Abstract:
A power amplifier system including: M main power amplifiers and one standby power amplifier, where M is a positive integer; an input switching module, connected to the inputs of the M main power amplifiers and the standby power amplifier; an output switching module, connected to the outputs of the M main power amplifiers and the standby power amplifier. In the system, M groups of signals are inputted to the input switching module, processed by the power amplifiers, and then outputted from the output switching module. The standby power amplifier is independent and is capable of taking place of the faulted main power amplifier immediately without a shut down. In the system there is no correlation between the isolation of various signals and the consistency of the power amplifies, which leads to a substantial decrease of the requirement on consistency of the power amplifiers.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of Chinese Patent Application No. 200510130296.X filed on Dec. 8, 2005. The disclosure of the above application is incorporated herein by reference.  
       FIELD  
       [0002]     The present disclosure relates to power amplifier technologies, and particularly, relates to a standby and concurring system of a power amplifier and a method for power amplifying.  
       BACKGROUND  
       [0003]     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.  
         [0004]     With the development of mobile communications, radio frequency power amplifiers are widely used in wireless access systems and microwave systems for signals amplifying, and become an important part of the systems. In a Code Division Multiple Access (CDMA) wireless access multi-carrier system, there is only one power amplifier in each sector. If the power amplifier of a sector goes wrong, the connection to the mobile terminals of the sector will fail. Therefore, the CDMA wireless access multi-carrier system puts a great emphasis upon the stability and reliability of the power amplifiers.  
         [0005]     Power amplifiers may go wrong easily because of the high-current and high-voltage working conditions and the poor thermal environment. It is necessary to develop standby techniques for power amplifiers so as to improve the stability. The so-called standby refers to: there are two same power amplifiers in the system; in normal state, one of the two power amplifiers is a working power amplifier and the other is a standby power amplifier; when the working power amplifier goes wrong, the standby power amplifier will automatically switch to the working state to take on the operation of the faulted one without a power cut. Besides, a concurring technology is proposed to increase the output power of a power amplifier system, wherein two same power amplifiers in a parallel connection are inputted with the same signals, perform the same operations, and output the same signals, so as to increase the processing capability and output power of the power amplifier system.  
         [0006]     A standby and concurring solution of the power amplifier according to the prior art is shown in  FIG. 1 . According to  FIG. 1 , the system in the prior art includes a pre-hybrid matrix, a power amplifier matrix, a post-hybrid matrix, two matching resistors R and antennae S 1 , S 2  and S 3 . The pre-hybrid matrix and the post-hybrid matrix both include four 3 dB electric bridges, respectively, with the pre-hybrid matrix providing a function of dividing signals and the post-hybrid matrix providing a function of combining signals. The power amplifier matrix includes four power amplifiers PA 1 , PA 2 , PA 3 , and PA 4 , each of which jointly amplifies the signals of the three sectors inputted from the inputs IN 1 , IN 2 , IN 3  respectively. The transmission lines A 1 , A 2 , A 3 , A 4  in  FIG. 1  have the same length, so do transmission lines B 1 , B 2 , B 3 , B 4 , transmission lines C 1 , C 2 , C 3 , C 4 , and transmission lines D 1 , D 2 , D 3 , D 4 .  
         [0007]     The input signal from IN 1  is divided into 4 equal-amplitude signals after passing through the pre-hybrid matrix and then goes to the inputs of the four power amplifiers. Then the four signals are amplified by the power amplifier matrices respectively, combined to one signal by the post-hybrid matrix, and sent to the antenna S 1  of sector  1 . Depending on the phase superposition of the multiple signals, in an ideal situation, the input signal from IN 1 , after being divided, amplified and combined, will neither be outputted at the ports of antennae S 2  and S 3 , nor appear on the matching resistor.  
         [0008]     Likewise, the input signal from IN 2  is outputted to the antenna S 2  rather than S 1 , S 3  or the matching resistor R after being divided by the pre-hybrid matrix, amplified by the power amplifier matrix and combined by the post-hybrid matrix; the input signal from IN 3  is outputted to the antenna S 3  rather than S 1 , S 2  or the matching resistor R after being divided by the pre-hybrid matrix, amplified by the power amplifier matrix and combined by the post-hybrid matrix.  
         [0009]     When any one of the power amplifiers in  FIG. 1  goes wrong, the three remaining power amplifiers still work normally. The input signals from IN 1 , IN 2 , and IN 3  can go to the antenna S 1 , S 2 , and S 3 , respectively, after being amplified by the system. Thus the mobile terminals of all the three sectors can access the system and it will not happen that no terminal in one sector is able to access the system.  
         [0010]     While being combined by the post-hybrid matrix, the hybrid signal divided by the pre-hybrid matrix will be counteracted from the signals of other sectors depending on the differences in amplitude and phase among the signals, therefore, the requirement on the amplitude and phase of the signals is very strict in the system. If the amplitude relationship and the phase relationship among the signals can not meet the requirement, the signals will not be fully counteracted, thus leading to a cross-interference and a poorer isolation between the sectors. Such is a fatal defect of a power amplifier system.  
         [0011]     The following factors will have an impact on the amplitude relationship and the phase relationship among the signals while the signals are divided and combined:  
         [0012]     1. Factors in design or technology may make the coupling of the 3 dB electric bridge coupler not be the ideal 3 dB. Even an ideal 3 dB electric bridge coupler can meet the requirement of phase and amplitude simultaneously only at the center frequency, and it is theoretically impossible to simultaneously meet the requirements on amplitude and phase differences at a frequency departing from the center frequency.  
         [0013]     2. If the four transmission lines A 1 , A 2 , A 3  and A 4  in the pre-hybrid matrix have different lengths, or the transmission lines B 1 , B 2 , B 3  and B 4  connecting the pre-hybrid matrix and the power amplifier matrix have different lengths, or the transmission lines C 1 , C 2 , C 3 , C 4  connecting the power amplifier matrix and the post-hybrid matrix have different lengths, or the transmission lines D 1 , D 2 , D 3 , D 4  in the post-hybrid matrix have different lengths, there will be an additional phase difference.  
         [0014]     3. The dispersion characteristic mainly resulted from the gain and phase differences among the power amplifiers PA 1 , PA 2 , PA 3 , and PA 4  calls for a strict matching among these power amplifiers. A typical requirement on gain difference is less than 0.5 dB while the requirement on phase difference is usually less than 10°.  
         [0015]     All the above factors can lead to a poorer isolation between the sectors. With the ordinary technology, it is very difficult to achieve the sector isolation of 25 dB while the performance of 25 dB is unable to meet the protocol requirement of CDMA systems, as well as the requirement on the adjacent frequency interference in the case of special sector configurations. In other words, the requirement on signals isolation between adjacent sectors will not be met with the solution in the prior art.  
         [0016]     In commercial applications of the solution according to the prior art, it is necessary to find another power amplifier having exactly the same characteristics of gain and phase as the replaced amplifier when a power amplifier should be replaced, which is very difficult.  
       SUMMARY  
       [0017]     A power amplifier system with standby and concurring functions as well as a method for power amplifying is disclosed in embodiments of the present invention, and the technical solution is as follows:  
         [0018]     A power amplifier system, includes:  
         [0019]     M main power amplifiers, wherein M is a positive integer;  
         [0020]     a standby power amplifier;  
         [0021]     an input switching module, connecting to inputs of the M main power amplifiers and an input of the standby power amplifier, respectively; and  
         [0022]     an output switching module, connecting to outputs of the M main power amplifiers and an output of the standby power amplifier, respectively;  
         [0023]     wherein, after being selected by the input switching module, M groups of signals are respectively inputted to one main power amplifier or the standby power amplifier and outputted by the output switching module.  
         [0024]     After being selected by the input switching module, M- 1  groups of signals are respectively inputted to one main power amplifier and outputted by the output switching module; the other group of signals are inputted to one main power amplifier and the standby amplifier and outputted by the output switching module.  
         [0025]     A method for power amplifying, applied in a system including M main power amplifiers, one standby power amplifier, an input switching module respectively connecting to inputs of the M main power amplifiers and an input of the standby power amplifier, and an output switching module respectively connecting to outputs of the M main power amplifiers and an output of the standby power amplifier, wherein M is a positive integer, includes:  
         [0026]     M groups of signals being respectively inputted to the M main power amplifier via the input switching module, and outputted by the output switching module after being respectively processed by the M main power amplifier;  
         [0027]     when any first main power amplifier goes wrong, switching the input switching module and the output switching module;  
         [0028]     the group of signals that are originally processed by the first main power amplifier being processed by the standby power amplifier.  
         [0029]     As can be seen from the above solution, as a separate standby power amplifier is provided besides the main power amplifiers in the embodiments of the invention, when any one of the main power amplifiers goes wrong, the standby power amplifier can take place of the faulted main power amplifier immediately without a power cut or a shut-down; when any one of the main power amplifiers calls for concurring, the standby power amplifier can work together with the main power amplifier requiring concurring in parallel connection so as to increase the output power of the corresponding signal. Either the main power amplifier or the standby power amplifier amplifies just one group of signals, thus the isolation between groups of signals has nothing to do with the consistency of the power amplifier, which reduces the requirement upon consistency of the power amplifiers. Moreover, the isolation between groups of signals can be enhanced by increasing the number of levels of the switching components corresponding to the standby power amplifier, which further reduces the requirement on consistency of the power amplifiers. Therefore, in the embodiments of the present invention, even if the consistency of the power amplifiers is poor, the isolation between groups of signals will not be affected.  
         [0030]     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     DRAWINGS  
       [0031]     The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.  
         [0032]      FIG. 1  is a schematic diagram of an existing standby and concurring power amplifier system in the prior art;  
         [0033]      FIG. 2  is a schematic diagram of a 1+1 standby and concurring power amplifier system in accordance with a first embodiment of the present invention;  
         [0034]      FIG. 3  is a schematic diagram of a 3+1 standby and concurring power amplifier system in accordance with a second embodiment of the present invention;  
         [0035]      FIG. 4  is a schematic diagram of a 1+1 standby and concurring power amplifier system in accordance with a third embodiment of the present invention;  
         [0036]      FIG. 5  is a schematic diagram of the structure of the power amplifier system in accordance with the embodiments of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0037]     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.  
         [0038]     A further description in detail is hereinafter given to this invention with reference to the accompanying drawings and embodiments.  
         [0039]     A power amplifier system in accordance with the embodiments of the present invention is illustrated in  FIG. 5 . As shown in  FIG. 5 , the power amplifier system includes: an input switching module, an output switching module, M main power amplifiers PA 1 , PA 2  . . . PAM and a standby power amplifier PA, wherein M is a positive integer. In the system, the input switching module connects to the inputs of M main power amplifiers and the standby power amplifier, respectively; the output switching module connects to the outputs of M main power amplifiers and the standby power amplifier, respectively. M groups of signals will be inputted to the corresponding power amplifiers through the input switching module, then be amplified by the power amplifiers, and be outputted through the output switching module. The power amplifiers which are in charge of the amplification may be M main power amplifiers, or (M- 1 ) main power amplifiers plus one standby power amplifier, or M main power amplifiers plus one standby power amplifier. The different combinations are related to different work states. The structure as well as the work state of the power amplifier system in accordance with the present invention is described in detail through the specific embodiments as follows.  
       THE FIRST EMBODIMENT  
       [0040]     The implementation of the first embodiment of the invention is demonstrated with the 1+1 standby and concurring technology. ‘1+1’ means that there are one main power amplifier and one standby power amplifier in the system. As shown in  FIG. 2 , the system includes a main power amplifier PA 1 , a standby power amplifier PA, an input switching module and an output switching module. Since there is only one main power amplifier, the input switching module includes one input switch circuit, and the output switching module includes one output switch circuit. The input switch circuit has the function of power distribution and microwave single-pole double-throw switch while the output switch circuit has the function of power combination and microwave single-pole double-throw switch.  
         [0041]     As shown in  FIG. 2 , the input switch circuit includes transmission lines A 1 , B 1 , C 1 , D 1 , E 1 , F 1 , G 1 , H 1 , I 1 , J 1 , K 1 , switch components SW 1 A, SW 2 A, SW 3 A, SW 4 A, SW 5 A, SW 6 A and a grounding resistor R 1 . One end of A 1  connects to the input IN and one end of B 1  and F 1 , the other end of A 1  connects to one end of D 1 , E 1 , H 1 , and SW 5 A; the other end of B 1  connects to one end of C 1 , J 1  and SW 4 A; the other end of F 1  connects to one end of G 1  and SW 6 A; the other end of G 1  connects to the other end of J 1  and the input of PA 1 ; the other end of C 1  connects to the other end of D 1  and one end of K 1  and SW 3 A; the other end of E 1  connects to one end of R 1  and SW 1 A; the other end of H 1  connects to one end of I 1  and SW 2 A; the other end of I 1  connects to the other end of K 1  and the input of PA; the other end of SW 1 A, SW 2 A, SW 3 A, SW 4 A, SW 5 A, SW 6 A, and R 1  connects to the ground, respectively.  
         [0042]     The above output switch circuit includes transmission lines A 2 , B 2 , C 2 , D 2 , E 2 , F 2 , G 2 , H 2 , I 2 , J 2 , K 2 , switch components SW 1 B, SW 2 B, SW 3 B, SW 4 B, SW 5 B, SW 6 B and a grounding resistor R 2 . One end of A 2  connects to the output OUT, and one end of B 2  and F 2 ; the other end of A 2  connects to one end of D 2 , E 2 , H 2 , SW 5 B; the other end of B 2  connects to one end of C 2 , J 2 , SW 4 B; the other end of F 2  connects to one end of G 2 , SW 6 B; the other end of G 2  connects to the other end of J 2  and the output of PA; the other end of C 2  connects to the other end of D 2 , K 2 , SW 3 B; the other end of E 2  connects to R 2 , SW 1 B; the other end of H 2  connects to I 2 , SW 2 B; the other end of I 2  connects to the other end of K 2  and the output of PA 1 ; the other end of SW 1 B, SW 2 B, SW 3 B, SW 4 B, SW 5 B, SW 6 B, R 2  connects to the ground, respectively.  
         [0043]     The electrical length of all the transmission lines mentioned above is ¼ waveguide wavelength, the characteristic impedance of the transmission lines A 1 , C 1 , E 1 , F 1 , G 1 , H 1 , I 1 , J 1 , K 1 , A 2 , C 2 , E 2 , F 2 , G 2 , H 2 , I 2 , J 2 , K 2  is Z 0 , and the characteristic impedance of the transmission lines B 1 , D 1 , B 2 , D 2  is Z 0 /√{square root over (2)}, where Z 0  is 50Ω, and the resistance of R 1  as well as R 2  is 50Ω.  
         [0044]     In other words, there is a transmission line with the characteristic impedance of Z 0  between SW 1 A and SW 5 A, SW 2 A and SW 5 A, SW 2 A and PA, SW 3 A and SW 4 A, SW 3 A and PA, SW 4 A and PA 1 , SW 5 A and IN, SW 6 A and IN, SW 6 A and PA 1 , SW 1 B and SW 5 B, SW 2 B and SW 5 B, SW 2 B and PA 1 , SW 3 B and SW 4 B, SW 3 B and PA 1 , SW 4 B and PA, SW 5 B and OUT, SW 6 B and OUT, SW 6 B and PA 1 , respectively; there is a transmission line with the characteristic impedance of Z 0 /{square root over (2)} between SW 3 A and SW 5 A, SW 4 A and IN, SW 3 B and SW 5 B, SW 4 B and OUT, respectively.  
         [0045]     According to the above structure, the power amplifier system in the first embodiment can work in the way as follows:  
         [0046]     Connect SW 1 A, SW 2 A, SW 3 A, SW 4 A, SW 5 A, and SW 1 B, SW 3 B, SW 4 B, SW 6 B and disconnect SW 6 A and SW 2 B, SW 5 B. The signals are inputted from IN, transmitted through the transmission lines F 1  and G 1 , amplified by the power amplifier PA 1 , and transmitted through the transmission lines I 2 , H 2 , A 2  before being outputted from OUT. The work state of the system at this time is normal, with the power amplifier PA 1  working and the standby power amplifier PA being idle. Different from the existing solution, in which each power amplifier amplifies the input signal, only PA 1  in this embodiment of the present invention amplifies the input signal in normal work state, while PA is not involved, thus reducing the consistency requirement on the power amplifiers.  
         [0047]     Connect SW 1 A, SW 3 A, SW 4 A, SW 6 A and SW 1 B, SW 2 B, SW 3 B, SW 4 B, SW 5 B, disconnect SW 2 A, SW 5 A and SW 6 B. The signals are inputted from IN, transmitted through the transmission lines A 1 , H 1 , I 1 , amplified by the power amplifier PA, then transmitted through the transmission line G 2 , F 2  before being outputted from OUT. The system works in a standby state now, with the standby power amplifier PA working and the power amplifier PA 1  being idle.  
         [0048]     Connect SW 2 A, SW 6 A, SW 2 B, SW 6 B, disconnect SW 1 A, SW 3 A SW 4 A, SW 5 A and SW 1 B, SW 3 B, SW 4 B, SW 5 B. The signals are inputted from IN, transmitted through the input switch circuit and divided into 2 groups before being amplified by the power amplifiers PA 1  and PA 2 , and the two groups of signals are then combined by the output switch circuit before being outputted from OUT. The system works in a concurring state at this time, with the power amplifier PA 1  and the standby power amplifier PA working together.  
       THE SECOND EMBODIMENT  
       [0049]     While the 1+1 standby and concurring power amplifier system is given in the first embodiment, a 3+1 standby and concurring power amplifier system will be given in the second embodiment of the invention. “3+1” means there are 3 main power amplifiers and 1 standby power amplifier in the system.  
         [0050]     As shown in  FIG. 3 , the power amplifier system in the second embodiment includes 3 main power amplifiers PA 1 , PA 2 , PA 3 , a standby power amplifier PA, an input switching module and an output switching module. Since there are 3 main power amplifiers, the input switching module includes 3 input switch circuits, each of which has a function of power distribution and microwave single-pole double-throw switch; and the output switching module includes 3 output switch circuits, each of which has a function of power combination and microwave single-pole double-throw switch.  
         [0051]     As shown in  FIG. 3 , PAn (n=1, 2, 3) refers to the main power amplifier PA 1 , PA 2  or PA 3 . Since the main power amplifier PAn and the standby power amplifier PA are coequal, the positions of the main power amplifier and the standby power amplifier are swapped in the second embodiment compared with the first embodiment. The n th  input switch circuit corresponding to the power amplifier PAn includes transmission lines A 1   n , B 1   n , C 1   n , D 1   n , E 1   n , F 1   n , G 1   n , H 1   n , I 1   n , J 1   n , K 1   n , switch components SW 1 An, SW 2 An, SW 3 An, SW 4 An, SW 5 An, SW 6 An and a grounding resistor R 1   n . The n th  output switch circuit corresponding to the main power amplifier PAn includes transmission lines A 2   n , B 2   n , C 2   n , D 2   n , E 2   n , F 2   n , G 2   n , H 2   n , I 2   n , J 2   n , K 2   n , switch components SW 1 Bn, SW 2 Bn, SW 3 Bn, SW 4 Bn, SW 5 Bn, SW 6 Bn and a grounding resistor R 2   n.    
         [0052]     In the n th  input switch circuit, one end of A 1   n  connects to one end of the input INn, B 1   n , F 1   n , the other end of A 1   n  connects to one end of D 1   n , E 1   n , H 1   n , SW 5 An; the other end of B 1   n  connects to one end of C 1   n , J 1   n , SW 4 An; the other end of F 1   n  connects to one end of G 1   n , SW 6 An; the other end of G 1   n  connects to the other end of J 1   n , the input of PA; the other end of C 1   n  connects to the other end of D 1   n  and one end of K 1   n , SW 3 An; the other end of E 1   n  connects to one end of R 1   n , SW 1 An; the other end of H 1   n  connects to I 1   n , SW 2 An; the other end of I 1   n  connects to the other end of K 1   n  and the input of PAn; the other end of SW 1 An, SW 2 An, SW 3 An, SW 4 An, SW 5 An, SW 6 An, R 1   n  connects to the ground, respectively.  
         [0053]     In the n th  output switch circuit, one end of A 2   n  connects to one end of the output OUTn, B 2   n , F 2   n , the other end of A 2   n  connects to one end of D 2   n , E 2   n , H 2   n , SW 5 Bn; the other end of B 2   n  connects to one end of C 2   n , J 2   n , SW 4 Bn; the other end of F 2   n  connects to one end of G 2   n , SW 6 Bn; the other end of G 2   n  connects to the other end of J 2   n  and the output of PAn; the other end of C 2   n  connects to the other end of D 2   n  and one end of K 2   n , SW 3 Bn; the other end of E 2   n  connects to one end of R 2   n , SW 1 Bn; the other end of H 2   n  connects to one end of I 2   n , SW 2 Bn; the other end of I 2   n  connects to the other end of K 2   n  and the output of PA; the other end of SW 1 Bn, SW 2 Bn, SW 3 Bn, SW 4 Bn, SW 5 Bn, SW 6 Bn, R 2   n  connects to the ground, respectively.  
         [0054]     The electrical length of the transmissions lines mentioned in the second embodiment is ¼ waveguide wavelength, the characteristic impedance of the transmission lines A 1   n , C 1   n , E 1   n , F 1   n , G 1   n , H 1   n , I 1   n , J 1   n , K 1   n , A 2   n , C 2   n , E 2   n , F 2   n , G 2   n , H 2   n ,  12   n , J 2   n , K 2   n  is Z 0 , the characteristic impedance of the transmission lines B 1   n , D 1   n , B 2   n , D 2   n  is Z 0 /√{square root over (2)}, where Z 0  is 50Ω, and the resistance of R 1   n  as well as R 2   n  is 50Ω.  
         [0055]     According to the structure described above, the power amplifier system in the second embodiment can work in the way as follows: Connect SW 1 An, SW 3 An, SW 4 An, SW 6 An and SW 1 Bn, SW 2 Bn, SW 3 Bn, SW 4 Bn, SW 5 Bn, disconnect SW 2 An, SW 5 An and SW 6 Bn. The signals are inputted from INn, transmitted through the transmission lines A 1   n , H 1   n , I 1   n , amplified by the power amplifier PAn, and transmitted through the transmission lines G 2   n , F 2   n  before being outputted from OUTn. The system works in the normal state at this time, with the main power amplifier PAn working and the standby power amplifier PA being idle. Different from the existing solution, in which each power amplifier amplifies every group of signals, each power amplifier in this embodiment amplifies just one signal, and each signal can only be amplified by one power amplifier, thus reducing the consistency requirement on the power amplifiers.  
         [0056]     Connect SW 1 An, SW 2 An, SW 3 An, SW 4 An, SW 5 An and SW 1 Bn, SW 3 Bn, SW 4 Bn, SW 6 Bn, disconnect SW 6 An and SW 2 Bn, SW 5 Bn. The signals are inputted from INn, transmitted through the transmission lines F 1   n , G 1   n , amplified by power amplifier PAn, and transmitted through the transmission lines I 2   n , H 2   n , A 2   n  before being outputted from OUTn. The work state of the system at this time is standby, with the standby power amplifier PA working and the power amplifier PAn being idle. Likewise, it is different from the existing solution, in which each power amplifier amplifies every group of signals, that each power amplifier in this embodiment amplifies only one signal, and each signal can only be amplified by one power amplifier, thus reducing the consistency requirement on the power amplifiers.  
         [0057]     Connect SW 2 An, SW 6 An and SW 2 Bn, SW 6 Bn, disconnect SW 1 An, SW 3 An, SW 4 An, SW 5 An and SW 1 Bn, SW 3 Bn, SW 4 Bn, SW 5 Bn. The signals are inputted from INn, transmitted through the input switch circuit and divided into two groups, which then are transmitted through PAn and PA, amplified by power amplifier PAn and PA and then combined by the output switch circuit before being outputted from OUT. The system at this time works in the PA &amp; PAn concurring state, with the power amplifier PAn and the standby power amplifier PA working together to amplify the signals amplified in the normal work state by the power amplifier PAn. Different from the existing solution, in which each power amplifier amplifies every group of signals, each power amplifier in this embodiment amplifies just one group of signal, and only the group of signals amplified by PA and PAn are the signals amplified by two power amplifiers while the other groups of signals are amplified by only one power amplifier. Thus, different from the existing solution, in which the requirement on consistency of all the power amplifiers has to be met, it is only needed to meet the requirement on consistency of PA and Pan in the embodiment. Therefore, the consistency requirement on the power amplifiers could be greatly reduced.  
         [0058]     It should be noted that both the standby function and the concurring function are implemented here only for one main power amplifier, with all the other main power amplifiers still working in normal state. In this way, it is ensured that there is no correlation between the isolation of sectors and the consistency of the power amplifiers.  
         [0059]     For instance, when the standby is configured with the power amplifier PA 1 , connect SW 1 A 1 , SW 2 A 1 , SW 3 A 1 , SW 4 A 1 , SW 5 A 1  and SW 1 B 1 , SW 3 B 1 , SW 4 B 1 , SW 6 B 1 , disconnect SW 6 A 1  and SW 2 B 1 , SW 5 B 1  in the first input switch circuit and the first output switch circuit; and connect SW 1 A 2 , SW 3 A 2 , SW 4 A 2 , SW 6 A 2 , SW 1 B 2 , SW 2 B 2 , SW 3 B 2 , SW 4 B 2 , SW 5 B 2 , SW 1 A 3 , SW 3 A 3 , SW 4 A 3 , SW 6 A 3 , SW 1 B 3 , SW 2 B 3 , SW 3 B 3 , SW 4 B 3 , SW 5 B 3 , disconnect SW 2 A 2 , SW 5 A 2 , SW 6 B 2 , SW 2 A 3 , SW 5 A 3  and SW 6 B 3  in the second input switch circuit, the second output switch circuit, the third input switch circuit and the third output switch circuit. In this case, PA 1  is not working, PA 2 , PA 3  and PA are working, and the signals being amplified by the standby power amplifier PA are the signals amplified by PA 1  in the normal state.  
         [0060]     For another instance, when the PA and PA 1  are concurring, connect SW 2 A 1 , SW 6 A 1  and SW 2 B 1 , SW 6 B 1 , disconnect SW 1 A 1 , SW 3 A 1 , SW 4 A 1 , SW 5 A 1  and SW 1 B 1 , SW 3 B 1 , SW 4 B 1 , SW 5 B 1 ; and in the second input switch circuit, the second output switch circuit, the third input switch circuit and the third output switch circuit, connect SW 1 A 2 , SW 3 A 2 , SW 4 A 2 , SW 6 A 2 , SW 1 B 2 , SW 2 B 2 , SW 3 B 2 , SW 4 B 2 , SW 5 B 2 , SW 1 A 3 , SW 3 A 3 , SW 4 A 3 , SW 6 A 3 , SW 1 B 3 , SW 2 B 3 , SW 3 B 3 , SW 4 B 3 , SW 5 B 3 , disconnect SW 2 A 2 , SW 5 A 2 , SW 6 B 2 , SW 2 A 3 , SW 5 A 3  and SW 6 B 3 . In this case, PA 1 , PA 2 , PA 3  and PA are working. PA 1  and PA are in the parallel connection to amplify the signals amplified by PA 1  in the normal state while PA 2  and PA 3  are working in the normal state.  
       THE THRID EMBODIMENT  
       [0061]     Compared with the first and the second embodiment, different structures of the input switch circuit and the output switch circuit are proposed in the third embodiment of the invention. The system is to be described in this embodiment by a 1+1 standby and concurring system.  
         [0062]     As shown in  FIG. 4 , the power amplifier system in the third embodiment includes a main power amplifier PA 1 , a standby power amplifier PA, an input switching module and an output switching module. Since there is only one main power amplifier, the input switching module includes one input switch circuit, and the output switching module includes one output switch circuit. The aforesaid input switch circuit has a function of power distribution and microwave single-pole double-throw switch, and the output switch circuit has a function of power combination and microwave single-pole double-throw switch.  
         [0063]     As shown in  FIG. 4 , the input switch circuit in the third embodiment includes transmission lines L 1 , P 1 , Q 1 , S 1 , T 1 , U 1 , V 1 , W 1 , X 1 , Y 1 , Z 1 , switch components SW 1 C, SW 2 C, SW 3 C, SW 4 C, SW 5 C, SW 6 C and a grounding resistor R 1 . One end of L 1  connects to one end of the input IN, X 1 , T 1 , V 1 , while the other end of L 1  connects to one end of P 1 , SW 1 C; the other end of P 1  connects to one end of Q 1 , SW 2 C; the other end of Q 1  connects to one end of S 1 , W 1  and the input of PA 1 ; the other end of S 1  connects to one end of U 1 , SW 6 C, R 1 ; the other end of T 1  connects to the other end of U 1 , and one end of Z 1 , SW 5 C; the other end of X 1  connects to one end of Y 1 , SW 4 C; the other end of Y 1  connects to the other end of Z 1 , and the input of PA; the other end of V 1  connects to the other end of W 1 , and one end of SW 3 C; the other end of SW 1 C, SW 2 C, SW 3 C, SW 4 C, SW 5 C, SW 6 C, R 1  connects to the ground, respectively.  
         [0064]     The output switch circuit in the third embodiment includes transmission lines L 2 , P 2 , Q 2 , S 2 , T 2 , U 2 , V 2 , W 2 , X 2 , Y 2 , Z 2 , switch components SW 1 D, SW 2 D, SW 3 D, SW 4 D, SW 5 D, SW 6 D and a grounding resistor R 2 . One end of L 2  connects to one end of the output OUT, X 2 , T 2 , V 2 , the other end of L 2  connects to one end of P 2 , SW 1 D; the other end of P 2  connects to one end of Q 2 , SW 2 D; the other end of Q 2  connects to one end of S 2 , W 2 , and the output of PA; the other end of S 2  connects to one end of U 2 , SW 6 D, R 2 ; the other end of T 2  connects to the other end of U 2  and one end of Z 2 , SW 5 D; the other end of X 2  connects to one end of Y 2 , SW 4 D; the other end of Y 2  connects to the other end of Z 2  and the output of PA 1 ; the other end of V 2  connects to the other end of W 2  and one end of SW 3 D; the other end of SW 1 D, SW 2 D, SW 3 D, SW 4 D, SW 5 D, SW 6 D, R 2  connects to the ground, respectively.  
         [0065]     The electrical length of each of the transmission lines mentioned above is ¼ waveguide wavelength, the characteristic impedance of the transmission lines L 1 , P 1 , Q 1 , S 1 , T 1 , U 1 , L 2 , P 2 , Q 2 , S 2 , T 2 , U 2  is Z 0 , the characteristic impedance of transmission lines V 1 , W 1 , X 1 , Y 1 , Z 1 , V 2 , W 2 , X 2 , Y 2 , Z 2  is √{square root over (2)} Z 0 , wherein Z 0  is 50Ω, and the resistance of R 1  as well as R 2  is 50Ω.  
         [0066]     In other words, there is a transmission line with the characteristic impedance of Z 0  between SW 1 C and SW 2 C, SW 1 C and IN, SW 2 C and PA 1 , SW 3 C and PA 1 , SW 5 C and IN, SW 6 C and PA 1 , SW 1 D and SW 2 D, SW 1 D and OUT, SW 2 D and PA, SW 3 D and PA, SW 5 D and OUT, SW 6 D and PA, respectively; there is a transmission line with the characteristic impedance of √{square root over (2)} Z 0  between SW 3 C and IN, SW 4 C and IN, SW 4 C and PA, SW 5 C and SW 6 C, SW 5 C and PA, SW 3 D and OUT, SW 4 D and OUT, SW 4 D and PA 1 , SW 5 D and SW 6 D, SW 5 D and PA 1 , respectively.  
         [0067]     According to the system structure in the third embodiment described above, the power amplifier system can work in the way as follows:  
         [0068]     Connect SW 1 C, SW 2 C, SW 4 C, SW 5 C, SW 6 C and SW 1 D, SW 2 D, SW 3 D, SW 5 D, SW 6 D, disconnect SW 3 C and SW 4 D. The signals are inputted from IN, transmitted through the transmission lines V 1  and W 1 , amplified by the power amplifier PA 1 , and transmitted through transmission lines Y 2  and X 2  before being outputted from OUT. At this time, the system works in the normal state, with the power amplifier PA 1  working and the standby power amplifier PA being idle. Different from the existing solution, in which each power amplifier amplifies the input signal, only PA 1  in this embodiment amplifies the input signal in the normal work state, and the input signal is amplified only by PA 1  while PA is not involved in amplification, thus the consistency requirement on the power amplifiers is reduced.  
         [0069]     Connect SW 1 C, SW 2 C, SW 3 C, SW 5 C, SW 6 C and SW 1 D, SW 2 D, SW 4 D, SW 5 D, SW 6 D, disconnect SW 4 C and SW 3 D. The signals are inputted from IN, transmitted through the transmission lines X 1  and Y 1 , amplified by the power amplifier PA, and transmitted through the transmission lines W 2  and V 2  before being outputted from OUT. The system at this time works in the standby state, with the standby power amplifier PA working and the power amplifier PA 1  being idle.  
         [0070]     Connect SW 3 C, SW 4 C and SW 3 D, SW 4 D, disconnect SW 1 C, SW 2 C, SW 5 C, SW 6 C and SW 1 D, SW 2 D, SW 5 D, SW 6 D. The signals are inputted from IN, divided into two groups by the input switch circuit and sent to PA 1  and PA, respectively. The two groups of signals are amplified by the power amplifiers PA 1  and PA, and then combined by the output switch circuit before being outputted from OUT. The system at this time works in the concurring state, with the power amplifier PA 1  and the standby power amplifier PA working together.  
         [0071]     According to the structure of the input switch circuit and the output switch circuit given in the third embodiment, and the relationship between the main power amplifier and the standby power amplifier, it is easy to deduce the structure of an N+1 standby and concurring system of power amplifier by using the input switch circuit and the output switch circuit of the third embodiment, the detailed description of which is thus omitted here. It can be appreciated by those skilled in the art that, just like the second embodiment, the consistency requirement on the power amplifiers is reduced in the N+1 standby and concurring system of power amplifier by using the input switch circuit and the output switch circuit of the third embodiment.  
         [0072]     Furthermore, when the input switch circuit in the first embodiment is employed as the input switch circuit of the input switching module, the output switch circuit in the third embodiment can be employed as the output switch circuit of the output switching module; alternatively, when the input switch circuit in the third embodiment is employed as the input switch circuit of the input switching module, the output switch circuit in the first embodiment can be employed as the output switch circuit of the output switching module.  
         [0073]     The descriptions above are just preferable embodiments of the present invention, and not to be used to limit the protection scope thereof. Any modifications, equivalent substitutions or improvements within the spirit and principles of the present invention should be covered by the protection scope of the present invention.