JP2002164710A - Stacked duplexer - Google Patents

Abstract

(57) [Problem] To provide a duplexer having two or more filters, in which a transmission line and a filter thereof can be reduced in size without interfering with each other and insertion loss can be suppressed. The purpose is to provide a duplexer. SOLUTION: A ground electrode 2 is formed on a main surface of a laminated body 1, one end of which is provided with a plurality of first strip lines 3 connected to the ground electrode 2; And a second filter 60 provided with a plurality of second strip lines 3 connected to the second strip line 3, from the other end of the first strip line to the end face of the laminate 1 facing the end of the first strip line 3. In the area,
This is a configuration in which a matching circuit 7 for matching the first filter 50 and the second filter 60 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a duplexer matching circuit used for microwave communication equipment.

[0002]

2. Description of the Related Art In recent years, with the development of mobile communication, miniaturization of telephones and electronic components used therein has been required. In general, a duplexer is formed as a coaxial type.

The main configuration of such a duplexer is composed of two filters for transmission and reception and a matching circuit for optimizing the impedance of both by utilizing the phase characteristics of the transmission line. -350306.

The transmission line used in such a matching circuit adjusts the transmission line length and the reception side impedance by adjusting the line length so as to make the characteristic impedance close to 50Ω. Specifically, when the phase characteristics of the transmitting and receiving filters are in the state shown in the Smith chart of FIG. 3, matching is obtained by rotating the impedance of the removal area of the receiving filter by about 180 ° on the Smith chart. This aims to prevent mutual interference by making the impedance characteristics of the transmitting and receiving filters contradictory.

[0005]

However, according to the above method, the transmission line as a matching circuit requires a certain length, so that the transmission line needs to be meandered.
In addition, it is necessary to newly provide a block as a matching circuit separately from the filter member so that the transmission line and the filter do not couple and interfere with each other, which hinders miniaturization.

[0006] Not only the problem due to such a shape, but also the insertion loss of the filter characteristics tends to increase due to the loss of the transmission line itself.

The present invention has been devised in view of the above-mentioned problems, and in a duplexer having two or more filters, the transmission line and the filters can be miniaturized without interfering with each other. It is another object of the present invention to provide a laminated duplexer capable of suppressing insertion loss.

[0008]

In order to solve the above-mentioned problems, a laminated type duplexer according to the present invention forms a ground electrode between a main surface or a dielectric layer of a rectangular laminated body in which a plurality of dielectric layers are laminated. A first filter in which a plurality of first strip lines are provided side by side with the ground electrode between the same layers of the laminate and one end of which is connected to the ground electrode; and a laminate in which the first strip lines are formed. And a second filter having a plurality of second strip lines, one end of which is connected to the ground electrode, between the same layers of the second filter, wherein the pass band of the first filter is higher than the pass band of the second filter. In the laminated duplexer that has been set, a region of the laminate from the other end of the first strip line to a side surface of the laminate facing the other end side has a front end. A structure which is disposed a matching circuit for matching the first filter and the second filter.

According to the structure of the present invention, the pass band of the first filter is set to a frequency band higher than the pass band of the second filter of the multilayer duplexer, so that the length of the first strip line is equal to the length of the first filter. 2 When the first and second filters are arranged side by side in a rectangular laminate and shorter than the length of the two strip lines, the laminate facing the end face of the first strip line from the other end region of the first strip line Since the area up to the end face becomes an empty area and a matching circuit can be formed in this empty area, it is possible to reduce the size and to form the LC matching by the strip line itself by meandering and stacking the strip lines. A highly reliable filter with very little change in characteristics due to coupling occurring in the transmission line can be realized.

Further, in the present configuration, the matching circuit has a configuration in which a capacitor is connected in series and an inductor is connected in parallel, so that a smaller, higher-performance, and higher-reliability matching circuit can be realized. Specifically, in a matching circuit formed in the laminate, one of the inductors is connected to one of the ground electrodes, and the other is connected to the center where two capacitors are connected in series to form a T-type circuit, or Similarly, by forming a π-type circuit in which a capacitor is connected in parallel to both the input and output sides of the inductor, one of which is connected to the ground electrode, the phase characteristic of the first filter is changed. The first and second filter phase characteristics can be matched by changing.

Further, when a material having a high dielectric constant is used as the material of the dielectric layer, the area of the capacitor and inductor of the matching circuit is reduced, and the overall size can be reduced.

Further, as the matching circuit, it is preferable to use a capacitor connected in series to the first filter and an inductor connected in parallel to the first filter, since it is simple and allows fine adjustment. .

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a perspective view of a multilayer duplexer A having a matching circuit according to an embodiment of the present invention. FIG. 1B is an enlarged view of the matching circuit. In FIG. 1A, in the multilayer duplexer A, 1 is a dielectric (laminate), 2 is a ground electrode, 3 is a strip line, 4 is an internal wiring terminal, 5 is a transmission filter,
6 is a reception filter, and 7 is a matching circuit.

The laminate 1 is formed by laminating a plurality of rectangular dielectric layers 1a, and is composed of a dielectric ceramic material and an oxide or a low-melting glass material which can be fired at a low temperature. . That is, the dielectric ceramic material is
For example, BaO-TiO ₂ system, Ca-TiO ₂ system, MgO
-TiO _{2 and the} like, and oxides for low-temperature firing include BiVO ₄ , CuO, Li ₂ O, B ₂ O _{3 and the} like. In the present invention, a material having a high dielectric constant is used in order to reduce the area of the capacitor and inductor of the matching circuit. For example, a material having a relative dielectric constant of 15 to 25 is used. In addition,
The dielectric layer 1a has a thickness of about 50 to 300 μm per layer.

The ground electrode 2 comprises a ground electrode 2a formed on the front and back surfaces of the rectangular laminate 1, and a ground electrode 2b formed on the side surface. The material of the ground electrode 2 is mainly composed of Ag, Cu, etc. (Ag alone or Ag-P
d, an Ag alloy such as Ag-Pt, Cu alone or a Cu alloy). Receive filter 6
Denotes a strip line 3 formed on the same dielectric layer 1a.
(30-32) and the strip line 30
32 are connected to the ground electrode 2b to form a 1/4 wavelength strip line. Similarly, in the transmission filter 5, the strip lines 33 to 35 each have the ground electrode 2.
b to form a 1/4 wavelength strip line. The configuration of the strip line 3 includes, for example, a main strip line portion 3 having one end short-circuited to the ground electrode 2b.
0a, via-hole conductor 30b, and folded electrode 30c
Consists of The via-hole conductor 30b is connected to the other end of the main strip line 30a.
a of the upper dielectric layer 1 different from the dielectric layer 1a on which the
a, and the through hole is filled with a conductor. The folded electrode 30c is folded at the end of the via-hole conductor 30b (the side not connected to the main strip line 30a) to the main strip line 30 side. Similarly, strip lines 31 to 35 are also configured, but description thereof is omitted.

The internal wiring terminal 4 includes a receiving terminal 40 facing the leftmost stripline 30 (main stripline portion 30a), and a rightmost stripline 3.
5 (a main strip line section 35a) and a transmitting side terminal 41 and an antenna terminal 42. The electrode part is
It is made of a conductive material containing Ag, Ag-Pd, Cu, or the like as a main component.

As shown in the circuit shown in FIG. 2, the reception filter 6 includes a reception terminal 40, a capacitance component C1 formed by the reception terminal 40 and the main strip line portion 30a, and a capacitance component formed by each of the strip lines 30 to 32. C3, C4, a capacitance electrode 4d described later, and a capacitance component Ci formed by the main strip line portion 32a are connected to each other.

The matching circuit 7 is provided on the side of the reception filter 6 having a higher pass band frequency among the pass bands of the transmission filter 5 and the reception filter 6. The position is formed in an empty area 70 from the other end of the strip lines 30 to 32 of the reception filter 6 to the side surface of the multilayer body 1 facing the other end of the strip line 3. Here, the other end of the strip line 3 means, for example, the strip line 3
In the case where 0 is turned back, it indicates the other end side of the main strip line 30a (the position where the main strip line 30a and the via-hole conductor 30b are connected) at the turning point. When the strip line 3 is not folded back, that is, for example, when the strip line 30 is formed only by the main strip line 30a, it becomes a short-circuit end of the main strip line 30a.

As for the circuit configuration, as shown in FIG. 1B, a capacitor electrode 4b is formed between arbitrary dielectric layers 1a in the empty area 7. In addition, a capacitor electrode 4c is formed between the dielectric layers 1a different from the capacitor electrode 4b and faces the capacitor electrode 4b and is connected to the antenna terminal 42 where the transmission filter 5 and the reception filter 6 are common. . One end is connected to the strip line 32 by a plurality of dielectric layers 1a.
The capacitor electrode 4d and the capacitor electrode 4b that face each other via the gate electrode are connected via the internal wiring 42 to the capacitor electrode 4a that faces via the plurality of dielectric layers 1a. Although the capacitor electrode 4d faces the strip line 32, the present invention is not limited to this, and the capacitor electrode 4d may face another strip line 31. further,
A band-shaped coil portion 400 is formed, one end of which is connected to the capacitance electrode 4b and the other end of which is connected to the ground electrode 2.
The band-shaped coil portion 400 is constituted by bent electrodes 41a to 41c and via holes 42a to 42c, and the coil portion 400 is formed toward the different dielectric layers 1a in the empty area 7.

As shown in FIG. 2, the matching circuit 7 is connected to the capacitance component C2 formed by the capacitance electrodes 4c and 4b connected in series to the antenna terminal 42 of the reception filter 6, and to the strip line 32 on the reception filter 6 side. Facing capacitance electrode 4d
, And a T-type circuit composed of an inductor L1 formed by the coil unit 400. In the present configuration, the impedance characteristic of the reception filter 6 is adjusted by the phase characteristic of the capacitance component Ci formed by the capacitance electrode 4d and the main strip line portion 32a to achieve matching.

FIG. 3 is a Smith chart showing the impedance characteristics of the transmission / reception filter. 3A shows the impedance of the transmission filter, and FIG. 3B shows the impedance of the reception filter. In each figure, the upper half shows the inductive component and the lower half shows the capacitive component with the center line as a boundary.

From this figure, when the impedances of the pass band と and the stop band の of the transmission filter 5 and the reception filter 6 provided in the duplexer A of the present invention have a relationship as shown in the figure, there is a mismatch (mismatch) as it is. As a result, desired insertion loss and attenuation cannot be obtained. Therefore, by adjusting the inductor L1 and the capacitances C0 and C2 of the matching circuit 7, the impedance of the reception filter 5 is converted from the characteristic of the dotted line to the characteristic of the solid line to match the reception filter 5 with the transmission filter 6. Can be.

As described above, the phase characteristics of the transmission / reception filters 5 and 6 are converted and matched using the capacitance components C0 and C2 and the inductor L1 in the duplexer A. Therefore, in order to convert the impedance, generally, the capacitance components C0 and C2 and the inductor L are compared with changing only the inductive component using only the wiring of the coil unit 400.
Using both the change in the capacitive component and the change in the inductive component at the same time using No. 1 can easily convert to a desired impedance characteristic and perform fine adjustment.

Further, according to the first embodiment, the influence of the electromagnetic coupling and the propagation loss of the high frequency due to the wiring of the coil section 400 are extremely small, and the position of the duplexer A Miniaturization is possible.

Next, a second embodiment will be described with reference to FIGS.
Shown in This is such that the folded electrode 32c of the strip line 32 near the antenna terminal 42 of the transmission filter 6 is folded to the opposite side to the main strip line portion 32a, and faces the flat portion 43 of the capacitor electrode 42.

With this configuration, a capacitance component C0 '(not shown) formed by the folded electrode 32c and the capacitance electrode 4b.
In FIG. 2, the capacitance component 4d can be omitted because the capacitance component Ci and the capacitance component C0 of FIG. 2 are used at once, and the matching circuit 7 can be further reduced in size.

Further, the above-described structure is equivalent to the capacitance electrodes 4a to 4a.
Although the LC matching circuit is formed by the coil 4c and the coil unit 400, the present invention is not limited to this, and the matching circuit 7 may be simply formed by the coil unit 400 in the third embodiment.

Next, the fourth embodiment will be described with reference to FIGS.
Shown in In addition to FIG. 4, the folded electrode 30c formed on the strip line 30 of the receiving filter 6 is also folded to the opposite side from the main strip line portion 30a. Further, the capacitance electrode 4b is also formed by being divided into the flat portions 43 and 44 via the connection portion 401 of the coil portion 400. further,
The folded electrode 30c and the flat portion 44 face each other. FIG. 6 shows an equivalent circuit. The multipath capacitance component Cm in FIG. 6 is formed by the reception filter 6 and the matching circuit 7. By the electromagnetic field coupling between the capacitance component Cm and the strip line 30, the attenuation pole x shown in FIG. 8 can be formed.

That is, FIG. 8 shows the filter characteristics of the reception filter 5 in the first to fourth embodiments. The condition is that the laminated duplexer A has a device size of 8 × 4 × 2 mm in which a dielectric layer formed of BiVO ₄ oxide and glass is laminated on a BaO—TiO ₂ dielectric ceramic material. . Assuming that the length of the first strip line (main strip line) is 7.5 mm and the length of the second strip line is 9 mm, the center frequencies in the pass band of the transmission / reception filter are 1.9 GHz and 2.06 G.
Hz.

As shown in the drawing, in the first to third embodiments, only two attenuation poles y and z are formed to form a stop band, but in the fourth embodiment, the reception filter 6 is formed. By adding the capacitance component Cm, another attenuation pole x is formed, and the attenuation of the attenuation pole can be sufficiently secured.

[0031]

According to the configuration of the present invention, since the pass band of the first filter is set to a higher frequency band than the pass band of the second filter of the multilayer duplexer, the length of the first strip line is reduced. Is shorter than the length of the second strip line, and when the first and second filters are arranged and aligned in a rectangular laminate, the end face of the first strip line is opposed to the other end area of the first strip line. The area up to the end face of the laminate becomes an empty area, and a matching circuit can be formed in this empty area. Therefore, the size can be reduced, and the strip line can be meandered and stacked to form an LC matching circuit by the strip line itself. Therefore, it is possible to provide a highly reliable laminated duplexer in which the characteristic change due to the coupling generated in the transmission line is extremely small.

[Brief description of the drawings]

FIG. 1A is a perspective view showing a first embodiment, and FIG. 1B is a partially enlarged view of a matching circuit.

FIG. 2 is an equivalent circuit diagram of a reception filter and a matching circuit of the present invention.

FIG. 3 (a) is an impedance characteristic of a transmission filter,
FIG. 3B is a diagram illustrating impedance characteristics of the reception filter.

FIG. 4A is a perspective view showing a second embodiment, and FIG. 4B is a partially enlarged view of a matching circuit.

FIG. 5A is a perspective view showing a third embodiment, and FIG. 5B is a partially enlarged view of a matching circuit.

FIG. 6 is an equivalent circuit diagram of the third embodiment.

FIG. 7 is a perspective view illustrating characteristics of the fourth embodiment.

FIG. 8 is a diagram showing filter characteristics of the reception filter of the present invention.

[Explanation of symbols]

 1: dielectric 2: earth electrode 3: strip line 4: internal wiring terminal 5: transmission filter 6: reception filter 7: matching circuit

Claims (1)

[Claims] An earth electrode is formed between a main surface or a dielectric layer of a rectangular laminate in which a plurality of dielectric layers are laminated, and the ground electrode faces the ground electrode between the same layers of the laminate.
And a plurality of first terminals each having one end connected to the ground electrode.
A first filter provided with a strip line, and a second filter provided with a plurality of second strip lines, one end of which is connected to the ground electrode, between the same layers of the laminate on which the first strip line is formed. Wherein the passband of the first filter is set to a higher frequency band than the passband of the second filter, wherein the laminate facing the other end from the other end of the first stripline Wherein a matching circuit for matching the first filter and the second filter is disposed in a region of the laminate up to the side surface of the multilayer duplexer.