JP3919194B2 - Front-end module - Google Patents

Description

  The present invention relates to a mobile communication terminal device such as a mobile phone terminal device, and more particularly to a front end module thereof.

  Currently, as a mobile communication terminal device, a dual operating in a GSM (Global System for Mobile communications) system using a plurality of frequency bands, for example, 900 MHz band, and a DCS (Digital Cellular System) system using a 1.8 GHz band. Band mobile phone terminal devices have been put into practical use (hereinafter, terminal devices are also simply referred to as terminals). In addition, a dual-band mobile phone terminal of a CDMA (Code Division Multiple Access) system using a plurality of frequency bands, for example, 800 MHz band and 900 MHz band in the same system has been put into practical use.

  The configuration shown in FIG. 1 is used when the use frequency band is relatively distant like the GSM and DCS dual band mobile phone terminal described above, and the diplexer 5 is used to separate a plurality of frequency bands. Has been. 1 includes a receiving circuit 2 that performs reception in a first frequency band, a transmission circuit 3 that performs transmission in a first frequency band, and a duplexer 4 that performs transmission and reception separation in the first frequency band. A receiving circuit 2 ′ for receiving in the second frequency band, a transmitting circuit 3 ′ for transmitting in the second frequency band, a duplexer 4 ′ for separating transmission and reception in the second frequency band, the first frequency It comprises a diplexer 5 that separates the band from the second frequency band, and an antenna 1.

  Examples of the configuration of the diplexer 5 include the configurations shown in FIGS. 3 and 4. The diplexer shown in FIG. 3 has a first filter composed of inductors 55 and 56 and a capacitor 54 and a second filter composed of an inductor 51 and capacitors 52 and 53. The diplexer of FIG. 4 has a first filter composed of an inductor 74 and capacitors 75 and 76, and a second filter composed of inductors 71 and 73 and a capacitor 72.

  FIG. 5 shows a configuration example of the receiving circuit shown in FIG. 1 and FIG. The reception circuit includes an input terminal 20, a low noise amplifier 21, a reception band bandpass filter (BPF) 22, a down-conversion mixer 23, a reception local oscillator (local oscillation) 26, a reception IF filter 24, a quadrature demodulator 25, and an IQ signal. It comprises output terminals 27 and 28.

  FIG. 6 shows a configuration example of the transmission circuit shown in FIG. 1 and FIG. The transmission circuit includes IQ signal input terminals 37 and 38, a quadrature modulator 35, a transmission IF filter 34, a transmission local oscillator 36, an up-conversion mixer 33, a transmission band BPF 32, a power amplifier 31, an isolator 39, and a transmission output terminal 30. Is done.

  Similarly, when the use frequency bands are close to each other as in the CDMA dual-band mobile phone terminal, the configuration as shown in FIG. 2 is used, and the switch 6 is used to separate a plurality of frequency bands. . The reason for this is that in a diplexer composed of a plurality of filters as described above, if the used frequency bands are close to each other, the diplexer becomes large in order to secure the required out-of-band attenuation and further increases the insertion loss, which is difficult to realize. It is.

  FIG. 7A and FIG. 7B are configuration examples of a conventional duplexer. A BPF 40 that attenuates the transmission band with the reception band as the pass band, a BPF 41 that attenuates the reception band with the transmission band as the pass band, and a phase shift circuit placed between the two BPFs and the antenna terminal 4a. A receiving circuit is connected to the terminal 4b, and a transmitting circuit is connected to the terminal 4c. 7A, a high-pass filter (HPF) composed of a capacitor 48, an inductor 46, and an inductor 47 and a low-pass filter (LPF) composed of an inductor 45, a capacitor 44, and a capacitor 43 are used as a phase shift circuit. An example used is shown. FIG. 7B shows an example in which the transmission line 42 and the transmission line 49 are used as a phase shift circuit.

  In general, in the duplexer, the output end of the transmission filter and the input end of the reception filter are connected to the antenna terminal, and the transmission signal that has passed through the transmission filter flows into the reception circuit via the reception filter. In order to prevent the reception signal received by the antenna from flowing into the transmission circuit via the transmission filter, a sufficient amount of attenuation is required in the band on the other side as the characteristics of the transmission filter and the reception filter. Is done. Furthermore, to prevent the insertion loss from the antenna terminal to the receiving circuit (that is, the insertion loss of the reception filter) from increasing due to the connection of the transmission filter, the impedance in the reception band viewed from the antenna terminal to the transmission filter side is set to “ It needs to be “open”. Conversely, in order to prevent the insertion loss from the antenna terminal to the transmission circuit (that is, the insertion loss of the transmission filter) from increasing due to the connection of the reception filter, the transmission band as seen from the antenna terminal to the reception filter side. Needs to be set to “open”. Therefore, a phase shift circuit is inserted in FIGS. 7A and 7B. For example, the phase shift circuit 42 has an electrical length so that the impedance in the reception band of the transmission BPF 40 is “open” at the antenna terminal 4a. And the electrical length of the phase shift circuit 49 is set so that the impedance in the transmission band of the reception BPF 41 is “open” at the antenna terminal 4a.

  On the other hand, in recent years, a direct conversion reception system (DCR) has been put into practical use, and a receiving circuit and a transmitting circuit used in a plurality of frequency bands can be configured by only one system each. As a result, the dual-band mobile phone terminal having the configuration shown in FIG. 2 can be realized with the configuration shown in FIGS. 8-A and 8-B. That is, in FIG. 8A, the reception circuit is shared in a plurality of frequency bands, and in FIG. 8-B, both the reception circuit and the transmission circuit are shared in a plurality of frequency bands (see Patent Document 1). As described above, by reducing the number of receiving circuits and transmitting circuits, it has become possible to reduce the size and cost of terminals. Direct conversion reception (DCR) is described in Non-Patent Document 1, for example.

Patent Document 2 discloses a front-end module for using three frequency bands in one mobile phone terminal, and sharing a transmission circuit in two adjacent frequency bands.
Japanese Patent Laid-Open No. 10-290176 JP 2002-101005 A AA Abidi, “Direct-Conversion Radio Transceivers for Digital Communications” Eye Triple E Journal of Solid State Circuits (IEEE J. Solid State Circuits), Vol. 30, No. 12 (Vol. 30, No. 12), 1995

  However, although the receiving circuit and the transmitting circuit can be partially reduced in the configuration examples of FIGS. 8A and 8B, a plurality of duplexers that perform transmission and reception separation in each frequency band are used, and this duplexer is large. Due to the high cost, there is a problem that the shape of the dual-band mobile phone terminal is large and the cost is high.

  Further, in the configuration examples of FIGS. 8A and 8B, it is necessary to add the switch 7 and the switch 11 as compared with the configuration of FIG. The addition of the switch 7 increases the loss from the receiving circuit to the antenna, which causes the reception sensitivity to deteriorate. Furthermore, when the switch 11 is added, the loss from the transmission circuit to the antenna increases. Therefore, in order to set the power at the antenna end to the standard value, it is necessary to increase the output power of the transmission circuit by the increased loss. There was a problem of increasing.

  For example, in a dual-band mobile phone terminal for CDMA for Japan and CDMA for the US, as shown in FIG. 17, the band (a) used for CDMA for Japan is terminal transmission: 887 to 925 MHz, terminal reception: 832 to 870 MHz. CDMA usage band (b) is terminal transmission: 824 to 849 MHz and terminal reception: 869 to 894 MHz. Looking at the reception band here, even if the CDMA band for Japan and the CDMA band for the United States are combined, it is 832 to 894 MHz, which is relatively close (partially overlapping) and can be handled by a single receiver circuit. Therefore, one type of reception BPF can be handled. However, in the configuration of FIG. 8A, since one reception filter is used in each of the two duplexers, the circuit is unnecessarily enlarged.

  The present invention has been made in such a background, and an object of the present invention is to simplify the configuration and to be small in size, which is suitable for a dual band system in which the reception frequency band interval between two systems is narrower than the transmission / reception interval frequency. To provide a low-cost front-end module.

  A first front-end module according to the present invention includes an antenna terminal, a reception terminal, a first transmission terminal, and a second transmission terminal, and is connected to the reception terminal in the dual-band front-end module. A reception band-pass filter that uses the second reception band as a pass band and attenuates the transmission band, and a terminal a and other terminals b and c connected to the reception band-pass filter, and the terminals b and c are selected. A first switch connected to the terminal a, a terminal a connected to the antenna terminal, and other terminals b and c, and the terminals b and c are selectively connected in conjunction with the first switch. a second switch connected to a, and the impedance on the reception band-pass filter side as seen from the antenna terminal, connected between the terminal c of the first switch and the terminal c of the second switch The first phase shifter that is “open” in the first transmission band, and the reception as viewed from the antenna terminal, connected between the terminal b of the first switch and the terminal b of the second switch The second phase shifter for making the impedance of the band pass filter side “open” in the second transmission band and the first transmission terminal are connected, and the reception band is attenuated with the first transmission band as the pass band. A first transmission band-pass filter; a second transmission band-pass filter connected to the second transmission terminal; wherein the second transmission band is a pass band and attenuates the reception band; and the first transmission band It is connected between a pass filter and a terminal c of the second switch, and the impedance on the first transmission band pass filter side viewed from the antenna terminal is “open” in the first and second reception bands. The third phase to make And the second transmission band-pass filter and the terminal b of the second switch, and the impedance on the second transmission band-pass filter side viewed from the antenna terminal is the first and And a fourth phase shifter that makes “open” in the second reception band.

  In this configuration, a single reception band-pass filter is shared by the first and second reception bands, and a single reception circuit is also shared. This works particularly useful in a dual-band system in which the reception frequency band interval between the two systems is narrower than the transmission / reception interval frequency.

  The second switch may further include a terminal d connected to an external connector. In this case, the terminal d is connected to the terminal c when the terminal a is connected to the terminal b, and is connected to the terminal b when the terminal a is connected to the terminal c. This second switch can be a DPDT (Dual Pole Dual Throw) type switch. This substantially prevents an increase in switch elements when an external connector is provided.

  A second front-end module according to the present invention includes an antenna terminal, a reception terminal, a first transmission terminal, and a second transmission terminal, and is connected to the reception terminal in the dual-band front-end module. A reception band-pass filter that attenuates the transmission band using the second reception band as a pass band, and is connected to the reception band-pass filter, and the impedance on the reception band-pass filter side as viewed from the antenna terminal is the first A first phase shifter that is “open” in the transmission band and the reception bandpass filter connected to the reception bandpass filter, and the impedance on the reception bandpass filter side viewed from the antenna terminal is “opened” in the second transmission band. And a second phase shifter connected to the other end of each of the first and second phase shifters, which are selectively connected to the amplifier. A switch connected to the first terminal, a first transmission terminal connected to the first transmission band, a first transmission band pass filter that attenuates the reception band with the first transmission band as a pass band, and a second transmission terminal; A second transmission bandpass filter that uses the second transmission band as a passband and attenuates the reception band; and is connected between the first transmission bandpass filter and the antenna terminal, as viewed from the antenna terminal. A third phase shifter that opens the impedance on the first transmission band-pass filter side in the first and second reception bands; the second transmission band-pass filter; and the antenna terminal; And a fourth phase shifter that opens the impedance on the second transmission band-pass filter side viewed from the antenna terminal in the first and second reception bands. The features.

  In this configuration, only one reception band-pass filter is required, and no switch is inserted in the transmission path, so only one switch is required. One switch is enough to be inserted into the path on the receiving side. Therefore, the insertion loss is reduced on either side of transmission / reception.

  The second front-end module further includes a fifth phase shifter, and the switch connects the second phase shifter to the fifth phase shifter when connecting the first phase shifter to the antenna terminal. When the phase shifter is connected and the second phase shifter is connected to the antenna terminal, the fifth phase shifter may be connected to the first phase shifter. As a result, the impedance in the reception band viewed from the phase shift circuit side in the non-selected state can be “opened” from the input of the reception band-pass filter.

  The fifth phase shifter may include two different phase shifters and a second switch that selects one of the two phase shifters in conjunction with the switch. Thereby, the phase shifter suitable for switching of a use band can be used and divided.

  A third front-end module according to the present invention includes an antenna terminal, a reception terminal, a first transmission terminal, and a second transmission terminal, and is connected to the reception terminal in the dual-band front-end module. A reception band-pass filter that attenuates the transmission band using the second reception band as a pass band, and is connected to the reception band-pass filter, and the impedance on the reception band-pass filter side as viewed from the antenna terminal is the first A first phase shifter that is “open” in the transmission band and the reception bandpass filter connected to the reception bandpass filter, and the impedance on the reception bandpass filter side viewed from the antenna terminal is “opened” in the second transmission band. And a second phase shifter connected to the other end of each of the first and second phase shifters, which are selectively connected to the amplifier. A switch connected to the first terminal, a first transmission terminal connected to the first transmission band, a first transmission band pass filter that attenuates the reception band with the first transmission band as a pass band, and a second transmission terminal; A second transmission bandpass filter that uses the second transmission band as a passband and attenuates the reception band; and is connected between the first transmission bandpass filter and the antenna terminal, as viewed from the antenna terminal. A third phase shifter that opens the impedance on the first transmission band-pass filter side in the first and second reception bands; the second transmission band-pass filter; and the antenna terminal; A fourth phase shifter that is connected between the first and second reception bands, and is configured to open the impedance on the second transmission band-pass filter side as viewed from the antenna terminal; Transfer And the switch connects the fifth phase shifter to the second phase shifter when connecting the first phase shifter to the antenna terminal, and the second phase shifter. The fifth phase shifter is connected to the first phase shifter when connecting to the antenna terminal.

  In this configuration, a single reception band-pass filter can be used, and a single switch can be inserted on both the transmission side and the reception side. Moreover, the effect | action of the above 5th phase shifters is also acquired.

  A fourth front-end module according to the present invention includes an antenna terminal, a reception terminal, and a transmission terminal. The front-end module corresponding to the dual band is connected to the reception terminal and uses the first and second reception bands as a pass band. A reception band-pass filter for attenuating the transmission band, and a first band that is connected to the reception band-pass filter and that opens the impedance on the reception band-pass filter side as viewed from the antenna terminal in the first transmission band. And a second phase shifter that is connected to the reception band-pass filter and makes the impedance on the reception band-pass filter side viewed from the antenna terminal “open” in the second transmission band. Connected to the other end of each of the first and second phase shifters and selectively connects them to the antenna terminal. A band rejection filter that is connected to the transmission terminal and that uses the first and second transmission bands as a pass band and attenuates the first and second reception bands; and between the band rejection filter and the antenna terminal. And a third phase shifter that opens the impedance of the band rejection filter side viewed from the antenna terminal in the first and second reception bands.

  In this configuration, not only the reception band-pass filter is single, but also the transmission-side filter can be single by using the band rejection filter. In addition, a single switch can be inserted on the receiving side, and a switch inserted on the transmitting side can be eliminated.

  According to the present invention, the reception frequency band interval between two systems is narrower than the transmission / reception interval frequency, which is suitable for a dual band system, which reduces the number of components used, and is a small and low cost dual band compatible front. An end module and thus a transmission / reception terminal device can be realized. In addition, by reducing the number of components used, loss from the transmission circuit to the antenna can be reduced, and power consumption can be reduced. Furthermore, loss from the antenna to the receiving circuit can be reduced and reception sensitivity can be improved.

  Hereinafter, preferred embodiments of the present invention will be described. In the present embodiment, it is assumed that the front-end module is used in a dual band system in which the reception frequency band interval between two systems is narrower than the transmission / reception interval frequency.

<First Embodiment>
FIG. 9 shows an example of the configuration of the front end module according to the first embodiment of the present invention. The front end module includes a BPF 40 that attenuates the transmission band with the reception band as a pass band, a BPF 41 that attenuates the reception band with the transmission band (a) as a pass band, and a BPF 41 that attenuates the reception band with the transmission band (b) as a pass band. ', The switch 6 and switch 7, the phase shift circuit 42, the phase shift circuit 42', the phase shift circuit 49, and the phase shift circuit 49 'for switching between using the transmission band (a) or the transmission band (b). Composed. The antenna is connected to the terminal 10a, the receiving circuit 2 is connected to the terminal 4b, and the transmitting circuits 3 and 3 'of the transmission bands (a) and (b) are connected to the terminals 10c and 10c ′, respectively. (The same applies to subsequent embodiments). As shown in the figure, the “front-end module” in the present invention is a circuit interposed between the transmission / reception circuit and the antenna of the dual-band system, and has a function of switching transmission / reception of the communication methods of the first and second systems.

  When the transmission band (a) is used, the switch 7 functions so that the terminals 7a and 7c are connected, and the switch 6 functions so that the terminals 6a and 6c are connected in conjunction with the switch 7. The phase shift circuit 42 is a phase shifter in which the electrical length is adjusted so that the impedance viewed from the terminal 6c when viewed from the terminal 6c is “open” in the transmission band (a), and the phase shift circuit 49 is connected from the terminal 6c to the transmission side. This is a phase shifter with the electrical length adjusted so that the impedance seen is “open” in the reception band.

  Further, when the transmission band (b) is used, the switch 7 functions so that the terminals 7 a and 7 b are connected, and the switch 6 functions so that the terminals 6 a and 6 b are connected in conjunction with the switch 7. The phase shift circuit 42 ′ is a phase shifter whose electrical length is adjusted so that the impedance viewed from the terminal 6b when viewed from the reception side is “open” in the transmission band (b), and the phase shift circuit 49 ′ is transmitted from the terminal 6b. This is a phase shifter with the electrical length adjusted so that the impedance viewed from the side becomes “open” in the reception band.

  In this manner, in the front end module shown in FIG. 9, the BPF on the receiving side can be reduced by one as compared with the configuration of FIG. As a result, a small and low-cost front-end module can be realized.

<Modification of the first embodiment>
FIG. 10 shows a modification of the first embodiment of the front end module of the present invention. This is a configuration in which a DPDT (Dual Pole Dual Throw) type switch 8 is used instead of the SPDT (Single Pole Dual Throw) type switch 6 used in the configuration of FIG.

  In a mobile phone terminal, it may be necessary not only to feed a transmission / reception signal only to an antenna but also to switch to an external connector for output. In this case, instead of newly providing a switch after the output terminal 10a in FIG. 9, it is possible to prevent an increase in loss by using the switch 8 as shown in FIG.

  The switch 8 shown in FIG. 10 has two types, a state in which the terminals 8a-8b and the terminals 8c-8d are connected in conjunction with each other, and a state in which the terminals 8a-8c and the terminals 8b-8d are connected in conjunction with each other. For example, when the transmission band (a) is used and the antenna is used, the terminal 8a-8c and the terminals 8b-8d are set to the first state, and the transmission band (a) is set. When the external connector 10 is used, it is set to the second state in which the terminals 8a-8b and the terminals 8c-8d are connected.

<Second Embodiment>
FIG. 11 shows a second embodiment of the front end module of the present invention. The front end module includes a BPF 40 that attenuates the transmission band with the reception band as a pass band, a BPF 41 that attenuates the reception band with the transmission band (a) as a pass band, and a BPF 41 that attenuates the reception band with the transmission band (b) as a pass band. ', Composed of a switch 7, a phase shift circuit 42, a phase shift circuit 42', a phase shift circuit 49, and a phase shift circuit 49 'for switching between using the transmission band (a) or the transmission band (b). . When the transmission band (a) is used, the switch 7 functions so that the terminals 7a and 7b are connected. The phase shift circuit 42 is a phase shifter whose electrical length is adjusted so that the impedance viewed from the terminal 7a when viewed from the terminal 7a is “open” in the transmission band (a), and the phase shift circuit 49 is connected from the terminal 7a to the transmission side. This is a phase shifter in which the electrical length is adjusted so that the viewed impedance is “open” in the reception band and the transmission band (b).

  Further, when the transmission band (b) is used, the switch 7 functions so that the terminals 7a and 7c are connected. The phase shift circuit 42 'is a phase shifter whose electrical length is adjusted so that the impedance viewed from the terminal 7a when viewed from the reception side is "open" in the transmission band (b), and the phase shift circuit 49' is transmitted from the terminal 7a. This is a phase shifter in which the electrical length is adjusted so that the impedance viewed from the side becomes “open” in the reception band and the transmission band (a).

  As described above, the configuration of FIG. 11 reduces the BPF on the reception side by one compared to the configuration of FIG. Further, since the insertion loss of the transmission side switch is reduced, the power consumption can be reduced, and the reception sensitivity can be improved because the insertion loss of the reception side switch is reduced.

<Modification of Second Embodiment>
FIG. 12 shows a configuration of a modification of the second embodiment of the present invention in which a DPDT type switch 8 is used instead of the SPDT type switch 7 used in FIG.

  In the configuration of FIG. 11, for example, when the transmission band (a) is used, the phase shift circuit 42 ′ remains connected to the input of the BPF 40, so that the reception band when the phase shift circuit 42 ′ side is viewed from the input of the BPF 40. If the impedance at is not “open”, the insertion loss of the reception band may deteriorate. In order to improve this, the switch 8 in FIG. 12 is configured so that, for example, when using the transmission band (a), the impedance in the reception band viewed from the input of the BPF 40 as viewed from the phase shift circuit 42 ′ can be “open”. A phase shifter 81 can be connected to the phase shift circuit. The same applies when the transmission band (b) is used. In addition, although the one side of the phase shifter 81 is grounded, a configuration of “opening” may be employed (the same applies to the following embodiments).

  Similarly to FIG. 11, the configuration of FIG. 12 does not pass through the switch from the transmission circuit to the antenna, so there is no need to increase the output power of the transmission circuit, and the power consumption can be reduced as compared with the conventional example.

  Instead of the phase shifter 81, the phase shift circuit 90 of FIG. The phase shifters 82 and 83, and a switch 9 for selecting one of them. For example, the phase shifter 82 is used by connecting the terminals 9a and 9b of the switch 9 when the transmission band (a) is used, and the phase shifter 83 is connected by connecting the terminals 9a and 9c when the transmission band (b) is used. Can be used, phase shifters optimized for the transmission band (a) and the transmission band (b) can be used. As a result, it is possible to more appropriately reduce the insertion loss of the reception band.

<Third Embodiment>
FIG. 14 shows a third embodiment of a front end module according to the present invention. BPF 40 that attenuates the transmission band with the reception band as the pass band, BPF 41 that attenuates the reception band with the transmission band (a) as the pass band, BPF 41 ′ that attenuates the reception band with the transmission band (b) as the pass band, ) Or the transmission band (b). The switch 8, the phase shift circuit 42, the phase shift circuit 42 ′, the phase shift circuit 49, the phase shift circuit 49 ′, and the phase shift circuit 81 are configured.

  The switch 8 in FIG. 14 has two types of states, a first state in which the terminals 8a-8b and the terminals 8c-8d are connected, and a second state in which the terminals 8a-8c and 8b-8d are connected. For example, when the transmission band (a) is used, the terminals 8a-8c and 8b-8d are set to be connected. When the transmission band (b) is used, the terminals 8a-8b are set. And 8c-8d are set to be connected.

  The phase shift circuit 42 is a phase shifter in which the electrical length is adjusted so that the impedance viewed from the terminal 8c when viewed from the terminal 8c is “open” in the transmission band (a), and the phase shift circuit 49 is connected to the transmission side from the terminal 8c. This is a phase shifter with the electrical length adjusted so that the impedance seen is “open” in the reception band.

  The phase shift circuit 42 ′ is a phase shifter whose electrical length is adjusted so that the impedance viewed from the terminal 8c when viewed from the reception side is “open” in the transmission band (b), and the phase shift circuit 49 ′ is the terminal 8c. In this phase shifter, the electrical length is adjusted so that the impedance viewed from the transmission side is “open” in the reception band.

  In this way, the configuration of FIG. 14 reduces the reception-side BPF and switch by one compared to the configuration of FIG. 8-A, and realizes a small and low-cost front-end module. Since the insertion loss 4 of the switch is reduced, the reception sensitivity can be improved. In the configuration of FIG. 14, the phase shift circuit 90 of FIG. 13 can be used instead of the phase shifter 81. For example, the phase shifter 82 is used by connecting the terminals 9a and 9b when the transmission band (a) is used, and the phase shifter 83 is used by connecting the terminals 9a and 9c when the transmission band (b) is used. By doing so, phase shifters optimized for the transmission band (a) and the transmission band (b) can be used, so that the insertion loss of the reception band can be reduced more appropriately.

  In any of the configuration examples of the front-end modules shown in FIGS. 9, 10, 11, 12, and 14, the BPF includes a BPF for a reception band, a BPF for a transmission band (a), and a transmission band (b ) Using only three BPFs, combining other phase shifters and switches, ensuring the attenuation characteristics required for the duplexer, and reducing the insertion loss of the reception filter and transmission filter without increasing the size The low-cost dual band compatible duplexer can be realized.

<Fourth embodiment>
FIG. 15 shows a fourth embodiment of a front end module according to the present invention. A BPF 40 that attenuates the transmission band with the reception band as a pass band, a band elimination filter (BEF) 80 that attenuates the reception band with the transmission band (a) and the transmission band (b) as a pass band, and a transmission band (a) And a phase shift circuit 42, a phase shift circuit 42 ′, and a phase shift circuit 49. When the transmission band (a) is used, the switch 7 functions so that the phase shift circuit 42 and the phase shift circuit 49 are connected. The phase shift circuit 42 is a phase shifter in which the electrical length is adjusted so that the impedance viewed from the antenna terminal 10a when viewed from the antenna terminal is “open” in the transmission band (a), and the phase shift circuit 49 is transmitted from the antenna terminal 10a. This is a phase shifter with the electrical length adjusted so that the impedance viewed from the side becomes “open” in the reception band.

  Further, when the transmission band (b) is used, the switch 7 functions so that the phase shift circuit 42 ′ and the phase shift circuit 49 are connected. The phase shift circuit 42 ′ is a phase shifter in which the electrical length is adjusted so that the impedance viewed from the antenna terminal 10a when viewed from the antenna terminal is “open” in the transmission band (b), and the phase shift circuit 49 ′ is the antenna terminal 10a. In this phase shifter, the electrical length is adjusted so that the impedance viewed from the transmission side is “open” in the reception band. A phase shift circuit that satisfies the above conditions in the reception band can be realized by one of the phase shift circuits 49. However, the phase shift circuit in which the impedance viewed from the reception side is “open” in the transmission band (a) and the transmission band (b). Since the amounts are not the same, the characteristics required of the duplexer are secured by switching the phase shift circuit with the switch 7.

  In this way, the configuration of FIG. 15 is reduced by one BPF and one switch on the receiving side (that is, equivalent to one duplexer and one switch) compared to the configuration of FIG. A small and low-cost front-end module can be realized, and the insertion loss of the transmission side switch can be reduced, so that the power consumption can be reduced, and the insertion loss of the reception / reception side switch is also reduced, so that the reception sensitivity can be improved.

<Modification of Fourth Embodiment>
The configuration of FIG. 16 shows a modification of the fourth embodiment of the present invention in which a DPDT switch 8 is used instead of the SPDT switch 7 used in FIG.

  In the configuration of FIG. 15, for example, when the transmission band (a) is used, the phase shift circuit 42 ′ remains connected to the input of the BPF 40, so the reception band viewed from the input of the BPF 40 to the phase shift circuit 42 ′ side. If the impedance at is not “open”, the insertion loss of the reception band may deteriorate. In order to improve this, the switch 8 in FIG. 16 is, for example, a phase shifter so that the impedance in the reception band seen from the input of the BPF 40 when viewed from the phase shift circuit 42 ′ can be “open” when using the transmission band (a). 81 can be connected.

  Similarly to FIG. 15, the configuration of FIG. 16 does not need to increase the output power of the transmission circuit because the switch does not pass through the path from the transmission circuit to the antenna, and the power consumption can be reduced compared to the conventional example. Also in this configuration, the phase shift circuit 90 of FIG. 13 can be used in place of the phase shifter 81.

  In the configuration example of the front-end module shown in FIG. 15 and FIG. 16, only two filters of a reception band BPF and a band elimination filter (BEF) that attenuates the reception band and passes two transmission bands are used. In combination with other phase shifters and switches, it is possible to realize a duplexer compatible with a small, low-cost dual band while ensuring the attenuation characteristics required for the duplexer.

It is a block diagram which shows the structure of the conventional dual band portable telephone terminal. It is a block diagram which shows the other structure of the conventional dual band portable telephone terminal. It is a circuit diagram which shows the structural example of a diplexer. It is a circuit diagram which shows the other structural example of a diplexer. FIG. 3 is a circuit diagram illustrating a configuration example of a receiving circuit illustrated in FIGS. 1 and 2. FIG. 3 is a circuit diagram illustrating a configuration example of a transmission circuit illustrated in FIGS. 1 and 2. It is a circuit diagram which shows the structural example of the conventional duplexer. It is a circuit diagram which shows the other structural example of the conventional duplexer. It is a block diagram which shows the structure of the dual band mobile telephone terminal which comprised the receiving circuit used by a several frequency band only by 1 system | strain. It is a block diagram which shows the structure of the dual band mobile telephone terminal which comprised the transmission circuit and receiving circuit which are used in a some frequency band only by one system each. It is a circuit diagram showing an example of composition of a front end module concerning a 1st embodiment of the present invention. It is a circuit diagram which shows the structural example of the front end module which concerns on the modification of the 1st Embodiment of this invention. It is a circuit diagram which shows the structural example of the front end module which concerns on the 2nd Embodiment of this invention. It is a circuit diagram which shows the structural example of the front end module which concerns on the modification of the 2nd Embodiment of this invention. It is a circuit diagram which shows the circuit replaced with the phase shifter 81 in the front end module of FIG. It is a circuit diagram which shows the structural example of the front end module which concerns on the 3rd Embodiment of this invention. It is a circuit diagram which shows the structural example of the front end module which concerns on the 4th Embodiment of this invention. It is a circuit diagram which shows the structural example of the front end module which concerns on the modification of the 4th Embodiment of this invention. It is explanatory drawing of the use band of the dual band mobile phone terminal of CDMA for Japan and CDMA for the United States.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Antenna, 4 ... Duplexer, 2 ... Reception circuit, 3 ... Transmission circuit, 5 ... Diplexer, 6 ... Switch, 6a, 6b, 6c ... Terminal, 7a, 7b, 7c ... Terminal, 7 ... Switch, 8 ... Switch, 8a, 8b, 8c, 8d ... terminal, 9 ... switch, 9a, 9b, 9c ... terminal, 10 ... external connector, 10a, 10b, 10c, 10d ... terminal, 11 ... switch, 40, 41, 41 '... band pass Filter (BPF), 42, 42 ', 49, 49' ... Phase shift circuit, 80 ... Band stop filter (BEF), 81, 82, 83 ... Phase shifter, 90 ... Phase shift circuit

Claims (15)

In the front end module corresponding to the dual band, comprising an antenna terminal, a reception terminal, a first transmission terminal, a second transmission terminal,
A reception band-pass filter that is connected to the reception terminal and attenuates the transmission band with the first and second reception bands as a pass band;
A first switch having a terminal a and other terminals b and c connected to the receiving bandpass filter, and selectively connecting the terminals b and c to the terminal a;
A second switch having a terminal a and other terminals b and c connected to the antenna terminal, and selectively connecting the terminals b and c to the terminal a in conjunction with the first switch;
The first switch is connected between the terminal c of the first switch and the terminal c of the second switch, and the impedance on the reception band-pass filter side viewed from the antenna terminal is “open” in the first transmission band. 1 phase shifter,
Connected between the terminal b of the first switch and the terminal b of the second switch, the impedance on the reception band-pass filter side viewed from the antenna terminal is “open” in the second transmission band. A second phase shifter;
A first transmission bandpass filter connected to the first transmission terminal and having a first transmission band as a passband and attenuating a reception band;
A second transmission band-pass filter connected to the second transmission terminal and having a second transmission band as a pass band and attenuating the reception band;
The first transmission band-pass filter is connected between the first transmission band-pass filter and the terminal c of the second switch, and the impedances on the first transmission band-pass filter side as viewed from the antenna terminal are the first and second impedances. A third phase shifter that “opens” in the reception band of
The second transmission band-pass filter is connected between the second transmission band-pass filter and the terminal b of the second switch, and the impedance on the second transmission band-pass filter side viewed from the antenna terminal is set to the first and second impedances. A fourth phase shifter that “opens” in the reception band of
A front-end module characterized by comprising:   2. The front end module according to claim 1, wherein the first and second switches are SPDT (Single Pole Dual Throw) type switches.   The second switch further has a terminal d connected to an external connector, which is connected to the terminal c when the terminal a is connected to the terminal b, and the terminal a is connected to the terminal c. 2. The front end module according to claim 1, wherein the front end module is connected to a terminal b.   4. The front end module according to claim 3, wherein the second switch is a DPDT (Dual Pole Dual Throw) type switch. In the front end module corresponding to the dual band, comprising an antenna terminal, a reception terminal, a first transmission terminal, a second transmission terminal,
A reception band-pass filter that is connected to the reception terminal and attenuates the transmission band with the first and second reception bands as a pass band;
A first phase shifter connected to the reception band-pass filter and opening the impedance on the reception band-pass filter side viewed from the antenna terminal in the first transmission band;
A second phase shifter connected to the reception band-pass filter to make the impedance on the reception band-pass filter side viewed from the antenna terminal “open” in a second transmission band;
A switch connected to the other end of each of the first and second phase shifters and selectively connecting them to the antenna terminal;
A first transmission bandpass filter connected to the first transmission terminal and having a first transmission band as a passband and attenuating a reception band;
A second transmission band-pass filter connected to the second transmission terminal and having a second transmission band as a pass band and attenuating the reception band;
The first transmission band-pass filter is connected between the first transmission band-pass filter and the antenna terminal, and the impedance on the first transmission band-pass filter side viewed from the antenna terminal in the first and second reception bands. A third phase shifter to be "open";
The second transmission band-pass filter is connected between the second transmission band-pass filter and the antenna terminal, and the impedance on the second transmission band-pass filter side as viewed from the antenna terminal in the first and second reception bands. A fourth phase shifter to be "open";
A front-end module characterized by comprising:   The switch further comprises a fifth phase shifter, and the switch connects the fifth phase shifter to the second phase shifter when connecting the first phase shifter to the antenna terminal, 6. The front end module according to claim 5, wherein when the second phase shifter is connected to the antenna terminal, the fifth phase shifter is connected to the first phase shifter.   The front end module according to claim 6, wherein the second switch is a DPDT type switch.   6. The front end according to claim 5, wherein the fifth phase shifter includes two different phase shifters and a second switch that selects one of the two phase shifters in conjunction with the switch. module.   9. The front end module according to claim 4, wherein the switch is an SPDT type switch. In the front end module corresponding to the dual band, comprising an antenna terminal, a reception terminal, a first transmission terminal, a second transmission terminal,
A reception band-pass filter that is connected to the reception terminal and attenuates the transmission band with the first and second reception bands as a pass band;
A first phase shifter connected to the reception band-pass filter and opening the impedance on the reception band-pass filter side viewed from the antenna terminal in the first transmission band;
A second phase shifter connected to the reception band-pass filter to make the impedance on the reception band-pass filter side viewed from the antenna terminal “open” in a second transmission band;
A switch connected to the other end of each of the first and second phase shifters and selectively connecting them to the antenna terminal;
A first transmission bandpass filter connected to the first transmission terminal and having a first transmission band as a passband and attenuating a reception band;
A second transmission band-pass filter connected to the second transmission terminal and having a second transmission band as a pass band and attenuating the reception band;
The first transmission band-pass filter is connected between the first transmission band-pass filter and the antenna terminal, and the impedance on the first transmission band-pass filter side viewed from the antenna terminal in the first and second reception bands. A third phase shifter to be "open";
The second transmission band-pass filter is connected between the second transmission band-pass filter and the antenna terminal, and the impedance on the second transmission band-pass filter side as viewed from the antenna terminal in the first and second reception bands. A fourth phase shifter to be "open";
A fifth phase shifter,
The switch connects the fifth phase shifter to the second phase shifter and connects the second phase shifter to the antenna terminal when connecting the first phase shifter to the antenna terminal. A front end module comprising: connecting the fifth phase shifter to the first phase shifter when connecting.   The front end module according to claim 10, wherein the switch is a DPDT type switch. In front end module that has antenna terminal, receiving terminal, transmitting terminal and supports dual band,
A reception band-pass filter that is connected to the reception terminal and attenuates the transmission band with the first and second reception bands as a pass band;
A first phase shifter connected to the reception band-pass filter and opening the impedance on the reception band-pass filter side viewed from the antenna terminal in the first transmission band;
A second phase shifter connected to the reception band-pass filter to make the impedance on the reception band-pass filter side viewed from the antenna terminal “open” in a second transmission band;
A switch connected to the other end of each of the first and second phase shifters and selectively connecting them to the antenna terminal;
A band rejection filter connected to a transmission terminal and having the first and second transmission bands as a pass band and attenuating the first and second reception bands;
A third phase shifter that is connected between the band rejection filter and the antenna terminal and makes the impedance on the band rejection filter side viewed from the antenna terminal “open” in the first and second reception bands. When,
A front-end module characterized by comprising:   The front end module according to claim 12, wherein the switch is an SPDT type switch.   The switch further comprises a fifth phase shifter, and the switch connects the fifth phase shifter to the second phase shifter when connecting the first phase shifter to the antenna terminal, 13. The front end module according to claim 12, wherein when the second phase shifter is connected to the antenna terminal, the fifth phase shifter is connected to the first phase shifter.   15. The front end module according to claim 14, wherein the switch is a DPDT type switch.

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