JP2021069088A - Receiver and method - Google Patents

Abstract

To enable downsizing of a device while suppressing occurrence of spurious.SOLUTION: First frequency conversion means 12 converts a reception signal into a first intermediate frequency signal by mixing the reception signal with a first local oscillation signal. Second frequency conversion means 14 converts the first intermediate frequency signal into a second intermediate frequency signal by mixing the first intermediate frequency signal with a second local oscillation signal. Frequency control means 15 controls a frequency of the first local oscillation signal and a frequency of the second local oscillation signal in accordance with a frequency of the reception signal. First demodulation means 17 performs demodulation on sampling data of the second intermediate frequency signal outputted by an ADC 16, and outputs a first demodulation signal. Second demodulation means 18 performs demodulation, whose phase is inverted, on the sampling data of the second intermediate frequency signal, and outputs a second demodulation signal. Selection means 19 selectively outputs the first demodulation signal or the second demodulation signal in accordance with the frequency of the reception signal.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to receivers and methods.

As a receiver for receiving a radio frequency (RF) signal, a superheterodyne receiver is known. The super heterodyne receiver converts the received RF signal into an intermediate frequency (IF) signal and the IF signal into a baseband signal. In recent years, a double superheterodyne receiver that converts to an IF signal twice has been generally used.

For example, Patent Document 1 discloses a double superheterodyne receiver. The receiver described in Patent Document 1 is configured as a multi-mode receiver capable of supporting a plurality of communication methods or a plurality of communication modes. The multi-mode receiver described in Patent Document 1 has a first frequency conversion unit and a second frequency conversion unit. The first frequency conversion unit converts the RF signal into the first IF signal. The second frequency conversion unit converts the first IF signal into the second IF signal.

The first frequency converter has a first local oscillator (LO) and a first mixer. The first local oscillator outputs the first LOCAL signal. The first mixer mixes the RF signal and the first LOCAL signal and outputs the first IF signal. The second frequency converter has a second local oscillator and a second mixer. The second local oscillator outputs the second LOCAL signal. The second mixer mixes the first IF signal and the second LOCAL signal and outputs the second IF signal. The second IF signal is sent to the demodulation unit, and the demodulation unit demodulates the received signal and the like.

Japanese Unexamined Patent Publication No. 2006-121160

When a superheterodyne system is adopted to improve spurious sensitivity in a receiver having a wide reception frequency range and a wide band reception bandwidth, the double superheterodyne system is adopted. However, it is difficult to take spurious measures in a double superheterodyne receiver having a wide reception frequency range and a wide band reception bandwidth due to the following factors.

First, the receiver needs to change the first LOCAL signal in a wide range in the first frequency conversion unit according to the reception frequency range. In this case, spurious generated by mixing the first LOCAL signal and the second LOCAL signal due to leakage of the mixer or the like increases. Secondly, in order to secure a wide band reception bandwidth, the pass bandwidth of the band pass filter (BPF) of the first frequency conversion unit and the second frequency conversion unit cannot be narrowed. Therefore, in order to suppress the generation of spurious, it is necessary to add a circuit for increasing the isolation between the first frequency conversion unit and the second frequency conversion unit.

Here, in the receiver, the occurrence of spurious can be suppressed by preparing a plurality of combinations of the IF signal and the LOCAL signal and appropriately selecting the combination to be used according to the reception frequency. However, in that case, when a combination of an IF signal and a LOCAL signal that suppresses the generation of spurious is selected, the phase of the IF signal and the received signal may be inverted. The data of the phase-inverted IF signal is inverted. When the phase of the IF signal is inverted, the data inversion can be corrected by demodulating with an I / Q demodulator using a LOCAL signal having an opposite phase. However, in that case, the circuit scale is increased because the LOCAL signals having opposite phases are required.

In particular, when a receiver having a wide dynamic range is miniaturized, it is difficult to secure isolation between the first frequency conversion unit and the second frequency conversion unit. A signal obtained by mixing the first LOCAL signal and the second LOCAL signal enters the reception band of the second IF signal, and spurious is generated. When the receiver is miniaturized, isolation measures such as division of modules and review of frequency settings cannot be taken, and it is difficult to effectively suppress the generation of spurious.

In view of the above circumstances, an object of the present disclosure is to provide a receiver and a method capable of downsizing the device while suppressing the generation of spurious.

In the present disclosure, in order to achieve the above object, a first local oscillator that outputs a first local oscillation signal whose frequency changes in a frequency range corresponding to the frequency of the received signal, the received signal, and the first local oscillation signal. A first frequency conversion means that converts the received signal into a first intermediate frequency signal by mixing with, a second local oscillator that outputs a second local oscillation signal, the first intermediate frequency signal, and the second local region. A second frequency conversion means that converts the first intermediate frequency signal into a second intermediate frequency signal by mixing with the oscillation signal, the frequency of the first local oscillation signal according to the frequency of the received signal, and the said. A frequency control means for controlling the frequency of the second locally oscillating signal, an analog digital converter that samples the second intermediate frequency signal in synchronization with the operating clock signal, and the second intermediate output by the analog digital converter. The first demodulation means that demodulates the sampled data of the frequency signal and outputs the first demodulated signal, and the demodulation of the sampled data of the second intermediate frequency signal in the first demodulation means are phase-inverted. A receiver including a second demodulation means for outputting the second demodulation signal and a signal selection means for selectively outputting the first demodulation signal or the second demodulation signal according to the frequency of the received signal. provide.

The present disclosure also converts the received signal into a first intermediate frequency signal by mixing the received signal with a first local oscillation signal whose frequency changes in a frequency range corresponding to the frequency of the received signal. By mixing the first intermediate frequency signal with the second local oscillation signal, the first intermediate frequency signal is converted into a second intermediate frequency signal, and the second intermediate frequency signal is sampled in synchronization with the operating clock signal. Then, the sampled data of the second intermediate frequency signal is demodulated to output the first demodulated signal, and the sampled data of the second intermediate frequency signal is demodulated with the first demodulated signal. Performs phase-inverted demodulation to output a second demodulated signal, controls the frequency of the first local oscillation signal and the frequency of the second local oscillation signal according to the frequency of the reception signal, and receives the reception. Provided is a receiving method for selectively outputting the first demodulated signal or the second demodulated signal according to the frequency of the signal.

The receiver and method according to the present disclosure can reduce the size of the device while suppressing the generation of spurious.

The block diagram which shows the schematic structure of the receiver which concerns on this disclosure. The block diagram which shows the receiver which concerns on 1st Embodiment of this disclosure. The block diagram which shows the structural example of the 1st IQ demodulation part and the 2nd IQ demodulation part. The figure which shows an example of a frequency setting. The block diagram which shows the receiver which concerns on 2nd Embodiment of this disclosure. The figure which shows another example of a frequency setting.

Prior to the description of the embodiments of the present disclosure, the outline of the present disclosure will be described. FIG. 1 shows a schematic configuration of a receiver according to the present disclosure. The receiver 10 includes a first local oscillator 11, a first frequency conversion means 12, a second local oscillator 13, a second frequency conversion means 14, a frequency control means 15, and an analog-to-digital converter (ADC) 16. It has a first demodulation means 17, a second demodulation means 18, and a selection means 19.

The first local oscillator 11 outputs a first local oscillator signal whose frequency changes in a frequency range corresponding to the frequency of the received signal. The first frequency conversion means 12 converts the received signal into the first intermediate frequency signal by mixing the received signal and the first local oscillation signal. The second local oscillator 13 outputs a second local oscillator signal. The second frequency conversion means 14 converts the first intermediate frequency signal into the second intermediate frequency signal by mixing the first intermediate frequency signal and the second local oscillation signal. The frequency control means 15 controls the frequency of the first local oscillation signal and the frequency of the second local oscillation signal according to the frequency of the received signal.

The ADC 16 samples the second intermediate frequency signal in synchronization with the operating clock signal. The first demodulation means 17 demodulates the sampling data of the second intermediate frequency signal output by the ADC 16 and outputs the first demodulation signal. The second demodulation means 18 demodulates the sampling data of the second intermediate frequency signal and outputs the second demodulation signal. The second demodulation means 18 performs demodulation whose phase is inverted from that of the demodulation in the first demodulation means 17. The selection means 19 selectively outputs the first demodulated signal or the second demodulated signal according to the frequency of the received signal.

In the present disclosure, the frequency control means 15 controls the frequency of the first local oscillation signal and the frequency of the second local oscillation signal according to the reception frequency. The frequency of the second local oscillation signal is, for example, the frequency at which the frequency of the signal obtained by mixing the first local oscillation signal and the second local oscillation signal, which changes according to the reception frequency, does not enter the signal band of the second intermediate frequency signal. Is controlled by. In the present disclosure, the first demodulation means 17 and the second demodulation means 18 perform demodulation in which the phases are reversed from each other. The selection means 19 selects the first demodulated signal or the second demodulated signal according to the reception frequency. By doing so, even when the received signal and the second intermediate frequency have opposite phases, the signal can be demodulated, and a combination of locally oscillated signals that suppresses the generation of spurious can be selected.

In the present disclosure, it is possible to demodulate an anti-phase signal without adding a local oscillator that generates an anti-phase. Further, since the combination of the local oscillation signals suppressing the generation of spurious can be selected, an additional circuit for increasing the isolation between the first local oscillation signal and the second local oscillation signal is unnecessary. Therefore, in the present disclosure, the receiver 10 can be miniaturized while suppressing the generation of spurious.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. FIG. 2 shows a receiver according to the first embodiment of the present disclosure. The receiver 100 includes a BPF 101, a frequency conversion unit 102, a signal processing unit 105, and a synthesizer unit 106.

The BPF 101 is a band limiting filter and band limits the received signal (RF signal). The BPF 101 band limits the RF signal with a wide band bandwidth corresponding to the range of the reception frequency. For example, if the reception frequency range is 30 MHz to 100 MHz and the reception bandwidth is 30 MHz, the BPF 101 passes signals in the frequency range from (30-15) MHz to (100 + 15) MHz to other frequencies. Attenuates the signal in the range.

The synthesizer unit 106 includes a first oscillator 161, a second oscillator 162, and a third oscillator 163. The first oscillator 161 and the second oscillator 162 are configured so that the oscillation frequency can be changed. The first oscillator 161 outputs a first local oscillation signal (LOCAL1 signal). The second oscillator 162 outputs a second local oscillation signal (LOCAL2 signal). The third oscillator 163 outputs an operation clock signal (CLK signal) used by the signal processing unit 105. In the present embodiment, it is assumed that the frequency of the clock signal CLK is four times the frequency of the baseband signal. The synthesizer unit 106 may be configured as one module including the first oscillator 161 and the second oscillator 162. The first oscillator 161 and the second oscillator 162 correspond to the first local oscillator 11 and the second local oscillator 13 in FIG. 1, respectively.

The frequency conversion unit 102 includes a first IF conversion unit 103 and a second IF conversion unit 104. The first IF conversion unit 103 converts the RF signal output from the BPF 101 into a first intermediate frequency signal (first IF signal). The first IF conversion unit 103 up-converts, for example, an RF signal into a first IF signal whose frequency is higher than the reception frequency. Alternatively, the first IF converter 103 may downconvert the RF signal to a first IF signal whose frequency is lower than the reception frequency. The second IF conversion unit 104 converts the first IF signal into a second intermediate frequency signal (second IF signal). In the present embodiment, the frequency of the second IF signal is assumed to be 3/4 times the frequency of the clock signal CLK. The frequency conversion unit 102 may be configured as one module including the first IF conversion unit 103 and the second IF conversion unit 104. The first IF conversion unit 103 and the second IF conversion unit 104 correspond to the first frequency conversion means 12 and the second frequency conversion means 14 of FIG. 1, respectively.

The first IF conversion unit 103 includes a mixer 131 and a BPF 132. The mixer 131 mixes the LOCAL1 signal output by the first oscillator 161 and the RF signal output by the BPF 101, and outputs the first IF signal. The frequency of the LOCAL1 signal is set according to the reception frequency. The BPF 132 band limits the first IF signal. The BPF 132 limits the first IF signal to the reception bandwidth by passing signals in the frequency range of the reception bandwidth centered on the first intermediate frequency and attenuating signals in other bands. For example, when the first intermediate frequency is 2200 MHz and the reception bandwidth is 30 MHz, the BPF 132 passes signals in the frequency range of (2200 ± 15) MHz and attenuates signals in other frequency ranges.

The second IF conversion unit 104 includes a mixer 141 and a BPF 142. The mixer 141 mixes the LOCAL2 signal output by the second oscillator 162 and the first IF signal output by the first IF conversion unit 103, and outputs the second IF signal. The BPF 142 band limits the second IF signal. The BPF 142 band limits the second IF signal to the reception bandwidth by passing signals in the frequency range of the reception bandwidth centered on the second intermediate frequency and attenuating signals in other bands. For example, when the second intermediate frequency is 90 MHz and the reception bandwidth is 30 MHz, the BPF 142 passes signals in the frequency range of (90 ± 15) MHz and attenuates signals in other frequency ranges.

The signal processing unit 105 controls the oscillation frequencies of the first oscillator 161 and the second oscillator 162. Further, the signal processing unit 105 performs signal processing on the second IF signal. The signal processing unit 105 includes an ADC 151, a clock conversion unit 152, a first IQ demodulation unit 153, a second IQ demodulation unit 154, a switch 155, and a frequency control unit 156.

The frequency control unit 156 controls the frequencies of the LOACL1 signal output by the first oscillator 161 and the LOCAL2 signal output by the second oscillator 162. The frequency control unit 156 controls the frequency of the LOCAL1 signal so that the frequency of the first IF signal becomes a predetermined first intermediate frequency according to the reception frequency. For example, the frequency control unit 156 controls the frequency of the LOCAL1 signal to a frequency obtained by adding the reception frequency to the first intermediate frequency.

Further, the frequency control unit 156 controls the frequency of the LOCAL2 signal so that the second IF signal becomes a predetermined second intermediate frequency with respect to the first intermediate frequency. For example, the frequency control unit 156 controls the frequency of the LOCAL2 signal to a frequency obtained by adding the second intermediate frequency to the first intermediate frequency or a frequency obtained by subtracting the second intermediate frequency from the first intermediate frequency, depending on the reception frequency. To do. In the present embodiment, the frequency control unit 156 controls the frequencies of the LOCAL1 signal and the LOCAL2 signal so that the generation of spurious can be suppressed. For example, the frequency control unit 156 controls the frequencies of the LOCAL1 signal and the LOCAL2 signal to a combination of frequencies in which the frequency of the signal generated when the harmonics of the LOCAL signals are mixed does not enter the frequency band of the second intermediate frequency. ..

The ADC 151 converts the second IF signal from an analog signal to a digital signal. The ADC 151 undersamples the second IF signal at a sampling rate according to the clock signal CLK output by the third oscillator 163. The ADC 151 outputs the sampling data of the second IF signal to the first IQ demodulation unit 153 and the second IQ demodulation unit 154. ADC 151 corresponds to ADC 16 in FIG.

The clock conversion unit 152 outputs a 1/4 clock signal obtained by reducing the frequency of the clock signal CLK to 1/4. The clock converter 152 includes, for example, a frequency divider. For example, when the frequency of the clock signal CLK is 120 MHz, the clock conversion unit 152 outputs a 1/4 clock signal having a frequency of 30 MHz synchronized with the clock signal CLK.

The first IQ demodulation unit 153 performs IQ demodulation on the second IF signal sampled by the ADC 151. The first IQ demodulation unit 153 performs IQ demodulation in synchronization with the 1/4 clock signal output by the clock conversion unit 152. The first IQ demodulation unit 153 outputs the Ia signal and the Qa signal (first demodulation signal) obtained by IQ demodulation. The second IQ demodulation unit 154 performs IQ demodulation on the second IF signal sampled by the ADC 151. The second IQ demodulation unit 154 performs IQ demodulation in synchronization with the 1/4 clock signal. The IQ demodulation performed by the second IQ demodulation unit 154 has a phase inverted with respect to the IQ demodulation performed by the first IQ demodulation unit 153. The second IQ demodulation unit 154 outputs the Ib signal and the Qb signal (second demodulation signal) obtained by IQ demodulation. The first IQ demodulation unit 153 and the second IQ demodulation unit 154 correspond to the first demodulation means 17 and the second demodulation means 18 of FIG. 1, respectively.

FIG. 3 shows a configuration example of the first IQ demodulation unit 153 and the second IQ demodulation unit 154. The first IQ demodulation unit 153 has multipliers 201 and 202. The multiplier 201 multiplies the sampling data of the second IF signal output by the ADC 151 by the first in-phase signal in synchronization with the 1/4 clock signal. The first in-phase signal is a signal that repeats the pattern of [1,0, -1,0]. The multiplier 201 outputs a signal obtained by multiplying the sampling data of the second IF signal by the first in-phase signal as an Ia signal. The multiplier 202 multiplies the sampling data of the second IF signal output by the ADC 151 by the first orthogonal signal in synchronization with the 1/4 clock signal. The first orthogonal signal is a signal that repeats the pattern of [0, -1, 0, 1]. The multiplier 201 outputs a signal obtained by multiplying the sampling data of the second IF signal by the first orthogonal signal as a Qa signal.

The second IQ demodulator 154 has multipliers 205 and 206. The multiplier 205 multiplies the sampling data of the second IF signal output by the ADC 151 by the second in-phase signal in synchronization with the 1/4 clock signal. The second common-mode signal is a signal that repeats the pattern of [0, -1, 0, 1]. The multiplier 205 outputs a signal obtained by multiplying the sampling data of the second IF signal by the second in-phase signal as an Ib signal. The multiplier 206 multiplies the sampling data of the second IF signal output by the ADC 151 by the second orthogonal signal in synchronization with the 1/4 clock signal. The second orthogonal signal is a signal that repeats the pattern of [-1,0,1,0]. The multiplier 206 outputs a signal obtained by multiplying the sampling data of the second IF signal by the second orthogonal signal as a Qb signal.

Returning to FIG. 2, the switch 155 selectively outputs the set of the Ia signal and the Qa signal output by the first IQ demodulation unit 153 and the set of the Ib signal and the Qb signal output by the second IQ demodulation unit 154. The switch 155 selects a set of Ia signal and Qa signal, or a set of Ib signal and Qb signal, according to a control signal input from a control unit (not shown).

The switch 155 selects a set of the Ia signal and the Qa signal output by the first IQ demodulation unit 153 when the received signal and the second IF signal are not phase-inverted. When the received signal and the second IF signal are phase-inverted, the switch 155 selects a set of the Ib signal and the Qb signal output by the second IQ demodulation unit 154. The switch 155 selects a set of the Ia signal and the Qa signal when, for example, the frequency control unit 156 controls the frequency of the LOCAL2 signal to a frequency obtained by adding the second intermediate frequency to the first intermediate frequency. The switch 155 selects a pair of Ib signal and Qb signal when the frequency control unit 156 controls the frequency of the LOCAL2 signal to a frequency obtained by subtracting the second intermediate frequency from the first intermediate frequency. The switch 155 corresponds to the selection means 19 of FIG. The set of signals output from the switch 155 is used for subsequent signal processing and the like.

Specific frequency settings will be described below. FIG. 4 shows an example of frequency setting. In this example, the lower limit (MIN) of the reception frequency is 30 MHz and the upper limit (MAX) is 100 MHz. It is assumed that the reception bandwidth and the baseband frequency are 30 MHz, and the frequency of the operating clock signal is 120 MHz. Further, it is assumed that the first intermediate frequency is 2200 MHz and the second intermediate frequency is 90 MHz.

FIG. 4 shows two settings (combinations) for the frequency of the LOCAL 1 signal and the frequency of the LOCAL signal 2. Regardless of which of the settings 1 and 2 is selected, the frequency control unit 156 controls the frequency of the LOCAL1 signal to the frequency selected from the range of 2230 MHz to 2300 MHz according to the reception frequency. The frequency control unit 156 controls the frequency of the LOCAL2 signal to 2290 MHz when setting 1 is selected. When setting 2 is selected, the frequency control unit 156 controls the frequency of the LOCAL2 signal to 2110 MHz. When setting 1 is selected, the phase is not inverted between the second IF signal and the received signal. On the other hand, when setting 2 is selected, the phases of the second IF signal and the received signal are inverted.

For example, consider the case where the reception frequency is 45 MHz. In this case, the frequency control unit 156 controls the frequency of the LOCAL1 signal to 45 + 2200 = 2245 MHz. In this case, a first IF signal having a frequency of 2200 MHz can be obtained with respect to a reception frequency of 45 MHz. When the first intermediate frequency is 2200 MHz, there are two frequencies of the LOCAL2 signal capable of obtaining the second intermediate frequency having a frequency of 90 MHz, 2290 MHz and 2110 MHz.

Suppose that setting 1 is selected for a reception frequency of 45 MHz. That is, it is assumed that the frequency of the LOCAL2 signal is controlled to 2290 MHz. In that case, when the second harmonics of the LOCAL1 signal having a frequency of 2245 MHz and the LOCAL2 signal having a frequency of 2290 MHz are mixed, the mixing of the second harmonics enters the reception band of the second IF signal. That is, 2245 × 2-2290 × 2 = 90 MHz. Therefore, if setting 1 is selected when the reception frequency is 45 MHz, spurious is generated when mixing of two LOCAL signals occurs.

The frequency control unit 156 selects setting 2 when the reception frequency is 45 MHz. That is, the frequency control unit 156 controls the frequency of the LOCAL1 signal to 2245 MHz and the frequency of the LOCAL2 signal to 2110 MHz. By selecting such a combination of frequencies, spurious caused by mixing of two LOCAL signals can be avoided. The frequency control unit 156 holds, for example, information indicating whether to select setting 1 or setting 2 according to the reception frequency, and selects setting 1 or setting 2 according to the information.

When setting 1 is selected, there is no phase inversion between the received signal and the second IF signal. In this case, the switch 155 selects a set of the Ia signal and the Qa signal output by the first IQ demodulation unit 153 and outputs the set to a circuit or the like in the subsequent stage. When setting 2 is selected, the phase of the received signal and the second IF signal are inverted. In that case, the switch 155 selects a set of the Ib signal and the Qb signal output by the second IQ demodulation unit 154 and outputs the set to a circuit or the like in the subsequent stage.

In the present embodiment, the frequency control unit 156 controls the frequencies of the LOCAL1 signal and the LOCAL2 signal according to the reception frequency. The phase of the second IF signal is inverted between the case where the frequency of the LOCAL2 signal is controlled to the first intermediate frequency + the second intermediate frequency and the case where the frequency is controlled to the first intermediate frequency-the second intermediate frequency. In the present embodiment, the switch 155 selectively outputs normal IQ demodulation and IQ demodulation corresponding to phase inversion according to the phase state of the second IF signal. In the present embodiment, the IQ signal can be extracted from the IF signal having a phase opposite to that of the received signal by IQ demodulating the IF signal after sampling the ADC. Therefore, in the present embodiment, it is possible to select a combination of LOCAL signals that suppresses the generation of spurious, depending on the reception frequency. Therefore, in the present embodiment, the generation of spurious can be suppressed without taking measures against isolation, and the device can be miniaturized.

Next, a second embodiment of the present disclosure will be described. FIG. 5 shows a receiver according to the second embodiment of the present disclosure. In the present embodiment, the receiver 100a includes a BPF (BPF_H) 101H, a BPF (BPF_L) 101L, a frequency conversion unit 102a, a signal processing unit 105, a synthesizer unit 106, and a pair of switches 111 and 112. In the present embodiment, the reception frequency is included in the first radio frequency band or the second radio frequency band. In the following, it is assumed that the first radio frequency band is a band having a higher frequency than the second radio frequency band. In the present embodiment, the signal processing unit 105 and the synthesizer unit 106 may be the same as those described in the first embodiment.

In the present embodiment, the BPF 101H and the BPF 101L have different pass bands. The BPF101H band limits the RF signal to a frequency band corresponding to the first radio frequency band. The BPF101L band-limits the RF signal to a frequency band corresponding to the second radio frequency band. For example, the BPF101H passes RF signals in the frequency band from 1901 MHz to 2600 MHz. The BPF101L passes RF signals in the frequency band from 10 MHz to 100 MHz. Part of the pass band of BPF101H and 101L may overlap. Hereinafter, for convenience, the frequency band from 1901 MHz to 2600 MHz is also referred to as an H band, and the frequency band from 10 MHz to 100 MHz is also referred to as an L band.

The switches 111 and 112 select BPF101H or 101L according to the frequency band of the reception frequency. The switches 111 and 112 select BPF101H when the reception frequency is included in the H band. The switches 111 and 112 select BPF101L when the reception frequency is included in the L band. Control signals are input to the switches 111 and 112 from a control unit (not shown). The switches 111 and 112 select BPF101H or 101L according to the control signal.

In the present embodiment, the frequency conversion unit 102a includes a first IF conversion unit 103a and a second IF conversion unit 104. The second IF conversion unit 104 may be the same as that described in the first embodiment. The first IF conversion unit 103a converts the RF signal into a first IF signal having a frequency selected from two intermediate frequencies. The first IF conversion unit 103a selectively generates, for example, a first IF signal in which the received RF signal is up-converted and a first IF signal in which the received RF signal is down-converted.

For example, the first IF conversion unit 103a converts the RF signal into a first IF signal having a frequency of 2200 MHz or a first IF signal having a frequency of 900 MHz. Here, for convenience, the higher frequency of the two intermediate frequencies is also referred to as the intermediate frequency H, and the lower frequency is also referred to as the intermediate frequency L. In the present embodiment, for example, when the received signal is included in the H band, the intermediate frequency L is selected as the first intermediate frequency. When the received signal is included in the L band, the intermediate frequency H is selected as the first intermediate frequency.

The first IF conversion unit 103a includes a mixer 131, BPF 132H and 132L, and a pair of switches 133 and 134. When the intermediate frequency H is selected, the frequency control unit 156 of the signal processing unit 105 controls the frequency of the LOCAL1 signal output by the first oscillator 161 to the reception frequency + the intermediate frequency H. The mixer 131 mixes the LOCAL1 signal and the RF signal whose frequency is the reception frequency + the intermediate frequency H.

The switches 133 and 134 select the BPF 132H when the intermediate frequency H is selected. The BPF 132H band limits the first IF signal of the intermediate frequency H. The BPF 132H passes signals in the frequency range of the reception bandwidth centered on the intermediate frequency H and attenuates signals in other bands. For example, when the intermediate frequency H is 2200 MHz and the reception bandwidth is 30 MHz, the BPF 132H passes signals in the frequency range of (2200 ± 15) MHz and attenuates signals in other frequency ranges.

When the intermediate frequency L is selected, the frequency control unit 156 controls the frequency of the LOCAL1 signal output by the first oscillator 161 to the reception frequency + the intermediate frequency L. The mixer 131 mixes the LOCAL1 signal and the RF signal whose frequency is the reception frequency + the intermediate frequency L. The switches 133 and 134 select the BPF 132L when the intermediate frequency L is selected. The BPF 132L band limits the first IF signal of the intermediate frequency L. The BPF 132L passes signals in the frequency range of the reception bandwidth centered on the intermediate frequency L and attenuates signals in other bands. For example, when the intermediate frequency L is 900 MHz and the reception bandwidth is 30 MHz, the BPF 132L passes signals in the frequency range of (900 ± 15) MHz and attenuates signals in other frequency ranges.

When the intermediate frequency H is selected, the frequency control unit 156 controls the frequency of the LOCAL2 signal output by the second oscillator 162 to the second intermediate frequency + the intermediate frequency H. When the intermediate frequency L is selected, the frequency control unit 156 controls the frequency of the LOCAL2 signal output by the second oscillator 162 to the second intermediate frequency + the intermediate frequency L. The second IF conversion unit 104 converts the first IF signal into a second IF signal having a predetermined second intermediate frequency regardless of whether the first intermediate frequency is the intermediate frequencies H and L.

Specific frequency settings will be described below. Here, it is assumed that the receiver 100a selectively receives the reception signal in the frequency band from 30 MHz to 100 MHz and the reception signal in the frequency band from 1901 MHz to 2600 MHz. The frequency setting when the receiver 100a receives the reception signal in the frequency band from 30 MHz to 100 MHz, that is, the reception signal included in the L band may be the same as the setting shown in FIG. When the received signal included in the L band is received, the frequency of the first IF signal is 2200 MHz. The 2200 MHz first IF signal is band-limited by the BPF 132H and sent to the second IF converter 104. The second IF conversion unit 104 converts the 2200 MHz first IF signal into a 90 MHz second IF signal.

FIG. 6 shows another example of frequency setting. The frequency setting shown in FIG. 6 is used when the receiver 100a receives a reception signal in the frequency band from 1901 MHz to 2600 MHz, that is, a reception signal included in the H band. FIG. 6 shows two settings (combinations) for the frequency of the LOCAL 1 signal and the frequency of the LOCAL signal 2. The frequency control unit 156 controls the frequency of the LOCAL1 signal to a frequency selected from the range of 2801 MHz to 3500 MHz according to the reception frequency regardless of which of the settings 3 and 4 is selected. In this case, the frequency of the first IF signal is 900 MHz. The 900 MHz first IF signal is band-limited by the BPF 132L and sent to the second IF converter 104.

The frequency control unit 156 controls the frequency of the LOCAL2 signal to 990 MHz when setting 3 is selected. The frequency control unit 156 controls the frequency of the LOCAL2 signal to 810 MHz when the setting 4 is selected. When setting 3 is selected, the phase is not inverted between the second IF signal and the received signal. On the other hand, when setting 4 is selected, the phases of the second IF signal and the received signal are inverted. The frequency control unit 156 selects a combination of LOCAL signals that can suppress the generation of spurious according to the reception frequency, as in the case where the reception frequency is included in the L band. By doing so, when mixing of the two LOCAL signals occurs, it is possible to suppress mixing of the second harmonics and the like from entering the reception band of the second IF signal, and it is possible to suppress the generation of spurious. In the example of FIG. 6, the setting 3 in which the second IF signal does not invert the phase is advantageous because the mixing between the LOCAL1 signal and the LOCAL2 signal has a higher dimension than the setting 4.

In the present embodiment, the receiver 100a converts the RF signal into the IF signal of the first intermediate frequency selected from the two kinds of frequencies in the first IF conversion unit 103a. In the receiver 100a, for example, a frequency having a large difference from the frequency of the received signal is selected as the first intermediate frequency. In the present embodiment, even when the first IF signal up-converted and the first IF signal down-converted are produced, the frequency at which the two LOCALs are mixed falls within the reception bandwidth of the second IF signal. Can be avoided. Other effects are the same as in the first embodiment.

In the second embodiment, the example in which the first IF conversion unit 103a outputs the first IF signal of the first intermediate frequency selected from the two frequencies has been described, but the present disclosure is not limited to this. For example, the number of first intermediate frequencies that can be selected is not limited to two, and may be three or more. That is, the first IF conversion unit 103a may convert the received signal into a first IF signal having a first intermediate frequency selected from a plurality of frequencies. Further, in the second embodiment, an example in which the receiver 100a has two BPF 101H and 101L has been described, but the present disclosure is not limited thereto. A reception frequency range may be further added, and a BPF that limits the band in the RF signal band may be further added.

Although the embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the above-described embodiments, and changes and modifications are made to the above-described embodiments without departing from the spirit of the present disclosure. Are also included in this disclosure.

For example, some or all of the above embodiments may also be described, but not limited to:

[Appendix 1]
A first local oscillator that outputs a first local oscillator signal whose frequency changes in the frequency range according to the frequency of the received signal,
A first frequency conversion means for converting the received signal into a first intermediate frequency signal by mixing the received signal with the first local oscillation signal.
A second local oscillator that outputs a second local oscillator signal,
A second frequency conversion means for converting the first intermediate frequency signal into a second intermediate frequency signal by mixing the first intermediate frequency signal and the second local oscillation signal.
A frequency control means for controlling the frequency of the first local oscillation signal and the frequency of the second local oscillation signal according to the frequency of the received signal.
An analog-to-digital converter that samples the second intermediate frequency signal in synchronization with the operating clock signal.
A first demodulation means that demodulates the sampling data of the second intermediate frequency signal output by the analog-to-digital converter and outputs the first demodulation signal.
A second demodulation means that performs phase-inverted demodulation of the sampled data of the second intermediate frequency signal with the demodulation in the first demodulation means and outputs a second demodulation signal.
A receiver including a signal selection means for selectively outputting the first demodulated signal or the second demodulated signal according to the frequency of the received signal.

[Appendix 2]
The receiver according to Appendix 1, wherein the analog-to-digital converter undersamples the second intermediate frequency signal.

[Appendix 3]
The receiver according to Appendix 1 or 2, wherein the frequency of the operating clock signal is four times the frequency of the baseband signal, and the second intermediate frequency signal is 3/4 times the operating clock signal.

[Appendix 4]
The first demodulation means demodulates the sampled data in synchronization with a 1/4 clock signal whose frequency is 1/4 times the frequency of the operation clock signal, which is synchronized with the operation clock signal.
The receiver according to Appendix 3, wherein the second demodulation means demodulates the sampling data in synchronization with the 1/4 clock signal.

[Appendix 5]
The first demodulator means outputs data obtained by multiplying the sampled data by a first in-phase signal synchronized with the 1/4 clock signal as an Ia signal, and synchronizes with the 1/4 clock signal. The data obtained by multiplying the first orthogonal signal is output as a Qa signal.
The second demodulator means outputs data obtained by multiplying the sampled data by a second in-phase signal synchronized with the 1/4 clock signal as an Ib signal, and synchronizes with the 1/4 clock signal. The receiver according to Appendix 4, which outputs data obtained by multiplying the second orthogonal signal as a Qb signal.

[Appendix 6]
The frequency control means controls the frequency of the first local oscillation signal to a frequency obtained by adding the frequency of the reception signal to the frequency of the first intermediate frequency signal, and sets the frequency of the second local oscillation signal to the reception signal. The frequency obtained by adding the frequency of the second intermediate frequency signal to the frequency of the first intermediate frequency signal, or the frequency obtained by subtracting the frequency of the second intermediate frequency signal from the frequency of the first intermediate frequency signal. The receiver according to any one of Supplementary note 1 to 5, which is controlled in 1.

[Appendix 7]
When the frequency control means controls the second intermediate frequency signal to a frequency obtained by adding the frequency of the second intermediate frequency signal to the frequency of the first intermediate frequency signal, the signal selection means controls the first demodulated signal. When the frequency control means controls the second intermediate frequency signal to a frequency obtained by subtracting the frequency of the second intermediate frequency signal from the frequency of the first intermediate frequency signal, the second demodulated signal is selected. The receiver according to 6.

[Appendix 8]
In the frequency control means, the frequency of the signal generated when the first local oscillation signal and the second local oscillation signal are mixed with the harmonics of the first local oscillation signal and the second local oscillation signal is the first. 2. The receiver according to any one of Supplementary note 1 to 7, which controls the combination of the frequency of the first local oscillation signal and the frequency of the second local oscillation signal that do not enter the frequency band of the intermediate frequency signal.

[Appendix 9]
The receiver according to any one of Supplementary note 1 to 8, wherein the first frequency conversion means converts the received signal into a first intermediate frequency signal having a first intermediate frequency selected from a plurality of frequencies.

[Appendix 10]
The receiver according to Appendix 9, wherein the first frequency conversion means selectively generates a first intermediate frequency signal obtained by up-converting the received signal and a first intermediate frequency signal obtained by down-converting the received signal.

[Appendix 11]
The first frequency conversion means
A mixer that mixes the first local oscillation signal with the received signal and outputs it,
A first band pass filter that limits the signal output from the mixer to the frequency band of the first intermediate frequency signal that up-converts the received signal.
A second band pass filter that limits the signal output from the mixer to the frequency band of the first intermediate frequency signal down-converted from the received signal.
The receiver according to Appendix 10, comprising the first band pass filter or a pair of switches for selecting the second band pass filter.

[Appendix 12]
The receiver according to any one of Supplementary note 1 to 11, further comprising a band limiting filter that limits the received signal to a band corresponding to the frequency band of the received signal in front of the first frequency conversion means.

[Appendix 13]
The frequency of the received signal is included in the first radio frequency band or the second radio frequency band, and is included in the first radio frequency band or the second radio frequency band.
The band limiting filter includes a first band limiting filter that limits the received signal to a band corresponding to the first radio frequency band, and a second band that limits the received signal to a band corresponding to the second radio frequency band. Including limit filter
The receiver according to Appendix 12, further comprising a pair of switches for selecting the first band limiting filter or the second band limiting filter according to the frequency of the received signal.

[Appendix 14]
By mixing the received signal and the first local oscillation signal whose frequency changes in the frequency range corresponding to the frequency of the received signal, the received signal is converted into a first intermediate frequency signal.
By mixing the first intermediate frequency signal and the second local oscillation signal, the first intermediate frequency signal is converted into a second intermediate frequency signal.
The second intermediate frequency signal is sampled in synchronization with the operating clock signal.
The sampled data of the sampled second intermediate frequency signal is demodulated and the first demodulated signal is output.
The sampled data of the second intermediate frequency signal is demodulated in phase inversion with the demodulation of the first demodulated signal, and the second demodulated signal is output.
The frequency of the first local oscillation signal and the frequency of the second local oscillation signal are controlled according to the frequency of the received signal, and the first demodulated signal or the second demodulated signal is controlled according to the frequency of the received signal. A receiving method that selectively outputs signals.

10: Receiver 11: First local oscillator 12: First frequency conversion means 13: Second local oscillator 14: Second frequency conversion means 15: Frequency control means 16: Analog digital converter 17: First demodulation means 18: First 2 Demodulation means 19: Selection means 100: Receiver 101: BPF
102: Frequency conversion unit 103: 1st IF conversion unit 104: 2nd IF conversion unit 105: Signal processing unit 106: Synthesizer unit 111, 112: Switch 131, 141: Mixer 132, 142: BPF
133, 134: Switch 151: AD converter 152: Clock converter 153: 1st IQ demodulation unit 154: 2nd IQ demodulation unit 155: Switch 156: Frequency control unit 161: 1st oscillator 162: 2nd oscillator 163: 3rd oscillator 201, 202, 205, 206: Multiplier

Claims (10)

A first local oscillator that outputs a first local oscillator signal whose frequency changes in the frequency range according to the frequency of the received signal,
A first frequency conversion means for converting the received signal into a first intermediate frequency signal by mixing the received signal with the first local oscillation signal.
A second local oscillator that outputs a second local oscillator signal,
A second frequency conversion means for converting the first intermediate frequency signal into a second intermediate frequency signal by mixing the first intermediate frequency signal and the second local oscillation signal.
A frequency control means for controlling the frequency of the first local oscillation signal and the frequency of the second local oscillation signal according to the frequency of the received signal.
An analog-to-digital converter that samples the second intermediate frequency signal in synchronization with the operating clock signal.
A first demodulation means that demodulates the sampling data of the second intermediate frequency signal output by the analog-to-digital converter and outputs the first demodulation signal.
A second demodulation means that performs phase-inverted demodulation of the sampled data of the second intermediate frequency signal with the demodulation in the first demodulation means and outputs a second demodulation signal.
A receiver including a signal selection means for selectively outputting the first demodulated signal or the second demodulated signal according to the frequency of the received signal. The receiver according to claim 1, wherein the analog-to-digital converter undersamples the second intermediate frequency signal. The frequency of the operating clock signal is four times the frequency of the baseband signal, and the second intermediate frequency signal is 3/4 times the operating clock signal.
The first demodulation means demodulates the sampled data in synchronization with a 1/4 clock signal whose frequency is 1/4 times the frequency of the operation clock signal, which is synchronized with the operation clock signal.
The receiver according to claim 1 or 2, wherein the second demodulation means demodulates the sampled data in synchronization with the 1/4 clock signal. The first demodulator means outputs data obtained by multiplying the sampled data by a first in-phase signal synchronized with the 1/4 clock signal as an Ia signal, and synchronizes with the 1/4 clock signal. The data obtained by multiplying the first orthogonal signal is output as a Qa signal.
The second demodulator means outputs data obtained by multiplying the sampled data by a second in-phase signal synchronized with the 1/4 clock signal as an Ib signal, and synchronizes with the 1/4 clock signal. The receiver according to claim 3, wherein the data obtained by multiplying the second orthogonal signal is output as a Qb signal. The frequency control means controls the frequency of the first local oscillation signal to a frequency obtained by adding the frequency of the reception signal to the frequency of the first intermediate frequency signal, and sets the frequency of the second local oscillation signal to the reception signal. The frequency obtained by adding the frequency of the second intermediate frequency signal to the frequency of the first intermediate frequency signal, or the frequency obtained by subtracting the frequency of the second intermediate frequency signal from the frequency of the first intermediate frequency signal. The receiver according to any one of claims 1 to 4 to be controlled. In the frequency control means, the frequency of the signal generated when the first local oscillation signal and the second local oscillation signal are mixed with the harmonics of the first local oscillation signal and the second local oscillation signal is the first frequency. 2. The receiver according to any one of claims 1 to 5, which controls the combination of the frequency of the first local oscillation signal and the frequency of the second local oscillation signal that do not enter the frequency band of the intermediate frequency signal. The receiver according to any one of claims 1 to 6, wherein the first frequency conversion means converts the received signal into a first intermediate frequency signal having a first intermediate frequency selected from a plurality of frequencies. The receiver according to claim 7, wherein the first frequency conversion means selectively generates a first intermediate frequency signal in which the received signal is up-converted and a first intermediate frequency signal in which the received signal is down-converted. The receiver according to any one of claims 1 to 8, further comprising a band limiting filter that limits the received signal to a band corresponding to the frequency band of the received signal in front of the first frequency conversion means. By mixing the received signal and the first local oscillation signal whose frequency changes in the frequency range corresponding to the frequency of the received signal, the received signal is converted into a first intermediate frequency signal.
By mixing the first intermediate frequency signal with the second local oscillation signal, the first intermediate frequency signal is converted into a second intermediate frequency signal.
The second intermediate frequency signal is sampled in synchronization with the operating clock signal.
The sampled data of the sampled second intermediate frequency signal is demodulated and the first demodulated signal is output.
The sampled data of the second intermediate frequency signal is demodulated in phase inversion with the demodulation of the first demodulated signal, and the second demodulated signal is output.
The frequency of the first local oscillation signal and the frequency of the second local oscillation signal are controlled according to the frequency of the received signal, and the first demodulated signal or the second demodulated signal is controlled according to the frequency of the received signal. A receiving method that selectively outputs signals.

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