JP2006237793A - High-frequency signal receiver and high-frequency signal receiver using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of the poor reception conditions, in an area having a large disturbance signal or an inferior receiving performance in a weak electric-field area. <P>SOLUTION: A high-frequency signal receiver has second AGC detector 28a, connected at an output from an intermediate-frequency filter 25 and a filter controller 32 being connected between the second AGC detector 28a, and an input 19b for controlling the band of a high-frequency filter 19, while voltage-controlling the bandwidth of the high-frequency filter 19. The bandwidth of the high-frequency filter 19 is changed by the filter controller 32. In this way, the problem can be solved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a high-frequency signal receiving unit capable of good reception corresponding to each of a reception condition in an area with a large interference signal or a reception condition in a weak electric field area, and a high-frequency signal receiving apparatus using the same It is about.

  Hereinafter, a conventional high-frequency signal receiver and a high-frequency signal receiver using the same will be described. As shown in FIG. 5, the conventional high-frequency signal receiving apparatus includes a high-frequency signal receiving unit 1 and a demodulation circuit unit 2 connected to the output of the high-frequency signal receiving unit 1.

  The high-frequency signal receiving unit 1 has the following configuration. That is, the high frequency signal received by the antenna is input to the input terminal 3. The high frequency signal input to the input terminal 3 is input to the high frequency amplifier 4 through the input filter, amplified by the high frequency amplifier 4, and then input to the high frequency filter 5. The output of the high-frequency filter 5 is supplied to one input of the mixer 6, and the output signal of the oscillator 7 is input to the other input of the mixer 6. A signal is output. This desired signal is output from the output terminal 10 via the intermediate frequency filter 9. The output signal output from the output terminal 10 is supplied to the demodulation circuit unit 2.

  The output signal of the mixer 6 is input to the gain controller 8b via the AGC detector 8a. The output of the gain controller 8b is input to the gain control terminal 4a of the high frequency amplifier 4, and the output level of the mixer 6 is set to a constant value.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
JP 2002-31657 A

  However, in a conventional high-frequency signal receiving unit and a high-frequency signal receiving device using the same, when a high level interference signal is input from the input terminal 3 to the desired signal, this high level interference signal is output at the output of the mixer 6. Will be dominated by. Accordingly, gain control is performed by the high frequency amplifier 4 so that the level of the interference signal becomes a constant value. As a result, the desired signal output from the high frequency amplifier 4 has a very small level, and the difference from the noise level becomes small, so that there is a problem that normal reception cannot be performed.

  Therefore, the present invention has been made to solve this problem, and an object thereof is to provide a high-frequency signal receiving unit that enables selection of either improvement of interference signal elimination capability or improvement of reception sensitivity in a weak electric field. It is.

  In order to achieve this object, the high-frequency filter used in the high-frequency signal receiving unit of the present invention uses a high-frequency filter that can variably control the passband width with a voltage applied to a band control input provided in the high-frequency filter. A second AGC detector to which an output of the intermediate frequency filter is supplied, and a filter controller connected between the second AGC detector and the band control input. The output bandwidth of the high frequency filter is controlled by the output from the AGC detector. This makes it possible to achieve the initial purpose.

  As described above, the high-frequency filter used in the high-frequency signal receiving unit of the present invention uses a high-frequency filter that can variably control the pass band width with the voltage applied to the band control input provided in the high-frequency filter, and has an intermediate frequency. A second AGC detector to which an output of the filter is supplied; and a filter controller connected between the second AGC detector and the band control input; and the second AGC detector. Since the output bandwidth of the high frequency filter is controlled by the output from the high frequency filter, the interference signal rejection capability can be improved by narrowing the pass bandwidth of the high frequency filter. In addition, the reception sensitivity in a weak electric field can be improved by widening the passband width of the high frequency filter. As described above, by changing the pass band width of the high-frequency filter, it is possible to select one of the improvement of the interference signal rejection capability and the improvement of the reception sensitivity in a weak electric field.

  Therefore, it is possible to obtain optimum reception performance corresponding to each of the reception condition in an area with a large interference signal or the reception condition in a weak electric field area.

  In addition, since the passband width of the high frequency filter can be directly controlled by the output from the second AGC detector, the optimum reception performance can be set in a short time before performing the BER calculation or the like.

(Embodiment 1)
Hereinafter, Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram of a high-frequency signal receiving apparatus. In this embodiment, a case where a digital broadcast signal for television is received is described as an example of a received signal received by the high-frequency signal receiver.

  The high-frequency signal receiving apparatus includes a high-frequency signal receiving unit 11 and a demodulation circuit unit 12, and an output of the high-frequency signal receiving unit 11 is connected to an input of the demodulation circuit unit 12.

  Hereinafter, the configuration of the high-frequency signal receiving unit 11 will be described. The high-frequency signal receiving unit 11 is provided with an input terminal 14 to which an antenna 13 is connected, an output terminal 15, and a data input terminal 16 for PLL channel selection. Between the input terminal 14 and the output terminal 15, the input filter 17, the high frequency amplifier 18, the high frequency filter 19, the mixer 20, and the first intermediate frequency from the input terminal 14 side to the output terminal 15 side. Are connected in this order to an intermediate frequency filter 25 through which the signal passes, an amplifier 26, and an intermediate frequency filter 27 through which the intermediate frequency signal passes.

  Here, the output of the high frequency filter 19 is connected to one input of the mixer 20, and the output of the oscillator 21 is connected to the other input of the mixer 20.

  The data input terminal 16 to which control data is input is connected to the input 22 a of the PLL circuit 22. A control voltage C is output from an output 22 b provided in the PLL circuit 22. This control voltage C is connected to the tuning control inputs 19a and 21a of the high frequency filter 19 and the oscillator 21, respectively, and controls the respective tuning frequencies.

  Further, the output of the mixer 20 is connected to the first gain controller 23b via the first AGC detector 23a, and the output of the first gain controller 23b is the input for AGC control of the high frequency amplifier 18. 18a.

  The output of the amplifier 26 is connected to the second AGC detector 28a. The output of the second AGC detector 28a is connected to the AGC control input 26a of the amplifier 26 via the second gain controller 28b. The output of the second gain controller 28 b is also connected to the input 32 a of the filter controller 32.

  The filter controller 32 includes a comparator 34 and a reference voltage 35. One input 34 a of the comparator 34 is connected to the output of the second AGC detector 28 a via the input 32 a of the filter controller 32. A reference voltage 35 is connected to the other input 34 b of the comparator 34.

  Further, the output of the comparator 34 is connected to the band control input 19 b of the high frequency filter 19. The output 22 c of the PLL circuit 22 is connected to the input 35 a of the reference voltage 35.

  Next, the configuration of the demodulation circuit unit 12 will be described. The output of the output terminal 15 of the high frequency signal receiving unit 11 is connected to the input terminal 41 of the demodulation circuit unit 12. The input terminal 41 is connected to the input of the amplifier 42. The output of the amplifier 42 is connected to the input of the A / D converter 43.

  The output of the A / D converter 43 is connected to the digital filter 44. The output of the digital filter 44 is connected to the input of the demodulator 45 and is also connected to the third AGC detector 47. Further, the output 47 a of the third AGC detector 47 is connected to the AGC control input 42 a of the amplifier 42 via the third gain controller 48. The output of the demodulator 45 is connected to the output terminal 46.

  The operation of the high-frequency signal receiving unit 11 of the high-frequency signal receiving apparatus configured as described above will be described with reference to FIG.

  A television digital broadcast signal received by the antenna 13 is input to the input filter 17 via the input terminal 14. In the input filter 17, unnecessary signals other than the television broadcast reception signal are suppressed, and a television reception signal is selected. This received signal is amplified by the high frequency amplifier 18 and then input to the high frequency filter 19. For example, an interference signal close to the desired signal is suppressed by the high frequency filter 19 and then supplied to one input 20 a of the mixer 20, and the output signal from the oscillator 21 controlled by the PLL circuit 22 is supplied to the other input 20 b. Is supplied.

  Here, control data is input to the input 22 a of the PLL circuit 22 via the data input terminal 16. Thus, the oscillation frequency of the oscillator 21 and the tuning frequency of the high frequency filter 19 are controlled by the control voltage C output from the PLL circuit 22. In the following description, the oscillation frequency of the oscillator 21 is assumed to be higher than the signal input to the input terminal 14.

  From the mixer 20, for example, a desired signal having a first intermediate frequency of 8 MHz is output. When this desired signal is input to the intermediate frequency filter 25, interference signals other than the desired signal are suppressed. Further, the output signal of the intermediate frequency filter 25 is amplified by the amplifier 26 and then input to the intermediate frequency filter 27. After the interference signal is further suppressed by the intermediate frequency filter 27, the desired signal is gain-controlled to a constant output level and output from the output terminal 15.

  The reception signal input to the input terminal 14 as described above is output from the output terminal 15 as the first intermediate frequency. Further, the output of the mixer 20 is supplied to the AGC control input 18a of the high-frequency amplifier 18 via the first AGC detector 23a and the first gain controller 23b. Thereby, the output signal level from the mixer 20 is controlled to be a constant value.

  The input to the first AGC detector 23 a is the same as that supplied from the output of the intermediate frequency filter 25. In this case, the output level of the intermediate frequency filter 25 is controlled to be a constant value. If there is an interference signal, the interference signal is controlled at the interference signal level after being suppressed by the intermediate frequency filter 25.

  The output of the amplifier 26 is connected to the gain control input 26a of the amplifier 26 via the second AGC detector 28a and the second gain controller 28b. Thereby, the signal level output from the amplifier 26 is controlled to be a constant value.

  As described above, the high-frequency amplifier 18 and the amplifier 26 of the high-frequency signal receiving unit 11 control the gain of the input high-frequency signal and output a constant output signal level from the output terminal 15. The input terminal 14 is supplied with a received signal having a weak electric field (−110 dBm) to a strong electric field (−10 dBm). Specific gain control of the high-frequency amplifier 18 and the amplifier 26 in this case will be described below.

  For example, when a received signal level from a weak electric field (−110 dBm) to a medium electric field (−70 dBm) is supplied to the input terminal 14, the amplifier 26 performs a gain control operation. Further, when a reception signal level from a medium electric field (−70 dBm) to a strong electric field (−10 dBm) is supplied to the input terminal 14, the high frequency amplifier 18 performs a gain control operation.

  In this way, in a weak electric field, the high-frequency amplifier 18 has the maximum gain, and therefore, a large received signal is input to the subsequent stage close to the output terminal 15, so that distortion easily occurs. For this reason, gain control is performed in the amplifier 26 in the subsequent stage.

  In a strong electric field, gain control is performed by both the high-frequency amplifier 18 at the front stage and the amplifier 26 at the rear stage.

  As described above, gain control is performed in the high-frequency amplifier 18 and the amplifier 26. As a result, a signal with a low noise level and a low distortion is output as a constant value from the output terminal 15.

  Next, the operation of the filter controller 32 when a received signal having a large desired signal and a small interference signal is input will be described below. When the interference signal is small as described above, the detection voltage A corresponding to the level of the desired signal input to the second AGC detector 28a is output from the second AGC detector 28a.

  Further, the output from the reference voltage 35 is referred to as a reference voltage B. This reference voltage B is assumed to be larger than the detection voltage A and will be described below.

  By inputting these two voltages to the comparator 34, a difference voltage (B−A) is output. When this detection voltage A is input to the input 34a of the comparator 34, a difference voltage (B−A) is output. In this case, since the detection voltage A is small, the difference voltage (B−A) becomes large. By using this voltage, the bandwidth of the high frequency filter 19 can be controlled as a narrow band.

  Next, the operation of the filter controller 32 when a received signal having a small desired signal and a large interference signal is input will be described below.

  In this case, the gain of the high frequency amplifier 18 is controlled by a large interference signal, so that the desired signal output from the mixer 20 has a small level. Since this small desired signal is input to the second AGC detector 28a, the detection voltage A from the second AGC detector 28a becomes small.

  When this detection voltage A is input to the input 34a of the comparator 34, a difference voltage (B−A) is output. In this case, since the detection voltage A is small, the difference voltage (B−A) becomes large. By using this voltage, the bandwidth of the high frequency filter 19 can be controlled as a narrow band.

  The input to the second AGC detector 28 a is the same as that supplied from the output of the intermediate frequency filter 27. In this case, the gain of the amplifier 26 is controlled so that the output level of the intermediate frequency filter 27 becomes a constant value. If there is an interference signal, the gain is controlled by the interference signal level after being suppressed by the intermediate frequency filter 27.

  The input to one input 34a of the comparator 34 is connected to the output of the intermediate frequency filter 25, the amplifier 26, or the intermediate frequency filter 27 instead of the second AGC detector 28a, and a fourth AGC detector (not shown). ) May be connected and supplied. Thereby, the interference signal is further suppressed by the intermediate frequency filters 25 and 27. Therefore, by inputting the signal from the output of the intermediate frequency filter 27 to the one input 34a of the comparator 34 via the fourth AGC detector, the influence of the interference signal is reduced. The band control of the high frequency filter 19 can be performed with high accuracy.

  The reference voltage 35 is set via the PLL circuit 22 by control data input from the data input terminal 16. Thereby, since the bandwidth of the high frequency filter 19 can be determined to an arbitrary value from the outside, it is easy to optimally set the bandwidth control for suppressing the interference signal.

  Next, the operation of the demodulation circuit unit 12 of the high frequency signal receiving device will be described with reference to FIG. The signal output from the output terminal 15 of the high-frequency signal receiving unit 11 is input to the input terminal 41 of the demodulation circuit unit 12. The signal input to the input terminal 41 is amplified by the amplifier 42, and then the analog signal is converted into a digital signal. The signal is input to an A / D converter 43 that converts the signal. The digital signal output from the A / D converter 43 has the interference signal removed by the digital filter 44. The desired signal from which the interference signal has been removed is demodulated by being input to the demodulator 45, and the demodulated signal is output from the output terminal 46.

  The output of the digital filter 44 is input to the gain control input 42a of the amplifier 42 via the third AGC detector 47 and the third gain controller 48, whereby the output level of the digital filter 44 is adjusted. Since it can be set to a constant value, the input to the A / D converter 43 can be made constant. Therefore, accurate digital conversion by the A / D converter 43 can be performed.

  Here, it is important to set the input signal level to the A / D converter 43 and the demodulator 45 to an optimum value. That is, when the input signals to the A / D converter 43 and the demodulator 45 are large, distortion occurs, and when the input signal is small, the noise level increases and C / N decreases.

  Since the desired signal levels to the A / D converter 43 and the demodulator 45 are gain-controlled by the high-frequency amplifier 18, the amplifier 26, and the amplifier 42 in the previous stage, a large signal is not input.

  However, when the desired signal level to the A / D converter 43 and the demodulator 45 is small, C / N is lowered. That is, when the disturbing signal is larger than the desired signal, for example, 30 dB or more, the gain control of the high-frequency amplifier 18 is determined by the disturbing signal. At the same time, since the desired signal is gain-controlled by the same gain control amount as that of the interference signal, the desired signal output from the output terminal 15 becomes smaller and C / N also decreases. Therefore, a good reception state is not achieved.

  In order to prevent the influence of this interference signal, it is important to increase the bandwidth suppression in the high-frequency filter 19. However, by increasing the suppression amount, the insertion loss of the high frequency filter 19 increases, and the reception sensitivity in a weak electric field decreases.

  Hereinafter, operations of gain control in the high frequency amplifier 18 and the amplifier 26 when a high frequency signal is input to the input terminal 14 will be described. First, the case where the bandwidth of the high frequency filter 19 is set to a constant value as in the conventional case will be described with reference to FIGS. That is, this case is the same as the case where the conventional high frequency filter 5 is used.

  FIGS. 2A to 2D are signal level diagrams at each point of the high-frequency signal receiving unit 11 of the present invention. The horizontal axis 61 represents the frequency, and the vertical axis 62 represents the signal level.

  FIG. 2A is a signal level diagram at the input terminal 14. In the input terminal 14, the interference signal 74 is in a state where the level is higher than the desired signal 73. The interference signal 74 has an input signal level of −25 dBm, for example. The desired signal 73 is, for example, −55 dBm. That is, the disturbance signal 74 is 30 dB larger than the desired signal 73.

  FIG. 2B is an output signal diagram of the high frequency amplifier 18. In the high frequency amplifier 18, gain control is performed so that the output signal from the mixer 20 becomes a preset constant level. As described above, as a result of the gain control of the output signal from the mixer 20, the output of the high-frequency amplifier 18 is gain-controlled so as to reach the constant level 62a.

  Therefore, the output of the high-frequency amplifier 18 is gain-controlled so that the interference signal 74 larger than the desired signal 73 becomes a constant level 62a, and becomes the interference signal 74a. The desired signal 73 is also gain-controlled by the same amount as the interference signal 74a to become the desired signal 73a. The level difference 77a represents the level difference between the interference signal 74a and the desired signal 73a.

  The noise level 75a is a noise level of the high-frequency amplifier 18. As described above, since the gain is largely controlled by the large interference signal 74 in the high-frequency amplifier 18, the noise level 75a becomes larger than the desired signal 73a.

  That is, in the high frequency amplifier 18, the gain control operation is performed based on the interference signal 74 that is a large signal, and therefore the level difference 76a between the desired signal 73a output from the high frequency amplifier 18 and the noise level 75a becomes small. C / N will deteriorate.

  FIG. 2C is an output signal diagram of the mixer 20. At this time, since the oscillation frequency of the oscillator 21 is higher than the signal input to the input terminal 14, the interference signal 74b is lower than the desired signal 73b.

  In FIG. 2C, the interference signal 74 b is controlled to a constant level 62 b by gain control of the high frequency amplifier 18. At this time, the interference signal 74 a supplied to one input of the mixer 20 is suppressed by the high frequency filter 19. The desired signal 73b approaches the level of the interference signal 74b by the amount of suppression of the interference signal 74b.

  However, since the bandwidth of the high frequency filter 19 is fixed, the interference signal 74b is not sufficiently suppressed. For this reason, the level difference 77b between the interference signal 74b and the desired signal 73b can be made smaller than the level difference 77a, but the suppression of the interference signal 74b by the high frequency filter 19 is not sufficient.

  Further, the noise level 75 b is a value obtained by adding the noise level of the mixer 20 to the noise level 75 a of the high-frequency amplifier 18. At this time, the gain of the high-frequency amplifier 18 is controlled by the large interference signal 74, so that the influence of the noise level of the mixer 20 as the subsequent stage becomes large, and the noise level 75b becomes a level close to the desired signal 73b.

  Accordingly, the level difference 76b between the desired signal 73b and the noise level 75b is reduced, and as a result, the C / N of the desired signal 73b output from the mixer 20 is deteriorated.

  FIG. 2D is an output signal diagram of a signal output from the output terminal 15. In FIG. 2D, the level of the desired signal 73c does not reach the constant level 62c. The reason for this will be described below.

  That is, the interference signal 74 b and the desired signal 73 b output from the mixer 20 are input to the intermediate frequency filters 25 and 27. Thereby, the interference signal 74b is suppressed to become the interference signal 74c. On the other hand, the desired signal 73c cannot be amplified to the constant level 62c by the amplifier 26 because the desired signal 73b inputted to the amplifier 26 is too small with respect to the constant level 62c.

  On the other hand, the noise level 75 c is a level obtained by adding the noise level of the amplifier 26 to the noise level 75 b output from the mixer 20. That is, the noise levels of the high-frequency amplifier 18, the mixer 20, and the amplifier 26 are added.

  As described above, when the interference signal 74 is larger than the desired signal 73, the desired signal 73c output from the output terminal 15 is not sufficiently large with respect to the constant level 62c which is a required value. Further, the level difference 76c between the desired signal 73c and the noise level 75c becomes small. As a result, the level of the desired signal 73c output from the output terminal 15 is small, and the output C / N deteriorates.

  Next, the operation of suppressing the interference signal by varying the bandwidth of the high-frequency filter 19 that is a feature of the present embodiment will be described with reference to FIGS.

  FIGS. 3A to 3D are signal level diagrams at each point of the high-frequency signal receiving unit 11. The same components as those in FIG. 2 are denoted by the same reference numerals and the description is simplified.

  FIG. 3A is a signal level diagram at the input terminal 14. At the input terminal 14, the disturbing signal 74 has a higher level than the desired signal 73, which is the same input signal level as in FIG.

  FIG. 3B is an output signal diagram of the high frequency amplifier 18. In the high-frequency amplifier 18, the interference signal output from the mixer 20 is gain-controlled so as to reach a preset constant level 62a.

  However, the interference signal 84 a output from the high-frequency amplifier 18 is optimally suppressed by the high-frequency filter 19 that can vary the bandwidth, and then input to the mixer 20. That is, a small interference signal that is most suppressed by the high frequency filter 19 is supplied to the input of the mixer 20. Therefore, since this small interference signal is output from the output of the mixer 20, the high frequency amplifier 18 acts to increase the gain.

  On the other hand, since the desired signal 83a is gain-controlled by the same amount as the interference signal 84a, the desired signal 83a can be made larger than the desired signal 73a. The level difference 88a represents the level difference between the interference signal 84a and the desired signal 83a. That is, the level difference 88a can be reduced by a value obtained by optimally suppressing the interference signal 74 by the high frequency filter 19 with respect to the conventional level difference 77a.

  The noise level 85a is generated by the noise figure of the high frequency amplifier 18. However, since the interference signal 74 is optimally suppressed by the high frequency filter 19 whose bandwidth can be varied, the gain control amount of the high frequency amplifier 18 becomes small. As a result, the noise level 85a from the high frequency amplifier 18 can be made smaller than the noise level 75a.

  Accordingly, the level difference 86a between the desired signal 83a output from the high-frequency amplifier 18 and the noise level 85a is larger than the level difference 76a in the conventional example, which is improved.

  FIG. 3C is an output signal diagram of the mixer 20. In FIG. 3C, since the oscillation frequency of the oscillator 21 is higher than the desired signal 83a and the disturbing signal 84b, the relationship between the disturbing signal 84b and the desired signal 83b is switched. The interference signal 84b is controlled to a constant level 62b by the gain control of the high frequency amplifier 18. At this time, the interference signal 84 a supplied to one input of the mixer 20 is suppressed by the high frequency filter 19. The desired signal 83b approaches the level of the interference signal 84b by the amount of suppression of the interference signal.

  Thus, since the bandwidth of the high frequency filter 19 can be made variable and optimally suppressed, the interference signal 84b can be optimally suppressed. For this reason, the level difference 88b between the interference signal 84b and the desired signal 83b can be made smaller than the level difference 77b in the high frequency filter 19 with a fixed bandwidth. As a result, the desired signal 83b output from the mixer 20 can be increased by an amount corresponding to the suppression of the interference signal 84b.

  Further, the noise level 85 b is a value obtained by adding the noise level of the mixer 20 to the noise level 85 a by the high frequency amplifier 18. At this time, in the high frequency amplifier 18, the gain is controlled by the interference signal optimally suppressed by the high frequency filter 19. For this reason, the gain control amount in the high-frequency amplifier 18 can be reduced by the amount that the interference signal 74 is suppressed by the high-frequency filter 19, so that the noise level 85b can be reduced.

  Accordingly, the level difference 86b between the desired signal 83b and the noise level 85b can be increased, and as a result, the C / N of the desired signal 83b output from the mixer 20 can be improved.

  FIG. 3D is an output signal diagram of the output terminal 15. The desired signal 83c will be described below with reference to FIG. That is, the interference signal 84 b and the desired signal 83 b output from the mixer 20 are input to the intermediate frequency filters 25 and 27. Thereby, the interference signal 84b is suppressed to become the interference signal 84c. On the other hand, the desired signal 83b can be made larger than the desired signal 73b because the interference signal 74 is suppressed by the high frequency filter 19 whose bandwidth can be varied. As a result, the desired signal 83c can be at a level close to or the same as the constant level 62c.

  Further, the noise level 85 c is a level obtained by adding the noise level of the amplifier 26 to the noise level 85 b output from the mixer 20. That is, the noise levels of the high-frequency amplifier 18, the mixer 20, and the amplifier 26 are added.

  As described above, even when the disturbing signal 74 is larger than the desired signal 73, the desired signal 73c and the disturbing signal 74 can be optimally controlled by the high-frequency filter 19 that can change the bandwidth, so that it is output from the output terminal 15. The desired signal 83c can be a level close to or the same level as the constant level 62c.

  As described above, the level difference 86c between the desired signal 83c and the noise level 85c can be improved. As a result, the desired signal level from the output terminal 15 can be increased to the predetermined level 62c, and the C / N can be improved.

  In addition, instead of inputting the output of the second AGC detector 28a to one input 34a of the comparator 34, a further AGC detector is provided at the output of the intermediate frequency filter 27 in the subsequent stage, for example. You may input via this AGC detector. In this case, the interference signal 84c is further suppressed by, for example, the intermediate frequency filter 27 in the subsequent stage. Accordingly, since the influence of the interference signal 74 can be reduced, the band control of the high frequency filter 19 by the filter controller 32 can be performed with high accuracy.

  In the above operation, since the bandwidth of the high frequency filter 19 is controlled by the voltage obtained by comparing the voltage obtained by AGC detection of the high frequency signal with the reference voltage, the operation can be completed reliably in a short time. The AGC detection is to convert the level of the high frequency signal into a voltage by detecting the peak value by detecting the envelope of the high frequency signal, for example, and averaging the peak value.

  Further, when the bandwidth of the high-frequency filter 19 is controlled by the filter controller 32, the BER (error correction rate) or the C / N detection value in the demodulator 45 can be used. That is, when the bandwidth of the high frequency filter 19 is controlled, when the BER of the demodulator 45 becomes a value corresponding to, for example, the detection limit, the voltage to the band control input 19b of the high frequency filter 19 is supplied to the PLL circuit 22. To maintain a constant value.

  Further, when the BER of the demodulator 45 becomes equal to or greater than the value corresponding to the detection limit, for example, the holding by the PLL circuit 22 is released, and the bandwidth of the high frequency filter 19 is controlled by the filter controller 32.

  Thereby, since the value of the BER or C / N detection of the demodulator 45 is used, the reception state can be improved more accurately.

  Further, the input filter 17 may be controlled by the filter controller 32 using the high frequency filter 19 of the present invention. In this case, since the distortion of the high frequency amplifier 18 due to the interference signal 74 can be reduced, the current of the high frequency amplifier 18 can be reduced.

  Furthermore, when it is built in a mobile phone or the like, distortion in the high-frequency amplifier 18 becomes a problem, but by reducing the bandwidth of the high-frequency filter 19, it is difficult to be disturbed by the transmission signal of the mobile phone. it can.

  As described above, the bandwidth of the high-frequency filter 19 can be optimally controlled by using the AGC detector 28a and the filter controller 32. Therefore, the reception condition in the area where the large interference signal 74 is present, or in the weak electric field area. Corresponding to each reception condition, the optimum reception performance can be set in a short time.

(Embodiment 2)
Hereinafter, Embodiment 2 of the present invention will be described with reference to FIG. FIG. 4 is a block diagram of a high-frequency signal receiving device according to Embodiment 2 of the present invention.

  In the first embodiment, the output of the second AGC detector 28a is connected to the input 34a of the comparator 34. On the other hand, in the second embodiment, the input to one input 34 a of the comparator 34 is connected to the output 47 a of the third AGC detector 47 provided in the demodulation circuit unit 64. In this respect, the first and second embodiments are different.

  In addition, about the component used in FIG. 4, the same number is attached | subjected about the same thing as FIG. 1, and description is simplified.

  The high-frequency signal receiving apparatus according to the second embodiment includes a high-frequency signal receiving unit 63 and a demodulation circuit unit 64 as shown in FIG. The output 47 a of the third AGC detector 47 of the demodulation circuit unit 64 is connected to one input 34 a of the comparator 34 via the AGC detection input terminal 49 of the high frequency signal receiving unit 63.

  Note that the output of the second AGC detector 28a in the first embodiment is not connected to one input 34a of the comparator 34.

  With the above configuration, the output 47 a of the third AGC detector 47 is input to one input 34 a of the comparator 34. That is, the interfering signal 74 is further suppressed by the intermediate frequency filter 27 or the digital filter 44 at the subsequent stage from the second AGC detector 28a. Thereby, since the influence of the interference signal 74 can be sufficiently reduced, the band control of the high frequency filter 19 by the filter controller 32 can be performed with higher accuracy.

  Accordingly, the bandwidth of the high frequency filter 19 can be optimally controlled by the AGC detector 47 and the filter controller 32, so that each of the reception conditions in an area where there is a larger interference signal or the reception conditions in a weak electric field area can be handled. Thus, the optimum reception performance can be set in a short time.

  Further, compared to the first embodiment, since the desired signal in which the interference signal 74 is sufficiently suppressed can be supplied to one input of the filter controller 32, the band control of the high-frequency filter 19 by the filter controller 32 is more accurate. It can be done well.

(Embodiment 3)
In the third embodiment, the first mixer 20 in the first embodiment is a direct conversion (not shown). That is, as the mixer 20, two I mixers 20c and two Q mixers 20d are provided. A reception signal is input to one input of each of the I and Q mixers 20c and 20d. The other input of the I and Q mixers 20c and 20d receives the output signal of the oscillator 21 having the same frequency as the received signal, and between the oscillator 21 and the other input of the Q mixer 20d. Is connected to a π / 2 phase shifter.

  In addition, the I and Q signals output from the I and Q mixers 20c and 20d are input to the amplifiers 26c and 26d via the low-pass filters connected in place of the intermediate frequency filter 25, respectively. . Further, the outputs of the amplifiers 26c and 26d are gain-controlled by a second AGC detector and a second gain controller connected to each of them. The I and Q signals output from the amplifiers 26c and 26d are output from the I and Q output terminals, respectively.

  The I and Q signals output from the I and Q output terminals are input to the demodulating circuit units connected to the I and Q output terminals, and then demodulated.

  As described above, even when the first mixer 20 is configured as a direct conversion, the output of the second AGC detector provided for I or Q is input to one input 34 a of the comparator 34. Thus, the bandwidth of the high frequency filter 19 can be optimally controlled. Therefore, the optimum reception performance can be set in a short time in accordance with the reception condition in the area where there is a large interference signal or the reception condition in the weak electric field area.

  According to the high-frequency signal receiving unit and the high-frequency signal receiving device using the same according to the present invention, there is an effect that both the characteristics of the interference signal elimination capability and the reception sensitivity in a weak electric field in the high-frequency signal receiving unit can be improved. This is useful when used in a high-frequency signal receiver used in an area having a large interference signal.

Block diagram of a high-frequency signal receiving device according to Embodiment 1 of the present invention (A) is a signal level diagram at the input terminal when the bandwidth of the high frequency filter is constant, (b) is a signal level diagram at the output of the high frequency amplifier, and (c) is a signal level at the output of the mixer. Level diagram, (d) is a signal level diagram at the output terminal. (A) is a signal level diagram at the input terminal when the bandwidth of the high frequency filter is variable, (b) is a signal level diagram at the output of the high frequency amplifier, and (c) is a signal level at the output of the mixer. Level diagram, (d) is a signal level diagram at the output terminal. Block diagram of a high-frequency signal receiving device in Embodiment 2 of the present invention Block diagram of a high-frequency signal receiving device in a conventional example

Explanation of symbols

DESCRIPTION OF SYMBOLS 14 Antenna input terminal 15 Output terminal 18 High frequency amplifier 18a AGC control input 19 High frequency filter 19b Band control input 20 1st mixer 23a 1st AGC detector 23b 1st gain controller 25 Intermediate frequency filter 28a Second AGC detector 32 Filter controller

Claims (9)

An antenna input terminal to which a high frequency signal is input, a high frequency amplifier to which a signal input to the antenna input terminal is supplied, a high frequency filter to which an output of the high frequency amplifier is connected, and an output of the high frequency filter are connected A first mixer, an intermediate frequency filter to which an output of the first mixer is supplied, an output terminal to which an output of the intermediate frequency filter is supplied, and an output of the first mixer are supplied And a first gain controller connected between the first AGC detector and an input for AGC control of the high-frequency amplifier. The high-frequency filter includes the high-frequency filter. And a second high frequency filter that is capable of variably controlling the pass band width with the voltage applied to the band control input provided in the second AGC detector. And a filter controller connected between the second AGC detector and the band control input, and an output from the second AGC detector determines a pass bandwidth of the high frequency filter. A high-frequency signal receiving unit to be controlled. The high frequency signal receiver according to claim 1, wherein the first mixer is a direct conversion. The high frequency signal receiving unit according to claim 1, wherein a second mixer is provided between the intermediate frequency filter and the output terminal. The high frequency signal receiver according to claim 3, wherein the second mixer is a direct conversion. The high-frequency signal reception according to claim 1, wherein the intermediate frequency filter has a multi-stage configuration, the connection with the first AGC detector is on the mixer side, and the connection with the second AGC detector is on the output terminal side. Department. In the filter controller, a filter comparator is provided in which the detection voltage from the first AGC detector is supplied to one input and the reference voltage is input to the other input. The high frequency signal receiver according to claim 1, wherein the output level of the desired signal output from the output terminal is set to a predetermined value by controlling. 7. The high frequency signal receiving unit according to claim 6, wherein the reference voltage input to the other of the filter comparators can be set by input data from a data input terminal provided in the high frequency signal receiving unit. A high-frequency signal receiving device comprising: the high-frequency signal receiving unit according to claim 1; and a demodulation circuit unit that demodulates an output signal from the high-frequency signal receiving unit. The second AGC detector includes the demodulation circuit unit. A high-frequency signal receiver to which a signal from the side is input. 9. The high-frequency signal receiving device according to claim 8, wherein the bandwidth of the high-frequency filter is variably controlled so that BER (error correction code) output from the demodulator or C / N becomes a predetermined value.

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