JPH1075153A - Branching filter package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the line length of a connection line as much as possible and to reduce insertion loss by arranging the branching point of a line for connecting an antenna and a filter for transmission and the line for connecting the antenna and the filter for reception near the storage part of the filter for the transmission. SOLUTION: The filter 100 for the transmission and the filter 101 for the reception are mounted on a multi-layer board, and the branching point of the line for connecting the antenna and the filter 100 and the line for connecting the antenna and the filter 101 for the reception is arranged near the storage part of the filter 100. Then, reception signals impressed to an ANT terminal, 1 connected to the antenna are supplied from the branching point 19 through a matching circuit 120 for the reception to the filter 101, and outputted through a reception output matching circuit 121 to an Rx terminal 5. On the other hand, transmission signals impressed to a Tx terminal are supplied through a transmission output matching circuit 111 to the filter 100, capable of passing through only a prescribed frequency band and outputted through a matching circuit 110 for the transmission to the ANT terminal 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a duplexer package having a transmitting filter and a receiving filter. In particular, the present invention relates to a duplexer package having a transmission filter and a reception filter mounted on a single substrate and having an impedance matching circuit.

[0002]

2. Description of the Related Art A duplexer used in a portable telephone or the like has a transmission filter and a reception filter. In recent years, there has been a strong demand for miniaturization of duplexers, and therefore, a surface acoustic wave filter (hereinafter, referred to as a SAW filter) has been often used as a filter element. Then, a duplexer package in which a transmission filter and a reception filter are mounted on the same substrate and which are modularized has been proposed. Such a configuration is disclosed in, for example, JP-A-5-167389.

[0003]

In recent years, with higher performance of mobile phones, higher performance has been required for SAW filters and duplexer modules. In particular, it is demanded that insertion loss be kept low. In order to reduce the insertion loss of the duplexer using the SAW filter, it is effective to minimize the line length. That is, an object of the present invention is to provide a duplexer with reduced insertion loss.

[0004]

SUMMARY OF THE INVENTION According to the present invention, the line length of the connection line is made as short as possible so that the input impedance of the SAW filter of the duplexer package is not affected as much as possible by the parasitic impedance between the matching circuit and the SAW filter. Is what you do.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. First, the configuration of the duplexer of the present invention will be described with reference to FIG. That is, an antenna (not shown) is connected to the ANT terminal 1. The reception signal applied to the ANT terminal 1 is supplied from the branch point 19 to the reception filter 101 via the reception matching circuit 120. The receiving filter 101 passes only a predetermined frequency band. Receive filter 101
Through the reception output matching circuit 121
Output to terminal 5. On the other hand, the transmission signal is applied to the Tx end, and is transmitted through the transmission output matching circuit 111 to the transmission filter 1.
00 given. This transmission filter 100 allows only a predetermined frequency band to pass. The signal that has passed through the transmission filter 100 is output to the ANT terminal 1 via the transmission matching circuit 110.

FIG. 2 shows a resonator type S realized by the present invention.
FIG. 3 is a diagram illustrating a configuration of an AW filter. As is clear from the figure, this filter is a five-stage resonator type SAW filter including three series arms and three parallel arms. An equivalent circuit of this configuration will be described with reference to FIG. Each resonance element is represented by a coil and a capacitor.

In FIG. 3, Zin (0) and Zin (0)
(1) has a relationship represented by the following equation (1).

(Equation 1)

That is, from equation (1), it can be seen that Zin (0) becomes infinite under the following conditions regardless of the value of Zin (1). Therefore, the input impedance of the matching circuit and the SAW filter can be obtained only with the resonator type SAW filter.

(Equation 2)

However, when an inductance L having a line length l exists between the matching circuit and the resonator type SAW filter, the input impedance is represented by the following equation (2). That is, due to the presence of L, the resonator type SAW
It can be seen that Zin (0) of the filter becomes negative and Zin decreases. That is, the characteristics of the duplexer deteriorate.

(Equation 3)

It is known that when a resonator-type SAW filter is used with a T-shaped input terminal, the input impedance in the attenuation band increases. Therefore, the line length in this case can be shortened. Therefore, according to the present invention, the line length of the transmission matching circuit is reduced by using the relationship shown in Expression (1), and a duplexer is configured. As a result, an increase in insertion loss when a duplexer is configured can be minimized.

In this case, it is necessary to reduce the parasitic impedance as much as possible. When this parasitic impedance is inductive, the high input impedance of the high-frequency attenuation band of the SAW filter becomes small. That is, in the duplexer shown in FIG. 1, the connection line between the transmission matching circuit and the transmission filter needs to be as short as possible. Also,
It is also necessary to reduce the area of the connection pad.

Hereinafter, the structure of the duplexer package according to the present invention will be described. FIG. 4 is a sectional view of a substrate of the duplexer package according to the present invention. As shown in FIG. 4, the substrate 10 is formed as a multilayer substrate having a three-layer structure. That is, the substrate 10 is a multilayer substrate including the first layer 10a, the second layer 10b, and the third layer 10c. First layer 1
An opening is formed in Oa and the second layer 10b. No opening is formed in the third layer 10c. As a result, two concave portions T and R are formed in the substrate 10. The transmitting SAW filter and the receiving SAW filter are stored in these recesses. The package is formed by covering the cover 20 on the multilayer substrate.

Next, the respective layers constituting the multilayer substrate will be sequentially described. First, FIG. 5 shows a plane of the first layer 10a as viewed from above. As described above, the opening T and the opening R are formed. Further, a terminal A, a terminal B, a terminal C, and a terminal D are arranged. In this embodiment, the terminal is realized as a semicircular depression formed on the side surface of the first layer 10a. In these terminal portions, the side surfaces of the first layer 10a are metallized. The periphery of these terminals is also metallized on the upper and lower surfaces of the layer. This is to ensure more reliable electrical contact with terminals in other layers described later. First layer 10
The upper surface of a is entirely metallized for the purpose of shielding. However, the periphery of each terminal is not metallized to prevent a short circuit. The lower surface of the first layer 10a is
No metallization (except for the metallization of the electrode portion).

Next, FIG. 6 shows a plan view of the second layer 10b as viewed from above. An opening T and an opening R are also formed in the second layer 10b. However, these openings are formed smaller than the openings formed in the first layer 10a. As a result, when a multilayer substrate is formed, the cross section has a stepped shape as shown in the cross-sectional view of FIG. And the second layer 1
Terminals A, B, C, D, E, and F are formed at 0b. These terminals are also realized as semicircular depressions formed on the side surfaces of this layer. In the terminal portion, the side surfaces and the upper and lower surfaces of the layer are also metallized. Thereby, when the first layer 10a and the second layer 10b are laminated, the terminal A formed on the first layer 10a and the second layer 1
The terminal A formed at 0b is electrically conducted. As for the other terminals, the terminals having the same reference numerals are electrically connected to each other.

A through hole 500 is formed in the second layer 10b. The pattern 501 and the pattern 508 are connected to the through hole 500. The pattern 501 is formed so as to reach the edge of the opening T. The pattern 508 is connected to the terminal C.
A pattern 504 and a pattern 507 are further formed on the second layer 10b. The pattern 504 is formed from the terminal A to the edge of the opening R. Also, the pattern 50
7 is formed from the edge of the opening R to the terminal E. The terminal C is connected to the pattern 21 formed on the cover 20 shown in FIG.
Is connected to the terminal A. As a result, the pattern 50
8 and the pattern 504 are connected.

Next, FIG. 7 shows a plan view of the third layer 10c as viewed from above. No opening is formed in the third layer 10c. Therefore, the SAW filter chip is mounted on the third layer 10c. In the third layer 10c,
Terminals B, D, E and F are formed. Further, a pattern 502 is formed. The pattern 502 connects the terminal B and the terminal D. Furthermore, these terminals B and D are connected to the land 505. The land 505 is arranged at a position corresponding to the through hole 500. Then, when the respective layers are stacked, they are electrically connected to the through holes 500.

The multilayer board 10 is formed by laminating these layers. Hereinafter, the correspondence between the laminated substrate 10 and the branching circuit shown in FIG. 1 will be described.

The ANT terminal 1 corresponds to the terminals B to D. That is, the antenna not shown is connected to terminals B to D
Connected to either An appropriate one may be selected according to actual design conditions. Next, the branch point 19 corresponds to the through hole 500. Therefore, the pattern 502 corresponds to the line from the ANT end 1 to the branch point 19. A line from the branch point 19 in FIG. 1 to the transmission filter 100 via the transmission matching circuit 10 corresponds to the pattern 501. The line from the transmission filter 100 to the Tx end 3 corresponds to the pattern 503. Tx end 3 is connected to terminal F
Connected to an external transmission circuit.

On the other hand, the lines from the branch point 19 shown in FIG. 1 to the receiving filter 101 via the receiving matching circuit 120 correspond to the pattern 508, the terminal C, the pattern 21, the terminal A, and the pattern 504. A line from the reception filter to the Rx end 5 via the reception output matching circuit 121 corresponds to the pattern 507. The Rx terminal 5 is connected to an external receiving circuit via a terminal E.

As described above, the transmitting SAW filter is accommodated in the opening T. Then, it is connected to the end of the pattern 501 and the pattern 503 by wire bonding. The receiving SAW filter is accommodated in the opening R. Then, it is connected to the pattern 504 and the end of the pattern 507 by wire bonding. Thus, the duplexer shown in FIG. 1 is configured.

[0021]

As described above, according to the present invention, a duplexer can be constructed without using a transmission matching circuit line. For this reason, insertion loss due to the configuration of the duplexer can be minimized.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a duplexer according to the present invention.

FIG. 2 is a diagram showing a configuration of a resonator type SAW filter.

FIG. 3 is a diagram illustrating an equivalent circuit of the configuration shown in FIG. 2;

FIG. 4 is a cross-sectional view of a multilayer substrate of the duplexer package according to the present invention.

FIG. 5 is a view showing a pattern of a first layer constituting the multilayer substrate.

FIG. 6 is a diagram showing a pattern of a second layer constituting the multilayer substrate.

FIG. 7 is a diagram showing a pattern of a third layer constituting the multilayer substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Multilayer board 20 ... Cover 100 ... SAW filter for transmission 101 ... SAW filter for reception 110 ... Matching circuit for transmission 120 ... Matching circuit for reception 121 ... Matching for reception output circuit

 ────────────────────────────────────────────────── ─── Continued from the front page (72) Inventor Tomokazu Komazaki 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd.

Claims (1)

[Claims] 1. A duplexer package having a transmission filter and a reception filter mounted on a multilayer substrate, wherein the first storage unit stores a transmission filter, and the second storage unit stores a reception filter. A first line connecting the antenna and the transmission filter; and a second line connecting the antenna and the reception filter. A branch point between the first line and the second line , The first
A duplexer package, wherein the duplexer package is disposed near a storage section of the duplexer.