Abstract:
The present invention provides a receiver for making an earphone cord of an earphone function as an earphone antenna. The receiver includes a receiver circuit for receiving a broadcast wave signal received at the earphone code of the earphone and outputting an audio signal, an earphone jack into which a earphone plug is inserted, a first detector circuit for detecting whether the earphone is one of stereo and monaural functionalities, and a second detector circuit for the earphone is connected to the receiver. The earphone jack has an antenna terminal, left channel audio terminal and right channel audio terminal, a first detection terminal and a second detection terminal, and a ground terminal.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS  
       [0001]     The present invention contains subject matter related to Japanese Patent Application JP 2005-336477 filed in the Japanese Patent Office on Nov. 22, 2005, the entire contents of which being incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a receiver and, more particularly, to earphones and a receiver configured to make a cord of earphones or headphones function also as an antenna.  
         [0004]     2. Description of the Related Art  
         [0005]     With portable FM receivers, a technology called an earphone antenna is known in which an earphone (or a headphone) cord is made function also as an antenna of each portable FM receiver. This technology makes it unnecessary for an FM broadcast listener to pull out a rod antenna of the listener&#39;s portable FM receiver. Therefore, each portable MF receiver user can listen to FM broadcasts in a crowded train, for example, without causing nuisance.  
         [0006]     Terrestrial digital television broadcasting is hardly affected by ghost signals, so that a portable receiver can be configured or a mobile phone can incorporate a terrestrial digital television broadcast receiver circuit. In these examples, making the earphone code function also as the receiver antenna allows the simple and convenient viewing of television broadcasts.  
         [0007]     If the earphone antenna is used on the mobile phone incorporating a terrestrial digital television broadcasting receiver circuit, the earphone antenna is configured as shown in  FIG. 3 , for example.  
         [0008]     To be more specific, referring to  FIG. 3 , reference numeral  10  denotes stereo earphones, reference numeral  20  denotes monaural earphones, and reference numeral  30  denotes a mobile phone. Each earphone unit is connected to an earphone plug with a lead wire formed by a cord, an intermediate unit  13 , and a cable  14 . In the stereo earphones  10 , a left-channel earphone unit (an electroacoustic transducer)  11 L and a right-channel earphone unit (an electroacoustic transducer)  11 R are connected to the intermediate unit  13  with cords  12 L and  12 R, respectively and the intermediate unit  13  is connected to an earphone plug  15  with a cable  14 .  
         [0009]     In this case, the cords  12 L and  12 R are each a two-core signal conductor. These cords  12 L and  12 R act as the effective part of the broadcast receiver antenna. The intermediate unit  13  has coupling capacitors C 11  and C 12  and high-frequency choke coils L 11  and L 12 .  
         [0010]     Further, the cable  14  is formed by combining a coaxial cable  14 A and two cables  14 L and  14 R into a single cable. The earphone plug  15  has 10 terminals (or contacts) A through J. It should be noted that, as will be described later, the mobile phone  30  has an earphone jack  31  corresponding to the earphone plug  15 . Terminals A through J of the earphone plug  15  and the earphone jack  31  are standardized and therefore common among manufacturers.  
         [0011]     One ends of the earphone units  11 L and  11 R are lead to the intermediate unit  13  through the cord  12 L or  12 R to be commonly connected in the Intermediate unit  13  and further connected to terminal A of the earphone plug  15  through the center conductor of the coaxial cable  14 A. The other ends of the earphone units  11 L and  11 R are lead to the intermediate unit  13  through the cord  12 L or  12 R and is connected terminals D and E of the earphone plug  15 , respectively, through the high-frequency choke coils L 11  and L 12  and the cables  14 L and  14 R.  
         [0012]     Further, the capacitor C 11  is connected to between one and the other of the codes  12 L and the capacitor C 12  is connected to between the one and the other of the codes  12 R. In the earphone plug  15 , the shield of the coaxial cable  14 A is connected to terminal J to connect terminal F with terminal J and, because the earphones  10  is for stereo, terminal C with terminal J.  
         [0013]     The monaural earphones  20  are also configured in substantially the same manner as the right channel of the stereo earphones  10 . It should be noted that, in the earphone plug  15 , terminal F is connected to terminal J, but terminal C and terminal J are not connected to each other because the monaural earphones  20  are for monaural use.  
         [0014]     As described above, the terminals A through J of the earphone plug  15  and the earphone jack  31  are standardized, the functions and uses thereof being specified as shown in  FIG. 4 .  
         [0015]     To be more specific, of the terminals A through J of the earphone plug  15  and the earphone jack  31 , terminal A is for the antenna and terminal C is for the detection whether the earphones are for stereo or monaural. Terminals D and E are for left and right channel audio signals. Terminal F is for the detection whether the earphone plug  15  is inserted into the earphone jack. Terminal J is for grounding. The remaining terminals B and G through I are reserved.  
         [0016]     When the earphone plug  15  of the stereo earphones  10  is inserted in the earphone jack  31 , the broadcast wave of FM broadcasting or terrestrial digital television broadcasting is received at the cord  12 L and the cord  12 R. The received broadcast wave signal is supplied to the mobile phone  30  along a signal line, from the cord  12 L and cord  12 R (or the cord  12 L and the cord  12 R to the capacitors C 11  and C 12 ), to the center conductor of the coaxial cable  14 A to the terminal A of the earphone plug  15  and to the terminal A of the earphone jack  31 .  
         [0017]     It should be noted that, in the above-mentioned case, the shield of the coaxial cable  14 A is connected to the ground of the mobile phone  30  through the terminal J of the earphone plug  15  and the terminal J of the earphone jack  31 . Because the high-frequency choke coils L 11  and L 12  are connected to the codes  12 L and the  12 R at this moment, the received broadcast wave signal on the cords  12 L and  12 R will not leak to the terminals E and D of the earphone plug  15 . Consequently, the FM broadcast or the terrestrial digital television broadcasting can be received.  
         [0018]     Then, audio signals L and R on the left and right channels obtained from this reception of broadcast are supplied to the earphone units  11 L and  11 R along a signal line, from the terminals E and D of the earphone jack  31  to the terminals E and D of the earphone plug  15  to the high-frequency choke coils L 11  and L 12  and to the cords  12 L and  12 R. At this moment, a return path is formed, from the earphone units  11 L and  11 R to the cords  12 L and  12 R to the central conductor of the coaxial cable  14 A to the terminal A of the earphone plug  15  to the terminal A of the earphone jack  31  to the high-frequency coke coil L 35  and to the ground.  
         [0019]     When the earphone plug  15  of the monaural earphones  20  is inserted into the earphone jack  31 , the FM broadcasting or the terrestrial digital television broadcasting can also be received to allow the user to listen to the received broadcast through the monaural earphones  20 .  
         [0020]     It should be noted that, if the earphone plug  15  of the stereo earphones  10  is inserted in the earphone jack  31 , the terminal C of the earphone jack  31  is grounded through the terminals C and J of the earphone plug  15 ; if the earphone plug  15  of the monaural earphones  20  is inserted in the earphone jack  31 , then the terminal C of the earphone jack  31  is open. Therefore, the DC potential on the terminal C of the earphone jack  31  indicates whether the earphones connected to the earphone jack  31  are the stereo earphones  10  or the monaural earphones  20 .  
         [0021]     If the earphone plug  15  of the stereo earphones  10  or the monaural earphones  20  is inserted in the earphone jack  31 , the terminal F of the earphone jack  31  is grounded through the terminals F and J of the earphone plug  15 ; if the earphone plug  15  of the stereo earphones  10  or the monaural earphones  20  is not inserted in the earphone jack  31 , then the terminal F of the earphone jack  31  is open. Therefore, the DC potential on the terminal F of the earphone jack  31  indicates whether the stereo earphones  10  or the monaural earphones  20  are connected to the earphone jack  31 .  
         [0022]     As described above, according to the stereo earphones  10  and the monaural earphones  20  shown in  FIG. 3 , each of the stereo earphones  10  and the monaural earphones  20  can be used also as the antenna for receiving the FM broadcasting and the terrestrial digital television broadcasting.  
         [0023]     The related-art documents include the following:  
         [0024]     Japanese Patent Laid-open No. 2003-163529;  
         [0025]     Japanese Patent Laid-open No. 2004-266434;  
         [0026]     Japanese Patent Laid-open No. 2004-274356; and  
         [0027]     Japanese Patent Laid-open No. 2005-64742.  
       SUMMARY OF THE INVENTION  
       [0028]     However, because the earphone plug  15  and the earphone jack  31  are configured and standardized as described above, incorporating a circuit for receiving terrestrial digital television broadcasting into the mobile phone  30  tends to lower the reception sensitivity as the antenna.  
         [0029]     To be more specific, as shown in  FIG. 5 , the earphone jack  31  is mounted on a printed circuit board  39  of the mobile phone  30 . At this moment, the terminals A through J of the earphone jack  31  are partially extended to be lead patterns  31 A through  31 J which are soldered to wiring patterns  39 A through  39 J of the printed circuit board  39 , respectively. In this case, the wiring pattern  39 J to which the lead pattern  31 J of the terminal J is soldered is the ground pattern.  
         [0030]     However, the earphone jack  31  is flat in shape and about 10 mm×5 mm in size, so that the lead patterns  31 A through  31 J of the terminals A through J are very thin. It should be noted that the broadcast wave signal from the coaxial cable  14 A is supplied to the terminal A, which is away from the ground terminal J, so that the effect of grounding for the antenna lowers. Further, the terrestrial digital television broadcasting is allocated with a frequency band of 470 MHz to 770 MHz of the UHF band.  
         [0031]     Consequently, the terminal J and the lead pattern  31 J present an impedance of inductance nature for the broadcast wave signal of terrestrial digital television broadcasting, this impedance giving a transmission loss to the broadcast wave signal, thereby lowering the sensitivity of reception.  
         [0032]     In this case, use of the remaining terminals B and G through I for the grounding of the coaxial cable  14 A as with the terminal J allows the reduction of the impedance, thereby lowering the transmission loss. However, due to the standards on which the earphone plug  15  and the earphone jack  31  are based, the terminals B and G through I are difficult to be used for arbitrary applications.  
         [0033]     Therefore, the present invention addresses the above-identified and other problems associated with related-art methods and apparatuses and solves the addressed problems by providing novel earphones and a novel receiver.  
         [0034]     According to an embodiment of the present invention, a receiver makes an earphone cord of an earphone function as an earphone antenna. This receiver has a receiver circuit for receiving a broadcast wave signal received at the earphone code of the earphones and outputting an audio signal; an earphone jack into which a earphone plug is inserted; a first detector circuit for detecting whether the earphones are one of stereo and monaural functionalities; and a second detector circuit for detecting the earphones being connected to the receiver.  
         [0035]     The above-mentioned earphone jack has an antenna terminal, left channel audio terminal and right channel audio terminal, a first detection terminal and a second detection terminal, and a ground terminal.  
         [0036]     The above-mentioned antenna terminal is connected to an antenna input end of the receiver circuit through a coupling capacitor. The above-mentioned left channel audio terminal and right channel audio terminal are connected to audio output ends of the receiver circuit through a first high-frequency choke coil and a second high-frequency choke coil, respectively.  
         [0037]     The above-mentioned first detection terminal and second detection terminal are connected to input ends of the first detector circuit and the second detector F circuit through a third high-frequency choke coil and a fourth high-frequency choke coil. At least one of the first detection terminal and the second detection terminal is connected to ground through a bypass capacitor. The above-mentioned ground terminal is connected to ground. A broadcast wave signal received at the earphone cord is supplied to the receiver circuit through the antenna terminal and the coupling capacitor, and at least one of the first detection terminal and the second detection terminal is grounded in a high-frequency manner through the bypass capacitor.  
         [0038]     As described and according to the above-mentioned configuration, the transmission loss for broadcast wave signals received at the earphone antenna can be significantly reduced to minimize the degradation of the reception sensitivity. In addition, the novel configuration can make the transmission loss approximately uniform regardless of frequency, thereby hardly causing a fluctuation in the reception sensitivity. Besides, the novel configuration eliminates the necessity for using otherwise excess terminals of the earphone plug and the earphone jack. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0039]      FIG. 1  is a connection diagram illustrating a receiver practiced as one embodiment of the invention;  
         [0040]      FIG. 2  is a graph indicative of characteristics of measurements;  
         [0041]      FIG. 3  is a connection diagram illustrating an earphone antenna;  
         [0042]      FIG. 4  is a diagram illustrating specifications of an earphone plug and a earphone jack; and  
         [0043]      FIG. 5  is an expanded diagram illustrating the earphone plug and the earphone jack. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0044]     This invention will be described in further detail by way of embodiments thereof with reference to the accompanying drawings. Now, referring to  FIG. 1 , there is shown one embodiment of the present invention in which the present invention is applied to a receiver circuit incorporated in a mobile phone.  FIG. 1  shows stereo earphones  10  and monaural earphones  20  in a simplified manner as compared with those shown in  FIG. 3 .  
         [0045]     To be more specific, in the stereo earphones  10 , a left channel earphone unit  11 L and a right channel earphone unit  11 R are connected to an intermediate unit  13  with a cord  12 L and a cord  12 R, and the intermediate unit  13  is connected to an earphone plug  15  with a cable  14 .  
         [0046]     In this case, the codes  12 L and  12 R are each a two-core signal conductor. These cords  12 L and  12 R act as the effective part of the broadcast receiver antenna. The cable  14  has three signal conductors  14 C,  14 L, and  14 R, which are covered with a shield  14 S, thereby forming a coaxial cable as a whole. In the intermediate unit  13 , one end of the cord  12 L is commonly connected with one end of the cord  12 R to be connected to one end of the signal conductor  14 C. The other end of the cord  12 L and the other end of the cord  12 R are connected to one end of the signal line  14 L and one end of the signal line  14 R, respectively.  
         [0047]     As described above, the earphone plug  15  has 10 terminals A through J and incorporates coupling capacitors C 11  and C 12  and a high-frequency coke coil  13  based on a ferrite bead inductor for example. Inside the earphone plug  15 , the other ends of the signal conductors  14 C,  14 R, and  14 L are connected the terminals A, D, and E, respectively and the other end of the shield  14 S is connected to the terminal J. The capacitor  12 C is connected between the terminal A and the terminal D, and the capacitor C 11  is connected between the terminal D and the terminal E. The high-frequency choke coil  13  is connected between the terminal A and the terminal C. Further, the terminal F is connected to the terminal J and, because the stereo earphones  10  are for stereo functionality, the terminal C is connected to the terminal J.  
         [0048]     The monaural earphones  20  are configured in substantially the same manner as the right channel of the stereo earphones  10 . However, in the earphone plug  15  of the monaural earphones  20 , although the terminal F and the terminal J are connected with each other, the terminal C and the terminal J are not connected with each other because the monaural earphones  20  are for monaural functionality.  
         [0049]     On the other hand, a mobile phone  30  has an earphone jack  31 , a receiver circuit  32  for receiving the FM broadcast and the terrestrial digital television broadcasting, and a system controller  33  based on a microcomputer. In this case, the receiver circuit  32  can select a receive band of the FM broadcasting or the terrestrial digital television broadcasting and tune in on a desired broadcast (or a channel) in the selected receive band, under the control of the system controller  33 . Then, the receiver circuit  32  outputs stereo or monaural audio signal L, R and, in the case of television broadcasting, displays a video image on a display monitor (not shown) connected to the receiver circuit  32 .  
         [0050]     In order to achieve the above-mentioned processing, various kinds of data and commands are transferred between the receiver circuit  32  and the system controller  33 . Also, the system controller  33  is connected with various operator switches, such as a band selector switch and a tuning switch, for example.  
         [0051]     The antenna terminal A of the earphone jack  31  is connected to the antenna input end of the receiver circuit  32  through a coupling capacitor C 35  and a high-frequency choke coil L 35  is connected between this terminal A and the ground. The audio output ends of the left and right channels of the receiver circuit  32  are connected to the audio terminals E and D of the earphone jack  31  through the high-frequency choke coils L 31  and L 32 , respectively.  
         [0052]     Detector circuits  35  and  36  are arranged. The detection terminals C and F of the earphone jack  31  are connected to the input ends of the detector circuits  35  and  36  through the high-frequency choke coils L 33  and L 34 , respectively. The detection outputs are supplied to the system controller  33 . Bypass capacitors C 33  and C 34  are connected between the terminals C and F of the earphone jack  31  and the ground. Further, the terminal J of the earphone jack  31  is connected to the ground. It should be noted that the inputs ends of the detector circuits  35  and  36  are pulled up, not shown.  
         [0053]     According to the above-mentioned configuration, if the earphone plug  15  of the stereo earphones  10  is inserted in the earphone jack  31 , the terminal C of the earphone jack  31  is grounded through the terminals C and J of the earphone plug  15 , so that the DC potential of the terminal C of the earphone jack  31  is “L” (or at logical Low level). However, if the earphone plug  15  of the monaural earphones  20  is inserted in the earphone jack  31 , the terminal C of the earphone jack  31  is opened. The DC potential thereof is “H” (or at logic High level).  
         [0054]     Then, the DC potential of the terminal C of the earphone jack  31  is detected by detector circuit  35  through the high-frequency coke coil L 33 . The detection output is supplied to the system controller  33 . Therefore, the system controller  33  can know which of the stereo earphones  10  and the monaural earphones  20  are connected to the earphone jack  31 . Consequently, the audio signals L and R to be outputted from the receiver circuit  32  can be switched to stereo or monaural.  
         [0055]     If the earphone plug  15  of the stereo earphones  10  is inserted in the earphone jack  31 , the FM broadcasting and the terrestrial digital television broadcasting are received through the cords  12 L and  12 R. The received broadcast wave signals are supplied to the receiver circuit  32  along a signal line, from the codes  12 L and  12 R to the signal conductors  14 C,  14 L, and  14 R to (and capacitors C 11  and C 12 ) to the terminal A of the earphone plug  15  to the terminal A of the earphone jack  31  and to the capacitor C 35 .  
         [0056]     The shield  14 S of the cable  14  is grounded through a line of the terminal J of the earphone plug  15  and the terminal J of the earphone jack  31 , and also through a line of the terminals C and F of the earphone plug  15  to the terminals C and F of the earphone jack  31  and to the capacitors C 33  and C 34 . It should be noted that, because the high-frequency coke coils L 31  and L 32  are connected to the terminals E and D of the earphone jack  31 , respectively, the broadcast wave signals received at the cords  12 L and  12 R will not leak from the terminals E and D of the earphone jack  31  to the receiver circuit  32 .  
         [0057]     Consequently, operating an operator switch  34  gets the FM broadcasting or the terrestrial digital television broadcasting selected and a desired channel tuned in. The audio signals L and R of the selected broadcast are outputted from the receiver circuit  32 .  
         [0058]     These audio signals L and R are supplied to the earphone units  11 L and  11 R, respectively, along a line of the high-frequency coke coils L 32  and L 32  to the terminals E and D of the earphone jack  31  to the terminals E and D of the earphone plug  15  to the signal conductors  14 L and  14 R.  
         [0059]     In this case, a line of the earphone units  11 L and  11 R to the codes  12 L and  12 R to the signal conductor  14 C to the high-frequency choke coil L 13  to the terminal J of the earphone plug  15  to the terminal J of the earphone jack  31  to the ground forms a return path. Further, a line of the earphone units  11 L and  11 R to the codes  12 L and  12 R to the signal conductor  14 C to the terminal A of the earphone plug  15  to the terminal A of the earphone jack  31  to the high-frequency choke coil L 35  to the ground forms a return path.  
         [0060]     Consequently, the broadcast can be heard in the stereo mode through the stereo earphones  10 . At the same time, if the terrestrial digital television broadcasting is being received, the video image thereof is displayed on a display monitor connected to the receiver circuit  32 .  
         [0061]     On the other hand, if the earphone plug  15  of the monaural earphones  20  is inserted in the earphone jack  31 , then a broadcast wave of the FM broadcasting and the terrestrial digital television broadcasting is received at the cord  12 R and the received broadcast wave signal is supplied to the receiver circuit  32  along a line of the cord  12 R to the signal conductor  14 C to the terminal A of the earphone plug  15  to the terminal A of the earphone jack  31  and to the capacitor C 35 . Consequently, the monaural audio signal of the selected broadcast is outputted from the receiver circuit  32 .  
         [0062]     Then, this audio signal is supplied to the earphone unit  11 R along a line of the high frequency choke coil L 32  to the terminal D of the earphone jack  31  to the terminal D of the earphone plug  15  to the signal conductor  14 R and to the cord  12 R.  
         [0063]     At this moment, a line of the earphone unit  11 R to the cord  12 R to the signal conductor  14 C to the high-frequency choke coil L 13  to the terminal J of the earphone plug  15  to the terminal J of the earphone jack  31  and to the ground forms a return path. Further, a line of the earphone unit  11 R to the cord  12 R to the signal conductor  14 C to the terminal A of the earphone plug  15  to the terminal A of the earphone jack  31  to the high-frequency choke coil L 35  and to the ground also forms a return path.  
         [0064]     Consequently, the broadcast can be heard in the monaural mode through the monaural earphones  20 . At the same time, if the terrestrial digital television broadcasting is being received, the video image thereof is displayed on a display monitor connected to the receiver circuit  32 .  
         [0065]     It should be noted that, if the earphone plug  15  of the stereo earphones  10  or the monaural earphones  20  is not inserted in the earphone jack  31 , the terminal F of the earphone jack  31  is open, so that the DC potential thereof is “H”. In contrast, if the earphone plug  15  is inserted in the earphone jack  31 , the terminal F of the earphone jack  31  is grounded through the terminals F and J of the earphone plug  15 , so that the DC potential thereof is “L”.  
         [0066]     This DC potential of the terminal F of the earphone jack  31  is detected by detector circuit  36  through the high-frequency choke coil L 34 , and the detection output is supplied to the system controller  33 . Consequently, the system controller  33  can determine whether or not the earphone plug  15  is inserted in the earphone jack  31 .  
         [0067]     As described above and according to the stereo earphones  10 , the monaural earphones  20 , and the mobile phone  30 , the FM broadcasting and the terrestrial digital television broadcasting can be heard and viewed by use of the stereo earphones  10  and the monaural earphones  20  each as a receiver antenna.  
         [0068]     In this embodiment, the shield  14 S of the coaxial cable  14  is ground, in a high-frequency manner, not only along a line of the terminal J of the earphone plug  15  to the terminal J of the earphone jack  31  but also along a line of the terminals C and F of the earphone plug  15  to the terminals C and F of the earphone Jack  31  and to the capacitors C 33  and C 34 . Also, the terminal C in the proximity of the terminal A to which broadcast signals are supplied from the coaxial cable  14  is grounded. Consequently, the impedance between the shield  14 S of the coaxial cable  14  and the ground gets smaller to lower the transmission loss for broadcast wave signals. In addition, this configuration minimizes the degradation of the reception sensitivity.  
         [0069]     Further, the configuration of the mobile phone  30  shown in  FIG. 1  allows the related-art stereo earphones  10  and monaural earphones  20  each to be used as an earphone antenna.  
         [0070]     Referring to  FIG. 2 , there is shown measurements of the transmission loss (or reception sensitivity) to be obtained when the embodiment of the present invention is applied and not. In the figure, characteristic A is indicative of the case in which the present invention is applied with the capacitances of the capacitors C 33  and C 34  each set to 10 pF. Characteristic B is indicative of the case in which the embodiment of the present invention is not applied, the capacitors C 33  and C 34  not connected. It should be noted that the losses at the lower end (470 MHz) of channel  13  and the upper end (770 MHz) of channel  62  are as shown in the figure.  
         [0071]     As clearly seen from the shown measurements indicative of a significant reduction in transmission loss, the configuration realized by the embodiment of the present invention can minimize the degradation of the reception sensitivity. In addition, not only the low transmission loss but also the approximate uniformity in transmission loss regardless of frequency will hardly cause a fluctuation in reception sensitivity and allows AGC to be effectively applied. Further, the above-mentioned novel configuration eliminates the necessity for using the terminals B and G through I. Besides, the above-mentioned novel configuration may only connect the capacitors C 33  and C 34 , thereby lowering the number of parts necessary for realizing the embodiments of the invention and making the parts mounting area relatively smaller.  
         [0072]     It should be noted that characteristic A has a dip in frequency fr (approximately 334 MHz), which is caused by the resonance between the inductance component between the coaxial cable  14  and the ground of the mobile phone  30  and the capacitors C 33  and C 34 . Therefore, changing the values of the capacitors C 33  and C 34  allows to change this resonance frequency (or dip frequency) fr.  
         [0073]     However, making the values of the capacitors C 33  and C 34  smaller makes the resonance frequency fr thereof approach the frequency band (channel  13  through channel  62 ) of the terrestrial digital television broadcasting, thereby lowering the sensitivity on the lower frequency side. In contrast, making the values larger makes the resonance frequency fr approach the frequency band (76 MHz to 90 MHz) of the FM broadcasting, thereby lowering the sensitivity on the high frequency side. The inductance component between the coaxial cable  14  and the ground of the mobile phone  30  also depends on the size (length and width) of the lead wires  31 C,  31 F, and  31 J of the earphone jack  31  and a method of mounting thereof onto a printed circuit board  39 , for example.  
         [0074]     Consequently, in the reception of the FM broadcasting and the terrestrial digital television broadcasting, the values of the capacitors C 33  and C 34  may suitably be 5 pF to 30 pF.  
         [0075]     As described and according to the above-mentioned circuit configured as described, the transmission loss for broadcast wave signals received at the earphone antenna can be significantly reduced to minimize the degradation of the reception sensitivity. In addition, the novel configuration can make the transmission loss approximately uniform regardless of frequency, thereby hardly causing a fluctuation in the reception sensitivity. Besides, the novel configuration eliminates the necessity for using the terminals B and G through I.  
         [0076]     In the above-mentioned novel configuration, a receiver circuit for receiving the FM broadcasting and the terrestrial digital television broadcasting is incorporated in a mobile phone. In the case of receiving the UHF band broadcasting, especially the terrestrial digital television broadcasting, the above-mentioned novel configuration according the present invention may be applied to a dedicated receiver. In this case, the earphone antenna can be used as it is as shown in  FIG. 1 . Also, in the above-mentioned novel configuration, only one of the high-frequency choke coils L 13  and L 35  and only one of the capacitors C 33  and C 34  may be used.  
         [0077]     Abbreviations as used herein:  
         [0078]     AGC=Automatic Gain Control  
         [0079]     FM=Frequency Modulation  
         [0080]     UHF=Ultra High Frequency  
         [0081]     While preferred embodiments of the present invention have been described using specific terms, such description is for illustrative purpose only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims.