JPWO2013118240A1 - Filter circuit and module - Google Patents

Abstract

A first band-pass filter 12, a second band-pass filter 14, a third band-pass filter 16, a fourth band-pass filter 18 each having an input terminal Tin and an output terminal Tout, and an input terminal of the first band-pass filter And a first terminal T1 in which one of the input terminal and the output terminal of the second bandpass filter is connected in common, and an input terminal and an output terminal of the third bandpass filter A second terminal T2 commonly connected to the one of the input terminal and the output terminal of the fourth bandpass filter, the other of the input terminal and the output terminal of the first bandpass filter, A third terminal T3 commonly connected to the other of the input terminal and the output terminal of the fourth bandpass filter; Filter circuit comprising said other input terminal and the output terminal of the bandpass filter, wherein the other input terminal and the output terminal of the third band-pass filter, and a fourth terminal T4 which are connected in common, the.

Description

  The present invention relates to a filter circuit and a module, for example, a filter circuit and a module having a plurality of bandpass filters.

  For example, in a mobile communication terminal, a plurality of band pass filters are used corresponding to various communication methods. The plurality of band-pass filters are combined into one component as one filter circuit, for example.

  Patent Document 1 describes that a duplexer is formed by using four band pass filters. Four band pass filters are integrated as one module.

Special table 2003-517239 gazette

  When a plurality of filters are used as one filter circuit, each filter has an input terminal and an output terminal. For this reason, the filter circuit has many terminals.

  The present invention has been made in view of the above problems, and an object thereof is to reduce the number of terminals of a filter circuit.

  The present invention includes a first bandpass filter, a second bandpass filter, a third bandpass filter, and a fourth bandpass filter each having an input terminal and an output terminal, and an input terminal and an output of the first bandpass filter. One of the terminals and the one of the input terminal and the output terminal of the second bandpass filter, and the one of the input terminal and the output terminal of the third bandpass filter. A second terminal commonly connected to the one of the input terminal and the output terminal of the fourth bandpass filter, the other of the input terminal and the output terminal of the first bandpass filter, and the fourth band. A third terminal commonly connected to the other of the input terminal and the output terminal of the pass filter; and an input terminal of the second band pass filter. Wherein the other fine output terminal, a filter circuit characterized by comprising a fourth terminal, the said the other input terminal and an output terminal, are connected in common of the third band-pass filter. According to the present invention, the number of terminals of the filter circuit can be reduced.

  In the above configuration, passbands of the first bandpass filter, the second bandpass filter, the third bandpass filter, and the fourth bandpass filter may be different from each other.

  In the above configuration, the passbands of the first bandpass filter and the second bandpass filter may be lower than the passbands of the third bandpass filter and the fourth bandpass filter.

  In the above configuration, the first terminal is a terminal connected to a first amplifier, the second terminal is a terminal connected to a second amplifier, and the third terminal and the fourth terminal are It can be set as the structure which is a terminal to which the switch which selects any one of a 3rd terminal and the said 4th terminal and connects to an antenna is connected.

  In the above configuration, at least one of the first terminal and the second terminal may be a balanced terminal.

  The present invention is a module including the filter circuit.

  The present invention is a module comprising the filter circuit and a switch for selecting one of the third terminal and the fourth terminal.

  The present invention is a module comprising the filter circuit, a first amplifier connected to the first terminal, and a second amplifier connected to the second terminal.

  The present invention provides the filter circuit, a switch for selecting one of the third terminal and the fourth terminal, a first amplifier connected to the first terminal, and a second terminal. And a second amplifier.

  According to the present invention, the number of terminals of the filter circuit can be reduced.

FIG. 1A is a circuit diagram of a filter circuit according to the first embodiment, and FIG. 1B is a circuit diagram of a filter circuit according to a comparative example. FIG. 2 is a circuit diagram of a receiving circuit in which the first embodiment is used. FIG. 3 is a circuit diagram of a receiving circuit in which the second embodiment is used. FIG. 4 is a circuit diagram of a module according to the third embodiment and its surroundings. FIG. 5 is a circuit diagram of a module according to a first modification of the third embodiment and its surroundings. FIG. 6 is a circuit diagram of a module according to a second modification of the third embodiment and its surroundings.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1A is a circuit diagram of a filter circuit according to the first embodiment, and FIG. 1B is a circuit diagram of a filter circuit according to a comparative example. Referring to FIG. 1A, the filter circuit 10 according to the first embodiment includes a first BPF (bandpass filter) 12, a second BPF 14, a third BPF 16, and a fourth BPF 18. Each of the BPFs 12 to 18 has an input terminal Tin and an output terminal Tout. A high frequency signal is input to the input terminal Tin. Each of the BPFs 12 to 18 passes a signal in a pass band among high-frequency signals and suppresses signals of other frequencies. A filtered high frequency signal is output from the output terminal Tout. The output terminal Tout of the first BPF 12 and the output terminal Tout of the second BPF 14 are electrically connected in common to the first terminal T1. The output terminal Tout of the third BPF 16 and the output terminal Tout of the fourth BPF 18 are electrically connected in common to the second terminal T2. The input terminal Tin of the first BPF 12 and the input terminal Tin of the fourth BPF 18 are electrically connected in common to the third terminal T3. The input terminal Tin of the second BPF 14 and the input terminal Tin of the third BPF 16 are electrically connected in common to the fourth terminal T4.

  1B, in the filter circuit 10a of the comparative example, the output terminal Tout of the first BPF 12 and the output terminal Tout of the second BPF 14 are commonly connected to the first terminal T1, and the second terminal T2 is connected to the second terminal T2. Are connected in common to the output terminal Tout of the third BPF 16 and the output terminal Tout of the fourth BPF 18. However, the input terminals Tin of the first BPF 12 to the fourth BPF 18 are connected to the terminals T31, T32, T41, and T42, respectively.

  According to the first embodiment, the number of terminals to which the high frequency signal of the filter circuit is input or output can be reduced as compared with the comparative example. For example, the filter circuit 10 may have a form in which the BPFs 12 to 18 are mounted in one package. Alternatively, the BPFs 12 to 18 may be mounted on one mounting board. Each of the BPFs 12 to 18 may be an elastic wave filter using a surface acoustic wave resonator, a Love wave resonator, a boundary acoustic wave resonator, or a piezoelectric thin film resonator. The acoustic wave filter may include a ladder filter or / and a multimode filter. Each BPF 12 to 18 may be an LC filter.

  An example of a circuit in which the first embodiment is used will be described. FIG. 2 is a circuit diagram of a receiving circuit in which the first embodiment is used. The receiving circuit 100 includes an antenna 22, a switch 20, a filter circuit 10, and an amplifier circuit 30. The amplifier circuit 30 includes LNAs (low noise amplifiers) 32 and 34. The passbands of the BPFs 12 to 18 are different from each other. For example, the passbands of BPFs 12 to 18 do not overlap each other. For example, the first BPF 12 is a GSM (registered trademark) 850 reception filter having a reception band of 869 MHz to 894 MHz. The second BPF 14 is a GSM900 reception filter having a reception band of 925 MHz to 960 MHz. The third BPF 16 is a GSM1800 reception filter having a reception band of 1805 MHz to 1880 MHz. The fourth BPF 18 is a GSM1900 reception filter having a reception band of 1930 MHz to 1990 MHz.

  The first BPF 12 reflects the signal in the pass band of the fourth BPF 18, passes the signal in the pass band of the first BPF 12, and the fourth BPF 18 reflects the signal in the pass band of the first BPF 12, and passes the signal in the pass band of the fourth BPF 18. Thus, the impedance when the first BPF 12 and the fourth BPF 18 are viewed from the third terminal T3 is set. For example, a matching circuit may be provided between the third terminal T3 and the first BPF 12 and the fourth BPF 18 so that the impedance is set as described above.

  The second BPF 14 reflects a signal in the pass band of the third BPF 16, passes a signal in the pass band of the second BPF 14, and the third BPF 16 reflects a signal in the pass band of the second BPF 14, and a signal in the pass band of the third BPF 16 Is set so that the second BPF 14 and the third BPF 16 are seen from the fourth terminal T34. For example, a matching circuit may be provided between the fourth terminal T4 and the second BPF 14 and the third BPF 16 so that the impedance is set as described above.

  The first BPF 12 reflects the signal in the pass band with the second BPF 14, and the second BPF 14 reflects the signal in the pass band of the first BPF 12, and the impedance viewed from the first terminal T1 of the first BPF 12 and the second BPF 14 is set. ing. For example, a matching circuit may be provided between the first terminal T1 and the first BPF 12 and the second BPF 14 so that the impedance is set as described above.

  The impedance as viewed from the second terminal T2 of the third BPF 16 and the fourth BPF 18 is set so that the third BPF 16 reflects the signal in the pass band with the fourth BPF 18, and the fourth BPF 18 reflects the signal in the pass band with the third BPF 16. ing. For example, a matching circuit may be provided between the second terminal T2 and the third BPF 16 and the fourth BPF 18 so that the impedance is set as described above.

  The switch 20 selects either the third terminal T3 or the fourth terminal T4 and electrically connects it to the antenna 22. Thereby, the signal received by the antenna 22 is input to one of the third terminal T3 and the fourth terminal T4.

  Among the signals input to the third terminal T3, the signal in the pass band of the first BPF 12 is output from the first terminal T1. Among the signals input to the third terminal T3, the signal in the pass band of the fourth BPF 18 is output from the second terminal T2. Similarly, among the signals input to the fourth terminal T4, the signal in the pass band of the second BPF 14 is output from the first terminal T1. Among the signals input to the fourth terminal T4, the signal in the pass band of the third BPF 16 is output from the second terminal T2.

  The signal output from the first terminal T1 is amplified by the LNA 32 and output from the terminal 42. The signal output from the second terminal T2 is amplified by the LNA 34 and output from the terminal 44. A broadband amplifier with good performance is difficult to realize. For example, the first BPF 12 passes a GSM850 received signal, and the second BPF 14 passes a GSM900 received signal. Since the LNA 32 amplifies a signal having a frequency close to that of the GSM850 reception signal and the GSM900 reception signal, the number of the LNAs 32 corresponding to the first BPF 12 and the second BPF 14 may be one. As a result, the output terminals Tout of the first BPF 12 and the second BPF 14 can be shared. Similarly, since the LNA 34 amplifies a signal having a frequency close to that of the received signal of the GSM 1800 and the received signal of the GSM 1900, the number of the LNA 34 corresponding to the third BPF 16 and the fourth BPF 18 may be one. As a result, the output terminals Tout of the third BPF 16 and the fourth BPF 18 can be shared.

  According to the first embodiment, the passbands of the first BPF 12 and the second BPF 14 are lower than the passbands of the third BPF 16 and the fourth BPF 18. Thereby, the signal which passed BPF with a close pass band can be amplified using the same LNA. Therefore, the LNA can be shared without using a broadband amplifier. On the other hand, the third terminal T3 is connected to the input terminals Tin of the first BPF 12 and the fourth BPF 18 having a pass band having a relatively large frequency difference. The fourth terminal T4 is connected to the input terminals Tin of the second BPF 14 and the third BPF 16 having a pass band having a relatively large frequency difference. Thus, when the switch 20 outputs the signal from the antenna 22 to the third terminal T3, the received signal of the GSM850 is amplified and output from the terminal 42. A received signal of GSM1900 is amplified from terminal 44 and output. On the other hand, when the switch 20 outputs the signal from the antenna 22 to the fourth terminal T4, the received signal of GSM900 is amplified and output from the terminal. The received signal of GSM 1800 is amplified from terminal 44 and output. As described above, the filter circuit 10 according to the first embodiment can reduce the number of terminals to which high-frequency signals are input or output as compared with the comparative example.

  Further, GSM850 and GSM1900 are communication systems mainly used in the United States. GSM900 and GSM1800 are communication systems mainly used in Europe. A BPF for a communication method used in the same area is connected to the third terminal T3 and the fourth terminal T4. For example, when used in the United States, the switch 20 selects the third terminal T3. As a result, the reception signals of the communication method used in the United States are simultaneously output to the terminals 42 and 44. For example, when used in Europe, the switch 20 selects the fourth terminal T4. As a result, a reception signal of a communication method used in Europe is simultaneously output to the terminal 42 and the terminal 44.

  The second embodiment is an example in which the output terminal of each BPF is a balanced output. FIG. 3 is a circuit diagram of a receiving circuit in which the second embodiment is used. Compared to FIG. 2, the output terminals Tout of the BPFs 12 to 18 are balanced outputs. A balanced signal is input to the LNAs 32 and 34. Therefore, two first terminals T11 and T12 and two second terminals T21 and T22 are provided. Other configurations are the same as those in FIG. As in the second embodiment, the first terminals T11 and T12 and the second terminals T21 and T22 may be balanced terminals, respectively. That is, at least one of the first terminal and the second terminal may be a balanced terminal.

  The third embodiment is an example of a module including the filter circuit according to the first and second embodiments. FIG. 4 is a circuit diagram of a module according to the third embodiment and its surroundings. As shown in FIG. 4, the module 50 a includes the switch 20 and the filter circuit 10 according to the first or second embodiment. In the module 50a, for example, the switch 20 and the filter circuit 10 are mounted on a wiring board or the like. The module 50a includes a terminal T50 connected to the switch 20, a terminal T51 connected to the first terminal T1, and a terminal T52 connected to the second terminal T2. Other configurations are the same as those of the first embodiment shown in FIG.

  FIG. 5 is a circuit diagram of a module according to a first modification of the third embodiment and its surroundings. As illustrated in FIG. 5, the module 50 b includes an amplifier circuit 30 and the filter circuit 10 according to the first or second embodiment. In the module 50b, for example, the amplifier circuit 30 and the filter circuit 10 are mounted on a wiring board or the like. The module 50b is electrically connected to the output of the terminal T53 electrically connected to the third terminal T3, the terminal T54 electrically connected to the fourth terminal T4, the terminal T55 electrically connected to the output of the LNA 32, and the output of the LNA 34. The terminal T56 to be connected is provided. Other configurations are the same as those of the first embodiment shown in FIG.

  FIG. 6 is a circuit diagram of a module according to a second modification of the third embodiment and its surroundings. As illustrated in FIG. 6, the module 50 c includes the switch 20, the amplifier circuit 30, and the filter circuit 10 according to the first or second embodiment. In the module 50c, for example, the switch 20, the amplifier circuit 30, and the filter circuit 10 are mounted on a wiring board or the like. The module 50c includes a terminal T50 electrically connected to the switch 20, a terminal T55 electrically connected to the output of the LNA 32, and a terminal T56 electrically connected to the output of the LNA 34. Other configurations are the same as those of the first embodiment shown in FIG.

  As in the third embodiment and its modifications, the module may include the filter circuit 10 of the first or second embodiment.

  In the first to third embodiments, the first terminal T1 and the second terminal T2 are connected to the output terminals Tout of the BPFs 12 to 18, and the third terminal T3 and the fourth terminal T4 are connected to the input terminals Tin of the BPFs 12 to 18. An example of connection has been described. The first terminal T1 and the second terminal T2 may be connected to the input terminals Tin of the BPFs 12 to 18, and the third terminal T3 and the fourth terminal T4 may be connected to the output terminals Tout of the BPFs 12 to 18. In this case, the transmission signal amplified by the power amplifier (PA) is input to the first terminal T1. Further, the transmission signal amplified by another power amplifier is input to the second terminal T2.

  As described above, one of the input terminal Tin and the output terminal Tout of each BPF 12 to 18 is connected to the first terminal T1 or T2, and the other of the input terminal Tin and the output terminal Tout is connected to the third terminal T3 or T4. It only has to be. It is sufficient that the first amplifier (LNA or PA) is connected to the first terminal T1, and the second amplifier (LNA or PA) is connected to the second terminal T2.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

10 Filter circuit 12 1st BPF
14 Second BPF
16 3rd BPF
18 4th BPF
20 switch 22 antenna 30 amplifier circuit 32 LNA
34 LNA
T1 1st terminal T2 2nd terminal T3 3rd terminal T4 4th terminal

Claims (9)

A first bandpass filter, a second bandpass filter, a third bandpass filter, and a fourth bandpass filter each having an input terminal and an output terminal;
A first terminal in which one of the input terminal and the output terminal of the first bandpass filter and the one of the input terminal and the output terminal of the second bandpass filter are connected in common;
A second terminal in which the one of the input terminal and the output terminal of the third bandpass filter and the one of the input terminal and the output terminal of the fourth bandpass filter are connected in common;
A third terminal in which the other of the input terminal and the output terminal of the first bandpass filter and the other of the input terminal and the output terminal of the fourth bandpass filter are connected in common;
A fourth terminal in which the other of the input terminal and the output terminal of the second bandpass filter and the other of the input terminal and the output terminal of the third bandpass filter are connected in common. A characteristic filter circuit.   2. The filter circuit according to claim 1, wherein pass bands of the first bandpass filter, the second bandpass filter, the third bandpass filter, and the fourth bandpass filter are different from each other.   3. The filter circuit according to claim 1, wherein pass bands of the first band pass filter and the second band pass filter are lower than pass bands of the third band pass filter and the fourth band pass filter. 4. .   The first terminal is a terminal connected to a first amplifier, the second terminal is a terminal connected to a second amplifier, and the third terminal and the fourth terminal are the third terminal and The filter circuit according to claim 3, wherein the filter circuit is a terminal to which a switch that selects one of the fourth terminals and connects to the antenna is connected.   5. The filter circuit according to claim 1, wherein at least one of the first terminal and the second terminal is a balanced terminal. 6.   A module comprising the filter circuit according to claim 1. A filter circuit according to claim 3;
A switch comprising: a switch that selects one of the third terminal and the fourth terminal and connects the selected terminal to an antenna. A filter circuit according to claim 3;
A first amplifier connected to the first terminal;
A second amplifier connected to the second terminal;
A module comprising: A filter circuit according to claim 3;
A switch that selects any one of the third terminal and the fourth terminal and connects to the antenna;
A first amplifier connected to the first terminal;
A second amplifier connected to the second terminal;
A module comprising:

Images