JP2008141716A - Electronic tuner and portable telephone device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic tuner of excellent reception sensitivity by reducing interference due to a transmission signal from a portable telephone during speech communication. <P>SOLUTION: A high-frequency amplifier 26 inserted between a television input terminal 25 and a first filter 27 and having a current control input 26a for controlling a current value is provided, together with a current control unit 42 inserted between the output of the high-frequency amplifier 26 and the current control input 26a to controlling the current of a high-frequency amplifier 26 by detecting the transmission signal, and the current of the high-frequency amplifier 26 is set larger when the portable telephone 23 is sending the transmission signal. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electronic tuner capable of receiving a television broadcast signal even when a mobile phone is in use, and a mobile phone device using the same.

  Hereinafter, a conventional mobile phone device 1 will be described with reference to FIG. The conventional cellular phone device 1 is composed of an electronic tuner 2 that receives a television broadcast signal and a cellular phone 3. The electronic tuner 2 is connected to a TV input terminal 5 to which a TV broadcast signal is input, a filter 6 that is connected to the TV input terminal 5 and suppresses signals other than the TV broadcast signal, and an output of the filter 6 is connected. A high-frequency amplifier 7 to which the output of the high-frequency amplifier 7 is connected and gain control is possible, the output of the high-frequency amplifier 8 is supplied to one input, and an oscillator 10 is connected to the other input. Is connected to the mixer 12, the filter 13 to which the output of the mixer 12 is connected, the TV demodulator circuit 14 to which the output of the filter 13 is connected, and the output of the TV demodulator circuit 14 to A connected output terminal 15 was provided.

  On the other hand, the cellular phone 3 includes a transmission / reception circuit 17 and a signal processing circuit 18 to which signals from the transmission / reception circuit 17 and the output terminal 15 are supplied.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
JP 2000-13357 A

  In such a conventional electronic tuner 2, distortion occurs in the electronic tuner 2 due to a transmission signal output from the mobile phone 3 during a call, and a television broadcast signal cannot be received with high quality. In order to suppress the transmission signal output from the mobile phone 3, a multi-stage filter 6 is connected to the TV input terminal 5 of the electronic tuner 2.

  However, for example, the transmission signal output from the mobile phone 3 is close to 830 MHz with respect to 770 MHz which is the highest channel of the UHF broadcast signal. The transmission signal output from the mobile phone 3 is very large, and the mobile phone antenna 3a and the television antenna 2a are close to each other. For this reason, the filter 6 of the electronic tuner 2 needs a large attenuation of about 70 dB or more.

  Therefore, in the conventional electronic tuner 2 of FIG. 11, it is necessary to insert such a filter 6 between the TV input terminal 5 and the high-frequency amplifier 7. As a result, the television broadcast signal can be received even when the mobile phone 3 is being used.

  However, the filter 6 having such a rapid attenuation of about 70 dB has a multistage configuration. For this reason, the insertion loss has increased to 3 to 4 dB, for example.

  Since the filter 6 having a large insertion loss is directly connected to the output of the television input terminal 5, the reception sensitivity when the television broadcast signal is small is equivalent to the insertion loss of 3 to 4 dB of the filter 6. There was a problem of deterioration.

  Accordingly, the present invention has been made to solve this problem, and an object of the present invention is to provide an electronic tuner having good reception sensitivity while eliminating the interference caused by the transmission signal output from such a cellular phone during a call. .

  In order to achieve this object, an electrode tuner of the present invention includes a first high-frequency amplifier inserted between a television input terminal and a first filter and having a current control input for controlling a current value; A current control unit is provided that is inserted between the output of the first high-frequency amplifier and the current control input and detects a transmission signal to control the current of the first high-frequency amplifier. During signal transmission, the current of the first high-frequency amplifier is set large.

  Thereby, the initial purpose can be achieved.

  As described above, the present invention includes the first high-frequency amplifier that is inserted between the television input terminal and the first filter and has a current control input for controlling the current value, and the first high-frequency amplifier. A current control unit that is inserted between an output and the current control input and detects a transmission signal to control a current of the first high-frequency amplifier is provided, and the mobile phone transmits the transmission signal while the transmission signal is being transmitted. The current of the high frequency amplifier 1 is set large.

  Thus, since the current value of the first high-frequency amplifier can be increased by the current control unit that detects the transmission signal of the mobile phone during a call, the interference by the mobile phone can be eliminated.

  In addition, since the first high-frequency amplifier is inserted between the television input terminal and the first filter, it is possible to improve reception sensitivity degradation.

  Further, when the cellular phone is not used, the current of the first high-frequency amplifier is set small, so that the power consumption can be reduced.

(Embodiment 1)
FIG. 1 is a block diagram of the mobile phone device 20. In FIG. 1, a mobile phone device 20 includes an electronic tuner 22 that receives a television broadcast signal (VHF broadcast signal, UHF broadcast signal) from a television antenna 21, and a mobile phone 23 that is connected to the mobile phone antenna 24. It is configured.

  First, the electronic tuner 22 will be described below. The electronic tuner 22 is a high-frequency amplifier 26 provided with a TV input terminal 25 connected to the TV antenna 21 and a current control input 26a connected to the TV input terminal 25 and capable of controlling the current value. And a first filter 27 that is connected to the output of the high-frequency amplifier 26 and suppresses signals other than the television broadcast signal, and is connected to the output of the first filter 27 and is capable of gain control. A high frequency amplifier 29 provided with an input 29a, a mixer 32 in which an output of the high frequency amplifier 29 is connected to one input and an output of the oscillator 30 is connected to the other input, and an output of the mixer 32 And a filter 33 for passing an intermediate frequency signal, a TV demodulator 34 to which the output of the filter 33 is connected, and A TV output terminal 35 to which a TS (transport stream) signal output from the TV demodulation circuit 34 is supplied, a PLL control circuit 36 for performing PLL control of the oscillator 30, and an input to which a transmission signal of the mobile phone 23 is supplied. A third filter 38 connected to the output terminal 23a, the output of the high-frequency amplifier 26 and passing the transmission signal from the mobile phone 23, and the output of the third filter 38 are connected to detect the transmission signal. The detection circuit 40 includes a current control circuit 41 that is connected between the output of the detection circuit 40 and the current control input 26 a and controls the current value of the high-frequency amplifier 26.

  Here, the current control unit 42 includes a third filter 38, a detection circuit 40, and a current control circuit 41. The output of the mixer 32 is connected to the input of the gain control circuit 44. The output of the gain control circuit 44 is connected to the gain control input 29a.

  In the third filter 38, a capacitor 38c and an inductor 38d are connected in order from the input terminal 38a to the output terminal 38b.

  The detection circuit 40 includes a detector 40a connected between the output terminal 38b of the third filter 38 and the ground, and a resistor connected between the connection point 38e of the capacitor 38c and the inductor 38d and the input of the current control circuit 41. 40b and a capacitor 40c connected between the input of the current control circuit 41 and the ground.

  An operation of the electronic tuner 22 configured as described above will be described. A television broadcast signal received by the antenna 21 is input to the high frequency amplifier 26. The output signal from the high frequency amplifier 26 is input to the first filter 27 that suppresses the transmission signal output from the mobile phone.

  The output signal from the first filter 27 is subjected to gain control by the high frequency amplifier 29, and then supplied to one input of the mixer 32, and the output signal of the oscillator 30 is supplied to the other input.

  For example, an interference signal other than the desired signal is suppressed by the filter 33 in the intermediate frequency signal of 57 MHz output from the mixer 32. The frequency of the oscillator 30 is controlled by a control signal output from the PLL control circuit 36.

  Further, the gain control voltage output from the gain control circuit 44 is supplied to the gain control input 29 a of the high frequency amplifier 29. As a result, the gain is controlled so that the output signal of the mixer 32 becomes a constant level.

  Note that the input to the gain control circuit 44 may supply the output of the filter 33. In this case, since interference signals such as transmission signals and adjacent channels can be suppressed by the filter 33, the influence of the interference signals on gain control can be reduced.

  The output signal of the mixer 32 is input to the television demodulation circuit 34 after the interference signal is sufficiently suppressed by the filter 33. The TS signal output from the television demodulation circuit 34 is output from the television output terminal 35.

  As described above, the television broadcast signal input to the television input terminal 25 is amplified by the high frequency amplifier 26, gain control is performed by the high frequency amplifier 29, the frequency is converted by the mixer 32, and the first filter 27. The signal whose transmission signal or interference signal is suppressed by the filter 33 is input to the television demodulation circuit 34. Then, the TS signal demodulated by the television demodulation circuit 34 is output from the television output terminal 35.

  Next, the mobile phone 23 will be described below. The cellular phone 23 includes an input / output terminal 23a to which the cellular phone antenna 24 is connected, a transmission / reception circuit 43 connected to the input / output terminal 23a, an output terminal 43b of the transmission / reception circuit 43, and a TV demodulation circuit 34. The decoding circuit 46 that decodes the input signal and the output are connected to each other, the video display unit 47 and the audio output unit 48 to which the output of the decoding circuit 46 is connected, and the audio / data signal are input. A voice / data input unit 49, a coding circuit 50 that is connected between the voice / data input unit 49 and the input terminal 43c of the transmission / reception circuit 43 and encodes a voice / data signal, the transmission / reception circuit 43, and a PLL The control unit 52 controls the control circuit 36.

  The operation of the mobile phone 23 configured as described above will be described. In response to a control signal from the control unit 52, the mobile phone 23 is placed in a call state. As a result, the transmission signal output from the transmission / reception circuit 43 of the mobile phone 23 is output from the mobile phone antenna 24.

  FIG. 2 shows the relationship between the television broadcast signal and the transmission signal in the mobile phone device 20. The horizontal axis 61 is frequency (MHz), and the vertical axis 62 is level (dBm).

  In FIG. 2, the VHF broadcast signal 65 has a band of 90 MHz to 220 MHz. The UHF broadcast signal 66 has a band of 470 MHz to 770 MHz.

  The transmission signals 67, 68, 69 output from the transmission / reception circuit 43 of the mobile phone 23 may be at a level of +28 dBm at the input / output terminal 23a in the domestic PDC system, for example. The transmission signal Vtx output from the input / output terminal 23 a is output from the mobile phone antenna 24, propagates in the air, and is received by the television receiving antenna 21 provided in the vicinity of the mobile phone antenna 24.

  The transmission signals 68 and 69 are examples of signals output from the transmission circuit of the mobile phone using different frequency bands, and have frequencies of 1.5 GHz and 1.9 GHz, respectively. Since these are sufficiently away from the frequency of the UHF broadcast signal 66, the influence is small.

  However, since the TV antenna 21 and the mobile phone antenna 24 are mounted on the miniaturized mobile phone device 20, the TV antenna 21 and the mobile phone antenna 24 cannot secure a sufficient distance in terms of high frequency. .

  For this reason, the transmission signal output from the cellular phone antenna 24 is received by the television antenna 21 through the air. Here, it is assumed that the isolation Viso from the cellular phone antenna 24 to the television antenna 21 is, for example, 30 dB.

  The transmission signal Vu received by the television antenna 21 is −2 dBm from (Equation 1).

  The transmission signal Vu is suppressed by the first filter 27 and the filter 33 and then input to the television demodulation circuit 34. However, the transmission signal is not sufficiently suppressed by the first filter 27. Such a transmission signal is amplified by the high frequency amplifiers 26 and 29 and input to the mixer 32. For this reason, in the mixer 32, distortion due to the transmission signal is most likely to occur, and the interference performance of the electronic tuner 22 is almost determined by the transmission signal Vu.

  In order to suppress the interference in the mixer 32, suppression of the transmission signal of the first filter 27 is important. The required suppression ratio S1 for the transmission signal of the first filter 27 will be described below.

  The input level V (P1 dB) of the mixer 32 is set to −40 dm. Note that V (P1 dB) is an input signal level at which the output signal level becomes −1 dB with respect to the increase in the input signal level and the output signal level is saturated.

  The required suppression ratio S1 in the first filter 27 inserted in the previous stage of the mixer 32 is 68 dB from (Equation 2), which is approximately 70 dB. The power gain G1 of the high frequency amplifier 26 is +15 dB, and the power gain G2 of the high frequency amplifier 29 is +15 dB.

  However, the interval 70 between the transmission signal 67 and the highest channel (62ch) of the UHF broadcast signal 66 is close to 60 MHz.

  The electronic tuner 22 that can improve both the performance of the interference characteristic due to the transmission signal and the reception sensitivity due to the loss of the filter will be described below.

  First, a method for improving the reception sensitivity will be described with reference to FIG. That is, a medium power type high frequency amplifier 26 having excellent noise figure and distortion characteristics is inserted between the TV input terminal 25 and the first filter 27.

  Thus, by inserting the high-frequency amplifier 26 before the first filter 27, the insertion loss due to the first filter 27 can be reduced. That is, reception sensitivity can be improved.

  Next, a method for improving the interference caused by the transmission signal of the high frequency amplifier 26 will be described with reference to FIGS.

  In the high frequency amplifier 26 inserted on the TV antenna 21 side from the first filter 27, interference is caused by the transmission signal of the mobile phone 23 in use. In order to improve this interference, the high-frequency amplifier 26 uses a medium power type semiconductor element having excellent distortion characteristics as shown in FIGS.

  FIG. 3A shows the amplification degree 92 with respect to the current 91, and the amplification degree 7b of the high-frequency amplifier 7 (see FIG. 11) and the amplification degree 26b of the high-frequency amplifier 26 are indicated by a dotted line and a solid line, respectively.

  FIG. 3B shows the noise figure 93 with respect to the current 91, and the noise figure 7c of the high-frequency amplifier 7 and the noise figure 26c of the high-frequency amplifier 26 are represented by a dotted line and a solid line, respectively.

  FIG. 3C shows V (P1 dB) 94 with respect to the current 91. V (P1dB) 7d of the high-frequency amplifier 7 is represented by a dotted line, and V (P1dB) 26d of the high-frequency amplifier 26 is represented by a solid line.

  3A to 3C, the high-frequency amplifier 7 is a semiconductor element having a maximum rating of 20 mA, and an actually used current is used as a current value 101 (8 mA). In particular, as shown in FIG. 3C, in the high-frequency amplifier 7, even if the current value 101a (15 mA) is increased, V (P1 dB) 94a is obtained, and the degree of improvement is small.

  On the other hand, in the high frequency amplifier 26, the maximum rating is 100 mA, and the actual current used can be used as the current value 101 (8 mA) or the current value 102 (40 mA), respectively. In particular, when used at a current value of 102 (40 mA), V (P1 dB) 94b can be greatly improved.

  Further, in the high frequency amplifier 26, both the amplification factor and the noise figure at the current value 102 (40 mA) are hardly deteriorated compared to the amplification factor and the noise figure at the current value 101 (8 mA).

  FIG. 4 shows a BER (bit error rate) 106 that is the reception quality of the electronic tuner 22 with respect to the transmission signal level 105 input from the TV input terminal 25 in the electronic tuner 22 using the high-frequency amplifier 26.

  The BER 107 of the electronic tuner at the current value 101 (8 mA) of the high-frequency amplifier 26 is represented by a dotted line, and the BER 108 of the electronic tuner at the current value 102 (40 mA) is represented by a solid line.

  In FIG. 4, at the BER 107 (dotted line), when the transmission signal level 105a is higher, the BER is deteriorated. However, in the BER 108 (solid line), the BER does not deteriorate even if the transmission signal level 105b is higher than the transmission signal level 105a.

  As described above, when the medium power type semiconductor element having excellent distortion characteristics is used for the high frequency amplifier 26 and the transmission signal level is higher than the transmission signal level 105a, the current control unit 42 sets the current of the high frequency amplifier 26 large. To do. Thereby, in the high frequency amplifier 26, V (P1 dB) can be greatly improved without impairing the noise figure. In this way, distortion of the high frequency amplifier 26 can be eliminated.

  When the transmission signal level is lower than the transmission signal level 105a, the current of the high frequency amplifier 26 is reduced. As a result, power consumption can be reduced when a call is not being made.

  FIG. 5 is a circuit diagram of the first filter 27. As the first filter 27, for example, a notch filter format for removing a specific frequency is used. The first filter 27 has an input terminal 27a and an output terminal 27b. In order from the input terminal 27a to the output terminal 27b, a parallel connection body 72 of an inductor 72a and a capacitor 72b and a parallel connection body 73 of an inductor 73a and a capacitor 73b are connected in series. Furthermore, a series connection body 75 of an inductor 75a and a capacitor 75b is connected between the connection point of the parallel connection bodies 72 and 73 and the ground.

  Here, the parallel resonance frequency of the parallel connection bodies 72 and 73 and the series resonance frequency of the series connection body 75 are set to around 830 MHz, and the vicinity of the 830 MHz is attenuated.

  FIG. 6 shows the selection characteristic 81 with respect to the frequency of the first filter 27 configured as described above. The horizontal axis 79 is frequency (MHz), and the vertical axis 80 is attenuation (dB).

  In FIG. 6, up to a frequency 83 of 770 MHz, which is the highest channel of the UHF broadcast signal 66 (FIG. 2), shows a substantially flat characteristic. A large attenuation amount of about 70 dB or more can be obtained at the frequency 84 of 830 MHz in which the transmission signal 67 (FIG. 2) as the interference signal exists.

  By using the first filter 27 configured as described above, it is possible to suppress interference caused by transmission signals in the high-frequency amplifier 29 and the mixer 32.

  Next, the current control unit 42 that detects the transmission signal and controls the current value of the high-frequency amplifier 26 based on the detection result will be described.

  A transmission signal from the transmission / reception circuit 43 is amplified by the high frequency amplifier 26 and supplied to the input terminal 38 a of the third filter 38. The third filter 38 is composed of a series resonance circuit of a capacitor 38c and an inductor 38d connected in order from the input terminal 38a to the output terminal 38b. The series resonance frequency is substantially equal to the frequency 830 MHz of the transmission signal. Match.

  The output terminal 38b of the third filter 38 is connected to the cathode of the detector 40a, and the anode of the detector 40a is connected to the ground. Thereby, the transmission signal that has passed through the third filter 38 is detected by the detector 40a. The detected voltage is averaged by an integrating circuit including a resistor 40b and a capacitor 40c. The resistor 40b is set to, for example, 500Ω because of the response time.

  One end of the 500Ω resistor 40b is connected to a connection point 38e between the capacitor 38c and the inductor 38d. Thereby, it can prevent that the transmission signal which is the high frequency input into the detector 40a is damped. Therefore, a sufficient detection voltage can be obtained in the detector 40a.

  For example, the case where the resistor 40b is connected between the output terminal 38b and the input of the current control circuit 41 will be described. The series resonance frequency of the capacitor 38c and the inductor 38d is matched with the frequency of the transmission signal. For this reason, the output terminal 38b is directly damped by the resistor 40b at the frequency of the transmission signal. For this reason, a detection voltage will be impaired.

  In this way, the voltage charged in the capacitor 40c is supplied to the current control circuit 41. The output of the current control circuit 41 is supplied to the current control input 26 a of the high frequency amplifier 26.

  For example, when there is a transmission signal, the charging voltage of the capacitor 40c increases, and the current value of the high-frequency amplifier 26 is set large. When the transmission signal does not exist or is small, the charging voltage of the capacitor 40c becomes small, and the current value of the high frequency amplifier 26 may be set small.

  As described above, when the transmission signal is detected, the current control unit 42 increases the current of the high-frequency amplifier 26. Thereby, even during a call on the mobile phone 23, it is possible to receive television. Further, when there is no transmission signal or when the transmission signal is small, the current of the high frequency amplifier 26 is reduced. As a result, power consumption can be reduced when a call is not being made.

  FIG. 7 shows an output level 111 of each signal with respect to time 110 in a mobile phone using a GSM transmission signal. This signal level represents a burst signal 113 which is a GSM transmission signal and a current control signal 114 output from the current control circuit 41.

  In FIG. 7, a burst signal 113, which is a GSM transmission signal, has a signal 113b next to a signal 113a, and the same signal is continuously transmitted.

  A period 110c from the start time 110a of the signal 113a to the start time 110b of the signal 113b is, for example, 4600 usec. Furthermore, the period 111e from the start time 110a of the signal 113a to the end time 110d is, for example, 570 usec.

  This signal 113a is set stepwise so that it becomes an output level 111a at time 110a, further increases to an output level 111b at time 110f, and reaches a final output level 111c at time 110g. The signal 113a set in stages is the same in the signal 113b or a signal subsequent to the signal 113b.

  Thus, the output levels of the signals 113a and 113b are set in stages. The reason for this is as follows. That is, the power amplifiers of the transmission circuit provided in the transmission / reception circuit 43 are configured in multiple stages, and the operations of these multi-stage power amplifiers are controlled to be started in order.

  As a result, sudden load fluctuations on the oscillator due to the power amplifier in the transmission / reception circuit 43 can be suppressed. Therefore, fluctuations in the oscillator frequency of this oscillator can be reduced.

  Next, the current control signal 114 output from the current control unit 42 will be described with reference to FIG. A burst signal 113 which is a transmission signal is supplied to the detection circuit 40 from the input terminal 38a.

  The voltage detected by the detector 40a of the detection circuit 40 is averaged by an integration circuit including a resistor 40b and a capacitor 40c. This averaged signal is supplied to the current control circuit 41.

  The period 110i from the time 110a of the current control signal 114a output from the current control circuit 41 to the rising time 110h is set to be smaller than the period 110j from the time 110a to the time 110f.

  Note that the relationship between the period 110i and the period 110j in the current control signal 114a is the same in the current control signal 114b.

  For example, if the period 110j is 10 usec, the period 110i needs to be set to 10 usec or less. For this reason, for example, the capacitance value of the capacitor 40c is 10 nF, and the resistance value of the resistor 40b is 500Ω.

  This period 110i is substantially determined by the time constant C * R based on the resistance value R of the resistor 40b and the capacitance value C of the capacitor 40c, as represented by (Equation 3).

  Thereby, the period 110i can be set to about 5 usec.

  Further, during the time when there is no signal other than the signals 113a and 113b, the charging voltage of the capacitor 40c is discharged in a short time by the load of the current control circuit 41. That is, the burst signal 113 falls at time 110d, and the current control signal 114 can be 0V at time 110m.

  In this way, the rising time 110h of the current control signal 114a can be detected within the rising period 110j of the burst signal 113a by detecting the output level 111a rising first. The falling time 110m of the current control signal 114a is determined by the falling time 110d of the burst signal 113a.

  The current control signal 114a is the same as the current control signal 114b corresponding to the burst signal 113b.

  In this manner, using the current control signal 114 from the current control unit 42, the current value of the high frequency amplifier 26 is set to be large at 40 mA in the period 111n corresponding to the period 111e in which the transmission signal is present, and there is no transmission signal. In the period 111p corresponding to the period 111f, the electrode flow value of the high-frequency amplifier 26 can be set as small as 8 mA.

  Note that the period 111p is a time from the falling time 110m of the current control signal 114a to the rising time 110k of the current control signal 114b.

  As described above, the current value of the high-frequency amplifier 26 can be set large by using the current control signal 114 before the burst signal 113a changes from the output level 111a to the output level 111b. Therefore, the high frequency amplifier 26 can suppress distortion due to the signal 113a. Further, since the current value can be set large only during the period 111n (570 usec), power consumption can be significantly reduced.

  The rise time 110h of the current control signal 114a may be earlier than the rise time 110g of the signal 113a.

  In this way, when the transmission signal is detected, the current control unit 42 increases the current of the high-frequency amplifier 26. As a result, even when a call is being made on the mobile phone 23, the high frequency amplifier 26 is not distorted by the transmission signal, so that high-quality television reception is possible.

  Further, since the high frequency amplifier 26 is inserted between the television input terminal 25 and the first filter 27, it is possible to improve the deterioration of the reception sensitivity.

  Further, when there is no transmission signal or when the transmission signal is small, the current of the high frequency amplifier 26 is reduced. As a result, power consumption can be reduced when a call is not being made.

  Further, a second filter 120 (not shown) may be inserted between the television input terminal 25 and the high frequency amplifier 26. The second filter 120 is capable of suppressing the transmission signal by 20 to 30 dB, and is set to be smaller than the suppression amount of the first filter 27 with respect to the transmission signal.

  In addition, for example, when the mobile phone device is further reduced in size, the isolation Viso from the mobile phone antenna 24 to the television antenna 21 is further deteriorated. Even in this case, the transmission signal can be suppressed by 20 to 30 dB by the second filter 120. Therefore, it is possible to realize a mobile phone device of a further reduced size without impairing reception sensitivity.

(Embodiment 2)
FIG. 8 is a block diagram of mobile phone device 420 according to the second embodiment. In the mobile phone device 20 according to the first embodiment, the current control unit 42 includes the third filter 38, the detection circuit 40, and the current control circuit 41. A UHF broadcast signal and a large transmission signal from the mobile phone 23 are input to the detection circuit 40 of the electronic tuner 22.

  For this reason, the detection circuit 40 generates a UHF broadcast signal on which a distortion signal is superimposed. The UHF broadcast signal flows back to the signal line that is the input of the first filter 27 and becomes an interference signal.

  On the other hand, in the cellular phone device 420 in the present embodiment, the current control unit 442 inserts the high frequency amplifier 39 between the filter 438 and the detection circuit 40. Another difference is that an extraction circuit 437 is inserted between the output of the high-frequency amplifier 26, the input of the first filter 27, and the input of the current control unit 442.

  The same components as those in the first embodiment are denoted by the same reference numerals, and the description is simplified.

  In FIG. 8, the mobile phone device 420 includes an electronic tuner 422 and a mobile phone 23. In the electronic tuner 422, the input terminal 437 a of the extraction circuit 437 is connected to the output of the high frequency amplifier 26. The input terminal 27a of the first filter 27 is connected to the output terminal 437b of the extraction circuit 437.

  Further, the input terminal 438a of the filter 438 is connected to the output terminal 437c of the extraction circuit 437. An input of the high frequency amplifier 39 is connected to the output terminal 438b of the filter 438. The input of the detection circuit 40 is connected to the output of the high frequency amplifier 39. The input of the current control circuit 41 is connected to the output of the detection circuit 40. The output of the current control circuit 41 is connected to the current control input 26 a of the high frequency amplifier 26.

  FIG. 9 is a circuit diagram of a directional coupler 439 which is another example of the extraction circuit 437 of FIG. The input terminal 439a and the output terminals 439b and 439c provided in the directional coupler 439 correspond to the input terminal 437a, the output terminals 437b and 437c of the extraction circuit 437, respectively.

  In FIG. 9, between the input terminal 439a and the output terminal 439b, a resonator 439d, a resonator 439e arranged as a directional coupler by being disposed close to the resonator 439d, and the resonator 439e It comprises a 50Ω resistor 439f connected between one end and the ground, and an output terminal 439c connected to the other end of the resonator 439e.

  It is desirable that both resonators 439d and 439e have a wavelength length of approximately λ / 4 of the frequency of the UHF broadcast signal.

  As described above, since the resonators 439d and 439e form a directional coupler, the transmission loss from the input terminal 439a to the output terminal 439b can be reduced to approximately 0.5 dB. Further, the signal level output from the output terminal 439c can be smaller than the signal level output from the output terminal 439b. Furthermore, the isolation from the output terminal 439c to the output terminal 439b can be increased to approximately 20 dB.

  FIG. 10 is a circuit diagram of a power distributor 440 that is an example of the extraction circuit 437 of FIG. The input terminal 440a and the output terminals 440b and 440c provided in the power distributor 440 correspond to the input terminal 437a and the output terminals 437b and 437c of the extraction circuit 437, respectively.

  In FIG. 10, an inductor 440d is connected between an input terminal 440a and an output terminal 440b. An inductor 440e is connected between the input terminal 440a and the output terminal 440c. A capacitor 440f is connected between the input terminal 440a and the ground. A capacitor 440g and a resistor 440h are connected between the output terminals 440b and 440c.

  The inductance of the inductor 440d is approximately 12 nH. The inductance of the inductor 440e is approximately 12 nH. The capacitance value of the capacitor 440f is approximately 3 pF. The capacitance value of the capacitor 440g is approximately 6 pF. The resistance value of the resistor 440h is approximately 100Ω.

  As described above, the signal from the input terminal 440a is divided into two by the power distributor 440 and output from the output terminals 440b and 440c. A large isolation of about 20 dB can be obtained between the output terminals 440b and 440c.

  As described above, the high-frequency amplifier 39, the directional coupler 439, or the power distributor 440 can sufficiently secure the isolation from the detection circuit 40 to the input terminal 27a of the first filter 27.

  Therefore, even if a nonlinear distortion component in the detection circuit 40 due to a large transmission signal is superimposed on the UHF broadcast signal, it is possible to prevent the UHF broadcast signal from flowing into the signal line that is the input of the first filter 27. it can.

  For this reason, even when the cellular phone 23 is in a call, no interference occurs, so that high-quality television reception is possible.

  In order to secure isolation from the detection circuit 40 to the input terminal 27a of the first filter 27, the connection between the output of the high-frequency amplifier 26 and the input terminal 27a of the first filter 27 is not used without using the extraction circuit 437. Even if an isolator is inserted between the point and the detection circuit 40, the same effect can be obtained.

  The mobile phone device 420 configured as described above also has the same effect as the mobile phone device 20 described in the first embodiment.

  The electronic tuner according to the present invention can receive a TV broadcast signal without being affected by the cellular phone 23 even when the cellular phone 23 is in a call. Therefore, the electronic tuner built in the cellular phone device or the like can be used. Useful as.

1 is a block diagram of a mobile phone device according to Embodiment 1 of the present invention. The figure showing the relationship between TV broadcast signals and mobile phone transmission signals (A) is a characteristic diagram of amplification with respect to current, (b) is a characteristic diagram of noise figure with respect to current, and (c) is a characteristic diagram of V (P1 dB) with respect to current. Same as above, BER characteristics of electronic tuner with respect to input signal level Same as above, circuit diagram of the first filter Same as above, selection characteristics of the first filter Same as above, time chart of transmission signal and current control signal Block diagram of a mobile phone device in Embodiment 2 of the present invention The circuit diagram of the extraction circuit using the directional coupler Same as above, circuit diagram of extraction circuit using power divider Block diagram of a conventional cellular phone device

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 Mobile phone apparatus 22 Electronic tuner 22a Input terminal 23 Mobile phone 25 Television input terminal 26 High frequency amplifier 26a Current control input 27 First filter 29 High frequency amplifier 30 Oscillator 32 Mixer 35 Television output terminal 42 Current control unit

Claims (13)

In the electronic tuner incorporated in the mobile phone device, the electronic tuner is supplied with a TV input terminal to which a TV broadcast signal is input, and a signal input to the TV input terminal is supplied to the mobile phone device. A first filter for blocking a transmission signal from a telephone; a mixer in which an output from the first filter is supplied to one input; an oscillator connected to the other input of the mixer; A first high frequency amplifier having a current control input for controlling a current value and being inserted between the television input terminal and the first filter. And a current control unit that is inserted between the output of the first high-frequency amplifier and the input for current control and detects the transmission signal to control the current of the first high-frequency amplifier Provided, the electronic tuner in which the mobile phone is sending the transmission signal to set a large current of the first high-frequency amplifier. 2. The electronic tuner according to claim 1, wherein the current control unit detects a signal that rises first among transmission signals that rise in a stepwise manner, and controls the current of the first high-frequency amplifier. An electronic tuner used in a GSM cellular phone device, wherein the current control unit sets a current of the first high-frequency amplifier large during a period in which a burst signal transmitted from the cellular phone exists, The electronic tuner according to claim 1, wherein the current of the first high-frequency amplifier is set to be small during the non-existing time. The electronic tuner according to claim 1, wherein the first filter includes a notch filter that suppresses a transmission signal. A second filter for suppressing the transmission signal is inserted between the television input terminal and the input of the first high-frequency amplifier, and the amount of suppression of the transmission signal of the second filter is the transmission of the first filter. The electronic tuner according to claim 1, wherein the electronic tuner is set to be smaller than a suppression amount for the signal. The current control unit includes a third filter that transmits the transmission signal, a detection circuit that detects the transmission signal from the third filter, an output of the detection circuit, and a current control input of the first high-frequency amplifier. The electronic tuner according to claim 1, further comprising: a current control circuit that is connected in between and controls a current of the first high-frequency amplifier. The electronic tuner according to claim 6, wherein a second high-frequency amplifier is inserted between the third filter and the detection circuit to increase isolation from the detection circuit to the input of the first filter. The electronic tuner according to claim 7, wherein the third filter includes a first capacitor and an inductor connected in series in order from the input to the output. The detection circuit includes a detector connected between the output of the third filter and the ground, a resistor connected between a connection point of the inductor and the first capacitor, and an input of the current control circuit, and the current control circuit. 9. The electronic tuner according to claim 8, further comprising: a second capacitor connected between the first input and the ground, wherein the detection voltage from the detector is supplied to the input of the current control circuit via the resistor. An extraction circuit which is inserted between the output of the first high-frequency amplifier and the input of the first filter and has an output terminal for outputting a part of the output signal of the first high-frequency amplifier; The electronic tuner according to claim 1, wherein the output terminal is connected to an input of a current control unit. A power distributor having an output terminal that is inserted between the output of the first high-frequency amplifier and the input of the first filter and that outputs a signal obtained by distributing the output signal of the first high-frequency amplifier; The electronic tuner according to claim 1, wherein the output terminal of the power distributor is connected to an input of a current control unit. An isolator having an output terminal inserted between an output of the first high-frequency amplifier and an input of the first filter and outputting a part of an output signal of the first high-frequency amplifier is provided; The electronic tuner according to claim 1, wherein the output terminal is connected to an input of the current control unit. A cellular phone device using the electronic tuner according to claim 1.

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