JP2008160629A - Wireless receiving circuit, wireless receiving device, and switching method of wireless receiving device - Google Patents

Abstract

A radio receiving circuit, a radio receiving apparatus, and a radio receiving apparatus switching method capable of selectively receiving an analog radio broadcast wave signal and a digital radio broadcast wave signal with low cost and high sound quality are provided.
A radio broadcast receiving apparatus includes a PLL circuit, a mixer, and switches. The PLL circuit 2 generates and outputs a local oscillation signal having a different local oscillation frequency according to the switching signal Ssw. The mixer 3 mixes the input radio reception signal and the local oscillation signal, and outputs a mixed signal. The switches 8 and 9 are connected in parallel to each other in accordance with the switching signal Ssw, and have a plurality of center frequencies of different pass bands and output a predetermined intermediate frequency signal from the mixed signal by band pass filtering. The band-pass filter 6 or 7 is switched between the selection of the band-pass filter 6 and the selection of the plurality of band-pass filters 6 and 7, and an intermediate frequency signal after band-pass filtering is output.
[Selection] Figure 1

Description

  The present invention particularly relates to a radio reception circuit, a radio reception device, and a radio reception device switching method used in a radio broadcast reception device.

  Digital radio broadcasting has already been put into practical use in the United States and Europe, and practical trial broadcasting has been started in some areas in Japan by the Digital Radio Promotion Association in Japan in October 2003. Digital radio broadcasting in Japan is operated in accordance with the ISDB-TSB standard established by the Japan Radio Industry Association. Digital radio broadcasting according to the ISDB-TSB standard has an advantage that it has a wider signal bandwidth than conventional analog radio broadcasting (FM and AM broadcasting) and can provide services to users with high sound quality. Conventionally, in order to receive a digital radio broadcast wave signal and an analog radio broadcast wave signal, separate receiving apparatuses are required.

  In recent years, mobile phones and the like that can receive analog radio broadcast wave signals have been sold, and further miniaturization of radio broadcast receivers is desired from the market. It has been difficult to mount an analog radio broadcast receiver and a digital radio broadcast receiver in a small electronic device such as a mobile phone in terms of size and cost. Therefore, Patent Document 1 discloses a small receiving device capable of receiving both a digital radio broadcast wave signal and an analog radio broadcast wave signal. The receiver according to the conventional example amplifies the intermediate frequency signal with the IF amplifier after band-limiting with a narrow-band IF filter, and amplifies the intermediate-frequency signal with the IF amplifier after band-limiting with a wideband IF filter. The gain of the IF amplifier is controlled by the AGC circuit, the output signal of the IF amplifier is demodulated by the demodulator for analog broadcast waves, the output signal of the IF amplifier is demodulated by the demodulator for digital broadcast waves, and the AGC circuit IF amplifier gain control signal output from the amplifier is amplified by a DC amplifier, and the amplified output signal is used as a gain control signal for the IF amplifier, so that the output signal level of the IF amplifier can be demodulated. To the level of control. The receiving apparatus according to the conventional example achieves simplification of the circuit scale and low cost by the above configuration.

JP 2005-73097 A.

  However, in the receiving apparatus according to the above-described conventional example, the input line for inputting the intermediate frequency signal is always connected to the two filters for digital radio broadcasting and analog radio broadcasting. There has been a problem that the signal input level to the filter is attenuated and the sound quality may be deteriorated.

  An object of the present invention is to solve the above-described problems and to provide a wireless reception circuit, a wireless reception device, and a wireless reception device that can selectively receive, for example, an analog radio broadcast wave signal and a digital radio broadcast wave signal with low cost and high sound quality. It is to provide a switching method.

  According to a first aspect of the present invention, there is provided a wireless reception circuit that generates and outputs a local oscillation signal having a different local oscillation frequency according to an input switching signal, an input wireless reception signal, and the local oscillation signal And mixing means for outputting a signal after mixing, and connected in parallel with each other in accordance with the switching signal, having center frequencies in different passbands and having a predetermined frequency from the signal after mixing At least one first band-pass filtering means is selected from among a plurality of first band-pass filtering means for outputting the intermediate frequency signal after band-pass filtering, or a plurality of predetermined first band-pass filters And a first switch means for switching the selection of the filtering means and outputting the intermediate frequency signal after the band-pass filtering.

  The wireless receiver circuit further includes an amplifying means for amplifying the intermediate frequency signal output from the first switch means.

  The wireless receiver circuit may further include a local oscillation unit that generates and outputs a local oscillation signal having a predetermined single local oscillation frequency instead of the local oscillation unit, and the first switch unit The center frequency of the pass band of the selected at least one first band pass filtering means and the center frequency of the pass band of the plurality of predetermined first band pass filtering means selected by the first switch means Are set to be substantially the same as each other.

  According to a second aspect of the present invention, there is provided a radio reception apparatus, the radio reception circuit, gain control means for generating and outputting a gain control signal based on the mixed signal, and the radio reception signal according to the gain control signal. And a high frequency amplifying means for adjusting the gain and outputting to the mixing means.

  The wireless reception device further includes the plurality of first bandpass filtering means.

  The wireless receiver further includes second band-pass filtering means for further band-pass filtering the intermediate frequency signal output from the first switch means. Here, in response to the switching signal, an intermediate frequency signal output from the first switch means is output to the second band-pass filtering means, or an intermediate signal output from the first switch means. And a second switch means for switching between outputting the frequency signal as it is and outputting an intermediate frequency signal.

  Furthermore, in the above wireless receiver, the first switch means selects at least one first band-pass filtering means when the wireless received signal is an analog broadcast wave signal, while the wireless received signal is In the case of a digital broadcast wave signal, the predetermined plurality of first band-pass filtering means are selected.

  According to a third aspect of the present invention, there is provided a radio receiver switching method comprising: a local oscillation means for generating and outputting a local oscillation signal having a different local oscillation frequency according to an input switching signal; an input radio reception signal; Mixing means for outputting a mixed signal by mixing with a local oscillation signal, and in accordance with the switching signal, connected in parallel to each other and having center frequencies of different passbands and the mixed signal A wireless receiver switching method comprising a plurality of first band-pass filtering means for outputting a predetermined intermediate frequency signal by band-pass filtering from a first switch according to the switching signal Means for selecting at least one first band-pass filtering means among the plurality of first band-pass filtering means, or selecting a predetermined plurality of first band-pass filtering means. Switch between Characterized in that it comprises a step.

  In the wireless receiver switching method, the wireless receiver includes, in place of the local oscillator, another local oscillator that generates and outputs a local oscillation signal having a predetermined single local oscillation frequency. The center frequency of the passband of at least one first bandpass filtering means selected by the first switch means and a plurality of predetermined first bandpass filtering selected by the first switch means The center frequency of the pass band of the means is set to be substantially the same as each other.

  In the wireless receiver switching method, the wireless receiver further includes second band-pass filtering means for further band-pass filtering the intermediate frequency signal output from the first switch means, In response to the switching signal, the second switch means is used to output the intermediate frequency signal output from the first switch means to the second bandpass filtering means, or the first switch means. The method further includes a step of switching whether to output the intermediate frequency signal output from the signal as it is.

  Further, in the method for switching a radio reception apparatus, the step of switching using the first switch means selects at least one first band-pass filtering means when the radio reception signal is an analog broadcast wave signal. On the other hand, when the radio reception signal is a digital broadcast wave signal, the predetermined plurality of first band-pass filtering means are selected.

  According to the wireless reception circuit, the wireless reception device, and the wireless reception device switching method according to the present invention, in accordance with the switching signal, the signals are connected in parallel to each other, have center frequencies in different passbands, and from the mixed signal. At least one first band-pass filtering means is selected from among a plurality of first band-pass filtering means for outputting a predetermined intermediate frequency signal after band-pass filtering, or a plurality of predetermined first frequency-pass filtering means Switching between band-pass filtering means and outputting the intermediate-frequency signal after band-pass filtering enables selective reception of analog radio broadcast wave signals and digital radio broadcast wave signals at low cost and high sound quality. There is an advantageous effect.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In addition, in each following embodiment, the same code | symbol is attached | subjected about the same component.

First embodiment.
FIG. 1 is a block diagram showing a configuration of a radio broadcast receiving apparatus according to the first embodiment of the present invention. In FIG. 1, the radio broadcast receiving apparatus according to the present embodiment includes a high frequency amplifier 1, a PLL circuit 2, a mixer 3, a variable gain control circuit 5, bandpass filters 6 and 7, and switches 8 and 9. The intermediate frequency amplifier 10 and the controller 18 are configured to selectively receive broadcast wave radio signals from the respective transmitting stations for analog radio broadcast wave signals and digital radio broadcast wave signals via the antenna 15. The PLL circuit 2, the mixer 3, the switches 8 and 9, and the intermediate frequency amplifier 10 are formed on one IC chip and constitute a radio reception circuit 16. Alternatively, the PLL circuit 2, the mixer 3, the switches 8 and 9, the intermediate frequency amplifier 10, the high frequency amplifier 1, and the variable gain control circuit 5 are formed on one IC chip, and the radio reception circuit 17. May be configured. The bandpass filters 6 and 7 and the switches 8 and 9 constitute a filter circuit 14. Since the band pass filters 6 and 7 are not formed on the same IC chip as the radio reception circuit 16 or 17, the radio broadcast receiving apparatus according to the present embodiment can easily replace the band pass filter to be connected. it can.

  In the description of the radio broadcast receiving apparatus according to each of the following embodiments, an FM radio broadcast wave signal generally used in Japan and a digital radio broadcast wave signal operated in Japan are selectively used. However, the present invention is not limited to these radio broadcasts. For example, instead of FM radio broadcast wave signals, other analog radio broadcast wave signals such as AM radio broadcast wave signals are received. Alternatively, another radio broadcast wave signal may be received instead of the analog radio broadcast wave signal and the digital radio broadcast wave signal, and the center frequency and bandwidth of the pass band used in the following description The typical value is merely an example, and other values may be applied.

  In FIG. 1, an antenna 15 receives a broadcast radio signal from each transmitting station of an analog radio broadcast wave signal or a digital radio broadcast wave signal, and outputs the radio reception signal to the high frequency amplifier 1. The high frequency amplifier 1 changes and amplifies the gain of the input radio reception signal in accordance with the gain control signal from the variable gain control circuit 5 so that the output signal level becomes substantially constant, and the mixer 3 Output to. The mixer 3 mixes the radio reception signal amplified by the high frequency amplifier 1 and the local oscillation signal from the PLL circuit 2, and outputs the mixed signal to the filter circuit 14. The variable gain control circuit 5 generates a gain control signal for controlling the amount of gain changed by the high-frequency amplifier 1 based on any of the power, current, and voltage of the mixed signal output from the mixer 3. And output to the high-frequency amplifier 1. For example, when the level of the mixed signal output from the mixer 3 is high, the variable gain control circuit 5 instructs the high frequency amplifier 1 to lower the gain of the radio reception signal and is output from the mixer 3. When the signal level after mixing is low, a gain control signal for instructing the high frequency amplifier 1 to increase the gain of the radio reception signal is output. The gain control signal is, for example, one of power, current, and voltage. The PLL circuit 2 selects one of the local oscillation frequency for analog radio broadcasting and the local oscillation frequency for digital radio broadcasting in accordance with the switching signal Ssw input from the controller 18, and has the selected local oscillation frequency. A local oscillation signal is generated and output to the mixer 3.

  The bandpass filters 6 and 7 are configured by, for example, a ceramic filter. The input terminal of the band pass filter 6 is connected to the output terminal of the mixer 3, and the output terminal is connected to the input terminal of the intermediate frequency amplifier 10. The input terminal of the band pass filter 7 is connected to the output terminal of the mixer 3 via the switch 8, and the output terminal is connected to the input terminal of the intermediate frequency amplifier 10 via the switch 9. The bandpass filters 6 and 7 have center frequencies in mutually different passbands, and output a predetermined intermediate frequency signal from the mixed signal input from the mixer 3 by bandpass filtering. The switches 8 and 9 are controlled to be in an on state or an off state by a switching signal Ssw from the controller 18 and connect the band pass filters 6 and 7 in parallel to each other in the on state, while the band pass filter 7 in the off state. Disconnect from the bandpass filter 6. The intermediate frequency amplifier 10 amplifies the intermediate frequency signal input from the filter circuit 14 to a predetermined level and outputs the amplified signal to a demodulation circuit (not shown). The controller 18 switches the local oscillation frequency of the local oscillation signal of the PLL circuit 2 depending on whether analog radio broadcasting or digital radio broadcasting is selected by the switch, for example, and switches 8 and 9 are turned on or off. A switching signal Ssw for switching is output.

  FIG. 2A is a characteristic diagram showing the frequency characteristics 21 and 22 of the bandpass filters 6 and 7 of the radio broadcast receiving apparatus of FIG. FIG. 2B is a characteristic diagram showing the synthesized frequency characteristic 23 of the band pass filters 6 and 7 of the radio broadcast receiving apparatus of FIG. In each frequency characteristic shown in FIG. 2A, the center frequency fc1 of the passband of the bandpass filter 6 is, for example, 10.7 MHz, and the lower limit f1 and the upper limit f2 of the passband width are, for example, 10.6 MHz and 10 respectively. .8 MHz and the passband width is 200 kHz. The center frequency fc2 of the passband of the bandpass filter 7 is, for example, 10.915 MHz, the lower limit f2 and the upper limit f3 of the passband width are, for example, 10.8 MHz and 11.03 MHz, respectively, and the passband width is 230 kHz. . Therefore, in the combined frequency characteristic 23 of the bandpass filters 6 and 7 shown in FIG. 2B, the center frequency fc3 of the passband is 10.815 MHz, and the lower limit f1 and the upper limit f3 of the passband width are 10.6 MHz and The frequency is 11.03 MHz, and the passband width is 430 kHz.

  The operation of the radio broadcast receiving apparatus having the above configuration will be described below. First, when receiving an analog radio broadcast wave signal, the controller 18 switches the local oscillation frequency of the local oscillation signal of the PLL circuit 2 to the local oscillation frequency for analog radio broadcast, and controls the switches 8 and 9 to be in an OFF state. A switching signal Ssw is output. As a result, the band pass filter 7 is separated from the band pass filter 6.

  The radio reception signal input via the antenna 15 is amplified by controlling the gain by the high frequency amplifier 1, mixed with the local oscillation signal from the PLL circuit 2 by the mixer 3, and input to the filter circuit 14. The At this time, how much the gain of the radio reception signal is changed in the high-frequency amplifier 1 is changed according to the gain control signal from the variable gain control circuit 5. Since the switches 8 and 9 are controlled to be in the OFF state and the band pass filter 7 is disconnected from the band pass filter 6, the frequency characteristic of the entire filter circuit 14 is the frequency characteristic of the band pass filter 6 shown in FIG. Equal to 21. The band pass filter 6 suppresses interference waves other than the desired channel by band-pass filtering a predetermined intermediate frequency signal from the mixed signal input to the filter circuit 14. The intermediate frequency signal from the filter circuit 14 is amplified to a predetermined level by the intermediate frequency amplifier 10 and output to a demodulation circuit (not shown).

  According to this configuration, the center frequency of the pass band of the filter circuit 14 is 10.7 MHz, which is the same as the center frequency of the pass band of the band pass filter 6, and the pass band width is 200 kHz. FM radio broadcast wave signals being received can be received.

  Next, when receiving the digital radio broadcast wave signal, the controller 18 switches the local oscillation frequency of the local oscillation signal of the PLL circuit 2 to the local oscillation frequency for digital radio broadcast, and turns on the switches 8 and 9. A switching signal Ssw to be controlled is output. Thereby, the band pass filters 6 and 7 are connected in parallel to each other.

  The radio reception signal input via the antenna 15 is controlled in gain by the high frequency amplifier 1, mixed with the local oscillation signal from the PLL circuit 2 by the mixer 3, and input to the filter circuit 14. At this time, how much the gain of the intermediate frequency signal is changed in the high frequency amplifier 1 is changed according to the gain control signal from the variable gain control circuit 5. Since the switches 8 and 9 are controlled to be in the ON state and the bandpass filters 6 and 7 are connected in parallel to each other, the frequency characteristics of the entire filter circuit 14 are the same as those of the bandpass filters 6 and 7 shown in FIG. It is equal to the synthesized frequency characteristic 23. The band-pass filters 6 and 7 suppress interference waves other than the desired channel by band-pass filtering a predetermined intermediate frequency signal from the mixed signal input to the filter circuit 14. The intermediate frequency signal from the filter circuit 14 is amplified to a predetermined level by the intermediate frequency amplifier 10 and output to a demodulation circuit (not shown).

  According to this configuration, since the center frequency of the pass band of the filter circuit 14 is 10.815 MHz and the pass band width is 430 kHz, a digital radio broadcast wave signal operated in Japan can be received.

  As described above, according to the radio broadcast receiving apparatus according to the present embodiment, when the analog radio broadcast wave signal is received, since the band pass filter 7 is separated from the band pass filter 6, the signal input level of the radio reception signal Therefore, it is possible to realize a radio broadcast receiving apparatus that can provide high-quality services to users without attenuation.

  Also, since the bandwidth of digital radio broadcast wave signals is wider than the bandwidth of analog radio broadcast wave signals, conventional receivers require a dedicated broadband filter for digital radio broadcasts, which is costly. It was. According to the radio broadcast receiving apparatus according to the present embodiment, the pass bandwidth of the band pass filter 7 may be a difference between the bandwidth of the digital radio broadcast wave signal and the pass bandwidth of the band pass filter 6. Digital radio broadcast wave signals can be received without the need for a dedicated filter by adding only one bandpass filter having a narrow passband width of about 200 kHz or 230 kHz used in analog radio broadcast wave signal reception. A low-cost radio broadcast receiving apparatus can be realized.

  Furthermore, in the present embodiment, the PLL circuit 2, the mixer 3, the switches 8 and 9, and the intermediate frequency amplifier 10 are integrated as a radio reception circuit 16 on one IC chip, or the PLL circuit 2, the mixer 3, the switches 8 and 9, the intermediate frequency amplifier 10, the high frequency amplifier 1, and the variable gain control circuit 5 are integrated as a wireless reception circuit 17 on one IC chip, A small radio broadcast receiver can be realized. Furthermore, the band-pass filters 6 and 7 are not formed on the same IC chip as the radio reception circuit 16 or 17, but can be easily replaced, thereby realizing a highly versatile radio broadcast reception apparatus.

  In this embodiment, in order to simplify the description, the local oscillation frequency of the local oscillation signal of the PLL circuit 2 is determined by the switching signal Ssw from the controller 18 for the local oscillation frequency for analog radio broadcasting and for the digital radio broadcasting. Switched to one of the local oscillation frequencies. However, the present invention is not limited to this configuration, and the local oscillation frequency of the local oscillation signal of the PLL circuit 2 may be switched for each reception channel in each of analog radio broadcasting and digital radio broadcasting.

Second embodiment.
FIG. 3 is a block diagram showing a configuration of a radio broadcast receiving apparatus according to the second embodiment of the present invention. 3, a switch 30, a band pass filter 31, a variable amplifier 32, and an intermediate frequency amplifier 33 are further provided, and a controller 18A is provided instead of the controller 18 of the radio broadcast receiving apparatus of FIG. This is different from the radio broadcast receiving apparatus according to the first embodiment shown in FIG. The other points are the same as those of the radio broadcast receiving apparatus according to the first embodiment shown in FIG. 1, and detailed descriptions of the components given the same reference numerals are omitted. The PLL circuit 2, the mixer 3, the switches 8 and 9, the intermediate frequency amplifiers 10 and 33, the switch 30, and the variable amplifier 32 are formed on one IC chip to constitute the radio reception circuit 16A. . Alternatively, the PLL circuit 2, the mixer 3, the switches 8 and 9, the intermediate frequency amplifiers 10 and 33, the switch 30, the variable amplifier 32, the high frequency amplifier 1, and the variable gain control circuit 5 are one The radio reception circuit 17A may be formed on an IC chip. Since the bandpass filters 6, 7, and 31 are not formed on the same IC chip as the radio reception circuit 16A or 17A, the radio broadcast receiving apparatus according to the present embodiment easily replaces the bandpass filter to be connected. be able to.

  In FIG. 3, the controller 18 </ b> A outputs a control signal Sctr to the variable amplifier 32 in addition to outputting the switching signal Ssw. The control signal Sctr uses power, current, or voltage. The contact of the switch 30 is switched by a switching signal Ssw from the controller 18A. The switch 30 connects the intermediate frequency amplifier 10 and the variable amplifier 32 by being controlled to the contact a side when receiving the digital radio broadcast wave signal, and is controlled to the contact b side when receiving the analog radio broadcast wave signal. Thus, the intermediate frequency amplifier 10 and the band pass filter 31 are connected. The band pass filter 31 is constituted by, for example, a ceramic filter or the like, has a frequency characteristic substantially the same as the frequency characteristic 21 of the band pass filter 6 shown in FIG. A predetermined intermediate frequency signal is further band-pass filtered from the intermediate frequency signal input from 10 and output to the intermediate frequency amplifier 33. The intermediate frequency amplifier 33 amplifies the intermediate frequency signal input from the band pass filter 31 to a predetermined level and outputs the amplified signal to an analog demodulation circuit (not shown). The variable amplifier 32 amplifies the intermediate frequency signal input from the intermediate frequency amplifier 10 via the switch 30 with an amplification factor corresponding to the control signal Sctr from the controller 18A, and outputs the amplified signal to a digital demodulation circuit (not shown).

  The operation of the radio broadcast receiving apparatus having the above configuration will be described below. Note that the processing until the radio reception signal input through the antenna 15 is processed by the mixer 3 and the filter circuit 14 and amplified to a predetermined level by the intermediate frequency amplifier 10 is described in the first embodiment. Since this is the same as the radio broadcast receiving apparatus, the description is omitted.

  When the analog radio broadcast wave signal is received, the switch 30 is controlled to the contact b side, so that the intermediate frequency signal amplified by the intermediate frequency amplifier 10 is input to the band pass filter 31. The band-pass filter 31 further band-pass-filters a predetermined intermediate frequency signal from the intermediate frequency signal amplified by the intermediate frequency amplifier 10. Since the band pass filter 31 has substantially the same band pass characteristic as the band pass filter 6, it further suppresses interference waves other than the frequency of the desired channel. The intermediate frequency signal filtered by the band pass filter 31 is amplified by the intermediate frequency amplifier 33 and then sent to an analog demodulation circuit (not shown).

  On the other hand, when the digital radio broadcast wave signal is received, the switch 30 is controlled to the contact a side, so that the intermediate frequency signal amplified by the intermediate frequency amplifier 10 is amplified or attenuated by the variable amplifier 32 and is not shown. Sent to the digital demodulation circuit. At this time, the amount of amplification or attenuation by the variable amplifier 32 is controlled by a control signal Sctr input from the controller 18A so as to improve the bit error rate characteristic of the digital demodulation circuit connected to the radio broadcast receiving apparatus.

  As described above, according to the radio broadcast receiving apparatus according to the present embodiment, when an analog radio broadcast wave signal is received, a predetermined intermediate frequency signal is filtered a plurality of times from the mixed signal by the band pass filters 6 and 31. Therefore, compared with the radio broadcast receiving apparatus according to the first embodiment, it is possible to improve frequency selectivity and improve sound quality. In addition, when the digital radio broadcast wave signal is received, the gain of the intermediate frequency signal is controlled by the variable amplifier 32, so that the bit error rate characteristic of the digital demodulation circuit connected to the radio broadcast receiver can be improved.

Third embodiment.
FIG. 4 is a block diagram showing a configuration of a radio broadcast receiving apparatus according to the third embodiment of the present invention. 4, the radio according to the second embodiment shown in FIG. 3 is provided in that a filter circuit 14A is provided instead of the filter circuit 14, and a bandpass filter 31A is provided instead of the bandpass filter 31. Different from the broadcast receiving device. The filter circuit 14 </ b> A includes bandpass filters 40 to 42 and switches 43 to 46. The other points are the same as those of the radio broadcast receiving apparatus according to the second embodiment shown in FIG. 3, and detailed description of the components given the same reference numerals is omitted. The PLL circuit 2, the mixer 3, the switches 43 to 46, the intermediate frequency amplifiers 10 and 33, the switch 30, and the variable amplifier 32 are formed on one IC chip to constitute the radio reception circuit 16B. . Alternatively, the PLL circuit 2, the mixer 3, the switches 43 to 46, the intermediate frequency amplifiers 10 and 33, the switch 30, the variable amplifier 32, the high frequency amplifier 1, and the variable gain control circuit 5 are one. The radio reception circuit 17B may be formed on an IC chip. Since the band pass filters 31A and 40 to 42 are not formed on the same IC chip as the radio receiving circuit 16B or 17B, the radio broadcast receiving apparatus according to the present embodiment easily replaces the band pass filter to be connected. be able to.

  In FIG. 4, the input terminal of the band pass filter 40 is connected to the output terminal of the mixer 3, and the output terminal is connected to the input terminal of the intermediate frequency amplifier 10. The input terminal of the band pass filter 41 is connected to the output terminal of the mixer 3 through the switch 43, and the output terminal is connected to the input terminal of the intermediate frequency amplifier 10 through the switch 45. The input terminal of the band pass filter 42 is connected to the output terminal of the mixer 3 via the switch 44, and the output terminal is connected to the input terminal of the intermediate frequency amplifier 10 via the switch 46. The band-pass filters 40 to 42 band-filter and output a predetermined intermediate frequency signal from the mixed signal input from the mixer 3. The switches 43 to 46 are controlled to be in an on state or an off state by a switching signal Ssw from the controller 18A, and connect the band pass filters 40 to 42 in parallel with each other in the on state, while the band pass filters 41, 42 is disconnected from the band pass filter 40. The band-pass filter 31A is composed of, for example, a ceramic filter or the like, has substantially the same frequency characteristics as the band-pass filter 40, and further filters a predetermined intermediate frequency signal from the intermediate frequency signal amplified by the intermediate frequency amplifier 10. Filter through.

  Fig.5 (a) is a characteristic view which shows each frequency characteristic 51-53 of the band pass filters 40-42 of the radio broadcast receiver of FIG. FIG. 5B is a characteristic diagram showing the composite frequency characteristic 54 of the band pass filters 40 to 42 of the radio broadcast receiving apparatus of FIG. In each frequency characteristic shown in FIG. 5A, the center frequency fc4 of the passband of the bandpass filter 51 is, for example, 10.7 MHz, and the lower limit f4 and the upper limit f5 of the passband width are, for example, 10.625 MHz and 10 respectively. .775 MHz and the passband width is 150 kHz. The center frequency fc5 of the passband of the bandpass filter 52 is, for example, 10.845 MHz, the lower limit f5 and the upper limit f6 of the passband width are, for example, 10.775 MHz and 10.915 MHz, respectively, and the passband width is 140 kHz. . The center frequency fc6 of the passband of the bandpass filter 53 is, for example, 10.985 MHz, the lower limit f6 and the upper limit f7 of the passband width are, for example, 10.915 MHz and 11.055 MHz, respectively, and the passband width is 140 kHz. . Therefore, in the synthesized frequency characteristic 54 of the bandpass filters 40 to 42 shown in FIG. 5B, the center frequency fc7 of the passband is 10.84 MHz, and the lower limit f1 and the upper limit f3 of the passband width are 10.625 MHz and 11.055 MHz, and the passband width is 430 kHz.

  The operation of the radio broadcast receiving apparatus having the above configuration will be described below. First, when receiving an analog radio broadcast wave signal, the controller 18A switches the local oscillation frequency of the local oscillation signal of the PLL circuit 2 to the local oscillation frequency for analog radio broadcast, and controls the switches 43 to 46 to be in an OFF state. The switch signal Ssw for controlling the switch 30 to the contact b side is output. Thereby, the band pass filters 41 and 42 are separated from the band pass filter 40.

  Since the switches 43 to 46 are controlled to be in the off state, the frequency characteristic of the entire filter circuit 14A is equal to the frequency characteristic 51 of the band pass filter 40 shown in FIG. The band-pass filter 40 suppresses interference waves other than the desired channel by band-pass filtering the intermediate frequency signal from the mixed signal input from the mixer 3 to the filter circuit 14A. The intermediate frequency signal from the filter circuit 14A is amplified to a predetermined level by the intermediate frequency amplifier 10. The band-pass filter 31A further band-pass-filters the intermediate-frequency signal from the intermediate-frequency signal amplified by the intermediate-frequency amplifier 10 to apply band limitation, and the intermediate-frequency amplifier 33 performs band-pass filtering by the band-pass filter 31A. The intermediate frequency signal thus amplified is amplified to a predetermined level and output to an analog demodulation circuit (not shown). According to this configuration, the center frequency of the passband of the filter circuit 14A is 10.7 MHz, which is the same as the center frequency of the passband of the bandpass filter 40, and the passband width is 150 kHz. FM radio broadcast wave signals being received can be received. It is to be noted that the interference wave can be further suppressed by narrowing the pass band width when receiving the analog radio broadcast wave signal from 200 kHz to 150 kHz as compared with the first and second embodiments.

  Next, when receiving the digital radio broadcast wave signal, the controller 18A switches the local oscillation frequency of the local oscillation signal of the PLL circuit 2 to the local oscillation frequency for digital radio broadcast, and turns on the switches 43 to 46. The switching signal Ssw for controlling the switch 30 to the contact a side is output. Thereby, the band pass filters 40-42 are mutually connected in parallel.

  Since the switches 43 to 46 are controlled to be in the ON state, the frequency characteristics of the entire filter circuit 14A are equal to the combined frequency characteristics 54 of the band pass filters 40 to 42 shown in FIG. The band-pass filters 40 to 42 suppress interference waves other than the desired channel by band-pass filtering the intermediate frequency signal from the mixed signal input from the mixer 3 to the filter circuit 14A. Hereinafter, since it is the same as that of the radio broadcast receiver which concerns on 2nd Embodiment, it abbreviate | omits. According to this configuration, since the center frequency of the pass band of the filter circuit 14A is 10.84 MHz and the pass band width is 430 kHz, a digital radio broadcast wave signal operated in Japan can be received.

  As described above, according to the radio broadcast receiving apparatus according to the present embodiment, when the analog radio broadcast wave signal is received, the band pass filters 41 and 42 are separated from the band pass filter 40. A radio broadcast receiving apparatus that can provide a high-quality service to the user without the input level being attenuated can be realized.

  Further, according to the radio broadcast receiving apparatus according to the present embodiment, the pass bandwidths of the band pass filters 41 and 42 are half of the difference between the bandwidth of the digital radio broadcast wave signal and the pass bandwidth of the band pass filter 40. It is only necessary to add two narrow bandpass filters having a passband width of about 140 kHz or 150 kHz, which are used in conventional analog radio broadcast wave signal reception, and without using a dedicated filter. A radio broadcast wave signal can be received, and a low-cost radio broadcast receiver can be realized.

  In this embodiment, as shown in FIG. 4, the band pass filter 41 is connected to the mixer 3 and the intermediate frequency amplifier 10 via switches 43 and 45, respectively, and the band pass filter 42 is connected to the switches 44 and 46, respectively. To the mixer 3 and the intermediate frequency amplifier 10. However, the present invention is not limited to this configuration, and as shown in FIG. 6, the band pass filter 41 is connected to the mixer 3 and the intermediate frequency amplifier 10 via the switches 43A and 45A, respectively. It may be connected to the mixer 3 and the intermediate frequency amplifier 10 via 43A, 44A and 45A, 46A. In this case, the switches 44A, 46A may be omitted.

  In the present embodiment, the center frequency of the pass band is switched between reception of an analog radio broadcast wave signal and reception of a digital radio broadcast wave signal, and accordingly, the local oscillation frequency of the local oscillation signal of the PLL circuit 2 is changed by the switching signal Ssw. Switched. However, the present invention is not limited to this configuration, and the center frequency of the same passband may be used when an analog radio broadcast wave signal is received and when a digital radio broadcast wave signal is received. For example, as shown in FIG. 7, bandpass filters 60 to 62 are provided instead of the bandpass filters 40 to 42, and the bandpass filters 60 to 62 have the respective frequency characteristics 71 to 73 shown in FIG. Also good. FIG. 8B shows the composite frequency characteristic 74 of the bandpass filters 60 to 62. As shown in FIGS. 8A and 8B, the center frequency of the pass band of the band pass filter 60 used when receiving the analog radio broadcast wave signal is set to be the same as the center frequency of the bandwidth of the digital radio broadcast wave signal. By doing so, it is not necessary to switch the local oscillation frequency of the PLL circuit 2, and the circuit configuration can be simplified.

  Further, in the first and second embodiments, two bandpass filters 6 and 7 are provided in the filter circuit 14, and in the third embodiment, three bandpasses 40 to 42 are provided in the filter circuit 14A. Provided. However, the present invention is not limited to this configuration, and four or more bandpass filters may be provided.

  Furthermore, in the frequency characteristics shown in FIGS. 2, 5, and 8, the upper limit frequency and the lower limit frequency of each pass bandwidth are shown using frequencies corresponding to the maximum relative power, but the present invention is not limited to this, In general, the frequency is shown using a frequency corresponding to a relative power lower by 3 dB than the maximum relative power.

  According to the present invention, it is possible to realize a radio reception circuit, a radio reception apparatus, and a radio reception apparatus switching method capable of selectively receiving an analog radio broadcast wave signal and a digital radio broadcast wave signal with low cost and high sound quality.

It is a block diagram which shows the structure of the radio broadcast receiver which concerns on the 1st Embodiment of this invention. (A) is a characteristic diagram which shows each frequency characteristic 21 and 22 of the band pass filters 6 and 7 of the radio broadcast receiver of FIG. (B) is a characteristic diagram showing the combined frequency characteristic 23 of the bandpass filters 6 and 7 of the radio broadcast receiving apparatus of FIG. It is a block diagram which shows the structure of the radio broadcast receiver which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows the structure of the radio broadcast receiver which concerns on the 3rd Embodiment of this invention. (A) is a characteristic view which shows each frequency characteristic 51-53 of the band pass filters 40-42 of the radio broadcast receiver of FIG. FIG. 5B is a characteristic diagram illustrating a composite frequency characteristic 54 of the band pass filters 40 to 42 of the radio broadcast receiving apparatus of FIG. 4. It is a block diagram which shows the structure of the radio broadcast receiver which concerns on the 1st modification of the 3rd Embodiment of this invention. It is a block diagram which shows the structure of the radio broadcast receiver which concerns on the 2nd modification of the 3rd Embodiment of this invention. (A) is a characteristic view which shows each frequency characteristic 71-73 of the band pass filters 60-62 of the radio broadcast receiver of FIG. FIG. 8B is a characteristic diagram illustrating a composite frequency characteristic 74 of the band pass filters 60 to 62 of the radio broadcast receiving apparatus of FIG.

Explanation of symbols

1 ... High frequency amplifier,
2 ... PLL circuit,
3 ... Mixer,
5 ... Variable gain control circuit,
6, 7, 31, 31A, 40-42, 60-62 ... band pass filters,
8, 9, 30, 43-46, 43A-46A ... switch,
10, 33 ... intermediate frequency amplifier,
14, 14A, 14B ... filter circuit,
15 ... antenna,
16, 16A, 16B, 17, 17A, 17B ... wireless receiving circuit,
18, 18A ... controller,
32: Variable amplifier.

Claims (12)

Local oscillation means for generating and outputting a local oscillation signal having a different local oscillation frequency according to an input switching signal;
A mixing means for outputting the mixed signal by mixing the input radio reception signal and the local oscillation signal;
A plurality of first bands connected in parallel according to the switching signal, having a center frequency of different pass bands, and outputting a predetermined intermediate frequency signal from the mixed signal by band-pass filtering The intermediate frequency after band-pass filtering is switched by selecting whether at least one first band-pass filtering means or a plurality of predetermined first band-pass filtering means is selected from among the pass filtering means. And a first switch means for outputting a signal.   2. The radio receiving circuit according to claim 1, further comprising amplifying means for amplifying the intermediate frequency signal output from the first switch means. In place of the local oscillation means, another local oscillation means for generating and outputting a local oscillation signal having a predetermined single local oscillation frequency,
The center frequency of the passband of at least one first bandpass filtering means selected by the first switch means and a plurality of predetermined first bandpass filtering selected by the first switch means 3. The radio receiving circuit according to claim 1, wherein the center frequency of the pass band of the means is set to be substantially the same. A radio reception circuit according to any one of claims 1 to 3,
Gain control means for generating and outputting a gain control signal based on the mixed signal;
A radio receiving apparatus comprising: a high frequency amplifying unit that adjusts a gain of the radio reception signal according to the gain control signal and outputs the adjusted signal to the mixing unit.   5. The radio receiving apparatus according to claim 4, further comprising a plurality of first band pass filtering means.   6. The radio communication apparatus according to claim 4, further comprising second band-pass filtering means for further band-pass filtering the intermediate frequency signal output from the first switch means.   In response to the switching signal, an intermediate frequency signal output from the first switch means is output to the second band-pass filtering means, or an intermediate frequency signal output from the first switch means is 7. The wireless communication apparatus according to claim 6, further comprising second switch means for switching whether to output the signal as it is and outputting an intermediate frequency signal.   When the wireless reception signal is an analog broadcast wave signal, the first switch means selects at least one first bandpass filtering means, while the wireless reception signal is a digital broadcast wave signal, The radio receiving apparatus according to any one of claims 4 to 7, wherein the predetermined plurality of first band-pass filtering means are selected. Local oscillation means for generating and outputting a local oscillation signal having a different local oscillation frequency according to an input switching signal;
A mixing means for outputting the mixed signal by mixing the input radio reception signal and the local oscillation signal;
A plurality of first bands connected in parallel according to the switching signal, having a center frequency of different pass bands, and outputting a predetermined intermediate frequency signal from the mixed signal by band-pass filtering A wireless receiver switching method comprising a passing filtering means,
In response to the switching signal, the first switch means is used to select at least one first band-pass filtering means from among the plurality of first band-pass filtering means, or a predetermined plurality of band-pass filtering means. A method for switching a radio reception apparatus, comprising: a step of switching whether to select a first band-pass filtering means. The wireless reception device includes, in place of the local oscillation unit, another local oscillation unit that generates and outputs a local oscillation signal having a predetermined single local oscillation frequency.
The center frequency of the passband of at least one first bandpass filtering means selected by the first switch means and a plurality of predetermined first bandpass filtering selected by the first switch means 10. The method of switching a radio receiving apparatus according to claim 9, wherein the center frequency of the pass band of the means is set to be substantially the same. The wireless reception device further includes second band-pass filtering means for further band-pass filtering the intermediate frequency signal output from the first switch means,
In response to the switching signal, the second switch means is used to output the intermediate frequency signal output from the first switch means to the second band-pass filtering means, or the first switch 11. The method of switching a radio receiving apparatus according to claim 9, further comprising a step of switching whether to output the intermediate frequency signal output from the means as it is.   The step of switching using the first switch means selects at least one first band-pass filtering means when the radio reception signal is an analog broadcast wave signal, while the radio reception signal is a digital broadcast wave. 12. The radio receiver switching method according to claim 9, wherein when the signal is a signal, the predetermined plurality of first band-pass filtering means are selected.

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