JPH07245510A - Integrated duplexer - Google Patents

Abstract

(57) [Summary] [Purpose] To reduce the passage loss and make it even smaller. In addition, trimming is facilitated to adjust the characteristics, and the grounding efficiency of the surface acoustic wave filter is improved. [Structure] First and second recesses 14 and 16 are formed in a dielectric substrate 12 that constitutes a stripline resonator 10, and a coupling circuit portion 18 is provided in the first recess. A surface acoustic wave filter chip 20 is mounted on and a hermetic seal 22 is applied. It is preferable to form the first and second recesses on the upper and lower surfaces of the dielectric substrate, respectively, because the size can be further reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a duplexer having an integrated structure in which a stripline dielectric filter and a surface acoustic wave filter are combined. This duplexer is useful as an antenna duplexer in mobile communication devices such as car phones and mobile phones.

[0002]

2. Description of the Related Art In various mobile wireless devices, a simultaneous call for transmission and reception is performed, and therefore, a duplexer that separates a transmission signal and a reception signal having different frequencies and shares an antenna is used. This type of duplexer has a configuration in which a transmission filter and a reception filter are connected to a common antenna terminal, and a duplexer in which various filters are combined has been proposed. One of them is a structure in which a surface acoustic wave filter is used as a transmission filter and a coaxial dielectric filter is used as a reception filter (for example, JP-A-2-211701).

This duplexer has a structure in which a surface acoustic wave filter for transmission, a coaxial dielectric filter for reception, and a coupling circuit for realizing a demultiplexing function are provided on a substrate made of alumina or the like. is there. The surface acoustic wave filter has a package structure in which a filter chip is mounted on a base having external terminals, bonded, and covered with a lid, like an IC or the like, and is mounted on the substrate as it is. This structure is suitable for downsizing of the duplexer because the surface acoustic wave filter is smaller than the dielectric filter even if it is housed in the case when compared with the shape of the filter alone.

[0004]

However, in the above construction, the surface acoustic wave filter housed in the case is used as it is, and the substrate requires the dimensions of the conductor pattern and the like for connecting it. Even if the surface acoustic wave filter itself is small, there is a limit to downsizing the duplexer. Further, since the case (package) is interposed, the surface efficiency of the surface acoustic wave filter is poor, and since there are many connecting portions of the conductor patterns, there is a problem that impedance mismatching causes an increase in passage loss.

Therefore, it is conceivable to dispose a coupling substrate in the vicinity of the coaxial dielectric resonator and mount a surface acoustic wave filter chip on the coupling substrate. However, even with such a configuration, it becomes necessary to mount the dielectric resonator and the coupling substrate on another substrate such as alumina, which causes a problem of electrical connection between the dielectric resonator and the coupling substrate. This structure does not change much in terms of downsizing compared with the conventional structure.

Recently, there has been proposed a structure in which a concave portion is formed in a part of a dielectric block constituting a coaxial type dielectric resonator and a surface acoustic wave filter is mounted in the concave portion (for example, Japanese Patent Laid-Open No. 5-291804). Gazette). However, in any case, the coaxial dielectric resonator structure has limitations in terms of molding and firing technology. That is, the inner diameter of the resonator hole is limited to about 0.8 mmφ, and if it is less than that, the pin will break during press molding, and molding will be impossible. Therefore, even if the inner diameter is set to 0.8 mmφ, the outer dimension is 2.8 mm to 3.0 mm on each side due to the restriction of the impedance of 50 Ω (if it is smaller than that, the characteristic deteriorates and it is not practical). For example, when a three-stage filter is configured with such a coaxial dielectric resonator,
The length dimension is 2.8 to 3.0 x 3 = 8.4 to 9.0 mm, and the height dimension is 2.8 to 3.0 mm (the width dimension is determined by the resonance frequency), which is smaller than that. It doesn't.

An object of the present invention is to provide a duplexer having a structure which has a small passage loss and can be further downsized.
Another object of the present invention is to provide an integrated duplexer in which the trimming for adjusting the characteristics of the strip line resonator is easy and the surface efficiency of the surface acoustic wave filter is good.

[0008]

According to the present invention, a coupling circuit portion is integrally provided on a dielectric substrate which constitutes a stripline resonator, and a recess is formed in the dielectric substrate, and an elastic member is provided in the recess. An integrated duplexer with a surface wave filter chip mounted and hermetically sealed. Here, it is desirable to form the first and second recesses in the dielectric substrate, provide the coupling circuit portion in the first recess, and mount the surface acoustic wave filter chip in the second recess. In that case, the resonator conductor of the strip line resonator is provided on the dielectric substrate so that a part of the resonator conductor is exposed in the first recess, and the exposed portion serves as a trimming portion for adjusting the characteristics. On the inner surface of the recess for mounting the surface acoustic wave filter chip, the input / output terminals are left in an island shape,
Other than that, almost all metallize to earth.

In particular, the structure in which the first concave portion is formed on one surface of the dielectric substrate to provide the coupling circuit portion and the second concave portion is formed on the opposite surface to mount the surface acoustic wave filter chip. Is preferred. The first concave portion provided with the coupling circuit portion includes not only a structure in which the periphery is completely surrounded, but also a groove, a notch, or the like. The second recess for mounting the surface acoustic wave filter chip preferably has a structure in which the metal flat plate is covered so that the periphery is completely surrounded by the side wall because of the hermetic seal.

[0010]

By using the strip line type structure for the dielectric filter, the dielectric substrate can be shared as the substrate of the coupling circuit section, and by arranging the surface acoustic wave filter chip on the dielectric substrate. , The entire duplexer is integrated, improving ground efficiency and impedance mismatch at the filter connection. In particular, if the coupling circuit section is mounted on one surface and the surface acoustic wave filter chip is mounted on the opposite surface, the size can be further reduced.

A part of the resonator conductor exposed in the first recess serves as a connecting portion of the coupling circuit and a trimming portion for adjusting the characteristics. Therefore, the characteristics can be easily adjusted by trimming this. If the inner surface of the recess for mounting the surface acoustic wave filter chip is almost entirely metalized and grounded, the grounding efficiency of the surface acoustic wave filter becomes good when the surface acoustic wave filter chip is mounted.

[0012]

1 is an explanatory view showing an embodiment of an integrated duplexer according to the present invention, in which A is a top view and B is a side view. In this duplexer, a first concave portion 14 and a second concave portion 16 are formed in a dielectric substrate 12 that constitutes a strip line type resonator 10, and a coupling circuit portion 18 is provided in the first concave portion 14. This is a structure in which the surface acoustic wave filter chip 20 is mounted in the second recess 16 and a hermetic seal 22 is provided. Here, the first recess 14 and the second recess 1
6 and 6 are both formed on the upper surface of the dielectric substrate 12.

In the strip line type resonator 10, a plurality of (two in the embodiment shown in FIG. 1) resonator conductors having a linear strip line structure are arranged in a dielectric substrate 12, and the dielectric substrate 1 is used.
An external electrode is formed on the outer surface of No. 2 by metallization so that one end of each resonator conductor is opened and the other end is short-circuited to form a quarter-wave resonator. The resonator conductor may have a tri-plate structure in which a thin metal plate is punched into a predetermined shape and sandwiched and bonded with a dielectric substrate, but a resonator conductor pattern is printed on a substrate made of a low-temperature sintering material and then bonded and sintered. An integrated structure is preferred. Such an integrated structure
The dielectric green sheet (unsintered sheet) can also be formed by a laminated integration technique.

As described above, the first recess 14 is formed in the dielectric substrate 12 so that one end of the resonator conductor therein is exposed.
To provide. Since it is not necessary to seal the coupling circuit portion, this first recess does not necessarily have to be an enclosed structure in which the entire wall surface is surrounded, and thus may be a groove or notch. A coupling circuit pattern is formed in the first recess 14, and necessary components (such as a coupling coil) are mounted in the first recess 14 to form the coupling circuit section 18. A flat plate-shaped cover 23 is provided on the upper surface of the first concave portion 14 to protect the coupling circuit portion 18.

Further, as described above, the surface acoustic wave filter chip 20 is provided in the second recess 16 formed in the dielectric substrate 12.
Is mounted and the hermetic seal 22 is applied. The surface acoustic wave filter chip 20 is a so-called bare chip without an ordinary metal case. Here, the hermetic seal 22 is made of a flat metal plate. The dielectric substrate 12 having the second recess 16 formed therein is a surface acoustic wave filter chip 20.
Since it is also used as a case, it is not necessary to provide an input / output terminal (a pattern for mounting the surface acoustic wave filter chip 20 and a connection pattern with the coupling circuit pattern) in the second recess 16. Needless to say. Also,
The inner surface of the second concave portion 16 is metallized on almost the entire surface (all side surfaces and bottom surface) while leaving the input / output terminals in an island shape to form a ground. Here, the second recess 16 has a stepped structure in which the center is one step deeper than the periphery, and the surface acoustic wave filter chip 20 is housed in the deepest part and fixed by adhesion or the like. Then, the electrode of the surface acoustic wave filter chip 20 and the input / output terminal of the step portion are electrically connected by wire bonding. Such a technique is a hybrid IC
This is an application of what is used in mounting technology. If there is a step between the mounting pattern and the coupling pattern, the connection pattern is formed using a through hole or the like.

External terminals for each terminal (transmission terminal Tx, reception terminal Sx, antenna terminal ANT) are formed on the side surface of the dielectric substrate 12 at the shortest distance position. For that purpose, the internal connection pattern is drawn to the side surface of the dielectric substrate, and external terminals are formed on the side surface so as to establish electrical connection with the inside.

When the resonator conductor pattern is formed on the dielectric substrate by screen printing, other patterns (coupling circuit pattern, input / output terminals of the surface acoustic wave filter chip, for connecting them to each other and to each terminal) are used. Pattern, ground pattern, etc.) can be formed at the same time. Further, each external terminal can be formed simultaneously with the external electrode formed on the outer surface of the dielectric substrate.

With such a structure, a duplexer having a circuit configuration as shown in FIG. 2 can be obtained. 1 / as a transmission filter
4-wavelength stripline resonator type dielectric filter 30
Is a surface acoustic wave filter 32 used as a reception filter, and a coupling circuit 34 for phase matching is provided between the surface acoustic wave filter 32 and the antenna terminal ANT. One end of the dielectric filter 30 is commonly connected to the antenna terminal ANT, and the other end is a transmission terminal Tx, which is connected to the transmitter side. The other end of the surface acoustic wave filter 32 is a receiving terminal Rx, which is connected to the receiver side.

FIG. 3 is a side view showing another embodiment of the present invention. In this embodiment, the surface acoustic wave filter chip 20 is provided on the surface opposite to the coupling circuit section. The basic configuration is the same as that shown in FIG. A first concave portion 14 is formed on the upper surface of a dielectric substrate 12 that constitutes the strip line resonator 10, a coupling circuit pattern is formed in the first concave portion 14, and the first concave portion 14 is used to form the coupling circuit pattern. A coupling coil or the like is mounted in the recess 14 to form a coupling circuit section 18. A second concave portion 16 is formed on the lower surface of the dielectric substrate 12, the surface acoustic wave filter chip 20 is mounted in the second concave portion 16, and a hermetic seal 22 is provided. In such a configuration,
Upper and lower coupling circuit section 18 and surface acoustic wave filter chip 20
Can be arranged, the area of the dielectric substrate 12 can be reduced, and the duplexer can be further downsized.

[0020]

As described above, according to the present invention, a coupling circuit portion is integrally provided on a dielectric substrate that constitutes a stripline type resonator, and a concave portion is formed to mount a surface acoustic wave filter chip and hermetically sealed. Since it is an integrated structure duplexer, not only can it be made smaller than before,
Since each component is directly connected without a package, the line length is shortened, and the number of connection parts is reduced, so that impedance mismatch is less likely to occur and the passage loss can be reduced. Particularly, in the configuration in which the coupling circuit section and the surface acoustic wave filter chip are arranged above and below the dielectric substrate, further miniaturization is achieved, and the space factor when mounting on the substrate of the communication device is significantly reduced.

When a part of the resonator conductor is exposed in the first recess, trimming for characteristic adjustment can be easily performed at the exposed part. If the inner surface of the recess for mounting the surface acoustic wave filter chip is almost entirely metalized and grounded, the surface efficiency of the surface acoustic wave filter is improved. With these, an integrated duplexer having good characteristics can be obtained.

Since the present invention is basically a strip line type dielectric resonator structure, it can be realized by a laminated integration technique. The dimensions of the resonator conductor are 1mm in width and 30μ in thickness.
Since the line shape is from m to 40 μm, the outer shape is naturally small, and for example, in the case of a three-stage filter, the length is 7.0 mm and the height is 2.0 mm, which can be remarkably downsized. Moreover, the production process is suitable for mass production, and a large number of pieces can be taken, which is effective in reducing the production cost.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of an integrated duplexer according to the present invention.

FIG. 2 is a circuit configuration diagram thereof.

FIG. 3 is an explanatory view showing another embodiment of the integrated duplexer according to the present invention.

[Explanation of symbols]

 10 Stripline Resonator 12 Dielectric Substrate 14 First Recess 16 Second Recess 18 Coupling Circuit 20 Surface Acoustic Wave Filter Chip 22 Hermetic Seal

Front page continuation (72) Inventor Kazuhisa Yamazaki 5-36-11 Shimbashi, Minato-ku, Tokyo Inside Fuji Electric Chemical Co., Ltd.

Claims (5)

[Claims] 1. A dielectric substrate constituting a strip line resonator is integrally provided with a coupling circuit portion, a recess is formed in the dielectric substrate, and a surface acoustic wave filter chip is mounted in the recess. An integrated duplexer featuring a hermetic seal. 2. A dielectric substrate having first and second recesses formed therein, a coupling circuit portion provided in the first recess, and a surface acoustic wave filter chip mounted in the second recess. Body type duplexer. 3. A strip line resonator resonator conductor is provided on a dielectric substrate such that a part of the resonator conductor is exposed in the first recess, and the exposed portion serves as a trimming portion for adjusting characteristics. Item 1. The integrated duplexer according to Item 2. 4. The integrated duplexer according to claim 1, wherein the inner surface of the recess for mounting the surface acoustic wave filter chip is grounded by substantially metallizing almost the entire surface, leaving the input / output terminals in an island shape. 5. A surface acoustic wave filter chip is mounted by forming a first concave portion on one surface of a dielectric substrate to provide a coupling circuit portion and forming a second concave portion on the opposite surface thereof. Item 5. The integrated duplexer according to items 2 to 4.