JPH0795110A - Radio equipment - Google Patents

Abstract

PURPOSE:To make the size of the radio equipment small and to make the weight light by improving a reference signal generator and the transmission reception system. CONSTITUTION:In the radio equipment provided with a reception section demodulating a base band signal obtained by applying frequency conversion to a reception signal to provide an output of reception data based on a reference signal with a frequency nearly equal to a center frequency of the reception signal and with a transmission section applying frequency conversion to a signal obtained by modulating the transmission data at the base band based on the reference signal with the frequency nearly equal to the center frequency of a transmission signal to provide an output of the transmission signal, a reference signal generator 106 applies a 1st reference signal within the frequency range of the reception signal to the reception section and to apply a 2nd reference signal in the frequency range of the transmission signal whose frequency range differs from the frequency range of the reception signal to the transmission section.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable wireless terminal and a wireless base station used in a wireless communication system.

[0002]

2. Description of the Related Art With the recent development of mobile communication, there is an increasing demand for miniaturization of mobile terminals and radio base stations.
In such a mobile terminal and a radio base station, miniaturization of the radio unit is an important issue for both the transmitting and receiving units.

Conventionally, in the field of mobile communication, there is a super-heterodyne transmission / reception system as shown in FIG. 15 as a system widely used as a radio unit of a mobile terminal and a radio base station. This is because in the receiving unit, the antenna unit 1
From the radio frequency (Radio Frequency) signal received at 501, the tuning unit 1502 selects and amplifies a signal component in a desired frequency band, and the first frequency conversion unit 1503 converts the signal component into a first intermediate frequency (Intermediated Frequency) signal. Perform frequency conversion. Further, the signal is filtered by the first intermediate frequency processing unit 1504 to perform tuning amplification and second frequency conversion unit 1.
By performing frequency conversion into a second intermediate frequency signal at 505, filtering and amplifying at the second intermediate frequency processing unit 1506, by performing digital signal processing, channel coding, voice coding at the signal processing unit 1507, It demodulates voice information and the like. Further, in the transmitting section, the information is transmitted by converting the voice information into a radio frequency signal by the operation reverse to that of the receiving section.

However, the radio unit using the super-heterodyne transmission / reception system, as shown in FIG.
A radio frequency (RF) signal of MHz is subjected to a first frequency conversion to obtain a signal of a first intermediate frequency of, for example, about 70 MHz, and further a second frequency conversion is performed, for example, 455k.
The received signal is demodulated by obtaining the signal of the second intermediate frequency of about Hz, and since the image response component other than the desired wave is generated along with the frequency conversion at the intermediate frequency, a steep image response removal is performed. A high-frequency filter with attenuation characteristics is required, a ceramic filter for channel selection, a crystal oscillator as a reference signal source, etc. are required for the intermediate frequency processing unit. It was an obstacle.

On the other hand, the direct conversion transmission / reception method (direct conversion transmission / reception method) is a method for realizing the miniaturization of the wireless device, which is advantageous because it can reduce the number of parts as compared with the heterodyne method described above. Since the signal in the frequency band is orthogonally demodulated or the signal in the base band is directly orthogonally modulated to the radio frequency, it may be difficult to realize in a circuit or the quality of radio communication may be insufficient.

Whichever transmission / reception system is adopted, a reference signal source is required for frequency conversion. For example, when a frequency synthesizer is used as the reference signal source, the frequency is up to about 5% of the center frequency. However, since the oscillation frequency can only be switched, there is a problem that a single frequency synthesizer cannot secure a sufficient switching frequency range.

[0007]

As described above,
A conventional wireless device using the super-heterodyne transmission / reception method has an enormous number of parts and is not suitable for downsizing the wireless device. Even if the direct conversion transmission / reception method is used, it is difficult to secure communication quality at the current technical level.
Further, there is a problem that the switching frequency range of the reference signal source is narrow. Therefore, an object of the present invention is to provide a wireless device suitable for downsizing without impairing communication quality.

[0008]

In the radio of the present invention, a baseband signal obtained by frequency-converting a local oscillation signal having a frequency substantially equal to the center frequency of the modulated reception signal is obtained. A frequency-modulated transmission signal is obtained by frequency-converting a reception section that demodulates and outputs reception data, and a signal obtained by modulating transmission data in the base band based on a local oscillation signal whose frequency is approximately equal to the center frequency of the transmission signal. And a transmitter for outputting, wherein a reference signal generator supplies a first local oscillation signal within the frequency range of the received signal to the receiver and the transmission different from the frequency range of the received signal. A second reference signal within a frequency range of the signal is supplied to the transmitter.

Preferably, the reference signal generator is
A voltage controlled oscillator, a frequency divider for dividing the output signal of the voltage controlled oscillator, a reference oscillator for generating a reference signal, a frequency of the output signal of the frequency divider and a reference signal from the reference oscillator. Comprising a comparator for comparing the frequency and outputting a difference signal, and a filter unit for removing unnecessary signal components from the difference signal, the output of the voltage controlled oscillator according to the output voltage of the low-pass filter unit A variable frequency oscillator for controlling the frequency of a signal, wherein the voltage controlled oscillator has a plurality of control characteristics corresponding to the first and second local oscillation signals, and the filter unit has the first and second By having a plurality of unnecessary signal component removal characteristics corresponding to the local oscillation signal, the first and second local oscillation signals are alternately switched.

Further, in the radio device of the present invention, it can be obtained by frequency-converting the received signal based on the output signal of the reference signal generator which outputs the reference signal having the frequency substantially equal to the center frequency of the modulated received signal. A receiving unit that demodulates the baseband signal and outputs received data, and a signal that modulates the transmitted data in the baseband is frequency-converted based on the reference signal from the local oscillator to convert it to an intermediate-frequency modulated signal, and the intermediate And a transmitter for outputting a frequency-modulated transmission signal by frequency-converting the frequency-modulated signal with the output signal of the reference signal generator.

Further, in the radio device of the present invention, the signal obtained by modulating the transmission data in the base band is frequency-converted based on the output signal of the reference signal generator which outputs the reference signal having the frequency substantially equal to the frequency of the transmission signal. , A transmitter that outputs a frequency-modulated transmission signal, and the frequency-modulated reception signal is converted into an intermediate-frequency modulation signal by the output signal of the reference signal generator, and the intermediate-frequency modulation signal from the local oscillator. And a receiver for demodulating a baseband signal obtained by frequency conversion based on a reference signal and outputting received data.

[0012]

In the radio device according to the present invention, the transmission and reception frequencies are largely detuned by constructing the direct conversion type transmission / reception unit using the reference signal generator capable of outputting the reference signals in a plurality of frequency bands. Even if there is, it is possible to transmit and receive with one reference signal generator.

Further, by constructing the transmitting / receiving unit by a hybrid of a direct conversion system and a heterodyne system, it is possible to provide a wireless device which satisfies the demands for downsizing and weight saving while complementing the drawbacks of each system.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is a diagram showing a first configuration of a wireless device according to the present invention. The upper side of the figure with respect to the reference signal source 106 shows the configuration of the receiving apparatus, and the lower side of the figure shows the configuration of the transmitting apparatus. In this embodiment, both the transmitter and the receiver are
The configuration of the direct conversion wireless system is shown, and the direct conversion wireless system will be described below.

In general, the direct conversion receiving system converts the received high frequency (Radio Frequency) signal into
This is a wireless system that performs detection by converting the frequency to the baseband in one frequency conversion operation using a reference signal of approximately the same frequency as this, and the transmission method and the reception method are reverse operations from the viewpoint of the signal flow. First, the receiving method will be described in detail. The high frequency signal received from the antenna unit 101 is amplified by the high frequency amplifier 102a, passed through the high frequency filter 103a, and then divided into two channels,
In the frequency converters 104a1 and a2, the reference signal source 1
The received high frequency signal from 06 is mixed with a carrier wave having substantially the same frequency. The reference signal source 106 is a 90 ° phase shifter 1
05a through a first frequency converter 104a1 and a second frequency converter 104a1
Of the frequency converter 104a2.
The received high frequency signal is transmitted to the first and second frequency converters 10
4a1 and 104a2 convert into a base frequency signal having a phase relationship of 90 °, and the low-pass filter 108a1
, 108a2 and then the baseband amplifier 109a1
, 109a2 and A / D converter 110
After being converted into a digital signal by a1 and 110a2, the digital demodulation unit 111a detects the signal by a detection method used for normal quadrature detection, for example, delay detection. After that, the voice is reproduced by the channel coding (decoding) 112a, the voice coding (decoding) 113a, and the like.

The direct conversion reception system having the above configuration has the advantage that it does not have an intermediate frequency and in principle has no image response because it converts the received high frequency signal directly into a baseband signal. Therefore, a steep and expensive filter for image removal which is usually used in the conventional high frequency stage of the heterodyne system is unnecessary, and a relatively wide band and low frequency filter 103a for attenuating only interference waves of other systems is inexpensive. It has the advantage of being replaced with.

Further, it is not necessary to use an expensive intermediate frequency stage ceramic filter for channel selection, a reference crystal for frequency conversion, etc., which are required in the conventional heterodyne system. Further, a filter 10 for selecting a channel of the base frequency
8a1 and 108a2 are L due to recent advances in LSI technology.
It is possible to realize SI, and there is an advantage that it can be made smaller and less expensive than the intermediate frequency filter used in the heterodyne system.

For this reason, the radio device using the direct conversion reception system can be made smaller and less expensive than the radio device using the conventional heterodyne reception system.

Here, when the detection method is an analog method, it is possible to omit the A / D converter in the subsequent stage of the baseband amplifiers 109a1 and 109a2 and perform detection using, for example, a multiplier / adder. is there. Further, the AC couplings 107a1 and 107a2 in the subsequent stage of the frequency converter are connected to the amplifier 109a by the DC component generated in the frequency converter.
To prevent 1 and 109a2 from saturating,
By inserting this, the DC component can be effectively removed.

Further, in FIG. 1, 90 ° phase shifters 105a, 1a
Output signals 05b having a phase shift difference of 90 ° from each other are input to the frequency converters 104a1 and 104a2, respectively. Instead of such a configuration, the reference signal source 1
The output signal of No. 06 is input to one of the frequency converters 104a1 and its phase is 90 ° with respect to the output signal of the reference signal source 106.
90 degrees through a 90 ° phase shifter that leads or slows
The output of the phase shifter may be input to the frequency converter 104a2. The order of the high-frequency amplifier 102a and the high-frequency filter 103a can be reversed depending on the system specifications.

Next, the direct conversion transmission system will be described with reference to FIG. In the transmission method, signal processing is performed in the reverse order of the reception method.
b, the channel-coded signal 112b is digitally modulated 111b, and then D / A converters 110b1 and 110b.
It is converted into an analog signal by b2. This signal is
After passing through the anti-aliasing filters 108b1 and 108b2, the frequency is directly converted into a radio frequency by the frequency converters 104b1 and 104b2. Here, the frequency converters 104b1 and 104b2 have 90 ° relative to each other generated by the reference signal source 106 and the 90 ° phase shifter 105b.
The reference carrier signals having the phase difference of are respectively supplied. The signal whose frequency has been converted into the radio frequency by the frequency converters 104b1 and b2 has its harmonic component removed by the high frequency filter 103b, and then the power amplifier 102b.
After power amplification by the antenna unit 101, it is radiated into the air by the antenna unit 101.

Also in this direct conversion transmission system, as in the case of the reception system, a channel filter in the intermediate frequency stage, a reference oscillator, etc. are not required, so that the number of parts can be reduced as compared with the conventional radio equipment. It is possible to reduce the size and cost of the transmitter. The order of the high frequency amplifier 102b and the high frequency filter 103b may be reversed depending on the specifications of the system.

Next, an example of a communication system suitable for using the wireless device of the present invention will be described. FIG. 2 is a diagram for explaining transmission and reception frequency allocation in this communication system.

The upper part of FIG. 2 shows an example of allocation of transmission and reception frequencies in this communication system. In this example, communication from the mobile station to the wireless base station is performed in the up frequency band, and communication from the wireless base station to the mobile station is performed in the down frequency band. For example, from the mobile station side, 201 in FIG. 2 is assigned as a reception band and 202 is assigned as a transmission band. Reference numeral 203 indicates a transmission / reception frequency interval. 204 is one reception channel in the reception frequency band 201, and 20
5 is one transmission channel in the transmission frequency band 202. Specifically, in the reception frequency band 201, 800 to
815 MHz, 900 to 915 in the transmission frequency band 202
Assuming that 100 MHz is assigned to the frequency band 203 for transmission and reception, the frequency bandwidth for transmission and reception is 1
It becomes 5 MHz. Normally, the frequency band that can be switched by a single frequency synthesizer is about 5% of the center frequency, so it is impossible to cover the band of 800 to 915 MHz with a single frequency synthesizer.

In this system, the case where the transmission frequency band is lower than the reception frequency band has been described.
The same applies to the case where the transmission frequency band is higher than the reception frequency band, contrary to this example.

Next, time division multiple connection
The lower part of FIG. 2 shows a configuration example of time slots of transmission and reception channels when communication is performed using the iple access) method. (A) is a configuration example of a time slot of a reception channel, and (b) is a configuration example of a time slot of a transmission channel. The reception channel is the reception frequency band 20 of FIG.
One of the reception channels is allocated to one of the transmission frequency bands 202, and one of the reception channels of the transmission frequency band 202 is allocated to the transmission channel. Each channel is divided into R1 to Rn and T1 to Tn for each unit time. By allocating time slots to a plurality of mobile stations,
We are trying to share frequencies. In this example, the transmission and reception timings of the mobile station are separated and the time slots of the transmission channel and the reception channel are alternately assigned.

Next, FIGS. 3 to 6 show examples of the configuration of the reference signal source 106. FIG. 3A shows a first configuration example of the reference signal source. The first reference oscillator 302 is a variable frequency oscillator, and its oscillation signal is output from the output end 306 and also input to the frequency converter 301. Frequency converter 3
01 includes a first reference oscillator 302 and a second reference oscillator 3
03 signal is injected and the frequency converter 301
Output signal of 305 through filter 304
It is output from 05.

The relationship between the frequency of the output signal of the first reference oscillator 302 and the frequency of the output signal from the output terminals 305 and 306 is shown in FIG. 3 (b). First reference oscillator 30
Assuming that the frequency of the second output signal is F2, the output signal of the first reference oscillator 302 is output to the output terminal 306 as it is, and thus the frequency of the output signal of the output terminal 306 is also F2. The frequency of the output signal of the second reference oscillator 303 is set to fc
Then, the output signal of the first reference oscillator 302 is frequency-converted by the frequency converter 301 into two components of F3 = F2 + fc F1 = F2-fc. Since the filter 304 selects only the desired frequency of F1 and removes the frequencies of F2 and F3, the frequency of the output signal from the output end 305 becomes F1. For example, when applied to the communication system shown in FIG. 2, the oscillation frequency F2 of the first reference oscillator 302 may be set to 900 to 915 MHz, and the oscillation frequency fc of the second reference oscillator 303 may be set to 100 MHz.

By constructing the reference signal source 106 of FIG. 1 in this way, even if the variable reference oscillator alone cannot change the output of a wide range of frequencies such as (F2-F1), it outputs a wide range. It is possible to change the frequency of the signal.

FIG. 4 shows a second configuration example of the reference signal source.
The oscillation signal of the first reference oscillator 402 is output from the output end 405, and the signal obtained by frequency-converting the output signals of the first and second reference oscillators is output from the output end 406 via the filter 404. 3 is different from the first configuration example of the reference signal source shown in FIG. That is, the first reference oscillator 402
If the frequency of the output signal of F is F1, the frequency of the signal output from the output terminal 405 is F1, and if the frequency of the output signal of the second reference oscillator 403 is fc, the frequency of the frequency converter 401 is F2 and F4. The components are combined, the frequency components such as F1 and F4 are removed by the filter 404, and the frequency of the signal output from the output end 406 is F2 =
It becomes F1 + fc.

For example, when applied to the communication system shown in FIG. 2, the oscillation frequency F1 of the first reference oscillator 402 is
Is set to 800 to 815 MHz, and the oscillation frequency fc of the second reference oscillator 403 is set to 100 MHz.

Next, FIG. 5 shows a third configuration example of the reference signal source. Reference numerals 502 and 503 are first and second reference oscillators, respectively. The output signals of the first and second reference oscillators are frequency-converted by the frequency converter 501, and the converted signals are output from the output terminals 505 and 506 via the filters 504-a and b, respectively.

If the frequencies of the output signals of the first and second reference oscillators are F5 and fc, the output of the frequency converter is (F5 + fc) and (F5-fc). Therefore, it is necessary to make (F5 + fc) and (F5 -fc) match the transmission frequency band and the reception frequency band, respectively.
By setting the oscillation frequency of the second reference oscillator, the output signal after frequency conversion becomes the transmission frequency and the reception frequency. For example, in the case of application to the communication system shown in FIG. 2, if the oscillation frequency F5 of the first reference oscillator 501 is set to 850 to 865 MHz and the oscillation frequency fc of the second reference oscillator is set to 50 MHz, these By converting the frequency of the output signal, F1 (800-815M
Hz) and F2 (900 to 915 MHz) signals can be combined.

Next, FIG. 6 shows a fourth configuration example of the reference signal source. Reference numerals 602 and 603 denote first and second reference oscillators,
Reference numerals 604-a and b are filters, and 607 is a control circuit that controls the operations of the first and second reference oscillators. Filter 60
4-a and 4-b are for removing components other than the transmission frequency band and the reception frequency band from the output signals of the reference oscillators 602 and 603, respectively. Assuming that the frequency of the output signal of the first reference oscillator 602 is F1 and the frequency of the output signal of the second reference oscillator 603 is F2, the range of F2 can be set in the application to the communication system shown in FIG. 90
0-915MHz, F1 range 800-815MHz
And it is sufficient. Further, the control circuit 607 may be controlled to selectively output the output signals of the first and second reference oscillators, or the output signals of the first and second reference oscillators may be simultaneously output. May be controlled, first, second
The output level of the output signal of the reference oscillator may be controlled. In particular, when the first and second reference oscillators are selectively operated, the operation of the other reference signal oscillator can be stopped even when only one of transmission and reception is performed. The overall power consumption of the oscillator can be reduced.

In the communication system shown in FIG.
For example, when a signal from a base station is received using the reception frequency R1, transmission and reception frequencies should always have a predetermined frequency difference so that transmission to the base station is performed using the transmission frequency T1. When the system configuration for channel selection is adopted, any of the reference signal sources shown in FIGS. 3 to 6 can be used, whereas when the reference signal source shown in FIG. 6 is used, Since the transmission frequency and the reception frequency can be independently changed, it is possible to flexibly cope with any communication system regardless of the configuration of the communication system shown in FIG.

In the reference signal source shown in FIG. 6, the first,
Since the circuit portion of the second reference oscillator can be configured in one chip, there is an advantage that it is possible to suppress variations in the characteristics of the circuit components of the respective reference oscillators, and the signals at the output terminals 605 and 606 can be suppressed. It is possible to reduce variations in the output level ratio.

Further, since it is possible to reduce variations in the characteristics of the circuit portions of the first and second reference oscillators, it becomes easy to adjust the output level of the reference signal source. Normally, there are restrictions on the signal amplitude, power, etc. injected into the frequency converter used for transmission and reception, and it is necessary to adjust the signal level from the reference signal source. However, the first and second reference oscillators are required. If the circuit portion of 1 is configured on a common substrate, variations in individual characteristics are reduced, and therefore it is not necessary to adjust each separately.

Next, the configuration of the frequency synthesizer which is a reference signal source suitable for the wireless device of this embodiment will be described with reference to FIGS.
Will be explained. FIG. 7 shows a first frequency synthesizer.
It is a figure which shows the structural example. 1001 is a reference signal oscillator,
1002 is a phase comparator, 1003 is a first switch, 1
004-a and b are first and second loop filters respectively, 1005-a and b are second and third switches respectively, 1006 is a voltage controlled oscillator (VCO), 1007 is a variable frequency divider, and 1008 is control. It is a device.

The basic operation is as follows. The signal from the voltage controlled oscillator 1006 is input to the phase comparator 1002 via the variable frequency divider 1007. Phase comparator 10
The signal from the reference signal oscillator 1001 is also input to 02, and the phase comparator 1001 outputs a voltage proportional to the phase difference between these two input signals. When a signal corresponding to this voltage is transmitted to the voltage controlled oscillator 1006 via the loop filter 1004, the voltage controlled oscillator 1006
The frequency of the output signal of changes. By repeating this operation, the output voltage of the phase comparator becomes constant and the oscillation frequency of the voltage controlled oscillator becomes stable. To change the oscillation frequency, the frequency division number of the variable frequency divider may be changed.

Here, the frequency synthesizer is characterized in that the voltage controlled oscillator 1006 has a plurality of control characteristics as shown in FIG. And the control device 1
The control signal of 008 allows the voltage controlled oscillator to selectively switch control patterns in the same voltage control range. For example, as shown in FIG. 7, two of the first high-frequency oscillator 1006-a and the second high-frequency oscillator 1006-b are used.
In the case of having two oscillation modes, the oscillation frequency of the frequency synthesizer is controlled in the low frequency region (F1 in FIG. 8) during the operation of the low frequency oscillation unit, and conversely, in the high frequency region (F1 of FIG. 8) during the operation of the high frequency oscillation unit. F2) controls the oscillation frequency of the frequency synthesizer. In addition, control is performed to select the loop filters 1004-a, b according to the target oscillation frequency.

According to the frequency synthesizer having such a control characteristic, it becomes possible to change the output frequency over a wide range which cannot be covered by the frequency synthesizer having a single characteristic. Further, since the oscillation characteristic of the voltage controlled oscillator can be selectively set, only the required frequency range can be oscillated, and waste of the oscillation frequency region can be eliminated as a frequency synthesizer.

FIG. 9 shows an example of the operating state of this frequency synthesizer. The vertical axis represents frequency and the horizontal axis represents time. Further, # 1 indicates a control region where the oscillation frequency is high, and # 2 indicates a control region where the oscillation frequency is low. The voltage controlled oscillator 1006 is switched to the low frequency oscillation mode at time t1, and the frequency synthesizer operates so as to stabilize at the oscillation frequency f1. When the oscillation frequency is switched to f2, the control device 1008 causes the voltage-controlled oscillator 100 to operate at time t2.
6 is switched to the high frequency oscillation mode, and the frequency synthesizer operates so as to stabilize at the oscillation frequency f2. Hereinafter, at times t3 and t5, the voltage controlled oscillator is operated in the low frequency oscillation mode in order to switch the oscillation frequency to f1, and at times t4 and t6, the voltage controlled oscillator is oscillated to a high frequency in order to switch the oscillation frequency to f2. Control to operate in mode. By performing such frequency control, it is possible to perform communication at the frequency f1 in the periods T1, T3 and T5 and to perform communication at the frequency f2 in the periods T2 and T4.

Further, FIG. 10 shows the second frequency synthesizer.
A configuration example of is shown. Common reference numerals are used for common parts with the first configuration example shown in FIG. 7. The first configuration example is
The difference is that a voltage holding circuit 1009 is added to the output ends of the loop filters 1004-a and b. Voltage holding circuit 100
9 holds the output voltage of the loop filter,
By inserting this, it is possible to stabilize the oscillation frequency at high speed even when the oscillation mode of the voltage controlled oscillator is switched.

That is, in the configuration example of FIG. 7, when the loop filter is switched according to the operation mode of the voltage controlled oscillator, the output voltage of the loop filter on the non-operating side drops to the ground, and the loop filter operates again. At this time, it takes a longer time to stabilize the oscillation frequency because the rise time of the output voltage is required. On the other hand, in the configuration example of FIG. 10, since the output voltage during operation is kept held even when the loop filter is not operating, there is no need to wait for the output voltage to rise when the loop filter operates again. It becomes possible to immediately stabilize the oscillation frequency at the target.

When the loop filter includes a capacitive element, the loop filter itself can have a voltage holding function, and in that case, it is not necessary to add a new voltage holding circuit. (Embodiment 2) FIG. 11 is a diagram showing a second configuration of a wireless device according to the present invention. In the configuration of the receiving device on the upper side of the drawing with respect to the reference signal source 106, the first embodiment of the wireless device described above
The same parts as those in the configuration of the receiving device shown in FIG. In the present embodiment, the configuration of the transmission device on the lower side of the drawing with respect to the reference signal source 106 is different from that of the first embodiment, so the transmission device will be described in detail below.

The input voice data is subjected to signal processing such as voice coding and communication channel coding, and then converted into a modulated signal by the modulator. This modulated signal is a low pass filter 1110-
1,2, after passing through the low frequency amplifier 1109-1,2,
Based on the reference signals generated by the reference oscillator 1108 and the 90 ° phase shifter 1107 and having a phase difference of 90 ° with each other, the frequency converters 1106-1 and 2 convert the intermediate frequency signals into mutually orthogonal intermediate frequency signals. These mutually orthogonal intermediate frequency signals are added, the harmonic component is removed by the filter 1105, amplified by the amplification stage 1104, and then frequency-converted to the transmission carrier frequency by the frequency converter 1103 based on the reference signal source 1. It After the harmonic components are removed by the high frequency filter 1102, the power is amplified by the power amplifier 1101 and the antenna unit 101 including the high frequency switch or the high frequency multiplexer (duplexer) is provided.
Emitted from the air.

When the transmitter is configured as described above, the frequency conversion is performed a plurality of times, so that the band of the image signal removal filter generated by the frequency conversion can be appropriately selected at each stage of the frequency conversion. The load on each filter can be reduced, and good characteristics can be obtained as a whole of the wireless device.

Compared to the case where the direct conversion system is adopted for both the transmitter and the receiver, it is sufficient in the present embodiment that the reference oscillator 106 can switch the reception frequency band. It is not necessary to construct such a complicated reference oscillator.

Further, in the case of application to a communication system adopting the diversity reception system, control is performed so that a receiving device of a plurality of systems is provided in the radio to select a reception signal of higher quality. Since the direct conversion receiving device that requires a small number of parts is used, the size of the entire wireless device can be reduced as compared with the wireless device using the super heterodyne system for both transmission and reception.

In this embodiment, the method of using the quadrature modulator in the base frequency band on the transmitting side has been described, but a method of modulating the voltage controlled oscillator by the modulation signal may be used. (Embodiment 3) FIG. 12 is a diagram showing a third configuration of a wireless device according to the present invention. In the configuration of the transmission device on the lower side of the drawing with respect to the reference signal source 106, the first embodiment of the wireless device described above
The same parts as those of the transmitter shown in FIG. In this embodiment, the configuration of the receiving device on the upper side of the drawing with respect to the reference signal source is different from that of the first embodiment, and therefore the receiving device will be described in detail below.

The antenna section 101 including a high-frequency switch or a duplexer for transmission / reception is used for both transmission and reception. A signal received by the antenna section 101 is amplified by a high-frequency amplifier 1201 and a high frequency for suppressing an image signal. After passing through the filter 1202, the frequency converter 1203 converts the reference carrier signal supplied from the reference signal source 106 into a first intermediate frequency signal.
Since the frequency of the first intermediate frequency signal corresponds to the difference between the frequency of the reference signal of the reference oscillator 106 and the received signal frequency,
By appropriately selecting the frequency of the reference signal of the reference oscillator 106, it is possible to convert it to an intermediate frequency signal of a desired frequency. For example, when the frequency of the received signal is 800 MHz, the frequency of the reference oscillator is (800-70) MHz in order to obtain an intermediate frequency signal of about 70 MHz.
Set to.

The reception signal converted into the first intermediate frequency is amplified by the amplification stage 1204, passes through the intermediate frequency filter 1205 for suppressing the image response, and then is passed through the reference oscillator 1.
Based on the mutually orthogonal reference signals generated by the 208 and 90 ° phase shifters 1207, the frequency converter 1206-
It is converted into a baseband signal by 1 and 2. Here, the oscillation frequency of the reference oscillator 1208 is fixed,
The oscillation frequency of 208 is 70 MHz in the above example.
Then, the baseband signals are low-frequency filters 1209-1, 2
Unnecessary wave is removed by the low pass amplifier 1210-1,
After the signal is amplified by 2, the information signal is detected by the detector 1211. Then, processing 1212 such as digital demodulation section (signal processing section), channel decoding, voice decoding, etc. is performed to obtain a voice signal. Here, the detector 1211
Can be an analog detection method or a digital detection method. In the case of digital demodulation, it is also possible to perform digital demodulation after analog-to-digital conversion.

If the receiving device is constructed in this manner, a plurality of parts having an amplifying action such as an amplification stage and a frequency converter can be provided, so that the restrictions on the gain specifications required for the respective constituent elements are loosened. The degree of freedom in designing the receiving device can be increased. In particular, since it is not possible for the receiving device to know in advance what level of signal is received, it is possible to increase the margin of the dynamic range.
This is a great advantage for radios.

Further, as compared with the case where the direct conversion receiving section is used, since the intermediate frequency filter 1205 can be constructed by passive elements, it is comparatively easier than the direct conversion receiving apparatus which performs channel selection only by the active filter. There is also an advantage that it is possible to configure a receiver having a wide dynamic range.

Next, another configuration example of the third embodiment described here is shown in FIG. The same reference numerals are used for the portions common to the configuration example described using FIG. Here, the frequency converter 1203 and the amplification stage 120 in FIG.
4 is a frequency converter 130 having an image response suppressing function
It is characterized in that it is replaced by 1.

The frequency converter having the image response suppressing function has, for example, the structure shown in FIGS. 14 (a) and 14 (b). In FIG. 14A, the frequency conversion unit 1401
The signals input to -1, 2 are frequency-converted into orthogonal signal components based on the reference signals that are orthogonal to each other via the 90-degree phase shifter 1402 and the reference signal source 1403. One of the mutually orthogonal signal components is input to the adder 1407 via the capacitor 1401-2 and the bandpass filter 1405-2, and the other is input to the bandpass filters 1405-1 and 90.
Input to the adder 1407 via the phase shifter 1406. When such processing is performed, the orthogonal components of the image response of the input signal cancel each other in the adder, and the frequency conversion in which the image response is suppressed can be performed.

In the configuration of FIG. 14A, the 90-degree phase shifter 1406 is removed and the band pass filter 1405 is used.
A 90-degree phase shifter may be inserted after the -2. 14
(B) shows a configuration of a frequency converter having a second image response suppressing function. First frequency conversion unit 1411-
The signals input to 1 and 2 are frequency-converted into orthogonal signal components based on mutually orthogonal reference signals via a 90-degree phase shifter 1412 and a reference signal source 1413. The signal components orthogonal to each other are respectively passed through the band pass filter 1414.
After passing through −1 and 2, the 90 ° phase shifter 1416 and the reference signal source 1417 are used to perform frequency conversion on the basis of the reference signals that are orthogonal to each other, and the adder 1418 performs the frequency conversion. Addition processing is performed. By such processing, it is possible to perform frequency conversion with the image response suppressed, as in the case shown in FIG.

In the frequency converter having such an image response suppressing function, the influence of the image response due to the frequency conversion can be removed in principle, so that it is required for the high frequency filter before the frequency converter. Performance can be reduced. That is, in the frequency converter used in the past, it was impossible in principle to remove the influence of the image response of a frequency different from the desired signal from the output signal after frequency conversion. Since a converter does not generate an image response due to frequency conversion, it has a manufacturing advantage that it requires a filter with relatively gentle characteristics compared to the image suppression filter required in the preceding stage of the frequency converter. .

[0059]

As described above, in the present invention, by improving the reference signal generator and the transmission / reception system, it is possible to reduce the size and weight of the radio device.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a first embodiment of a wireless device of the present invention.

FIG. 2 is an example of frequency allocation in a communication system suitable for the wireless device of the present invention.

FIG. 3 is a diagram showing a first configuration example of a reference signal source suitable for the wireless device of the present invention.

FIG. 4 is a diagram showing a second configuration example of a reference signal source suitable for the wireless device of the present invention.

FIG. 5 is a diagram showing a third configuration example of a reference signal source suitable for the wireless device of the present invention.

FIG. 6 is a diagram showing a fourth configuration example of a reference signal source suitable for the wireless device of the present invention.

FIG. 7 is a diagram showing a configuration example of a frequency synthesizer suitable for the wireless device of the present invention.

FIG. 8 is a diagram for explaining the principle of a frequency synthesizer suitable for the wireless device of the present invention.

FIG. 9 is a diagram for explaining the operation of the frequency synthesizer suitable for the wireless device of the present invention.

FIG. 10 is a diagram showing another configuration example of the frequency synthesizer suitable for the wireless device of the present invention.

FIG. 11 is a diagram showing the configuration of a second embodiment of a wireless device of the present invention.

FIG. 12 is a diagram showing the configuration of a third embodiment of a wireless device of the present invention.

FIG. 13 is a diagram showing another configuration of the third embodiment of the wireless device of the present invention.

FIG. 14 is a diagram showing a configuration of a frequency converter having an image response suppressing function.

FIG. 15 is a diagram showing a configuration example of a conventional wireless device.

FIG. 16 is a diagram showing a frequency spectrum of each stage of a conventional wireless device.

[Explanation of symbols]

101 ... Antenna part, 102-a, b ... High frequency amplifier 103a, b ... High frequency filter, 104a1, a2, b
1, b2 ... Frequency converter 105a, b ... 90 ° phase shifter, 106 ... Reference signal source 107a, b ... AC coupling, 108a1, a2,
b1, b2 ... Low-pass filter 109a1, a2, b1, b2 ... Baseband amplifier 110a1, a2 ... A / D converter, 110b1, b2.
D / A converters 111a, b ... Digital demodulators (modulators) 112a, b ... Channel encoders (decoders) 113a, b ... Speech encoders (decoders)

Claims (4)

[Claims] 1. A receiver for demodulating a baseband signal obtained by frequency-converting the received signal based on a local oscillation signal having a frequency substantially equal to the center frequency of the received signal to output received data, and a baseband In a radio equipped with a transmitter that outputs a transmission signal by frequency-converting a signal obtained by modulating transmission data based on a local oscillation signal having a frequency substantially equal to the center frequency of the transmission signal, the reference signal generator is the reception unit. First in the frequency range of the signal
And a second reference signal in the frequency range of the transmission signal different from the frequency range of the reception signal, the radio signal being supplied to the reception unit. 2. The reference signal generator comprises a voltage controlled oscillator, a divider for dividing an output signal of the voltage controlled oscillator, a reference oscillator for generating a reference signal, and an output of the divider. Comprising a comparator for comparing the frequency of the signal and the frequency of the reference signal from the standard oscillator to output a differential signal, and a filter unit for removing unnecessary signal components from the differential signal, the low-pass filter unit of A variable frequency oscillator for controlling a frequency of an output signal of the voltage controlled oscillator according to an output voltage, wherein the voltage controlled oscillator has a plurality of control characteristics corresponding to the first and second reference signals. The filter unit has a plurality of unnecessary signal component removal characteristics corresponding to the first and second reference signals, and thus can output the first and second local oscillation signals. Claim 1 characterized by the above-mentioned. Radio. 3. A baseband signal obtained by frequency-converting the received signal based on the output signal of a reference signal generator that outputs a reference signal having a frequency substantially equal to the center frequency of the modulated received signal is demodulated. The receiving unit that outputs the received data and the signal that is obtained by modulating the transmitted data in the base band are frequency-converted based on the reference signal from the local oscillator to the intermediate frequency modulated signal, and the intermediate frequency modulated signal is converted into the reference signal. And a transmitter that outputs a modulated transmission signal by performing frequency conversion on the output signal of the signal generator. 4. A modulated transmission signal is obtained by frequency-converting a signal obtained by modulating transmission data in a base band based on an output signal of a reference signal generator that outputs a reference signal having a frequency substantially equal to the frequency of the transmission signal. By converting the transmitting section that outputs and the modulated received signal to an intermediate frequency modulated signal by the output signal of the reference signal generator, and performing frequency conversion of the intermediate frequency modulated signal based on the reference signal from the local oscillator. A radio unit comprising: a receiving unit that demodulates the obtained baseband signal and outputs received data.