupler and also as the L element of the low-pass filter, the directional coupler and the low-pass filter are integrated, the number of elements is reduced, and the size is reduced. To achieve.
[0014]
In the structure of the present invention, the main line has a coil structure in which the main line is wound at least once, and the sub line has a coil structure in which the main line is wound at least once or less than once, and the respective winding portions overlap each other. The structure is used. This makes it possible to configure the main line and the sub-line having a length of 1/4 wavelength conventionally by the main line and the sub-line whose length is shortened to about 1/8 to 1/15 wavelength. , Can achieve miniaturization. In other words, in the conventional directional coupler, the main line and the sub-line are coupled with the lines facing each other for a certain length at a predetermined interval. However, in the present invention, the main line and the sub-line are coiled. And are coupled by magnetic coupling by the coil. In other words, the present invention is a structure in which the coils are opposed to each other rather than the lines being opposed to each other at a predetermined interval.
[0015]
In the present invention, a laminated structure of laminated directional couplers is used, and a capacitance forming electrode layer is provided between one earth electrode and the third earth electrode constituting the laminated directional coupler. It is arranged. This capacitance forming electrode layer can be composed of two electrode layers. Each of the electrode layers is opposed to the ground electrode, and each electrode layer is partially opposed.
[0016]
Thereby, the structure which connects a capacitor | condenser to the both ends of the main line of a coil structure is attained. The main line of this coil structure can be seen as an L element, and a capacitor connected to the ground is connected to both ends of the L element to constitute a so-called π-type low-pass filter. Further, a capacitor is connected between both ends of the L element. That is, the coiled main line has the role of the main line of the directional coupler and the role of the L element of the low-pass filter, and can be easily combined and reduced in size.
[0017]
According to this structure, it is possible to obtain an arbitrary degree of coupling by changing the cross-sectional area of the coil to be wound and the interval between the main line and the sub line and by making the number of turns of the sub line less than one. Further, by changing the cross-sectional area of the coil to be wound, the size of the capacitance forming electrode, and the distance from the ground electrode, it is possible to easily cope with systems of various frequencies.
[0018]
In addition, by separating the main line, the sub line portion and the capacitance forming electrode portion with the second ground electrode, unnecessary stray capacitance and interference that hinder the directionality can be eliminated, and a directional coupler with excellent characteristics can be obtained. Obtainable.
[0019]
Thus, according to the present invention, a laminated directional coupler with a low-pass filter function can be configured with a very simple structure. Further, by combining the components, it is possible to reduce the number of steps for mounting the components, and it is possible to suppress variation in characteristics due to variation among components.
[0020]
【Example】
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an internal pattern structure diagram of one embodiment according to the present invention. FIG. 2 is a perspective view of a laminated directional coupler 1 according to an embodiment of the present invention.
[0021]
A laminated directional coupler 1 according to an embodiment of the present invention includes a first earth electrode dielectric layer 2, dielectric layers 3 and 4 on which main line coil electrodes are formed, and a sub line. Dielectric layers 5 and 6 on which coil electrodes are formed, second earth electrode dielectric layer 7, dielectric layers 10 and 11 on which capacitance forming electrodes are formed, and third earth electrode dielectric layer 9 and a protective dielectric layer 8 are laminated. For each of these dielectric layers, a ceramic green sheet for low-temperature sintering is used.
[0022]
The dielectric layer 2 is formed with a first ground electrode 2a on one surface of the ceramic green sheet, leaving a little edge. Two protrusions are provided at the center end of the ground electrode 2a and connected to the two external electrodes 2b on the side surface.
The main line dielectric layer 3 has a stripline electrode 3a formed on one surface of a ceramic green sheet. One end of the strip line electrode 3a is connected to the external electrode 3b, and a through hole 12 is formed at the other end.
Another main line dielectric layer 4 has a stripline electrode 4a formed on one surface of a ceramic green sheet. One end of the stripline electrode 4a is connected to the external electrode 4b, and the other end is connected to the through hole 12 of the dielectric layer 3. As a result, a coil of about two turns is formed and used as the main line.
[0023]
The sub-line dielectric layers 5 and 6 have the same configuration as that of the main-line dielectric layers 3 and 4, and the stripline electrodes 5 a and 6 a are connected through the through-hole 12, and the coil has about two turns. It becomes the composition of. And it is connected to the external electrodes 5b and 6b on the side surfaces, respectively.
The dielectric layer 7 has the same configuration as that of the dielectric layer 2, and a second ground electrode 7a is formed on one surface of the ceramic green sheet, leaving a little edge. Then, it is connected to the two external electrodes 2b on the side surface.
The first ground electrode 2a and the second ground electrode 7a realize a shielding effect that prevents high-frequency power of the main line and the sub-line from leaking to the outside.
[0024]
A capacitor forming electrode 10 a is formed on the capacitor forming dielectric layer 10. One end of the capacitance forming electrode 10a is connected to the external electrode 4b. The external terminal 4b is connected to the end of the main line. Similarly, a capacitor forming electrode 11 a is formed on the capacitor forming dielectric layer 11. One end of the capacitance forming electrode 11a is connected to the external electrode 3b. The external terminal 3b is connected to the end of the main line. Further, the capacitance forming electrodes 10a and 11a are formed so that parts thereof are opposed to each other.
[0025]
The dielectric layer 9 is provided with a third earth electrode 9a. This is the same as the first and second ground electrodes.
A protective dielectric layer 8 is provided as the uppermost layer.
[0026]
The dielectric layers are stacked after predetermined electrodes are formed by a printing technique, and are baked and integrated at a temperature of about 900 ° C. As a result, the directional coupler 1 shown in FIG. 2 is completed. The external electrodes 2b, 3b, 4b, 5b, and 6b on the side surfaces were formed by printing and baking after firing a laminate of green sheets.
The ceramic green sheet of this example is a dielectric material having a relative dielectric constant εr of about 8 and can be fired at 900 ° C. The outer dimensions of a laminated directional coupler with a low-pass filter function completed by monolithic firing after lamination. Was 3.2 × 1.6 × 1.0 t (mm). The electrode was formed by screen printing using an Ag paste.
[0027]
An equivalent circuit diagram of this embodiment is shown in FIG. The main line connecting the strip line electrodes 3a and 4a is indicated by L1, and the sub line connecting the strip line electrodes 5a and 6a is indicated by L2. Further, the capacitor forming electrode 10a and the second ground electrode 7a form the capacitor C2, the capacitor forming electrode 11a and the third earth electrode 9a form the capacitor C1, and the capacitor forming electrode 10a and the capacitor forming. A capacitor C3 is constituted by the electrode 11a. The main line L1 and the sub line L2 are combined to form a directional coupler, and L1, C1, C2, and C3 form a low-pass filter. That is, L1 is the main line of the directional coupler and the L element of the low-pass filter, and plays two roles.
[0028]
Example 1
In the above embodiment, the cross-sectional area of the coil constituting the main line and the sub line (area of the inner peripheral portion of the annular portion of the coil) is 1.26 mm ² , and the distance between the main line 4a and the sub line 5a is 200 μm. In addition, the area of the capacitance forming electrodes 10a and 11a was 1.7 mm ² and the distance between the capacitance forming electrodes 10a and 11a and the ground electrodes 7a and 9a was 50 μm to obtain a stacked directional coupler.
The coupling characteristics of Example 1 are shown in FIG. 7, and the isolation characteristics are shown in FIG. As shown in FIGS. 7 and 8, in Example 1, a coupling degree of 14 dB and an isolation of 24 dB are obtained at 900 MHz. FIG. 9 shows the pass characteristics. At 900 MHz (f ₀ ), the insertion loss is 0.5 dB, the second harmonic (2f ₀ : 1800 MHz), and the third harmonic (3f ₀ : 2700 MHz) attenuation is also 30 dB, which has a good low-pass filter characteristic. As described above, Example 1 has excellent characteristics as a directional coupler having a low-pass filter function.
[0029]
Example 2
The lamination pattern diagram of Example 2 is shown in FIG. The second embodiment is substantially the same as the internal structure of the first embodiment (FIG. 1), and the pattern shape is changed. A first ground electrode 15a is formed on the dielectric layer 15, a second ground electrode 20a is formed on the dielectric layer 20, a third ground electrode 23a is formed on the dielectric layer 23, and the line electrodes 16a of the dielectric layers 16 and 17 are formed. 17a is connected through the through hole 12 to form a coil of about two turns, a main line is formed, and the line electrodes 18a and 19a of the dielectric layers 18 and 19 are connected through the through hole 12 to be about twice The coil of winding is comprised and the subline is comprised. Capacitance forming electrodes 21 a and 22 a are formed on the dielectric layers 21 and 22. The circuit structure and the external terminal structure are the same as in the first embodiment.
[0030]
In the second embodiment, the cross-sectional area of the coil constituting the main line and the sub line (the area of the inner peripheral portion of the annular portion of the coil) is 0.36 mm ² , and the distance between the main line 17a and the sub line 18a is A laminated directional coupler was obtained by setting the area of the capacitance forming electrodes 21a and 22a to 1.2 mm ² and the distance between the capacitance forming electrodes 21a and 22a and the ground electrodes 20a and 23a to 100 μm. The outer dimension is 3.2 × 1.6 × 1.0 t (mm), and a dielectric material having a relative dielectric constant εr of about 8 and capable of being fired at 900 ° C. is used. Moreover, Ag was used for the electrode material.
[0031]
The coupling characteristics of Example 2 are shown in FIG. 10, and the isolation characteristics are shown in FIG. As shown in FIGS. 10 and 11, in Example 2, the coupling degree of 15 dB and the isolation of 26 dB are obtained at 1700 MHz. FIG. 12 shows the pass characteristics. At 1700 MHz (f ₀ ), the insertion loss is 0.5 dB, the second harmonic (2f ₀ : 3400 MHz), and the third harmonic (3f ₀ : 5100 MHz) attenuation is also 30 dB or more, which has a good low-pass filter characteristic. Thus, Example 2 also has excellent characteristics as a directional coupler having a low-pass filter function.
[0032]
Example 3
A lamination pattern diagram of Example 3 is shown in FIG. In this third embodiment, the number of turns of the sub-line is less than one in the internal structure of the first embodiment. A first ground electrode 26 a is formed on the dielectric layer 26, a second ground electrode 30 a is formed on the dielectric layer 30, and a third ground electrode 33 a is formed on the dielectric layer 33. The line electrodes 27a and 28a of the dielectric layers 27 and 28 are connected by the through hole 12, constitute a coil of about two turns, and constitute a main line. The line electrode 29a of the dielectric layer 29 constitutes a coil having about 0.7 turns and constitutes a sub line. Capacitance forming electrodes 31 a and 32 a are formed on the dielectric layers 31 and 32. The circuit structure and the external terminal structure are the same as in the first embodiment.
[0033]
In the third embodiment, the cross-sectional area of the coil constituting the main line is 1.26 mm ² as in the first embodiment, the distance between the main line 28a and the sub-line 29a is 250 μm, and the capacitance forming electrodes 31a and 32a A laminated directional coupler was obtained with an area of 1.7 mm ² and an interval between the capacitance forming electrodes 31a and 32a and the ground electrodes 30a and 33a of 50 μm.
FIG. 14 shows the coupling characteristics of Example 3, and FIG. 15 shows the isolation characteristics. As shown in FIGS. 14 and 15, in this example, a coupling degree of 20 dB and an isolation of 35 dB are obtained at 900 MHz. FIG. 16 shows the pass characteristics. At 900 MHz (f ₀ ), the insertion loss is 0.3 dB, the second harmonic (2f ₀ : 1800 MHz), and the third harmonic (3f ₀ : 2700 MHz) attenuation is also 30 dB, which has a good low-pass filter characteristic. Thus, Example 3 also has excellent characteristics as a directional coupler having a low-pass filter function.
[0034]
According to the embodiment of the present invention, a stacked directional coupler having a low-pass filter function can be configured in a very small size. In addition, by sharing the main line of the directional coupler and the L element of the low-pass filter, the internal structure can be simplified, the combination can be facilitated, and the size can be reduced.
[0035]
【The invention's effect】
According to the present invention, a directional coupler having a low-pass filter function can be achieved with a simple structure, and a stacked directional coupler having a very small and high-performance low-pass filter function can be obtained. .
[Brief description of the drawings]
FIG. 1 is an internal pattern structure diagram of an embodiment according to the present invention.
FIG. 2 is a perspective view of an embodiment according to the present invention.
FIG. 3 is an equivalent circuit diagram of an embodiment according to the present invention.
FIG. 4 is a perspective view of the prior art.
FIG. 5 is a circuit block diagram of a usage example of a directional coupler.
FIG. 6 is an internal pattern structure diagram of a second embodiment according to the present invention.
FIG. 7 is a graph of coupling characteristics of Example 1 according to the present invention.
FIG. 8 is a graph of isolation characteristics of Example 1 according to the present invention.
FIG. 9 is a graph of pass characteristics of Example 1 according to the present invention.
FIG. 10 is a graph of coupling characteristics of Example 2 according to the present invention.
FIG. 11 is a graph of isolation characteristics of Example 2 according to the present invention.
FIG. 12 is a graph of pass characteristics of Example 2 according to the present invention.
FIG. 13 is an internal pattern structure diagram of Embodiment 3 according to the present invention.
FIG. 14 is a graph of coupling characteristics of Example 3 according to the present invention.
FIG. 15 is a graph showing the isolation characteristics of Example 3 according to the present invention.
FIG. 16 is a graph of pass characteristics of Example 3 according to the present invention.
[Explanation of symbols]
1 Directional coupler 2,7,9,15,20,23,26,30,33 Dielectric layer for earth electrode 3, 4, 5, 6, 16, 17, 18, 19, 27, 28, 29 Dielectric layers 8, 24, 25 Protective dielectric layers 2a, 15a, 26a First ground electrodes 3a, 4a, 5a, 6a, 16a, 17a, 18a, 19a, 27a, 28a, 29a Strip line electrode 2b, 3b, 4b, 5b, 6b External electrodes 7a, 20a, 30a Second ground electrodes 9a, 23a, 33a Third ground electrodes 10a, 11a, 21a, 22a, 31a, 32a Capacitance forming electrodes

Claims (4)

A multilayer directional coupler having a low-pass filter function in which a coil electrode forming a main line and a coil electrode forming a sub line are formed in different dielectric layers and a ground capacitor is connected to both ends of the main line. And
At least the main line is a coil in which coil electrodes formed on a plurality of dielectric layers are connected by through holes and wound one or more times, in a region sandwiched between the first ground electrode and the second ground electrode The main line and the sub line are arranged opposite to each other, and the first capacitance forming electrode and the second capacitance forming electrode are arranged in a region sandwiched between the second earth electrode and the third earth electrode, and the grounding is performed. A capacitor is formed, and the first capacitor-forming electrode and the second capacitor-forming electrode are formed in different dielectric layers and overlap in the stacking direction and are connected in parallel with the main line. A laminated directional coupler characterized by the above. 2. The stacked directional coupler according to claim 1, wherein the main line and the sub line have a length of 1/15 wavelength to 1/8 wavelength .   The laminated directional coupler according to claim 1 or 2, wherein the sub-line has a coil structure wound once or more.   The laminated directional coupler according to claim 1 or 2, wherein the sub-line has a coil structure wound less than once.

Images