High frequency composite component

1. Field of the Invention

The present invention relates to a high-frequency composite component, and more particularly, to a high-frequency composite component for use in a plurality of different mobile communication systems.

2. Description of the Related Art

Presently, in Europe, as a mobile communication device, a dual-band portable telephone has been proposed which can operate in a plurality of frequency bands, for example, in the DCS system using a 1.8 GHz band and the GSM system using a 900 MHz band.

FIG. 18 shows a portion of the structure of a general dual-band portable telephone which includes an antenna 1 , a diplexer 2 , and two signal paths of a DCS system 3 (1.8 GHz band) and a GSM system 4 (900 MHz band).

The diplexer 2 selects a transmission signal from the DCS system 3 or the GSM system 4 in transmission and selects a reception signal to the DCS system 3 or the GSM system 4 in reception. The DCS system 3 includes a high-frequency switch 3 a for separating a transmission portion Txd and a reception portion Rxd and a filter 3 b for allowing the fundamental frequency of the DCS system to pass through and for attenuating the second and third harmonics. In the same manner, the GSM system 4 also includes a high-frequency switch 4 a for separating a transmission portion Txg and a reception portion Rxg and a filter 4 b for allowing the fundamental frequency of the GSM system to pass through and for attenuating the third harmonics.

In recent years, a balanced-type (balanced-output type) high-frequency composite component having two signal terminals in the reception portion has been proposed and, in such a balanced type, the impedance matching to a low-noise amplifier (LNA) is required.

In Japanese Unexamined Patent Application Publication No. 2003-142981 (Patent Document 1), as shown in FIG. 19 , an inductor 6 is disposed in parallel between the balanced output terminals Rx of a bandpass filter defined by a balanced-output type surface acoustic wave filter. However, it is difficult to set a desired impedance (complex impedance, in particular). According to the knowledge of the present inventor, in order to lower the impedance, a capacitor must be inserted in series to each of the balanced output terminals, and, to increase the impedance, one more inductor must be inserted in parallel between the balanced output terminals in addition to the above-described capacitors. However, when capacitors and inductors as separate components are added between such a high-frequency composite component and an LNA, the number of components and the mounting area increase which increases the size of the equipment, and the matching between the bandpass filter 5 and the LNA becomes more complicated.

To overcome the problems described above, preferred embodiments of the present invention provide a high-frequency composite component in which a desired impedance is easily set in the high-frequency composite component itself, no matching adjustment to an LNA is required, the number of components is reduced, and the overall size is reduced.

Furthermore, preferred embodiments of the present invention provide a high-frequency composite component in which interference between the elements is prevented, and in which excellent characteristics are achieved.

A high-frequency composite component according to a preferred embodiment of the present invention includes a switch for selectively switching a signal path between an antenna terminal and a transmission-side input terminal and a signal path between the antenna terminal and a reception-side balanced output terminal, an LC filter having an inductor and capacitors disposed between the antenna terminal and the transmission-side input terminal, a surface acoustic wave filter disposed between the switch and the reception-side balanced output terminal, and a matching element having an inductor and capacitors disposed between the surface acoustic wave filter and the reception-side balanced output terminal. In the high-frequency composite component, the switch, the LC filter, the surface acoustic wave filter, and the matching element are integrated in an integrated block having a plurality of laminated dielectric layers.

In the high-frequency composite component according to this preferred embodiment of the present invention, since a matching element having an inductor and capacitors is disposed between a surface acoustic wave filter and a reception-side balanced output terminal, it is possible to freely set the impedance of the reception-side balanced output terminal by an appropriate combination of the inductor and the capacitors. Moreover, since the inductor and the capacitors are integrated in a laminated block with other circuit components, as compared to where the inductor and the capacitors are discretely arranged on a printed-circuit board, the mounting area on the printed-circuit board is reduced, the distance between the surface acoustic wave filter and the matching element is minimized, and the loss between the filter and the matching element is suppressed to improve high-frequency characteristics.

An important consideration when the switch, the LC filter, the surface acoustic wave filter, and the matching element are integrated in a laminated block having a plurality of dielectric layers laminated is to arrange the components such that interference between the matching element and the LC filter is prevented. In particular, regarding the inductance of the matching element, a high Q value and stability are required.

In a high-frequency composite component according to this preferred embodiment of the present invention, it is desirable that the inductor of the matching element be disposed in a first area of the laminated block, and that the inductor and the capacitors of the LC filter be disposed in a second area different from the first area as viewed from the top.

In the same manner, it is desirable that the inductor of the matching element be disposed on the surface of the laminated block and that the inductor and the capacitors of the LC filter be disposed inside the laminated block. Furthermore, it is desirable that a ground electrode be disposed between the inductor of the matching element and the inductor and the capacitors of the LC filter. Alternatively, it is desirable that a shunt capacitor of the capacitors of the LC filter be disposed in the vicinity of the lowest layer of the laminated block.

The inductor and the capacitors of the matching element are disposed on the surface of the laminated block, and the inductor of the matching element may be disposed so as to be directly next to the capacitors of the matching element with no other elements disposed therebetween.

Furthermore, the surface acoustic wave filter may be a balanced-type surface acoustic wave filter having balanced output ports or the surface acoustic wave filter may be an unbalanced-type surface acoustic wave filter having unbalanced output ports. When the surface acoustic wave filter is a balanced-type filter, the inductor of the matching element is connected in parallel between the balanced output ports, and the capacitors of the matching element are connected in series to the balanced output ports. Furthermore, when the surface acoustic wave filter is an unbalanced-type filter, the inductor and the capacitors of the matching element function as a balun.

Moreover, a high-frequency composite component according to a preferred embodiment of the present invention is a high-frequency composite component of a dual-band type in which signals in two different frequency bands can be processed. In such a high-frequency composite component of a dual-band type, a diplexer for branching a signal path for a first frequency band and a signal path for a second frequency band different from the first frequency band is provided at the rear stage of the antenna terminal. In the signal path for a first frequency band, a first switch for selectively switching a signal path between the antenna terminal and a first transmission-side input terminal and a signal path between the antenna terminal and a first reception-side balanced output terminal, a first LC filter having an inductor and capacitors disposed between the first switch and the first transmission-side input terminal, a first surface acoustic wave filter disposed between the first switch and the first reception-side balanced output terminal, and a first matching element having an inductor and capacitors disposed between the first surface acoustic wave filter and the first reception-side balanced output terminal are provided. In the signal path for a second frequency band, a second switch for selectively switching a signal path between the antenna terminal and a second transmission-side input terminal and a signal path between the antenna terminal and a second reception-side balanced output terminal, a second LC filter having inductors and capacitors disposed between the second switch and the second transmission-side input terminal, a second surface acoustic wave filter disposed between the second switch and the second reception-side balanced output terminal, and a second matching element having an inductor and capacitors disposed between the second surface acoustic wave filter and the second reception-side balanced output terminal are provided. The diplexer, the first and second switches, the first and second LC filters, the first and second surface acoustic wave filters, and the first and second matching elements are integrated in a laminated block having a plurality of laminated dielectric layers.

A high-frequency composite component according to another preferred embodiment of the present invention is a high-frequency composite component of a triple-band type in which signals in three different frequency bands can be processed. In such a high-frequency composite component of a triple-band type, a diplexer for branching a signal path for a first frequency band and a signal path for a second frequency band different from the first frequency band is provided at the rear stage of the antenna terminal. In the signal path for a first frequency band, a first switch for selectively switching a signal path between the antenna terminal and a first transmission-side input terminal and a signal path between the antenna terminal and a first reception-side balanced output terminal, a first LC filter having an inductor and capacitors disposed between the first switch and the first transmission-side input terminal, a first surface acoustic wave filter disposed between the first switch and the first reception-side balanced output terminal, and a first matching element having an inductor and capacitors disposed between the first surface acoustic wave filter and the first reception-side balanced output terminal are provided. In the signal path for a second frequency band, a second switch for selectively switching a signal path between the antenna terminal and a second transmission-side input terminal and a signal path between the antenna terminal and second and third reception-side balanced output terminals, a second LC filter having inductors and capacitors disposed between the second switch and the second transmission-side input terminal, a duplexer branching a signal path disposed between the second switch and the second reception-side balanced output terminal and a signal path disposed between the second switch and the third reception-side balanced output terminal, a second surface acoustic wave filter disposed between the duplexer and the second reception-side balanced output terminal, a second matching element having an inductor and capacitors disposed between the second surface acoustic wave filter and the second reception-side balanced output terminal, a third surface acoustic wave filter disposed between the duplexer and the third reception-side balanced output terminal, and a third matching element having an inductor and capacitors disposed between the third surface acoustic wave filter and the third reception-side balanced output terminal are provided. The diplexer, the first and second switches, the first and second LC filters, the first, second, and third surface acoustic wave filters, and the first, second, and third matching elements are integrated in a laminated block having a plurality of laminated dielectric layers.

Other features, elements, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the present invention with reference to the attached drawings.

FIG. 1 is a block diagram showing the basic structure of a first preferred embodiment of a high-frequency composite component according to the present invention.

FIG. 2 is an equivalent circuit diagram of the first preferred embodiment.

FIG. 3 is a block diagram showing the basic structure of a second preferred embodiment of a high-frequency composite component of the present invention.

FIG. 4 is an equivalent circuit diagram of the second preferred embodiment.

FIG. 5 is a schematic illustration showing the shape of electrodes provided on each sheet layer (first to eighth layers from the bottom) of a ceramic multilayer substrate of the second preferred embodiment.

FIG. 6 is a schematic illustration showing the shape of electrodes provided on each sheet layer (ninth to fifteenth layers from the bottom) of a ceramic multilayer substrate of the second preferred embodiment.

FIG. 7 is a schematic illustration showing the shape of electrodes provided on each sheet layer (sixteenth and seventeenth layers from the bottom) of a ceramic multilayer substrate of the second preferred embodiment.

FIG. 8 is a top view showing the mounting state of each circuit element on the surface of the ceramic multilayer substrate of the second preferred embodiment.

FIG. 9 is a block diagram showing the basic structure of a third preferred embodiment of a high-frequency composite component according to the present invention.

FIG. 10 is an equivalent circuit diagram of the third preferred embodiment.

FIG. 11 is an equivalent circuit diagram of a fourth preferred embodiment of a high-frequency composite component according to the present invention.

FIG. 12 is a schematic illustration showing the shape of electrodes provided on each sheet layer (first to eighth layers from the bottom) of a ceramic multilayer substrate of the fourth preferred embodiment.

FIG. 13 is a schematic illustration showing the shape of electrodes provided on each sheet layer (ninth to fifteenth layers from the bottom) of a ceramic multilayer substrate of the fourth preferred embodiment.

FIG. 14 is a schematic illustration showing the shape of electrodes provided on each sheet layer (sixteenth and seventeenth layers from the bottom) of a ceramic multilayer substrate of the fourth preferred embodiment.

FIG. 15 is a top view showing the mounting state of each circuit element on the surface of the ceramic multilayer substrate of the fourth preferred embodiment.

FIG. 16 is an equivalent circuit diagram of a fifth preferred embodiment of a high-frequency composite component according to the present invention.

FIG. 17 is an equivalent circuit diagram of a sixth preferred embodiment of a high-frequency composite component according to the present invention.

FIG. 18 is a block diagram showing a switching circuit of a related dual-band portable telephone.

FIG. 19 is a block diagram showing the outline of the structure of a related bandpass filter.

Hereinafter, the preferred embodiments of a high-frequency composite component according to the present invention are described with reference to the accompanied drawings.

First Preferred Embodiment (FIGS. 1 and 2 )

In a high-frequency composite component of a single-band type according to the first preferred embodiment, as shown in a block diagram of FIG. 1 , an inductor L is connected in parallel between the balanced output portion of a balanced-typed surface acoustic wave filter SAW and the reception-side balanced output terminal Rx, and capacitors C 1 and C 2 are connected in series, respectively.

In detail, as shown in an equivalent circuit diagram of FIG. 2 , the high-frequency composite component includes a high-frequency switch 11 , an LC filter 12 , a balanced-type surface acoustic wave filter SAW, and a matching element 13 .

The high-frequency switch 11 is for selectively switching a signal path between an antenna terminal ANT and a transmission-side input terminal Tx and a signal path between the antenna terminal ANT and a reception-side balanced output terminal Rx. The LC filter 12 is disposed between the high-frequency switch 11 and the transmission-side input terminal Tx and is a low-pass filter including an inductor GLt 1 and capacitors. The capacitors of the low-pass filter include a capacitor GC connected in parallel to the inductor GLt 1 and two grounding capacitors (shunt capacitors) GCu 1 and GCu 2 connected to the ground.

In the matching element 13 , as described above, the inductor L is connected in parallel and the capacitors C 1 and C 2 are connected in series, respectively, between the balanced output portion of the surface acoustic wave filter SAW and the reception-side balanced output terminal Rx.

Furthermore, in the first preferred embodiment, the above-described high-frequency switch 11 , LC filter 12 , surface acoustic wave filter SAW, and matching element 13 are integrated in a laminated block in which a plurality of dielectric layers are laminated.

The high-frequency composite component according to the first preferred embodiment, which is a single-band type, is included in high-frequency composite components of second and third preferred embodiments of a dual-band type and a high-frequency composite component of a fourth preferred embodiment of a triple-band type as a component thereof. Accordingly, the more detailed structure and operation of the first preferred embodiment are disclosed with reference to the second, third, fourth, fifth, and sixth preferred embodiments to be described later.

Second Preferred Embodiment (FIGS. 3 to 8 )

A high-frequency composite component according to the second preferred embodiment is a high-frequency composite component (front-end module) of a dual-band type having GSM and DCS systems, as shown in a block diagram in FIG. 3 . Inductors Lg and Ld are connected in parallel between the balanced output portions of balanced-type surface acoustic wave filters SAWg and SAWd and reception-side balanced output terminals Rxg and Rxd, and capacitors C 1 g and C 2 g , and C 1 d and C 2 d are connected in series, respectively.

In detail, as shown in an equivalent circuit diagram of FIG. 4 , the high-frequency composite component includes a diplexer 20 for branching a GSM-system signal path and a DCS-system signal path at the rear stage of the antenna terminal ANT. Moreover, the GSM system includes a first high-frequency switch 11 G, a first LC filter 12 G, the first balanced-type surface acoustic wave filter SAWg, and a first matching element 13 G. In the same manner, the CS system also includes a second high-frequency switch 11 D, a second LC filter 12 D, the second balanced-type surface acoustic wave filter SAWd, and a second matching element 13 D.

The first high-frequency switch 11 G selectively switches a signal path between the antenna terminal ANT and a first transmission-side input terminal Txg and a signal path between the antenna terminal ANT and a first reception-side balanced output terminal Rxg. The first LC filter 12 G is disposed between the first high-frequency switch 11 G and the first transmission-side input terminal Txg. The first surface acoustic wave filter SAWg is disposed between the first high-frequency switch 11 G and the first reception-side balanced output terminal Rxg.

In the first matching element 13 G, the inductor Lg is connected in parallel on the side of the first surface acoustic wave filter SAWg, and the capacitors C 1 g and C 2 g are connected in series between the inductor Lg and the reception-side balanced output terminal Rxg, respectively.

The second high-frequency switch 11 D selectively switches a signal path between the antenna terminal ANT and a second transmission-side input terminal Txd and a signal path between the antenna terminal ANT and a second reception-side balanced output terminal Rxd. The second LC filter 12 D is disposed between the second high-frequency switch 11 D and the second transmission-side input terminal Txd. The second surface acoustic wave filter SAWd is disposed between the second high-frequency switch 11 D and the second reception-side balanced output terminal Rxd.

In the second matching element 13 D, an inductor Ld is connected in parallel on the side of the second surface acoustic wave filter SAWd, and the capacitors C 1 d and C 2 d are connected in series between the inductor Ld and the reception-side balanced output terminal Rxd, respectively.

The diplexer 20 selects a transmission signal from the DCS system or the GSM system during transmission and selects a reception signal to the DCS system or the GSM system during reception. The antenna terminal ANT is connected to a first port P 11 of the diplexer 20 , the first port P 31 g of the first high-frequency switch 11 G is connected to a second port P 12 , and the first port P 31 d of the second high-frequency switch 11 D is connected to a third port P 13 .

In the GSM system, a first port P 21 g of the first LC filter 12 G is connected to a second port P 32 g of the first high-frequency switch 11 G, and the first surface acoustic wave filter SAWg is connected to a third port P 33 g . The first transmission-side input terminal Txg is connected to a second port P 22 g of the first LC filter 12 G.

In the DCS system, a first port P 21 d of the second LC filter 12 D is connected to a second port P 32 d of the second high-frequency switch 11 D, and the second surface acoustic wave filter SAWd is connected to a third port P 33 d . The transmission-side second input terminal Txd is connected to a second port P 22 d of the second LC filter 12 D.

The diplexer 20 includes inductors Lt 1 and Lt 2 , and capacitors Cc 1 , Cc 2 , Ct 1 , Ct 2 , and Cu 1 . A parallel circuit defined by the inductor Lt 1 and the capacitor Ct 1 is connected between the first port P 11 and the second port P 12 , and the side of the second port P 12 of the parallel circuit is grounded through the capacitor Cu 1 . Furthermore, the capacitors Cc 1 and Cc 2 are connected in series between the first port P 11 and the third port P 13 , and the connection point between them is grounded through the inductor Lt 2 and the capacitor Ct 2 .

The first high-frequency switch 11 G includes diodes GD 1 and GD 2 as switching elements, inductors GSL 1 and GSL 2 , capacitors GC 5 and GC 6 , and a resistor RG. The diode GD 1 is connected between the first port P 31 g and the second port P 32 g such that the anode is on the side of the first port P 31 g , and the cathode is grounded through the inductor GSL 1 . The cathode of the diode GD 2 is connected to the first port P 31 g through the inductor GSL 2 , and the anode is grounded through the capacitor GC 5 . A control terminal Vc 1 is connected to the connection point between the diode GD 2 and the capacitor GC 5 through the resistor RG. Furthermore, the connection point between the cathode of the diode GD 2 and the third port P 33 g is grounded through the capacitor GC 6 .

The second high-frequency switch 11 D includes diodes DD 1 and DD 2 as switching elements, inductors DSL 1 , DSL 2 , and DSLt, capacitors DC 6 , DC 7 , and DCt 1 , and a resistor RD. The diode DD 1 is connected between the first port P 31 d and the second port P 32 d such that the anode is on the side of the first port P 31 d , and the cathode is grounded through the inductor DSL 1 . Furthermore, a series circuit of the capacitor DCt 1 and the inductor DSLt is connected in parallel to the diode DD 1 between the first port P 31 d and the second port P 32 d . The cathode of the diode DD 2 is connected to the first port P 31 d through the inductor DSL 2 , and the anode is grounded through the capacitor DC 5 . A control terminal Vc 2 is connected to the connection point between the diode DD 2 and the capacitor DC 5 through the resistor RD. Furthermore, the cathode of the diode DD 2 is connected to the third port P 33 d through the capacitor DC 6 , and the connection point between the cathode and the capacitor DC 6 is grounded through the capacitor DC 7 .

In the first LC filter 12 G, a parallel circuit of an inductor GLt 1 and a capacitor GCc 1 is connected between the first port P 21 g and the second port P 22 g . Both ends of the inductor GLt 1 are grounded through capacitors GCu 1 and GCu 2 , respectively.

In the second LC filter 12 D, a parallel circuit of an inductor DLt 1 and a capacitor DCc 1 and a parallel circuit of an inductor DLt 2 and a capacitor DCc 2 are connected in series between the first port P 21 d and the second port P 22 d . Both ends of the inductor DLt 1 are grounded through capacitors DCu 1 and DCc 2 , respectively.

FIGS. 5 to 7 show capacitor electrodes and strip line electrodes formed by screen printing or other suitable method, on each sheet layer defining a ceramic multilayer substrate of a high-frequency composite component according to the second preferred embodiment. The ceramic multilayer substrate is formed such that first to seventeenth sheet layers 61 a to 61 q made of ceramics having barium oxide, aluminum oxide, and silica as main components are laminated in order from the bottom and sintered at a temperature of about 1000° C. or less.

Various terminal electrodes for external connection are provided on the first sheet layer 61 a . A ground electrode G 1 is provided on the second sheet layer 61 b , the electrodes for the capacitors GCu 1 , GCu 2 , Ct 2 , and GC 5 are provided on the third sheet layer 61 c to define capacitances together with the ground electrode G 1 . A ground electrode G 2 is provided on the fourth sheet layer 61 d , and the electrodes for the capacitors DCu 1 and DCu 2 are provided on the fifth sheet layer 61 e to define capacitances with the ground electrode G 2 .

The inductors Lt 1 , Lt 2 , DLt 1 , DLt 2 , GLt 1 , DSL 1 , and DSL 2 are defined by stripline electrodes on the seventh and ninth sheet layers 61 g and 61 i and are connected by via holes. Moreover, the inductors Lt 1 , Lt 2 , DLt 1 , DLt 2 , GLt 1 , and DSL 2 are defined by stripline electrodes on the eleventh sheet layer 61 k and are connected to the same electrodes on the lower layers by via holes.

The electrodes of the capacitors Ct 1 and DCc 1 are provided on the twelve sheet layer 611 , and the electrodes of the capacitors Ct 1 , Cc 1 , DCt 1 , and GCc 1 and the ground electrode G 3 are provided. The electrodes of the capacitors Cc 1 , DCt 1 , GCc 1 , and DC 5 are provided on the fourteenth sheet layer 61 n . The electrodes of the capacitors Cc 2 and DCt 1 and the ground electrode G 4 are provided on the fifteenth sheet layer 61 o.

As shown in FIG. 8 , various connection terminal electrodes are provided on the surface of the seventeenth sheet layer 61 q defining the surface of the ceramic multilayer substrate 50 . Then, on the surface, the first and second surface acoustic wave filters SAWg and SAWd and the diodes GD 1 , GD 2 , DD 1 , and DD 2 are mounted, and the inductor Lg and the capacitors C 1 g and C 2 g defining the first matching element 13 G and the inductor Ld and the capacitors C 1 d and C 2 d defining the second matching element 13 D are mounted. Moreover, the resistors RG and RD and the inductors DSL 1 , DSLt, and GSL 1 are mounted on the surface of the ceramic multilayer substrate 50 .

Here, the operation of the high-frequency composite component having the circuit structure shown in FIG. 4 is described. First, when a transmission signal of the DCS system (1.8 MHz band) is sent, in the second high-frequency switch 11 D, the transmission signal of the DCS system passes through the second LC filter 12 D, the second high-frequency switch 11 D, and the diplexer 20 and is transmitted from the antenna terminal ANT connected to the first port P 11 of the diplexer 20 such that, for example, about 3 V is applied to the control terminal Vc 2 to turn on the diodes DD 1 and DD 2 .

At this time, in the first high-frequency switch 11 G of the GSM system, the transmission signal of the GSM system is not transmitted such that, for example, 0 V is applied to the control terminal Vc 1 to turn off the diode GD 1 . Furthermore, the transmission signal of the DCS system does not enter the first transmission-side input terminal Txg and the first reception-side balanced output terminal Rxg of the GSM system due to the connection of the diplexer 20 . Moreover, the second and third harmonics of the DCS system are attenuated in the second LC filter 12 D of the DCS system.

Next, when a transmission signal of the GSM system (900 MHz band) is sent, in the first high-frequency switch 11 G, the transmission signal of the GSM system passes through the first LC filter 12 G, the first high-frequency switch 11 G, and the diplexer 20 and is transmitted from the antenna terminal ANT connected to the first port P 11 of the diplexer 20 such that, for example, about 3 V is applied to the control terminal Vc 1 to turn on the diodes GD 1 and GD 2 .

At this time, in the second high-frequency switch 11 D of the DCS system, the transmission signal is not transmitted such that, for example, 0 V is applied to the control terminal Vc 2 to turn off the diode DD 1 . Furthermore, the transmission signal of the GSM system does not enter the second transmission-side input terminal Txd and the second reception-side balanced output terminal Rxd of the DCS system due to the connection of the duplexer 20 .

Moreover, the second harmonic of the GSM system is attenuated in the low-pass filter made up of the capacitor Ct 1 , the inductor Lt 1 , and the shunt capacitor Cu 1 of the diplexer 20 and the third harmonic of the GSM system is attenuated in the first LC filter 12 G of the GSM system.

Next, when reception signals of the DCS system and the GSM system are received, in the second high-frequency switch 11 D of the DCS system, a reception signal of the DCS system does not enter the second transmission-side input terminal Txd such that, for example, 0 V is applied to the control terminal Vc 2 to turn off the diodes DD 1 and DD 2 , and in the first high-frequency switch 11 G of the GSM system, a reception signal of the GSM system does not enter the first transmission-side input terminal Txg of the GSM system such that 0 V is applied to the control terminal Vc 1 to turn off the diodes GD 1 and GD 2 . Then, the signals input from the antenna terminal ANT are output to the reception-side balanced output terminal Rxd of the DCS system and the reception-side balanced output terminal Rxg of the GSM system, respectively.

Furthermore, the reception signal of the DCS system does not enter the GSM system and the reception signal of the GSM system does not enter the DCS system due to the connection of the diplexer 20 .

In the high-frequency composite component according to the second preferred embodiment, since the matching elements 13 G and 13 D including the inductors Lg and Ld and the capacitors C 1 g , C 2 g , C 1 d , and C 2 d are disposed between the surface acoustic wave filters SAWg and SAWd and the reception-side balanced output terminals Rxg and Rxd, it is possible to freely set the impedance of the reception-side balanced output terminals Rxg and Rxd by appropriate combinations of the inductors and capacitors.

Furthermore, since the inductors Lg and Ld and the capacitors C 1 g , C 2 g , C 1 d , and C 2 d are integrated in the ceramic laminated substrate together with the other circuit components, as comparison to when such inductors and capacitors are discretely disposed on a printed circuit board, the mounting surface on the printed substrate is reduced and simultaneously the distance between the surface acoustic wave filters SAWg and SAWd and the matching elements 13 G and 13 D is minimized so as to suppress the loss between the filters SAWg and SAWd and the matching elements 13 G and 13 D and improve the high-frequency characteristics.

Furthermore, since the inductors Lg and Ld of the matching elements 13 G and 13 D are arranged so as not to overlap with the inductors and capacitors of the LC filters 12 G and 12 D in the ceramic laminated substrate as seen from the top, the isolation between the transmission and reception lines is secured and the mixture of a signal is prevented. Since the inductors Lg and Ld of the matching elements 13 G and 13 D are mounted on the surface of the ceramic laminated substrate, the same effect is attained by the inductors and capacitors of the LC filters 12 G and 12 D being disposed inside the ceramic laminated substrate.

Moreover, in the present preferred embodiment, the capacitors C 1 g , C 2 g , C 1 d , and C 2 d of the matching elements 13 G and 13 D are arranged so as not to overlap with the inductors and capacitors of the LC filters 12 G and 12 D as seen from the top. In this manner, the mixture of a signal between the transmission and reception lines is more effectively prevented.

Furthermore, since the ground electrode G 4 is disposed between the inductors Lg and Ld of the matching elements 13 G and 13 D and the inductors and capacitors of the LC filters 12 G and 12 D, the interference between these components is effectively prevented. In addition, since the capacitors of the LC filters 12 G and 12 D, that is, the shunt capacitors GCu 1 , GCu 2 , DCu 1 , and DCu 2 , in particular, are disposed in the vicinity of the lower layer of the ceramic laminated substrate, the same effect is obtained. Since the inductors Lg and Ld and the capacitors C 1 g , Cg 2 , C 1 d , and C 2 d of the matching elements 13 G and 13 D are disposed on the surface of the ceramic laminated substrate, and since the inductors Lg and Ld of the matching elements 13 G and 13 D are arranged next to the capacitors C 1 g , C 2 g , C 1 d , and C 2 d of the matching elements 13 G and 13 D with no other elements disposed therebetween, mutual interference is effectively prevented.

Moreover, in the present preferred embodiment, the ground electrode G 4 is also disposed between the capacitors C 1 g , C 2 g , C 1 d , and C 2 d and the inductors capacitors of the LC filters 12 G and 12 D. Thus, the interference between these components effectively prevented.

Furthermore, as shown in FIG. 8 , on the surface of the ceramic multilayer substrate, the surface mounting components defining the matching elements 13 G and 13 D are disposed so as to be next to the surface mounting components defining the high-frequency switches 11 G and 11 D and the diplexer 20 through the surface acoustic wave filters SAWg and SAWd. With such an arrangement, the interference between the matching elements 13 G and 13 D and the other elements is more effectively suppressed.

Third Preferred Embodiment (FIGS. 9 and 10 )

A high-frequency composite component according to a third preferred embodiment is a dual-band type high-frequency composite component having GSM and DCS systems similar to the second preferred embodiment. As shown in a block diagram in FIG. 9 , the capacitors C 1 g and C 2 g , and Cd and C 2 d are connected in series to the balanced output portions of the balanced-type surface acoustic wave filters SAWg and SAWd, and the inductors Lg and Ld are connected in parallel to the reception-side balanced output terminals Rxg and RXd.

Thus, the impedance of the first and second reception-side balanced output terminals Rxg and Rxd can be freely set and the impedance can be increased, in particular, such that the capacitors C 1 g and C 2 g and the capacitors C 1 d and C 2 d are connected in series to the side of the first and second surface acoustic wave filters SAWg and SAWd, and the inductors Lg and Ld are connected in parallel to the side of the first and second reception-side balanced output terminals Rxg and Rxd, respectively.

Moreover, in the third preferred embodiment, the circuit structure and operation, except for the first and second matching elements 13 G and 13 D, are the same as in the second preferred embodiment and the overlapping description is omitted.

Fourth Preferred Embodiment (FIGS. 11 to 15 )

A high-frequency composite component according to a fourth preferred embodiment is a triple-band type high-frequency composite component having a GSM system and a DCS system branching off into two reception-side balanced output terminals Rxd 1 and Rxd 2 , as shown in an equivalent circuit diagram of FIG. 11 .

That is, the GSM system includes a first high-frequency switch 11 G, a first LC filter 12 G, a balanced-type first acoustic wave filter SAWg, and a first matching element 13 G. The structure and operation of the GSM system is the same as that in the above-described second and third preferred embodiments and the overlapping description is omitted.

The diplexer 20 also includes substantially the same structure as that in the second and third preferred embodiments and, in addition, a capacitor Cant is connected between the first port P 11 and the antenna terminal ANT, and the connection point is grounded through an inductor Lant.

The DCS system includes a second high-frequency switch 11 D′, a second LC filter 12 D, and a second transmission-side input terminal Txd. The circuit structure of this portion is the same as that in the second and third preferred embodiments and the overlapping description is omitted.

In the DCS system, the third port P 33 d of the second high-frequency switch 11 D′ is connected to a duplexer 14 D, and the duplexer 14 D branches the path of a reception signal into a second reception-side balanced output terminal Rxd 1 and a third reception-side balanced output terminal Rxd 2 .

The second high-frequency switch 11 D′ selectively switches a signal path between the antenna terminal ANT and the second transmission-side input terminal Txd and a signal path between the antenna terminal ANT and the second and third reception-side balanced output terminals Rxd 1 and Rxd 2 .

The second high-frequency switch 11 D′ includes the diodes DD 1 , and DD 2 as switching elements, inductors DPSL 1 , DSL 2 , and DPSLt, capacitors DC 5 , DC 6 , DPCt, and a resistor DR 1 . The diode DD 1 is connected between the first port P 31 d and the second port P 32 d such that the anode is on the side of the second port P 32 d , and the anode is grounded through the inductor DPSL 1 and the capacitor DC 6 . The control terminal Vc 2 is connected to the connection point between the inductor DPSL 1 and the capacitor DC 6 . Furthermore, a series circuit of the capacitor DPCt and the inductor DPSLt is connected between the first port P 31 d and the second port P 32 d so as to be parallel to the diode DD. The anode of the diode DD 2 is connected to the first port P 31 d through the inductor DSL 2 , and the cathode is grounded through the capacitor DC 5 . The connection point between the diode DD 2 and the capacitor DC 5 is grounded through the DR 1 .

In the duplexer 14 D, an inductor PSL 2 is connected between a first port P 41 d and a second port P 42 d , and the connection point between the inductor PSL 2 and the second port P 42 d is grounded through a capacitor PC 7 . The second port P 42 d is connected to a second surface acoustic wave filter SAWd 1 . Furthermore, a capacitor DC 7 is connected between the first port P 41 d and a third port P 43 d of the duplexer 14 D. The connection point between the capacitor DC 7 and the first port P 41 d is grounded through a capacitor Cj, and simultaneously, the connection point between the capacitor DC 7 and the third port P 43 d is grounded through the inductor DSL 1 .

A second matching element 13 D 1 is connected to the balanced output portion of the second surface acoustic wave filter SAWd 1 , and a third matching element 13 D 2 is connected to the balanced output portion of a third surface acoustic wave filter SAWd 2 . In the second and third matching elements 13 D 1 and 13 D 2 , in the same manner as in the second preferred embodiment, the inductors Ld are connected in parallel on the side of the surface acoustic wave filters SAWd 1 and SAWd 2 , and the capacitors C 2 d and C 2 d are connected in series between the inductors Ld and the reception-side balanced output terminals Rxd 1 and Rxd 2 , respectively. The operation-effect is the same as in the second preferred embodiment. Moreover, the second and third matching elements 13 D 1 and 13 D 2 may have the same circuit structure as in the third preferred embodiment, and in this case, the same operation effect is obtained as in the third preferred embodiment.

FIGS. 12 to 14 show the capacitor electrodes and stripline electrodes formed by a screen printing or other suitable method, on each sheet layer defining the ceramic multilayer substrate of a high-frequency composite component according to the fourth preferred embodiment.

Various external connection terminal electrodes are provided on the first sheet layer 62 a . A ground electrode G 11 is provided on the second sheet layer 62 b , and the electrodes of capacitors Cu 1 , Ct 2 , and DC 6 are provided on the third sheet layer 62 c to define a capacitance together with the ground electrode G 11 . A ground electrode G 12 is provided on the fourth sheet layer 62 d , and the electrodes of capacitors DCu 1 , DCu 2 , Cj, GCu 1 , and GCu 2 are provided on the fifth sheet layer 62 e to define a capacitance together with the ground electrode G 12 .

The inductors Lt 1 , Lt 2 , DLt 1 , DLt 2 , GLt 1 , GSL 2 , DSL 2 , and PSL 2 are provided on the eight sheet layer 62 h using stripline electrodes. Inductors GSL 2 and Lt 1 are provided on the ninth sheet layer 62 i using stripline electrodes and connected to the electrodes on lower layers through via holes.

The inductors Lt 1 , Lt 2 , DLt 1 , DLt 2 , GLt 1 , GSL 2 , DSL 2 , and DSL 2 are provided on the tenth sheet layer 62 j using stripline electrodes and connected to the electrodes of the same kind on lower layers through via holes. Inductors Lt 1 and GSL 2 are provided on the eleventh sheet layer 62 k using stripline electrodes and connected to the electrodes of the same kind on lower layers through via holes.

The inductors Lt 2 , DLt 1 , DLt 2 , GLt 1 , GSL 2 , and DSL 2 are provided on the twelve sheet layer 621 using stripline electrodes and connected to the electrodes of the same kind on lower layers through via holes. The electrodes of the capacitors Ct 1 and DCc 2 are provided on the thirteenth sheet layer 62 m , and the electrodes of the capacitors Ct 1 and Cc 1 and the ground electrode G 13 are provided on the fourteenth sheet layer 62 n . The electrodes of the capacitors DC 5 , Ct 1 , Cc 1 , GCc 1 , GC 5 , DCu 1 , and DCc 2 are provided on the fifteenth sheet layer 62 o . The electrodes of the capacitors Cc 2 and CCc 1 and a ground electrode G 14 are provided on the sixteenth sheet layer 62 p . The electrodes of the capacitor DCc 1 are provided on the seventeenth sheet layer 62 q.

The surface of the nineteenth sheet layer 62 s is the surface of the ceramic multilayer substrate 50 , as is shown in FIG. 15 , and various connection terminal electrodes are provided and the first to third surface acoustic wave filters SAWg, SAWd 1 , and SAWd 2 and the diodes GD 1 , GD 2 , DD 1 , and DD 2 are mounted thereon. Moreover, the inductor Lg and the capacitors C 1 g and C 2 g defining the first matching element 13 G and the inductor Ld and the capacitors C 1 d and C 2 d defining the second and third matching elements 13 D 1 and 13 D 2 are mounted thereon.

Moreover, on the surface of the ceramic multilayer substrate 50 , the resistors RG and DR 1 are mounted, the inductors Lant, DPCt, DPSLt, DSL 1 , and DPSL 1 are mounted, and the capacitors Cant, DC 7 , and PC 7 are mounted.

In the high-frequency composite according to the fourth preferred embodiment, a reception signal can be switched to the second reception-side balanced output terminal Rxd 1 and the third reception-side balanced output terminal Rxd 2 by turning on and off the diode of the second high-frequency switch 11 D′. The other basic operations are the same as described in the second preferred embodiment and the operation effect is also the same as in the second preferred embodiment.

In particular, as shown in FIG. 15 , on the surface of the ceramic multilayer substrate, the surface mounting components defining the matching elements 13 G, 13 D 1 , and 13 D 2 are disposed so as to be opposite to the surface mounting components defining the high-frequency switches 11 G and 11 D′, the diplexer 20 , and the duplexer 14 D through the surface acoustic wave filters SAWg, SAWd 1 , and SAWd 2 . Such an arrangement further suppresses the interference between the matching elements 13 G, 13 D 1 , and 13 D 2 and the other elements.

Fifth Preferred Embodiment (FIG. 16 )

A high-frequency composite component according to a fifth preferred embodiment is a triple-band type, as shown in an equivalent circuit of FIG. 16 . The structure is basically the same as that of the fourth preferred embodiment (see FIG. 11 ) and the operation effect is also the same as the fourth preferred embodiment. The different between the fifth preferred embodiment and the fourth preferred embodiment is that the reception-side balanced output terminals Rxd 1 and Rxd 2 are separated by a diode switch 15 D, instead of by the duplexer 14 D.

The diode switch 15 D includes diodes SDD 1 and SDD 2 as switching elements, inductors SID 1 and SID 2 , capacitors SC 1 , SC 2 , and SC 3 , and a resistor SR. A first port P 51 d is connected to the third port P 33 d of the second high-frequency switch 11 D′, and the other end of the capacitor SC 3 , one end of which is connected to the first port P 51 d , is connected to the anode of the diode SDD 2 through the cathode of the diode SDD 1 and the inductor SID 2 .

The anode of the diode SDD 1 is grounded through the inductor SID 1 and the capacitor SC 1 , and a control terminal Vc 3 is connected to the connection point between the inductor SID 1 and the capacitor SC 1 . The cathode of the diode SDD 2 is grounded through the capacitor SC 2 , and the connection point between the cathode and the capacitor SC 2 is grounded through the resistor SR. The second port P 52 d connected to the anode of the diode SDD 1 is connected to the second surface acoustic wave filter SAWd 1 . Furthermore, the third port P 53 d connected to the anode of the diode SDD 2 is connected to the third surface acoustic wave filter SAWd 2 .

Sixth Preferred Embodiment (FIG. 17 )

A high-frequency composite component according to the sixth preferred embodiment is a triple-band type high-frequency composite component, as shown in FIG. 17 . The structure is basically the same as that of the fourth preferred embodiment (see FIG. 11 ) and the operation effect is also the same as in the fourth preferred embodiment. The difference is that the surface acoustic wave filters SAWd 1 and SAWd 2 having unbalanced output ports are of an unbalanced type and the matching elements 13 D 1 and 13 D 2 connected to the unbalanced output ports are defined as baluns.

Other Embodiments

Moreover, the high-frequency composite components according to the present invention are not limited to the above-described embodiments, and various modifications can be made without departing from the spirit and the scope of the invention.

For example, in the above-described preferred embodiments, high-frequency composite components of a single-band type, a dual-band type, and a triple-band type were described, but the present invention can be also applied to high-frequency composite components of any multi-band type, such as a quad-band type.

Furthermore, in the above-described preferred embodiments, although the LC filters 12 , 12 G, and 12 D for attenuating higher-order harmonics are disposed between the high-frequency switches are 11 , 11 G, 11 D, and 11 D′ and the transmission-side input terminals Tx, Txg, and Tsd, they may be disposed between the antenna terminal ANT (diplexer 20 ) and the high-frequency switch.

As described above, the present invention is useful for a high-frequency composite component which can be utilized in a plurality of different mobile communication systems and, in particular, is advantageous because a desired impedance can be easily set and no matching adjustment to LNAs is required.

While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.