JP2600602B2 - Wireless communication device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication apparatus, and more particularly to a CSMA (Carrier Sense Multipipe).
le Access) wireless LAN (L
OcalArea Network).

[0002]

2. Description of the Related Art The recent development of wireless communication technology has been remarkable, and even in fields such as high-speed data communication, which has conventionally been performed exclusively using a cable as a transmission medium, a high-frequency band such as a wireless LAN has a high frequency band such as a wireless LAN. The use of frequency bands is making wireless.

[0003] A LAN is a network that connects devices including a plurality of independent computers to each other, and exists in a limited area such as a building or a premises which is controlled by the user. As an example of this LAN,
There is a computer in which a relatively high-performance computer serving as a "server" and a plurality of personal computers serving as a "client" are connected by a data communication line to share a database and exchange data between the personal computers.
This type of LAN is becoming widespread due to the enhancement of the performance of personal computers, and is well known by the term "downsizing of computers".

[0004] A wireless LAN is used for wirelessly performing data communication in this LAN, and does not require installation of a cable for data transmission. Therefore, construction at the time of introduction is simple, and expansion or layout change after introduction is performed. Is very easy.

[0005] Further, as personal computers, which are terminals, become smaller, it becomes possible to share databases and process data while moving, and future development is greatly expected. To this end, it goes without saying that the size of the wireless transceiver for data communication and the price thereof need to be reduced as well as the size of the computer.

Several types of wireless LAN wireless data communication systems have been proposed. Among them, a microwave band such as a 2-3 GHz band is used, and a spread spectrum technology, particularly a frequency hopping system, is used. The method used is promising.

[0007] As an example of this type of conventional radio communication apparatus, 100 channels of 1 MHz in the 2.4 MHz to 2.5 GHz band of 100 MHz, which is being studied by the IEEE 802.11 committee in the United States, are being studied. There is a system with a transmission rate of about 1 Mbps, which is set, performs FSK modulation of data using a frequency hopping method, and transmits and receives data.

The communication multiplexing system uses the CSMA system.
In this CSMA system, each terminal station serving as a server / client performs a carrier sense operation prior to the start of transmission to check the presence / absence of radio waves of a frequency channel to be used in a reception state, that is, whether or not a carrier is emitted from another terminal station. This is a method for preventing transmission collision between a plurality of terminal stations by starting transmission on the frequency channel immediately after confirming that there is no carrier emission.

Referring to FIG. 2 which shows a block diagram of a conventional wireless communication device used for a terminal station of this kind of wireless LAN system, the conventional wireless communication device includes a shared antenna including an antenna shared for transmission and reception and a reference transmission source. A transmission / reception sharing unit 100, a receiving unit 200 that amplifies and demodulates the supplied reception signal and outputs reception data DR, and receives a supply of transmission data DT to perform modulation, frequency conversion, amplification, and a predetermined transmission frequency. And a transmission unit 300 that outputs the transmission signal of

The transmission / reception sharing unit 100 includes an antenna 1 shared for transmission / reception, and a band pass filter (BPF) 2 connected to the antenna 1 and passing only signals in a predetermined frequency band of 2.4 to 2.5 GHz corresponding to transmission / reception channels. And the receiving unit 2 at the time of carrier sense and reception.
At the time of transmission at 00, the antenna switching circuit (ASW) 3 connected to the transmission unit 300 and the local oscillation synthesizers 30 of the reception unit 200 and the transmission unit 300, respectively.
An oscillation circuit 31 including a temperature-compensated crystal oscillation circuit for supplying a reference frequency signal FR to 29 and 33, and a voltage controlled oscillation circuit (VCO) 28 for supplying a first local oscillation signal LO1
And a synthesizer 30 that receives the supply of the reference signal FR and controls the VCO 21.

The receiving section 200 is of a double superheterodyne type, and receives an RF amplifier 4 for amplifying the received signal R supplied from the ASW 3 with low noise and a first local oscillation signal LO1 and outputs the output signal of the RF amplifier 4 to the first amplifier. A mixer 5 for converting into a 1IF signal, IF amplifiers 7 and 9 for amplifying the first IF signal, and a SA which is a bandpass filter having predetermined band characteristics and removing spurious signals such as image signals.
W filter 8, mixer 11 receiving supply of second local oscillation signal LO2, converting output signal of IF amplifier 9 into second IF signal, and IF amplifiers 13, 1 for amplifying second IF signal
6, a SAW filter 14 having a predetermined band characteristic and removing a spurious signal such as an image signal, which is a band-pass filter for a second IF, a limiter 17 for limiting an amplitude of an output signal of the IF amplifier 16, and a limiter 17 A demodulation circuit 18 that demodulates the output signal of the above and outputs a demodulated signal, a comparator 19 that shapes the waveform of the demodulated signal and outputs the received data DR, and receives the output S of the IF amplifier 16 and responds to the amplitude of this output S. RS representing the received signal strength
A received signal strength display circuit (RSSI) 20 for outputting
A voltage controlled oscillator (VCO) 21 for supplying a second local oscillation signal LO2;
And a synthesizer 29 for controlling the control unit 1.

The transmitting unit 300 supplies a transmission IF signal IFT modulated by FSK in response to the supply of the transmission data DT, and receives a supply of the reference signal FR from the VCO 32.
, A mixer 25 that receives the supply of the transmission IF signal IFT and the first local signal and converts the transmission IF signal IFT into a converted signal TS of a predetermined frequency, and a spurious signal such as an image signal of the converted signal TS. It comprises a BPF 26 for removing and an RF power amplifier 27 for power-amplifying the converted signal TS and outputting a transmission signal T.

Here, for convenience of explanation, as the general values of the main signal frequencies, the reception / transmission frequency FRT of each channel is 2.4 to 2.5 GHz, the channel interval is 1 MHz,
First IF frequency and transmission IF frequency 400 MHz, second IF frequency 40 MHz, first local oscillation frequency LO1
(FRT-400 MHz) = 2.0 to 2.4 GHz, the second local oscillation frequency LO2 is 360 MHz, and the reference frequency F
R10 MHz is set for each.

The operation will be described with reference to FIG.
First, in a reception state, a reception signal received by the antenna 1 is a desired frequency band of 2.4 to 2.5 GHz by the BPF 2.
A received signal R having a frequency corresponding to the predetermined channel is extracted and A
The signal is supplied to the RF amplifier 4 via the SW 3 and amplified.
The output signal of the RF amplifier 4 is supplied to a mixer 5, which mixes the amplified received signal with the 2.0 to 2 ..
The first IF signal I1 of 400 MHz is generated by receiving the supply of the first local oscillation signal LO1 having a frequency corresponding to the set channel in the 4 GHz band. For example, if the set channel frequency is 2.45 GHz, the frequency of the signal LO1 is 2.05
GHz. The signal I1 is amplified by the IF amplifier 7 and
The spurious signal is removed by the AW filter 8, further amplified by the IF amplifier 9, and supplied to the mixer 11 as a signal I1A. The mixer 11 receives the signal I1A and the second local oscillation signal LO2 having a frequency of 360 MHz from the VCO 21 and generates a second IF signal I2 of 40 MHz. The signal I2 is amplified by the IF amplifier 13, the spurious signal is removed by the SAW filter 14, and the
Are supplied to the limiter 17 as the signal I2A and to the RSSI 20 as the signal S. The limiter 17 receives the supply of the signal I2A, limits the amplitude of the signal I2A to a predetermined value, and supplies the generated signal IL to the demodulation circuit 18. The demodulation circuit 18 demodulates the signal IL and supplies the demodulated signal to the comparator 19. The comparator 19 shapes the demodulated signal to generate and output reception data DR which is a digital data signal. On the other hand, the RSSI 20
, A signal RS corresponding to the amplitude of the signal S, that is, the received signal strength, is supplied to an external control system. This signal RS is also used for checking whether or not another terminal station transmits on the set channel.

The frequency synthesizer 30 divides the first local oscillation signal LO1 by a frequency division ratio corresponding to the set channel, and
A frequency dividing circuit, which is a prescaler for generating a frequency-divided signal of 0 MHz, compares a phase of the frequency-divided signal with a reference frequency signal FR, and generates a control signal for the VCO 28 in response to the phase error. ) Circuit. The frequency synthesizer 30 is 10M from the oscillation circuit 31.
The VCO 28 receives the supply of the reference frequency signal FR of 1 Hz, performs a phase synchronization operation using the reference frequency signal FR as the reference frequency, and generates the first local oscillation signal LO1 having a frequency corresponding to the set channel.
Control.

Next, in the transmission state, the transmission data D
T is supplied to the VCO 32. The oscillation frequency of this VCO 32 is 400 MHz of the transmission IF signal IFT, and is controlled by the control signal PT of the frequency synthesizer 33 based on the frequency of 10 MHz of the reference frequency signal FR. The VCO 32 responds to the supply of the transmission data DT by changing the oscillation frequency corresponding to the control signal PT to the transmission data DT.
To generate a FSK-modulated transmission IF signal IFT. This transmission IF signal is supplied to the mixer 25. The mixer 25 converts the transmission IF signal IFT and the first local oscillation signal LO1 into the converted signal TS of the set channel frequency in response to the supply of the transmission IF signal IFT and the first local oscillation signal LO1, and the RF power amplifier 2 via the BPF 26 for removing the spurious signal.
7 The RF power amplifier 27 converts the converted signal TS
Is amplified, a transmission signal T is generated, and ASW3 and B
The signal is supplied to the antenna 1 via the PF 2 and the transmission signal T
Is transmitted as radio waves.

Selection of the channel to be used is performed by setting the oscillation frequency of the VCO 28, that is, the frequency of the first local oscillation signal LO1 by the frequency synthesizer 30 of the transmission / reception sharing unit 100. As described above, each terminal station needs to confirm that the channel selected in the carrier sense state prior to the start of transmission is free, that is, that no other terminal stations are transmitting using that channel. For this reason, the channel must be set to the reception state first, and after confirming that the channel is an empty channel by referring to the output signal RC of the RSSI 20, the transmission state must be set without a break. It is natural that the shorter this time is, the better to prevent collision with other terminal stations, but in an actual system, as the time required from the reception state to the transmission start-up,
10 μs or less is required based on the following grounds.

As described above, while the required value of the required time in the frequency hopping type wireless LAN is under study, the required value in the direct spread type wireless LAN having the same data transmission rate is 1994. Document I of the IEEE 802.11 Committee of the United States, issued in January 1998
It is specified as 10 μs or less in EEE802.11-93 / 232rl.

On the other hand, frequency synthesizers 30, 29 and 33 using a PLL circuit and corresponding VCs
The time required for stabilizing the frequency corresponding to the channel setting in combination with O28, 21, and 32, that is, the lock time, is the internal reference frequency of this kind of general PLL and the time constant of the loop filter which are set based on the following grounds. From the corresponding response time, it is at least several tens of μs.

That is, the lock time of the PLL circuit becomes shorter as the internal reference frequency generated by dividing the frequency of the reference frequency signal FR becomes higher, and as the cutoff frequency of the loop filter becomes higher. In this example, since the channel is set at 2.4 MHz to 2.5 GHz at 1 MHz intervals, the prescaler needs to use a 2-modulus type of 64/65 frequency division.
Even if 50 MHz, which is the practical upper limit of the present technology, is used as the clock frequency, the internal reference frequency is 500K.
Hz is the upper limit. Further, the cutoff frequency of the loop filter needs to be set to an optimum value in consideration of the carrier-to-noise ratio.

Therefore, in order to quickly start transmission on that channel from the confirmation of an empty channel in the reception state, as described above, the frequency of the first local oscillation signal LO1 is the same for transmission and reception, and therefore the reception is performed. The frequency of the first IF signal IF1 and the frequency of the transmission IF signal IFT must be the same 400 MHz, and the VCO 32 of the transmission unit 300 must always oscillate even in the reception state.

[0022]

In the above-mentioned conventional radio communication apparatus, the transmission first frequency and the transmission intermediate frequency are the same and the transmission is performed in preparation for the high-speed transmission startup in the carrier sense state prior to the transmission. Since the VCO for supplying the intermediate frequency signal is always in oscillation,
In order to prevent that an empty selected channel is regarded as being used and transmission cannot be started due to malfunction of the received signal strength display circuit due to interference of the radiation leakage signal from the CO to the receiving unit, the transmitting unit and the receiving unit It is necessary to have a structure in which the parts are strictly shielded and separated from each other, and there is a disadvantage that it is extremely difficult to reduce the size and thickness of the apparatus to a credit card size, for example.

[0023]

According to the present invention, there is provided a radio communication apparatus comprising: an arbitrary selected one of a plurality of communication channels having the same transmission / reception frequency obtained by dividing a reception signal and a predetermined frequency band;
A first receiving mixer that receives a supply of a first local oscillation signal of a first frequency corresponding to a selected channel frequency that is one of the two channels and generates a first intermediate frequency signal of a second frequency;
A second receiving mixer for receiving a supply of the first intermediate frequency signal and a second local oscillation signal of a third frequency to generate a second intermediate frequency signal of a fourth frequency, and the first local oscillation; A first local oscillation circuit for generating a signal, a second local oscillation circuit for generating the second local oscillation signal, and a reference for generating a reference frequency signal to be supplied to the first and second local oscillation circuits. A first signal generating circuit for generating a transmission signal of the selected channel frequency by receiving a supply of a transmission intermediate frequency signal of the second frequency and a first local oscillation signal which have been subjected to predetermined modulation by transmission data; A transmission mixer of the carrier sense multiplexing system for transmitting the transmission signal of the own station by confirming before the start of transmission that the selected channel is an empty channel where no transmission signal of another station exists. , Indecisive A multiplying circuit that is controlled to an operation state at a first level corresponding to transmission of a transmission / reception switching signal using an element, multiplies the reference frequency signal by a predetermined multiplication factor, and generates a transmission local oscillation signal of the fourth frequency, A modulation oscillation circuit which oscillates at the third frequency and receives the supply of the transmission data at the time of transmission and performs the modulation to generate a transmission modulation signal; and a transmission / reception control device controlled to an operation state at the first level of the transmission / reception switching signal. A second transmission mixer configured to receive the local oscillation signal and the transmission modulation signal and generate the transmission intermediate frequency signal.

[0024]

FIG. 1 is a block diagram showing an embodiment of the present invention, in which components common to those in FIG. 2 are denoted by common reference characters / numerals, and FIG. The radio communication device of the present embodiment is different from the conventional transmission / reception sharing unit 100, the reception unit 200, and the transmission unit 300, respectively, in that
0A and a transmission unit 300A.

The transmission / reception sharing unit 100A includes an antenna 1, a band-pass filter (BPF) 2, an antenna switching circuit (ASW) 3, an oscillation circuit 31, a voltage-controlled oscillation circuit (VCO) 28, In addition to the synthesizer 30, a non-linear circuit element is used to operate when the transmission / reception switching signal CT is at a level corresponding to the transmission state, and the reference frequency signal FR is set to 4
A multiplying circuit 24 for multiplying and generating a transmission local oscillation signal LOT of 40 MHz is provided.

The receiving unit 200A includes mixers 5 and 11, which are common with the conventional ones, IF amplifiers 7, 9, 13, and 16,
Filters 8, 14, a limiter 17, and a demodulation circuit 18
, A comparator 19, and a received signal strength display circuit (RS
SI) 20, a synthesizer 29, and a VCO2
A VCO 21A that performs a frequency shift corresponding to the code value of the transmission data DT supplied at the time of transmission in place of 1 to generate an FSK-modulated transmission local oscillation signal / second local oscillation signal L2T / LO2, and a transmission local oscillation A switch circuit (SW) 22 for switching the signal / second local oscillation signal L2T / LO2 between the reception RX side and the transmission TX side in accordance with the respective states of reception and transmission, and a level corresponding to the transmission state of the transmission / reception switching signal CT. Between the mixer 23 that generates the transmission IF signal IFT from the supplied filtered local oscillation signal LOX from which the spurious signal has been removed and the first local oscillation signal LO1 from the SW 22, and the mixer 5 and the IF amplifier 7 To switch between the signal IFT and the first IF signal IF1,
A SW 6 to be supplied to the F-amplifier 8 and a SW inserted between the IF amplifier 9 and the mixer 11 to switch and output the output signal of the IF amplifier 9 to one of the mixer 11 and the mixer 25
10, the second IF signal from the mixer 11 inserted between the mixer 11 and the IF amplifier 13 and the transmission local oscillation signal LO.
SW 12 that switches to T and supplies one to IF amplifier 13
And a SW 15 inserted between the SAW filter 14 and the IF amplifier 16 to switch and supply the output signal of the SAW filter 14 to one of the IF amplifier 16 and the mixer 23. These SW22, 6, 10, 12, and 1
5 perform the switching operation in response to the L and H levels respectively corresponding to the reception and transmission states of the transmission / reception switching signal CT.

The transmitting section 300A has a conventional VCO 32 and a frequency synthesizer 33 eliminated, and therefore includes a mixer 25, a BPF 26 and an RF power amplifier 27 which are common with the conventional one.

As in the prior art, for the main signal frequencies,
Reception / transmission frequency FRT 2.4 to 2.5 G for each channel
Hz, channel interval 1 MHz, first IF frequency and transmission IF frequency 400 MHz, second IF frequency 40 MH
z, the first local oscillation frequency LO1 (FRT-400MH
z) = 2.0-2.4 GHz, second local oscillation frequency LO
2 is set to 360 MHz and the reference frequency FR10 MHz.

Next, the operation of this embodiment will be described with reference to FIG. 1. First, in the receiving state, the transmission / reception switching signal C
In response to the L level of T, each of SWs 22, 6, 10, 12, and 15 is set on the receiving RX side. The mixer 23 and the multiplying circuit 24 are set to a non-operating state.
These setting states are the same as those in the above-described reception state of the conventional wireless communication apparatus, and therefore, the operation of each unit of the receiving unit is exactly the same. However, since the multiplying circuit 24 and the mixer 23 are in an inactive state, there is no transmission IF signal IFT having the same frequency as the first IF signal IF1, and there is no possibility of interference with the reception unit 200A. Therefore, in the reception state prior to the start of transmission, that is, in the carrier sense state, the RSSI 20 can reliably operate, and the corresponding reception signal strength signal RS is generated when the selected channel is empty or in use. When the selected channel is empty, the external control system (not shown) immediately sets the transmission / reception switching signal CT to the H level corresponding to the transmission state in response to the signal RS corresponding to the empty channel.

Next, in the transmission state, each of the SWs 22, 6, 10, 12, and 15 is set to the transmission TX side in response to the H level of the transmission / reception switching signal CT. Mixer 2
The 3 and the multiplying circuit 24 are set to an operating state by power-on control in response to the H level of the transmission / reception switching signal CT. As a result, the 10 MHz reference frequency signal FR from the oscillation circuit 31 is multiplied by 4 in the multiplication circuit 24 to 40 MHz.
A z local transmission signal LOT is generated. Multiplication circuit 24
Is constituted by a known circuit for pulse driving a non-linear circuit element such as a logic gate circuit or a step recovery diode. The signal LOT is supplied to the SAW filter 15 via the SW 12 and the IF amplifier 13, where the spurious signal component is removed from the filtered transmission local oscillation signal LO.
X is supplied to one input of the mixer 23 via the SW 15.

On the other hand, the transmission data DT is supplied to the VCO 21A. The oscillation frequency of this VCO 21A is 360 MHz of the second local oscillation signal LO2, and the reference frequency signal F
It is controlled by a control signal QT of the frequency synthesizer 29 based on the R frequency of 10 MHz. VCO21
A receives the control signal QT in response to the supply of the transmission data DT.
The corresponding oscillation frequency is shifted in frequency corresponding to the code value of the transmission data DT to generate an FSK-modulated transmission second local oscillation signal L2T. This signal L2T is supplied to the other input of the mixer 23 via the SW22. The mixer 23 responds to the supply of the signals LOX and L2T by 400 MHz.
The transmission IF signal IFT of z is generated and supplied to the SAW filter 8 via the SW 6 and the IF amplifier 7. The SAW filter 8 removes a spurious signal component of the signal IFT, and outputs the filtered transmission IF signal ITX as an IF amplifier 9, SW
The signal is supplied to one input of a mixer 25 via the input terminal 10.

The mixer 25 has a filtered transmission IF signal IT.
In response to the supply of X and the first local oscillation signal LO1, the signal is converted into a converted signal TS of the set channel frequency and supplied to the RF power amplifier 27 via the BPF 26 in the same manner as in the related art. The RF power amplifier 27 power-amplifies the converted signal TS, generates a transmission signal T, supplies the transmission signal T to the antenna 1 via the ASW 3 and the BPF 2, and transmits the transmission signal T as a radio wave.

Each of the VCOs 31, 28 and 21 is always in an oscillating state at a frequency corresponding to the selected channel even in the above-described carrier sense / reception state, and a multiplication circuit which does not include a special time constant circuit such as a synthesizer. 24,
Since each of the mixers 23 typically rises within 1 μs from the operation state setting by turning on the power supply or the like, the required reception / transmission switching time of 10 μs or less can be easily satisfied.

As described above, since the transmission system signal does not interfere with the reception system in the carrier sense / reception state in principle, the shielding between the transmission system and the reception system can be simplified, and both of them can be simplified. High integration by forming on the same semiconductor chip is also possible. This makes it possible to reduce the size and thickness of the outer shape, and to reduce the outer size to, for example, 85.6 mm × 54 m.
It can be stored in a so-called credit card size of about mx 5 mm.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications can be made. For example, it is a matter of course that an independent band-pass filter may be used instead of using the SAW filter of the receiving unit to remove spurious components of a transmission signal, and the related switch circuit may be deleted without departing from the gist of the present invention. .

[0036]

As described above, the radio communication apparatus according to the present invention comprises a multiplying circuit which is controlled to an operating state during transmission to generate a transmission local oscillation signal using a non-linear element, and a modulation oscillation of a second local oscillation frequency. Receiving a transmission system signal in a carrier sense / reception state by including a circuit and a second transmission mixer controlled to an operating state during transmission to generate a transmission intermediate frequency signal from a transmission local oscillation signal and a transmission modulation signal Since interference with the system does not exist in principle, shielding between the transmission system and the reception system can be simplified, and high integration can be achieved by forming both on the same semiconductor chip. There is an effect that the outer shape can be reduced in size and thickness down to, for example, the size of a credit card while securing a high-speed transmission start-up from the sense state.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an embodiment of a wireless communication device according to the present invention.

FIG. 2 is a block diagram illustrating an example of a conventional wireless communication device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Antenna 2,26 BPF 3 ASW 4 RF amplifier 5,11,23,25 Mixer 6,10,12,15,22 SW 7,9,13,16 IF amplifier 8,14 SAW filter 17 Limiter 18 Demodulation circuit 19 Comparator Reference Signs List 20 RSSI 21, 28, 32, 21A VCO 27 RF power amplifier 29, 30, 33 Frequency synthesizer 30 Frequency synthesizer 31 Oscillator circuit 100, 100A Transmission / reception common unit 200, 200A Receiver 300, 300A Transmitter

Claims (4)

(57) [Claims] 1. A first local oscillation of a first frequency corresponding to a selected channel frequency, which is a selected one of a plurality of communication channels having a same transmission / reception frequency obtained by dividing a reception signal and a predetermined frequency band. A first receiving mixer for receiving a signal and generating a first intermediate frequency signal of a second frequency; and a second mixer for receiving the first intermediate frequency signal and a second frequency of a third frequency.
A second receiving mixer for receiving a supply of the local oscillation signal of the first frequency and generating a second intermediate frequency signal of a fourth frequency; a first local oscillation circuit for generating the first local oscillation signal; A second local oscillation circuit for generating a second local oscillation signal; a reference frequency signal oscillation circuit for generating a reference frequency signal to be supplied to the first and second local oscillation circuits; A first transmission mixer for receiving a supply of the transmission intermediate frequency signal of the second frequency and the first local oscillation signal and generating a transmission signal of the selected channel frequency, wherein the selected channel is connected to another station. In the wireless communication apparatus of the carrier sense multiplexing method for transmitting before transmitting the confirmation that the transmission channel of the transmission signal does not exist and transmitting the transmission signal of the own station, the transmission corresponding to the transmission and reception switching signal using the nonlinear element A multiplying circuit that is controlled to an operating state at a level of 1 and multiplies the reference frequency signal by a predetermined multiplying number to generate a transmission local oscillation signal of the fourth frequency; A modulation oscillation circuit that receives the supply of transmission data and performs the modulation to generate a transmission modulation signal; and supplies the transmission local oscillation signal and the transmission modulation signal that are controlled to an operation state at the first level of the transmission / reception switching signal. And a second transmission mixer for receiving the transmission intermediate frequency signal. 2. The wireless communication apparatus according to claim 1, wherein said modulation oscillation circuit shares a function of said second local oscillation circuit for supplying said second local oscillation signal at the time of reception. 3. A first and a second oscillator, each of which is controlled by a first and a second synthesizer including a phase locked loop circuit in which each of the first local oscillation circuit and the modulation oscillation circuit operates based on the reference frequency signal. The wireless communication device according to claim 1, further comprising a second voltage controlled oscillation circuit. 4. The method according to claim 1, wherein the transmission modulation signal is transmitted in response to first and second levels of the transmission / reception switching signal.
A first switch circuit for switching the second local oscillation signal to be supplied to the second mixer for transmission, respectively, to the transmission mixer, and the transmission circuit in response to the first and second levels, respectively. A second switch circuit for selecting any one of a modulation signal and the first intermediate frequency signal and supplying the selected signal to the first intermediate frequency amplifier circuit; and the first intermediate circuit in response to the first and second levels, respectively. A third switch circuit for supplying an output signal of a frequency amplification circuit to one of the first transmission mixer and the second reception mixer; and a third switch circuit responsive to the first and second levels, respectively. A fourth switch circuit that selects one of a second reception mixer and the transmission local oscillation signal and supplies the selected signal to the first second intermediate frequency amplification circuit; and a response to the first and second levels, respectively. And a fifth switch circuit for supplying an output signal of the bandpass filter for the second intermediate frequency signal to one of the second transmission mixer and the second second intermediate frequency amplifier circuit. The wireless communication device according to claim 1, wherein: