Abstract:
The radio signal receiving device that has an input terminal for inputting an input signal and an output terminal for amplifying the signal inputted to the input terminal and then outputting the signal, comprises an insulating container comprising the input terminal and the output terminal, and an amplifier that is contained in the insulating container and amplifies the signal and then outputs the signal as the output signal. Bias voltage from one of the amplifier input terminal of the amplifier and the amplifier output terminal of the amplifier is applied to the output signal outputted to the amplifier output terminal of the amplifier.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a radio signal receiving device. More particularly, the present invention relates to a receiving device having an input terminal for inputting an input signal and an output terminal for amplifying the input signal from the input terminal and then outputting the output signal.  
           [0003]    2. Description of the Related Art  
           [0004]    The conventional radio signal receiving device extracts signals from a predetermined frequency band with low noise by maintaining a band pass filter for filtering the predetermined frequency band from the input signal in a constant temperature. The band pass filter that is made from a superconductor for this object is contained within an insulating container and thereby can be maintained in the constant temperature.  
           [0005]    [0005]FIG. 1 shows a block diagram of the structure of the conventional radio signal receiving device. The conventional radio signal receiving device includes a band pass filter  10 , a low noise amplifier  20 , an insulating container  80 , a cooling means  40 , an input terminal  60 , an output terminal  50 , a first power line  81 , a second power line  82 , a third power line  83 , a fourth power line  84 , a cooling member  44 , a temperature sensor  46  and a temperature control heater  48 .  
           [0006]    Band pass filter  10  filters the frequency band of the input signal from input terminal  60 . Insulating container  80  contains band pass filter  10  so that the filter is insulated from the outside. Low noise amplifier  20  amplifies the signal that is filtered by band pass filter  10  and then outputs the amplified signal to output terminal  50 . Low noise amplifier  20  is powered from first power line  81  and second power line  82 .  
           [0007]    Cooling means  40  cools band pass filter  10  to maintain it at a temperature where the filter operates in a superconducting state, using cooling member  44 . The power for operating cooling means  40  is supplied from the outside via a power terminal for cooling means  42 . A temperature monitor signal showing the temperature of cooling member  44  detected by temperature sensor  46  is outputted from third power line  83 . The temperature control signal for controlling temperature control heater  48  mounted in cooling member  44  is inputted from fourth power line  84 .  
           [0008]    The amplifier connected to the band pass filter is contained in the insulating container together with the band pass filter, thereby reducing heat noise. Thus, it is preferable that the temperature of cooling member  44  is constantly maintained. However, since the conventional radio signal receiving device has heat transfer from first power line  81 , second power line  82 , third power line  83  and fourth power line  84 , it is difficult to maintain the temperature in the insulating container at a constant temperature. Thus, an insulating container, that contains the band pass filter and has higher insulating capability, has been demanded.  
         SUMMARY OF THE INVENTION  
         [0009]    It is an object of the present invention to provide a radio signal receiving device, which is capable of overcoming the above drawbacks accompanying the conventional art. The above and other objects can be achieved by combinations described in the independent claims. The dependent claims define further advantageous and exemplary combinations of the present invention.  
           [0010]    The receiving apparatus according to the first aspect of the present invention includes an input terminal inputting input signal, an output terminal outputting an amplified output signal, an insulating container having the input terminal and the output terminal, and an amplifier, contained in the insulating container, for amplifying the signal and outputting the signal as the output signal. Bias voltage from one of the amplifier input terminal of the amplifier and the amplifier output terminal of the amplifier is applied to the output signal that is outputted to the amplifier output terminal of the amplifier.  
           [0011]    The amplifier may be a field-effect transistor and may include a self-bias circuit that allows source voltage to be higher than gate voltage.  
           [0012]    The device may include a grounding part for grounding a gate of the amplifier. The amplifier may include a bypass circuit, which connects the amplifier output terminal with the amplifier input terminal, for extracting DC voltage from the input signal and then applying it to the output signal.  
           [0013]    The device may comprise a band pass filter that is contained in the insulating container and filters a frequency band of the input signal, and the amplifier may amplify the signal that is filtered by the band pass filter.  
           [0014]    The insulating container may include a first input terminal, a second input terminal, a first output terminal and a second output terminal. The device may further include a first amplifier that is contained in the insulating container and that amplifies the signal and then outputs the signal as output signal and a second amplifier that is contained in the insulating container and that amplifies the signal and then outputs the signal as output signal. Further, bias voltage from one of the first input terminal, the second input terminal, the first output terminal, and the second output terminal, may be applied to the first output signal that is outputted to the amplifier output terminal of the first amplifier, and second output signal that is outputted to the amplifier output terminal of the second amplifier.  
           [0015]    The device may include a cooling means for cooling the band pass filter, and the temperature control signal for controlling the temperature of the cooling means may be inputted from the output terminal or the input terminal.  
           [0016]    The device may further include a temperature sensor for measuring the temperature of the cooling means, and the temperature sensor may output a temperature monitor signal relating to the measured temperature of the cooling means to the output terminal or the input terminal.  
           [0017]    The summary of the invention does not necessarily describe all necessary features of the present invention. The present invention may also be a sub-combination of the features described above. The above and other features and advantages of the present invention will become more apparent from the following description of the embodiments taken in conjunction with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    [0018]FIG. 1 shows a block diagram of the structure of the conventional radio signal receiving device.  
         [0019]    [0019]FIG. 2 shows a block diagram of the structure of a radio signal receiving device according to the first embodiment of the present invention.  
         [0020]    [0020]FIG. 3 shows the structure of low noise amplifier according to the first embodiment.  
         [0021]    [0021]FIG. 4 shows a block diagram of the structure of a radio signal receiving device according to the second embodiment of the present invention.  
         [0022]    [0022]FIG. 5 shows the structure of low noise amplifier according to the second embodiment.  
         [0023]    [0023]FIG. 6 shows a block diagram of the structure of the radio signal receiving device according to the third embodiment of the present invention.  
         [0024]    [0024]FIG. 7 shows the structure of low noise amplifier according to the third embodiment. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0025]    The invention will now be described based on the preferred embodiments, which do not intend to limit the scope of the present invention, but exemplify the invention. All of the features and the combinations thereof described in the embodiments are not necessarily essential to the invention.  
         [0026]    [0026]FIG. 2 shows a block diagram of the structure of the radio signal receiving device according to an embodiment of the present invention. The radio signal receiving device of the present embodiment is, for example, a receiving device of a base station that is used for mobile communications and satellite communications. The radio signal receiving device comprises a band pass filter  10 , a low noise amplifier  20 , an insulating container  80 , a cooling means  40 , an input terminal  60 , an output terminal  50 , a first power line  90 , a choke coil  85  and a capacitor  95 .  
         [0027]    Band pass filter  10  filters the frequency band of the input signal that is inputted from input terminal  60 . Band pass filter  10  is, for example, a superconductor filter that has a constituent element made from superconducting material. It is preferred that the superconducting material is a high-temperature superconductor in order to maintain the superconducting material in the superconducting state. For example, the superconducting material may be a copper oxide material of, for example, Bi system, Ti system, Pb system, Y system or the like. High temperature superconducting filter (HTSF) is, for example, a thin film HTSF of micro-strip structure or a thick film HTSF of cavity resonant structure.  
         [0028]    Insulating container  80  contains band pass filter  10  to insulate the filter from the outside. It is preferred that insulating container  80  prevents heat from entering the container by vacuum insulation. Insulating container  80  is, for example, a Dewar bottle.  
         [0029]    Low noise amplifier  20  amplifies the signal that is filtered by band pass filter  10  and outputs the amplified signal to output terminal  50 . It is preferred that low noise amplifier  20  is contained within insulating container  80  in order to lower noise. It is preferred that low noise amplifier  20  is a low noise amplifier. The first power line  90  passes choke coil  85  and the high frequency cable to supply power to low noise amplifier  20  via output terminal  50 .  
         [0030]    Cooling means  40  cools band pass filter  10  to keep it at the temperature in which band pass filter  10  shows a superconducting state, using cooling member  44 . The power for operating cooling means  40  is supplied via power terminal  42  for the cooling means, from the outside. Cooling means  40  is, for example, a super cold temperature refrigerator. It is preferable that the super cold temperature refrigerator maintains a super cold temperature of several tenth Kelvin, using a heat exchange cycle that compresses and expands Helium gas or the like. Further, if low noise amplifier  20  is contained in heat-preventing container  30 , cooling means  40  further cools low noise amplifier  20 . Furthermore, cooling means  40  may cool band pass filter  40  and low noise amplifier  20  in different temperatures, respectively.  
         [0031]    [0031]FIG. 3 shows the structure of low noise amplifier  20 . Low noise amplifier  20  includes a transistor Q 1 , a capacitor  202 , a choke coil  204 , matching circuits  206 ,  208 , a resistor  210 , and a capacitor  212 . Transistor Q 1  is, for example, a field-effect transistor such as GaAs, FET and HEMT. In this way, a self-bias circuit is formed.  
         [0032]    Matching circuit  206  matches impedance between band pass filter  10  and transistor Q 1 . Further, matching circuit  208  matches impedance between the drain of transistor Q 1  and the outside device.  
         [0033]    Further, the source of transistor Q 1  is grounded via resistor  210 . Thus, DC potential of the source increases by the potential difference between both ends of resistor  210  with respect to the DC potential of the gate.  
         [0034]    [Second Embodiment] 
         [0035]    The second embodiment of the present invention will be described in the following. Low noise amplifier  20  according to the first embodiment is powered via output terminal  50 , however, low noise amplifier  20  of the second embodiment is powered through input terminal  60 .  
         [0036]    [0036]FIG. 4 shows a block diagram of the structure of the radio signal receiving device according to the second embodiment. The radio signal receiving device of the second embodiment is different from that of the first embodiment in that it does not include first power line  90 , choke coil  85 , capacitor  95  and in that it further comprises a second power line  70 , a choke coil  75 , and a capacitor  65 . The second power line  70  passes choke coil  75  and the high frequency cable to supply power to low noise amplifier  20  via input terminal  60 .  
         [0037]    [0037]FIG. 5 shows the structure of low noise amplifier  20  according to the second embodiment. Low noise amplifier  20  is different from low noise amplifier  20  of the first embodiment in that it further comprises bypass circuit  216 . Bypass circuit  216  connects amplifier input terminal  218  with amplifier output terminal  220 . The circuit extracts DC voltage from the input signal that is inputted from the amplifier input terminal and then applies the voltage to the output signal.  
         [0038]    Other structure and operation of the radio signal receiving device of the second embodiment is the same as those of the radio signal receiving device of the first embodiment, and thus, the description thereto is omitted.  
         [0039]    Next, the third embodiment of the present invention will be described in the following. The radio signal receiving device of the third embodiment is provided with a plurality of band pass filters, and low noise amplifiers of the same number as the band pass filters, in a row, respectively.  
         [0040]    [0040]FIG. 6 shows a block diagram of the structure of the radio signal receiving device according to the third embodiment. The radio signal receiving device includes a first band pass filter  11 , a second band filer  12 , a third band pass filter  14 , a fourth band pass filter  16 , a first low noise amplifier  21 , a second low noise amplifier  22 , a third low noise amplifier  24 , a fourth low noise amplifier  26 , a first input terminal  61 , a second input terminal  62 , a third input terminal  64 , a fourth input terminal  66 , a first output terminal  51 , a second output terminal  52 , a third output terminal  54 , and a fourth output terminal  56 .  
         [0041]    First and second operating powers are supplied to each of the low noise amplifiers. First power line  90   a  supplies the first operating power to first low noise amplifier  21 , second low noise amplifier  22 , third low noise amplifier  24 , fourth low noise amplifier  26 , passing through choke coil  85   a  and the high frequency cable and further through first output terminal  51  and choke coil  21 L. Second power line  90   b  supplies the second operating power to first low noise amplifier  21 , second low noise amplifier  22 , third low noise amplifier  24  and fourth low noise amplifier  26 , passing through choke coil  85   b  and the high frequency cable and further through second output terminal  52  and choke coil  22 L.  
         [0042]    Temperature sensor  46  measures the temperature of cooling member  44  and outputs the temperature monitor signal indicating the measured temperature. Temperature sensor  46  outputs the temperature monitor signal to third power line  90   c , via choke coil  24 L, third output terminal  54 , and choke coil  85   c . Fourth power line  90   d  outputs the temperature control signal to temperature control heater  48 , passing through choke coil  85   d , fourth output terminal  56  and choke coil  26 L.  
         [0043]    The insulating container  80  according to the third embodiment shown in FIG. 6 also contains capacitors  21 C,  22 C,  24 C and  26 C which couple to the choke coils  21 L,  22 L,  24 L and  26 L, respectively.  
         [0044]    Cooling member  44 , temperature sensor  46 , and temperature control heater  48  may be two or more. In the event that cooling member  44 , temperature sensor  46 , and temperature control heater  48  are two or more, temperature control signal, temperature monitor signal, power line and the like may increase in accordance with the numbers of the cooling member, the temperature sensor and the temperature control heater. Further, circuits may be added accordingly.  
         [0045]    [0045]FIG. 7 shows the structure of low noise amplifier  20  according to the third embodiment. Power line  226  supplies the first operating power supplied from the first power line  90   a , via choke coil  222 . Power line  228  supplies the second operating power supplied from the second power line  90   b , via choke coil  224 .  
         [0046]    The modified embodiments will be described in the following. In the event that the radio signal receiving device includes a plurality of low noise amplifier  20  and band pass filters as the third embodiment, the operating power of low noise amplifier  20  is not supplied from the amplifier output terminal as shown in FIG. 7. However, the power may be supplied from the amplifier output terminal of low noise amplifier  20  as shown in FIG. 3.  
         [0047]    As described in the above, the present invention can provide the radio signal receiving device that has an insulating container that contains a band pass filter and an amplifier and has higher insulating capability.  
         [0048]    Although the present invention has been described by way of exemplary embodiments, the scope of the present invention is not limited to the embodiments. Those skilled in the art might make many changes and improvements. It is clearly understood from the claims that the changes and improvements fall within the scope of the present invention.