JP2000315963A - Mobile radio unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mobile radio unit whose circuit configuration is not complicated even when an indirect modulation system is adopted. SOLUTION: The mobile radio unit is provided with a mixer 1 that converts a radio band signal RX-RF received by an antenna 10 into an intermediate frequency signal RX-IF, a reception orthogonal demodulation use IC 2 that converts the intermediate frequency signal RX-IF into a base band signal RX-BB, a transmission orthogonal modulation IC 3 that converts the transmission use base band signal RX-BB into the intermediate frequency signal RX-IF, a mixer 4 that converts the intermediate frequency signal RX-IF into a radio band signal TX-HP, a PLL/VCO circuit 5 that generates a local oscillation signal for the mixers 1, 4, and a PLL-IC6 that supplies a reference signal to the transmission orthogonal modulation IC 3. Since the PLL/VCO circuit to generate a local oscillation signal for an orthogonal demodulator 11 and the PLL/VCO circuit to generate the local oscillation signal for an orthogonal modulator 20 are integrated, the number of the PLL/VCO circuits can be reduced and the circuit scale can be made small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile radio apparatus of an indirect modulation system for converting a radio band signal transmitted and received by an antenna and a base band signal into an intermediate frequency signal once. .

[0002]

2. Description of the Related Art In a mobile communication system, as a method for transmitting radio waves from a mobile station to a base station, a direct modulation method for directly modulating a baseband signal to a radio band signal (RF signal), and a baseband signal. There is an indirect modulation method in which the signal is converted into an intermediate frequency signal (IF signal) and then converted into an RF signal using an up-converter.

The direct modulation method has an advantage that the circuit configuration can be simplified, but has an RF signal band (several hundred MHz to several G).
Hz), the power consumption of the modulator and the signal amplifier increases. For this reason, mobile communication systems often employ an indirect modulation scheme.

In the case of the indirect modulation method, a local oscillator (PLL / VCO circuit) used for performing frequency conversion between an RF signal and an IF signal, and frequency conversion between an IF signal and a baseband signal are performed. Local oscillator (PLL /
VCO circuit).

Since the former PLL / VCO circuit has a larger circuit scale and consumes more power than the latter PLL / VCO circuit, the former PLL / VCO circuit transmits and receives the former PLL / VCO circuit from the viewpoint of miniaturization and cost reduction. It is common for both to share.

FIG. 8 is a block diagram showing a schematic configuration of a conventional mobile terminal of this type. The mobile terminal shown in FIG. 8 converts the radio band signal RX-RF received by the antenna 50 into the intermediate frequency signal RX-IF.
, A quadrature demodulator 52 that converts the intermediate frequency signal RX-IF into a baseband signal RX-BB, and a quadrature modulation that converts the baseband signal TX-BB for transmission into an intermediate frequency signal TX-IF. And a mixer 54 for converting the intermediate frequency signal TX-IF into a radio band signal TX-RF.

[0007]

Normally, the frequency of the radio band signal RX-RF received by the antenna 50 and the frequency of the antenna 50
Are set to different frequencies from each other in order to avoid interference.

[0008] The mobile terminal shown in FIG. 8 uses radio band signals RX-RF, T
The PLL / VCO circuit 55 used when performing frequency conversion between the X-RF and the intermediate frequency signals RX-IF and TX-IF is shared.
Therefore, the frequency of the intermediate frequency signal for transmission RX-IF and the frequency of the intermediate frequency signal for reception TX-IF are different from each other, and the frequency of the local oscillation signal for the quadrature demodulator 52,
It is necessary to set the frequency of the local oscillation signal for the quadrature modulator 53 separately. That is, the PLL /
It is necessary to separately provide the VCO circuit 56 and the PLL / VCO circuit 57 for the quadrature modulator 53.

Therefore, in the indirect modulation method, the number of PLL / VCO circuits is increased and the number of components is increased as compared with the direct modulation method.

The present invention has been made in view of the above points, and an object of the present invention is to provide a mobile radio apparatus in which a circuit configuration is not complicated even when an indirect modulation method is adopted. .

[0011]

In order to solve the above-mentioned problems, a first aspect of the present invention provides a first frequency converter for converting a radio band signal received by an antenna into a first intermediate frequency signal, A quadrature demodulator that demodulates the first intermediate frequency signal to generate a baseband signal for reception; a quadrature modulator that modulates a baseband signal for transmission to generate a second intermediate frequency signal; A second frequency converter that converts the intermediate frequency signal into a radio band signal and supplies the signal to an antenna, and a first local oscillation signal that is commonly used by the first and second frequency converters. A second local oscillator that generates a second local oscillation signal used for demodulation processing in the quadrature demodulator; and a second local oscillator that generates a second local oscillation signal. Based on the signal, the quadrature modulator And a third frequency converter for generating a third local oscillation signal used for halftone processing, the.

According to the first aspect of the present invention, the third local oscillation signal used for the modulation process by the quadrature modulator is generated using the second local oscillation signal used for the demodulation process by the quadrature demodulator.
As a result, the number of local oscillators can be reduced, the circuit scale can be reduced, and power consumption can be reduced.

According to a second aspect of the present invention, there is provided a first frequency converter for converting a radio band signal received by an antenna into a first intermediate frequency signal, and a baseband for reception by demodulating the first intermediate frequency signal. A quadrature demodulator for generating a signal, a quadrature modulator for modulating a transmission baseband signal to generate a second intermediate frequency signal, and converting the second intermediate frequency signal into a radio band signal and supplying the radio band signal to an antenna A second frequency converter,
A first local oscillator that generates a first local oscillation signal that is commonly used by the first and second frequency converters. A second local oscillator for generating a second local oscillation signal used in the second demodulator, and a third local oscillation signal used for demodulation processing in the quadrature demodulator based on the second local oscillation signal. And a third frequency converter for generating.

According to the third aspect of the present invention, the third local oscillation signal used by the quadrature demodulator for demodulation is generated using the second local oscillation signal used for modulation by the quadrature modulator.
As a result, the number of local oscillators can be reduced, the circuit scale can be reduced, and power consumption can be reduced.

According to the fourth aspect of the present invention, the third local oscillation signal is generated by using the image frequency rejection mixer.
Only desired frequency components can be extracted with high accuracy.

According to the fifth aspect of the present invention, since the third local oscillation signal is generated by using a signal used in another circuit block in the device as a reference signal, it is not necessary to separately provide a circuit for generating a reference signal. In addition to simplifying the circuit configuration,
It is possible to set a frequency that optimizes spurious characteristics.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a mobile radio device according to the present invention will be described in detail with reference to the drawings.

(First Embodiment) FIG. 1 is a block diagram of a first embodiment showing a configuration of a main part of a mobile radio apparatus according to the present invention, and FIG. 2 is a block diagram showing a schematic configuration of the mobile radio apparatus. is there.

The mobile radio apparatus according to the first embodiment includes a local oscillator (PLL / VCO circuit) for supplying a local oscillation signal to a quadrature demodulator, and a local oscillator (PLL / VCO) for supplying a local oscillation signal to a quadrature modulator. Circuit) is integrated into one.

As shown in FIG. 1, the mobile radio apparatus according to the first embodiment has a radio band signal RX-R received by an antenna 10.
A mixer (first frequency converter) 1 for converting F into an intermediate frequency signal (first intermediate frequency signal) RX-IF, and an intermediate frequency signal
RX quadrature demodulation IC (first semiconductor device) 2 for converting RX-IF to baseband signal RX-BB and intermediate frequency signal (second intermediate frequency signal) TX for transmitting baseband signal TX-BB -
Transmission quadrature modulation IC for converting to IF (second semiconductor device)
3, a mixer 4 for converting the intermediate frequency signal TX-IF into a radio band signal TX-RF, and a local oscillator (PLL / VCO circuit) for generating a local oscillation signal for the mixers 1 and 4 (first local oscillator) 5 and a PLL-IC 6 for supplying a local oscillation control signal to the reception quadrature demodulation IC 2.

As shown in FIG. 2, a quadrature demodulator 11, a VCO circuit (second local oscillator) 12, and a buffer 13 are provided inside the reception quadrature demodulation IC 2. Inside the transmission quadrature modulation IC 3, a quadrature modulator 20 and a frequency conversion circuit (third frequency converter) 23 including a frequency dividing circuit 21 and an image frequency removal mixer 22 are provided. Inside the PLL-IC 6, a PLL circuit 31 that generates a local oscillation control signal based on the reference signal output from the PLL reference signal source 7 is provided. PLL-IC
6 and the VCO circuit 12 in the reception quadrature demodulation IC 2 constitute a local oscillator.

In this embodiment, the VCO circuit 12 and the PLL-IC 6 in the reception quadrature demodulation IC 2 are connected to the quadrature demodulator 11.
And the quadrature modulator 20.

Next, the operation of the mobile radio apparatus according to the first embodiment will be described with reference to FIGS. Antenna 10
Is converted into a 110 MHz intermediate frequency signal RX-IF by the mixer 1. The VCO circuit 12 based on the local oscillation control signal generated by the PLL-IC 6 supplies a local oscillation signal (a second local oscillation signal) of 220 MHz to the quadrature demodulator 11 and also outputs the same frequency signal. The signal is supplied to the transmission quadrature modulation IC 3 via the buffer 13.

The quadrature modulator 20 in the transmission quadrature modulation IC 3
Performs modulation processing by synthesizing the intermediate frequency signal RX-IF and a signal obtained by dividing the frequency of the 220 MHz signal supplied from the VCO circuit 12 by 2 and then shifting the phase by π / 2.

The image frequency rejection mixer 22 in the transmission quadrature modulation IC 3 converts the 330 MHz local oscillation signal for the quadrature modulator 20 based on the local oscillation signal supplied from the VCO circuit 12 and its frequency-divided signal. Generate.

FIG. 3 is a block diagram showing the detailed configuration of the image frequency rejection mixer 22. As shown, the image frequency rejection mixer 22 includes mixers 31 and 32.
And phase shifters 33 and 34 for shifting the phase by π / 2, and an adder / subtractor 35 for adding or subtracting frequencies.

The mixer 31 outputs the local oscillation signal f1 generated by the VCO circuit 12 and the output signal f2 of the frequency divider 21.
And a signal whose phase is shifted by π / 2. As a result, the mixer 31 shifts the phase by π / 2 (f1 + f
(F) whose phase is shifted by (-π / 2) from the frequency component of (2).
1-f2).

The mixer 32 outputs the local oscillation signal f1.
Is synthesized with a signal whose phase is shifted by π / 2 and the output signal f2 of the frequency dividing circuit 21. As a result, the mixer 32
A signal including a frequency component of (f1 + f2) shifted in phase by only the frequency component and a frequency component of (f1-f2) shifted in phase by π / 2 is output.

When performing the addition processing, the addition / subtraction unit 35
Outputs only (f1 + f2) frequency component signals whose phases are shifted by π / 2. When performing the subtraction process, the adder / subtractor 35 shifts the phase by (−π / 2) (f1
-F2) Only the frequency component signal is output.

As described above, the image frequency removal mixer 22 outputs only one of the frequency component signal obtained by adding the frequencies f1 and f2 or the frequency component signal obtained by subtracting the frequencies f1 and f2, and outputs the other frequency signal. The component signal is removed. Therefore, the configuration of the external filter can be simplified.

For example, when adding processing is performed by the adder / subtractor 35, the frequency of the local oscillation signal f1 of 220 MHz and the frequency-divided signal f2 of 110 MHz are added, and the local oscillation signal of 330 MHz is added to the image frequency removing mixer 22. Output from

The quadrature modulator 20 converts the baseband signal TX-BB into the intermediate frequency signal TX-IF based on the 330 MHz local oscillation signal output from the image frequency removal mixer 22.
Convert to

As described above, in the first embodiment, the PLL / VCO circuit that generates the local oscillation signal for the quadrature demodulator 11 and the PLL / VCO that generates the local oscillation signal for the quadrature modulator 20
PLL / VCO
The number of circuits can be reduced, and the circuit scale can be reduced. Therefore, power consumption can be reduced, and component costs can be reduced.

Further, by sharing the PLL / VCO circuit for modulation and demodulation, it is easy to form by a bipolar process, and the noise characteristics can be improved as compared with the conventional case of using a Bi-CMOS circuit. At the same time, the chip cost can be reduced.

Since the image frequency rejection mixer 22 is provided in the transmission quadrature modulation IC 3, the local oscillation signal f1 generated in the reception quadrature demodulation IC 2 and its divided signal f
2, only one of the frequency addition signal (f1 + f2) and the frequency subtraction signal (f1-f2) can be selectively generated. Therefore, the configuration of the frequency discrimination filter can be simplified, and the circuit scale can be further reduced.

The reference signal source 7 shown in FIG. 2 does not need to be provided exclusively for the PLL circuit 31, and any signal source in the mobile radio device can be used as the reference signal source 7.

(Second Embodiment) The second embodiment is a modification of the first embodiment, in which a local oscillation signal for the quadrature modulator 20 is generated inside the reception quadrature demodulation IC 2. is there.

FIG. 4 is a block diagram showing a configuration of a main part of the mobile radio apparatus according to the second embodiment. The mobile radio apparatus shown in FIG. 4 includes a frequency conversion circuit 23 comprising a frequency divider 21 for dividing the local oscillation signal for the quadrature modulator 20 generated by the VCO circuit 12 by 2 and an image frequency rejection mixer 22 for receiving quadrature demodulation. It is characterized in that it is provided in the IC2.

With such a configuration, the configuration of the transmission quadrature modulation IC 3 can be simplified. Also, in the case of the second embodiment, similarly to the first embodiment, the number of PLL / VCO circuits can be reduced, so that the circuit scale can be reduced and the power consumption can be reduced.

(Third Embodiment) In the third embodiment, a VCO circuit 12 is provided inside the transmission quadrature modulation IC 3, and the local output signal from the VCO circuit 12 is different from the first embodiment. A local oscillation signal for the quadrature demodulator 11 is generated based on the oscillation signal.

FIG. 5 is a block diagram showing a configuration of a main part of the mobile radio apparatus according to the third embodiment. The transmission quadrature modulation IC 3 in FIG. 5 includes a quadrature modulator 20, a VCO circuit 12 that outputs a local oscillation signal for the quadrature modulator 20, and a buffer 13 that supplies the local oscillation signal to the reception quadrature demodulation IC 2. .

Further, the reception quadrature demodulation IC 2 includes a frequency dividing circuit 21 a for dividing the local oscillation signal supplied from the transmission quadrature modulation IC 3 by two, and a frequency dividing circuit 2 for dividing the local oscillation signal by six.
1b and a frequency conversion circuit 23 including an image frequency rejection mixer 22 having the same configuration as that of FIG. 3 and a quadrature demodulator 11 for performing quadrature demodulation based on a local oscillation signal output from the image frequency rejection mixer 22.

Next, the operation of the mobile radio apparatus according to the third embodiment shown in FIG. 5 will be described. The PLL-IC 6 generates a local oscillation control signal based on the reference signal output from the PLL reference signal source 7, and the VCO circuit 1 based on this signal.
2 outputs a local oscillation signal of 330 MHz. Based on the local oscillation signal, the quadrature modulator 20 quadrature modulates the transmission baseband signal TX-BB to generate an intermediate frequency signal TX-IF.

The local oscillation signal is input to the frequency dividing circuit 21a and the frequency dividing circuit 21b in the reception quadrature demodulation IC 2 via the buffer 13. The frequency divider 21a outputs a frequency-divided signal f1 of 165 MHz, and the frequency divider 21b outputs a frequency-divided signal f2 of 55 MHz.

The image frequency elimination mixer 22 performs a frequency addition process using the output signal f1 of the frequency dividing circuit 21a and the output signal f2 of the frequency dividing circuit 21b, and (f1 + f
A local oscillation signal having a frequency component of 220 MHz in 2) is output.

The quadrature demodulator 11 in the reception quadrature demodulation IC 2
Performs demodulation processing using the local oscillation signal generated by the image frequency rejection mixer 22, and outputs the intermediate frequency signal RX-IF
To the baseband signal RX-BB.

As described above, the third embodiment generates the local oscillation signal for the quadrature modulator 20 based on the local oscillation signal for the quadrature demodulator 11 generated inside the reception quadrature demodulation IC 2. As in the first embodiment, the number of PLL / VCO circuits can be reduced as compared with the related art, the circuit size can be reduced, and the power consumption can be reduced.

(Fourth Embodiment) The fourth embodiment is a modification of the third embodiment, in which a local oscillation signal for the quadrature demodulator 11 is generated inside the transmission quadrature modulation IC 3. is there.

FIG. 6 is a block diagram showing a configuration of a main part of the mobile radio apparatus according to the fourth embodiment. The mobile radio apparatus shown in FIG. 6 includes a frequency conversion circuit 23 comprising a frequency dividing circuit 21 for dividing the local oscillation signal for the quadrature demodulator 11 generated by the VCO circuit 12 by 3 and an image frequency removing mixer 22 for transmitting quadrature modulation. It is characterized in that it is provided inside the IC 3.

The mobile radio apparatus shown in FIG. 5 comprises a frequency dividing circuit 21a for dividing the local oscillation signal for the quadrature demodulator 11 by two,
And a frequency dividing circuit 21b that divides the frequency by six.
The mobile radio apparatus of FIG. 6 includes only one frequency dividing circuit 21. However, the operation is the same as that of the third embodiment, and the image frequency removal mixer 22 outputs a local oscillation signal of 220 MHz.

In the case of the fourth embodiment, the first and third
As in the embodiment, since the number of PLL / VCO circuits can be reduced, the circuit scale can be reduced, and the power consumption can be reduced.

(Fifth Embodiment) The fifth embodiment is a modification of the third embodiment, and uses an image frequency removal mixer based on a reference signal from an arbitrary reference signal source in a mobile radio apparatus. At 22, a local oscillation signal is generated.

FIG. 7 is a block diagram showing a configuration of a main part of the mobile radio apparatus according to the fifth embodiment. The basic configuration of the mobile radio apparatus of FIG. 7 is the same as that of the third embodiment (FIG. 5), but not only the local oscillation signal for the quadrature modulator 20 generated by the VCO circuit 12 but also any arbitrary internal apparatus. It is characterized in that a local oscillation signal for the quadrature demodulator 11 is generated by the image frequency rejection mixer 22 using the 19.2 MHz reference signal from the reference signal source 7.

VCO circuit 12 in transmission quadrature modulation IC 3
Outputs a local oscillation signal of 320.4 MHz. The quadrature modulator 20 performs a modulation process based on the local oscillation signal. This local oscillation signal is also input to the reception quadrature demodulation IC 2.

In the receiving quadrature demodulation IC 2, a multiplier 21 for doubling the local oscillation signal from the transmission quadrature modulation IC 3 is used.
a, a frequency dividing circuit 21 for dividing the output signal of the multiplier 21a by 3
b, a frequency dividing circuit 21c for dividing the 19.2 MHz reference signal by six,
A frequency conversion circuit 23 comprising an image frequency rejection mixer 22 for outputting a local oscillation signal including only a predetermined frequency component based on an output signal of the frequency dividing circuit 21c, and the quadrature demodulator 11 are provided.

Next, the operation of the mobile radio apparatus shown in FIG. 7 will be described. The PLL circuit 31 in the PLL-IC 6 generates a local oscillation control signal based on a 19.2 MHz reference signal from an arbitrary reference signal source 7 in the device, and generates a VC based on this signal.
The O circuit 12 outputs a local oscillation signal of 320.4 MHz. Based on the local oscillation signal, the quadrature modulator 20 modulates the transmission baseband signal TX-BB to generate an intermediate frequency signal TX-IF of 160.2 MHz.

Further, 320.
The 4 MHz local oscillation signal is input to the multiplier 21a in the reception / transmission quadrature modulation IC 3 via the buffer 13 and is multiplied by two, and then input to the frequency dividing circuit 21b to be frequency-divided by three.
As a result, a signal of 213.6 MHz is generated.

On the other hand, the frequency dividing circuit 21c outputs a 3.2 MHz signal obtained by dividing the 19.2 MHz reference signal by six. The image frequency removal mixer 22 performs a frequency subtraction process based on the output signals f1 and f2 of the frequency divider circuits 21b and 21c.
A local oscillation signal of f1-f2 = 210.4 MHz is generated. This local oscillation signal causes the quadrature modulator 20 to output the intermediate frequency signal RX.
-Convert IF to baseband signal RX-BB.

As described above, in the fifth embodiment, since a local oscillation signal is generated by diverting a reference signal used in another circuit block in the mobile radio apparatus, it is necessary to newly provide a PLL reference signal source. And the circuit scale can be reduced.

Further, by switching the frequency division ratio of the frequency dividing circuits 21a, 21b, 21c, a signal of an arbitrary frequency can be used as a reference signal of the PLL reference signal source 7.
Frequency setting that optimizes spurious characteristics becomes possible.

In each of the above-described embodiments, the description has been made taking the 800 MHz band radio band signal as an example, but the frequency of the radio band signal is not particularly limited.

In each of the above embodiments, the quadrature demodulator 11
In addition, an example has been described in which the VCO circuit 12 that generates a local oscillation signal used in the quadrature modulator 20 is provided in either the reception quadrature demodulation IC 2 or the transmission quadrature modulation IC 3. May be provided with a VCO circuit 12. Further, the PLL circuit 31 may be provided in the reception quadrature demodulation IC 2 or the transmission quadrature modulation IC 3.

[0063]

As described above in detail, according to the present invention, both the quadrature demodulator and the quadrature modulator demodulate using the second local oscillation signal generated by the second local oscillator. Since the processing and the modulation processing are performed, the number of local oscillators can be reduced as compared with the conventional case, the circuit size can be reduced, and the power consumption can be reduced.

Further, by sharing the PLL / VCO circuit for modulation and demodulation, it is easy to form the circuit by a bipolar process. Conventionally, reception quadrature modulation IC / transmission quadrature modulation IC
In the case where a PLL circuit is incorporated in a semiconductor device, a BiCMOS process is generally used. However, according to the present invention, noise characteristics can be improved and chip cost can be reduced as compared with the case where a Bi-CMOS process is used. .

Further, since the second local oscillation signal can be generated by using the reference signal used in another circuit block,
A dedicated reference signal source for generating the second local oscillation signal is not required, and the circuit size can be further reduced.
In addition, since the degree of freedom in setting the frequency of the intermediate frequency signal for transmission / reception is increased, it is possible to set a frequency with excellent spurious characteristics.

[Brief description of the drawings]

FIG. 1 is a block diagram of a first embodiment showing a configuration of a main part of a mobile wireless device.

FIG. 2 is a block diagram showing a schematic configuration of a mobile wireless device.

FIG. 3 is a block diagram showing a detailed configuration of an image frequency removal mixer.

FIG. 4 is a block diagram illustrating a configuration of a main part of a mobile wireless device according to a second embodiment.

FIG. 5 is a block diagram illustrating a configuration of a main part of a mobile wireless device according to a third embodiment.

FIG. 6 is a block diagram illustrating a configuration of a main part of a mobile wireless device according to a fourth embodiment.

FIG. 7 is a block diagram illustrating a configuration of a main part of a mobile wireless device according to a fifth embodiment.

FIG. 8 is a block diagram showing a schematic configuration of a conventional mobile terminal.

[Explanation of symbols]

 1, 4 mixer 2 reception quadrature demodulation IC 3 transmission quadrature modulation IC 5 local oscillator 6 PLL-IC 7 PLL reference signal source 11 quadrature demodulator 12 VCO circuit 20 quadrature modulator 21 image frequency rejection mixer 22 frequency divider 23 frequency Conversion circuit

Continued on the front page F term (reference) 5K011 BA03 DA03 DA06 DA15 JA01 KA01 KA03 KA04 5K020 AA00 DD12 DD13 FF04 GG04 5K067 AA05 AA42 AA43 BB02 EE02

Claims (5)

[Claims] 1. A first frequency converter for converting a radio band signal received by an antenna into a first intermediate frequency signal, and a quadrature for demodulating the first intermediate frequency signal to generate a baseband signal for reception. A demodulator; a quadrature modulator that modulates a transmission baseband signal to generate a second intermediate frequency signal; and a second frequency that converts the second intermediate frequency signal into a radio band signal and supplies the radio band signal to an antenna. A quadrature demodulator, comprising: a converter; and a first local oscillator that generates a first local oscillation signal that is commonly used in the first and second frequency converters. A second local oscillator that generates a second local oscillation signal used for demodulation processing, and a third local oscillator that is used for modulation processing in the quadrature modulator based on the second local oscillation signal. Third frequency for generating local oscillation signal Mobile radio apparatus comprising: the exchangers, the. 2. A first frequency converter for converting a radio band signal received by an antenna into a first intermediate frequency signal, and a quadrature for demodulating the first intermediate frequency signal to generate a baseband signal for reception. A demodulator; a quadrature modulator that modulates a transmission baseband signal to generate a second intermediate frequency signal; and a second frequency that converts the second intermediate frequency signal into a radio band signal and supplies the radio band signal to an antenna. A quadrature modulator, comprising: a converter; and a first local oscillator that generates a first local oscillation signal that is commonly used in the first and second frequency converters. A second local oscillator that generates a second local oscillation signal used for modulation processing, and a third local oscillator that is used for demodulation processing in the quadrature demodulator based on the second local oscillation signal. Third frequency for generating local oscillation signal Mobile radio apparatus comprising: the exchangers, the. 3. A semiconductor device further comprising: a first semiconductor device having at least the quadrature demodulator; and a second semiconductor device having at least the quadrature modulator, wherein the second local oscillator is an arbitrary device in the device. A control signal output circuit that outputs a reference signal based on a signal from a reference signal source; and a voltage-controlled oscillator that generates the second local oscillation signal based on the control signal; The converter is provided in the first or second semiconductor device, and the control signal output circuit and the voltage controlled oscillator are respectively in the first or second semiconductor device or the first and second semiconductor devices. The mobile radio device according to claim 1, wherein the mobile radio device is provided in a semiconductor device other than the semiconductor device. 4. The frequency converter according to claim 1, wherein the third frequency converter comprises: at least one frequency divider for dividing the second local oscillation signal; and only a predetermined frequency component based on an output signal of the frequency divider. The mobile radio apparatus according to any one of claims 1 to 3, further comprising: an image frequency rejection mixer that generates the third local oscillation signal. 5. The image frequency rejection mixer generates the third local oscillation signal based on an output signal of the frequency dividing circuit and a signal from an arbitrary reference signal source in the device. The mobile radio device according to claim 4, wherein