JPH08167918A - Communication equipment - Google Patents

Abstract

PURPOSE: To use the communication equipment without remodeling even when the system is revised by enhancing the accuracy of a 90 deg. phase difference of a carrier so as to improve the modulation accuracy when an orthogonal modulation circuit is used to generate a digital modulation signal and the signal is transmitted. CONSTITUTION: An orthogonal modulation circuit 2 being one device is provided with a local oscillator 2F oscillating a frequency of a multiple of two or four of a carrier frequency and its output is frequency-divided by a 90 deg. phase shifter 2C to obtain a carrier of 90 deg. phase difference. I, Q signals received from input terminals 1A, 1B are respectively multiplexed with the carrier of 90 deg. phase difference from the 90 deg. phase shifter 2C at mixer circuits 2A, 2B respectively and the results are added by an adder 2D and a carrier from a 1st local VCO 2 is multiplied with the sum at a mixer circuit 2E to obtain an orthogonal modulation signal as a transmission signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication device such as a mobile phone which transmits and receives by using a digitally modulated signal, and particularly, generates a transmission signal by using a quadrature modulation circuit such as QPSK modulation. Regarding a communication device.

[0002]

2. Description of the Related Art In the field of mobile phones, a method of transmitting and receiving by using a digital modulation signal has been developed and has already been put into practical use from the viewpoints of call quality, confidentiality, effective use of frequency and the like. In addition, the same technology will be used to promote the digitization of cordless phones in the future. In Japan, the former is P
DC (Personal Digital Cellular), the latter is PHS
(Personal Handyphone System) is used. For example, in the former case, the standard is
Radio System Development Center, Digital Car Telephone System Standard RCR STD-27B (1992 1992)
(February) As described in pp. 15-29, the transmission signal is a π / 4 shift QPSK modulation signal. This is as shown in Figure 3.3-1 of the same document, in which data of every 2 bits is used as a modulation symbol and a pair of I and Q signals obtained by differential encoding are orthogonally modulated and generated. You can

FIG. 5 is a block diagram showing a conventional example of a communication device for transmitting and receiving data centering on a quadrature modulation circuit.
1A and 1B are input terminals, 3 is a band limiting filter, 4 is an HPA (High Power Amplifier), 5 is an antenna duplexer, 6 is an antenna, and 7 is an LNA.
(Low Noise Amplifier), 8 is a band limiting filter, 9 is a mixer circuit, 10 is a band limiting filter, 11 is a mixer circuit, 12 is a band limiting filter, 13 is an output terminal, 14 and 15 are VCO (Voltage
Controlled Oscillator), 20 is a quadrature modulation circuit, 20A and 20B are mixer circuits, 20C is a 90-degree phase shifter, 20D is an adder, and 20E is a mixer circuit.

In the figure, the circuit surrounded by double lines is one independent active device (IC, module, single FET, etc.). Since the operation of the entire transmission / reception circuit will be described in detail in the section of the embodiment of the present invention, only the second local oscillator VCO 15 and the quadrature modulation circuit 20 will be described here.

The I signal after differential encoding is input from the input terminal 1A, and the Q signal is input from the input terminal 1B.
It is supplied to the quadrature modulation circuit 20. In the quadrature modulation circuit 20, these I and Q signals are mixed in the mixer circuits 20A and 20B, respectively.
And is mixed with the carrier of the IF frequency from the 90-degree phase shifter 20C. However, the carrier waves supplied to these mixer circuits 20A and 20B are quadrature carrier waves which are generated by the 90-degree phase shifter 20C from the carrier wave of the IF frequency output from the second local VCO 15 and have 90-degree phases different from each other.

Two configurations are conceivable as the 90-degree phase shifter 20C. One uses the Gilbert circuit, the second
The frequency of the carrier of the IF frequency output from the local VCO 15 is multiplied by 2 (for this purpose, basically, a mixer circuit having the same configuration as the mixer circuits 20A and 20B is provided, and two input terminals of this mixer circuit are provided. The carrier wave may be input from the above) and the positive edge trigger type flip-flop and the negative edge trigger type flip-flop are triggered by the doubled carrier wave, and the signals whose frequencies are counted down to ½ are respectively generated. The outputs of these flip-flops are equal in frequency to the original IF frequency and are 90 degrees out of phase with each other. The other one is an RC type LPF whose time constants are equal to each other.
(Low Pass Filter) and CR type HPF (High Pass Filter)
Filters) are used to supply the carrier waves of the above IF frequency to each of them, and the respective filters can obtain signals having a phase difference of 90 degrees and a frequency equal to the IF frequency.

In FIG. 5, mixer circuits 20A and 20B are provided.
The output signals of 1 are added and mixed by the adder 20D to obtain a quadrature modulated signal of IF frequency. The quadrature modulation signal is further integrated by the mixer circuit 20E with the carrier wave from the first local VCO 14 and up-converted into a transmission signal having a predetermined transmission frequency.

[0008]

By the way, in the above-mentioned conventional technique, the quadrature modulation circuit 20 in particular has the following problems.

First, in the above method in which the carrier wave from the VCO 15 is doubled in order to generate two carrier waves that are phase-shifted by 90 degrees to each other, the occurrence of the second harmonic is suppressed and the rising edge and the falling edge are suppressed. If the duty is not good, the accuracy of the 90-degree phase difference cannot be ensured, and the modulation accuracy decreases. Conventionally, it is common to use a Gilbert circuit to multiply the frequency by 2, but even harmonics are likely to be generated by multiplication of the fundamental wave and the third harmonic. In order to reduce this, the input level of the carrier wave to the Gilbert circuit may be reduced, but if this is done, the leakage of the input carrier wave to the doubled signal due to the characteristic variation of the circuit element becomes a problem, and this causes Again, the duty of the rising edge and the falling edge is reduced. Therefore, the BP for removing the unnecessary wave component mixed in the output doubled signal
It is necessary to have F (Band Pass Filter). Of course, the time constant of this BPF varies depending on the system and is the IF frequency (transmission frequency depending on the configuration of the quadrature modulation circuit 20).
If it changes, you must change it accordingly.

Further, in the above method of phase shifting the carrier wave from the VCO 15 to obtain the orthogonal carrier wave by using two filters having the same time constant, I of the system to be applied is also applied.
The time constant must be changed according to the F frequency (or transmission frequency), and there is a problem that circuit components cannot be shared between systems.

The object of the present invention is to solve this problem and
An object of the present invention is to provide a communication device capable of ensuring the accuracy of 0-degree phase difference, obtaining good modulation accuracy, and enabling sharing of circuit components between different systems.

[0012]

In order to achieve the above-mentioned object, the present invention provides a quadrature modulation circuit for generating a transmission signal in a transmission system in a communication device for transmitting or transmitting a signal by digital modulation. A local oscillator that generates a carrier signal having a frequency twice the frequency, a first carrier wave which is triggered by the rising edge of the carrier signal and whose frequency is counted down to ½, and a trailing edge of the carrier wave. A 90-degree phase shifter whose frequency is counted down to ½ and which is phase-shifted by 90 degrees with respect to the first carrier and outputs a second carrier, and a first carrier after differential encoding with the first carrier. A first mixer circuit for accumulating the first input signal, a second mixer circuit for accumulating the second carrier wave and a second input signal after differential encoding, and the first and second mixer circuits. Of the mixer circuit Including an adder for generating a quadrature modulated signal of the IF frequency by adding the force signal, and a third mixer circuit for up-converting the transmission frequency the frequency of the output signal of the adder.

Further, according to the present invention, the first and second reception systems are provided to enable diversity reception, and the reception signals in the first and second reception systems are converted into the second intermediate frequency signal. The first and second carrier waves from the 90-degree phase shifter are used as the carrier waves of.

[0014]

The duty between the rising edge and the falling edge of the carrier wave is eliminated by using the local oscillator for generating the carrier signal having the frequency twice the IF frequency and eliminating the multiplication circuit by the Gilbert circuit. Is improved, the phase accuracy in the 90-degree phase shifter is improved, and the modulation accuracy is improved.

Further, since it is not necessary to remove the unnecessary wave component of the carrier signal having a frequency twice the IF frequency by BPF or the like, the number of parts can be reduced, and even if the system changes, it can be used without any change. You can

Further, compared to the case where the 90-degree phase shifter is constructed by using the LPF of RC and the HPF of CR, the system can be used as it is even if the system to which it is applied is changed, and the trouble of changing the constant is unnecessary.

Furthermore, in a device provided with two receiving systems for diversity reception, a carrier for converting the two carriers from the 90-degree phase shifter into the second intermediate frequency signals of the receiving signals in each receiving system. Since the loads of the two outputs of the 90-degree phase shifter are completely the same, the phase accuracy is further improved and the modulation accuracy is improved.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit block diagram showing an embodiment of a communication device according to the present invention, in which 2 is a quadrature modulation circuit, 2A, 2B,
2E is a mixer circuit, 2C is a 90-degree phase shifter, 2D is an adder, 2F is a second local VCO, 2G is a first local VCO, and parts corresponding to those in FIG.

In this embodiment, the quadrature modulation circuit 2 in FIG. 1 is different from the quadrature modulation circuit 20 in FIG. 5 as compared with the prior art shown in FIG. That is, in FIG. 5, the first local VCO 14 and the second local VCO 14
Although 15 and 15 are separate devices from the quadrature modulation circuit 20, in this embodiment, the first local VCO 2G and the second local VCO 2F corresponding to these devices are included in the device of the quadrature modulation circuit 2. . The configuration other than this is the same as that of FIG.

However, in the following description, these local V
The CO2G and 2F are PLL together with a reference oscillator, a prescaler unit for dividing the output of the local VCO, a comparator, and the like.
Although a loop is formed and the entire PLL loop is included in the device of the quadrature modulation circuit 2, this is not always necessary, and only the prescaler portion may be included in this device. Also, only the second local VCO 2F of these local VCOs 2G, 2F (or the prescaler part of the PLL loop that it comprises) may only be present in this device.

Next, the operation of this embodiment will be described.

The differentially encoded I signal input from the input terminal 1A and the same Q signal input from the input terminal 1B are respectively supplied to the quadrature modulation circuit 2 and the mixer circuits 2A and 2B.
Is integrated with the carrier of the IF frequency supplied from the 90-degree phase shifter 2C. These carrier waves supplied to the mixer circuits 2A and 2B are quadrature carrier waves having a phase difference of 90 degrees from each other, and the frequency of the output of the second local VCO in the quadrature modulation circuit 2 as one device is set to 2 of the IF frequency.
Doubled and down-converted to 1/2 by the 90-degree phase shifter 2C.

The output signals of the mixer circuits 2A and 2B are added by the adder 2D to be a quadrature modulation signal of IF frequency. This quadrature modulation signal is further integrated by the mixer circuit 2E with the carrier wave from the first local VCO 2G, and becomes a quadrature modulation signal of a predetermined transmission frequency.

This quadrature modulation signal is an output signal of the quadrature modulation circuit 2. The band limiting filter 3 removes an unnecessary wave component (image component) generated in the mixer circuit 2E and is amplified by the HPA 4 to obtain the required power. , And is supplied from the antenna duplexer 5 to the antenna 6 and transmitted.

On the other hand, the weak received signal from the antenna 6 is supplied to the LNA 7 via the antenna duplexer 5 and amplified to a level required for signal processing in the subsequent stage. The reception signal output from the LNA 7 has a band limiting filter 8 removing unnecessary wave components out of the band, and then is mixed with a carrier wave from the first local VCO 2G by the mixer circuit 9 to form a first intermediate frequency signal. The band limiting filter 10 removes the image component associated with this. Thereafter, the first intermediate frequency signal is integrated with the carrier of one IF frequency output from the 90-degree phase shifter 2C in the mixer circuit 11 to become a second intermediate frequency signal, and the band limiting filter 12 After the image component accompanying this is removed, it is supplied from the output terminal 13 to a demodulator (not shown) in the subsequent stage.

For example, like PHS, the carrier frequency is the same at the time of transmission and at the time of reception (1895.150 to 19).
In a system with 17.950 MHz and a carrier interval of 300 kHz, the oscillation frequency of either the first local VCO 2G or the second local VCO 2F is a little during transmission and during reception (for the second intermediate frequency on the receiving side, for example, 1
0.8 MHz) shift. In general, the first local VCO 2G having a higher oscillation frequency requires a smaller ratio of the shift amount to this, so it is better to shift this.

For example, an example of locking the above two VCOs in a crystal oscillator oscillating at 19.2 MHz is as follows. Second local VCO 2F
Is oscillated at 458.5 MHz (the transmission signal after quadrature modulation is 229.25 MHz), and the output obtained by dividing this by 4585 (100 kHz) and the output obtained by dividing the output of the crystal oscillator by 192 (100 kHz) are phase-compared. Since switching between transmission and reception and switching of channels are not performed here, the frequency is constant. On the other hand, the first local V
The oscillation frequency of CO2G is 10.8M when transmitting and when receiving.
Hz shift. When the first intermediate frequency on the receiving side is 240.05 MHz, for example, 1665.9-
1688.7 MHz, reception time 1655.1 to 1677.9
Switching to MHz and 3 depending on the channel used
It must be locked every 00 kHz.

Therefore, the output (300 kHz) obtained by dividing the output of the crystal oscillator by 64 and the output of the first local VCO 2G are divided by 1/5553 to 1/5629 at the time of transmission and 1/5517 to 1/5 at the time of reception. The output (300 kHz) obtained by switching the 5593 frequency division and the frequency division ratio may be compared in phase. Every time the frequency division ratio is changed, the oscillation frequency is shifted by 300 kHz, and the channel can be switched. When the output of the crystal oscillator is multiplied by 9/16, the second intermediate frequency on the receiving side becomes 10.8 MHz. This output can be used as a clock for the demodulation circuit in the subsequent stage, and the demodulation circuit does not need to have its own crystal oscillator.

The feature of this embodiment is that the oscillation frequency of the second local VCO 2F is selected to be twice the IF frequency. Conventionally, as shown in FIG. 5, since the quadrature modulation circuit 20 and the second local VCO 15 are composed of different devices, it is not possible to select twice because of the carrier wave given to the mixer circuit 11 on the receiving side. It wasn't right. In that case, an external countdown circuit is required. In this embodiment, since the second local VCO 2F is in the same device as the quadrature modulation circuit 20 as shown in FIG. 1, there is no problem even if it is selected twice.

That is, the 90-degree shifter 2C is not of the type using the LPF and HPF having the same time constant as described above so that it can be used as it is in a system having different carrier frequencies. Therefore, although the method of counting down the doubled wave is used, the second local VCO 2F is oscillated at twice the IF frequency instead of using the method of multiplying the carrier wave by the Gilbert circuit as in the conventional example. I will. Therefore, there is no problem that an error of 90-degree phase difference is generated due to the leakage of the even harmonics and the carrier wave and the unnecessary wave removing filter is required. Further, since the 90-degree phase shifter 2C is originally composed of a positive edge trigger and a negative edge trigger flip-flop, the carrier wave to be given to the mixer circuit 11 on the receiving side can be obtained here, and a new countdown circuit is required. There is also the advantage that there is nothing.

FIG. 2 is a block diagram showing another embodiment of the communication apparatus according to the present invention, in which 2 is a quadrature modulation circuit, 2H is a frequency dividing circuit, and the same symbols are given to the portions corresponding to FIG. A duplicate description will be omitted.

In the embodiment shown in FIG. 1, the carrier wave of the mixer circuit 11 on the receiving side is one of the carrier waves output from the 90-degree phase shifter 2C, but the embodiment shown in FIG.
The output signal of the local VCO 2F is obtained by dividing the output signal of the local VCO 2F by 2. This 2
The frequency divider 2H is a quadrature modulation circuit 2 as one device.
Included in.

The second local VCO 2F is a prescaler circuit that divides the output of the reference oscillator or the second local VCO 2F, and the output signal of this prescaler circuit is phase-compared with the output signal of the reference oscillator to obtain the second local VCO 2
The PLL is formed with a phase comparison circuit or the like that generates the F control signal. However, the first stage of this prescaler circuit may be a divide-by-2 stage, and its output signal may be the carrier of the mixer circuit 11, and the divide-by-2 divider 2H may be used. Can be omitted. Even in this case, there is no problem of 90 degree phase difference error generation as compared with the conventional one, and it can be used as it is for a system having a different carrier frequency.

FIG. 3 is a block diagram showing still another embodiment of the communication apparatus according to the present invention. 2I is a second local VCO, 2J is a frequency divider by 2, and the portion corresponding to FIG. The same reference numerals are given and duplicate description is omitted.

In the figure, the second local VCO 2I
Oscillates at a frequency four times as high as the IF frequency, and its output is frequency-divided by a frequency divider 2J by 2 and supplied to a 90-degree phase shifter 2C. The configuration other than this point is the same as that of the embodiment shown in FIG.

The frequency divider 2J has a second local VCO2.
It is triggered by either the rising edge or the falling edge of the I output signal, and the frequency is halved for output. Therefore, even when the duty of the output signal of the second local VCO 2I is not good, the input signal of the 90-degree shifter 2C has no harmonics at even times, and the modulation accuracy is further improved.

Also in this case, similarly to the embodiment shown in FIG. 2, the output signal of the divide-by-2 circuit 2J may be further divided into two to be used as the carrier wave of the mixer circuit 11 on the receiving side.

Here, as a quadrature modulation method,
The IF modulation method is used in which the mixer circuit 2E up-converts the signal to the transmission frequency band after modulating the signal once with the IF frequency. In addition, the carrier of the transmission frequency band is generated,
There is a direct modulation method that uses this to perform quadrature modulation.
When oscillating a frequency four times the IF frequency, PH
In S, the direct modulation method has an extremely high frequency of 7.6 GHz, which is not practical. However, in the IF modulation method,
The value is 960 MHz, which is sufficiently possible. That is, particularly in this embodiment shown in FIG. 3 and the like, it may be implemented in combination with the IF modulation method.

FIG. 4 is a block diagram showing still another embodiment of the communication apparatus according to the present invention, in which 2K, 2L, 2M,
2N is a mixer circuit, 16 is an antenna, 17 is an LNA, 1
Reference numerals 8, 19, and 21 denote band limiting filters, and 22 denotes an output terminal. The parts corresponding to those in FIG.

In the figure, this embodiment differs from the embodiment shown in FIG. 1 in that the antenna 16, the LNA 17, the band limiting filter 18 for the received signal, and the mixer circuit for converting the received signal into the first intermediate frequency signal. 2L, a band limiting filter 19 for the first intermediate frequency signal, a mixer circuit 2N for converting the first intermediate frequency signal into a second intermediate frequency signal, and a band limiting filter 21 for the second intermediate frequency signal A receiving system is added, and the mixer circuits 2L, 2
Quadrature modulation circuit 2 in which K, 2M and 2N form one device
Included in. Of course, these mixer circuits 2L, 2K,
2M and 2N may be in different devices.

As described above, by adding one receiving system to form two receiving systems, it is possible to perform the well-known diversity reception, and the output terminals 13 and 2 of these receiving systems.
The output with the better sound quality, whichever of the two, is always selected.
In particular, PDC and the like often take this configuration.

Further, here, the signals separately output from the 90-degree phase shifter 2C are used as the carrier waves of the mixer circuits 2M and 2N, respectively. As a result, the 90 degree phase shifter 2C
The load is completely symmetrical between the two outputs whose phases are different by 90 degrees, and the phase difference error can be completely eliminated.

[0043]

As described above, according to the present invention,
In a transmission circuit or a transmission / reception circuit of a communication device using a digital modulation method such as QPSK that uses a quadrature modulation circuit,
The accuracy of 90-degree phase difference can be secured, good modulation accuracy can be obtained, and the circuit parts can be shared between the systems to reduce the number of parts such as filters. The accuracy of the 90-degree phase difference can be further improved even during diversity reception.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing another embodiment of a communication device according to the present invention.

FIG. 3 is a block diagram showing still another embodiment of the communication device according to the present invention.

FIG. 4 is a block diagram showing still another embodiment of the communication device according to the present invention.

FIG. 5 is a block diagram showing an example of a conventional communication device.

[Explanation of symbols]

 1A, 1B Input terminal 2 Quadrature modulation circuit 2A, 2B Mixer circuit 2C 90 degree phase shifter 2D Adder 2E Mixer circuit 2F 2nd local VCO 2G 1st local VCO 2H 2 frequency divider 2I 2nd local VCO 2J 2 Frequency divider 2K, 2L, 2M, 2N Mixer circuit 3 Band limiting filter 4 High power amplifier 5 Antenna duplexer 6 Antenna 7 Low noise amplifier 8 Band limiting filter 9 Mixer circuit 10 Band limiting filter 11 Mixer circuit 12 Band limiting Filter 13 output terminals 19 and 21 band limiting filter 22 output terminals

Claims (9)

[Claims] 1. A communication device for providing a quadrature modulation circuit for generating a transmission signal in a transmission system and transmitting a signal by digital modulation, wherein the quadrature modulation circuit has a frequency twice that of a carrier wave of the quadrature modulation signal to be generated. And a local oscillator that generates a carrier signal of
A first carrier down-converted to 2 and a second carrier triggered at the falling edge of the carrier signal to down-convert the frequency to 1/2 and phase-shift 90 degrees with respect to the first carrier. And a 90-degree phase shifter for generating and outputting, a first mixer circuit for integrating the first carrier wave from the 90-degree phase shifter and the first input signal after differential encoding, and the 90-degree phase A second mixer circuit that integrates the second carrier wave from the shifter and the second input signal after the differential encoding, and the output signals of the first and second mixer circuits are added to obtain a quadrature modulation signal. And an adder for generating the. 2. The local oscillator according to claim 1, wherein the local oscillator is a voltage-controlled oscillator in a phase-locked loop, and the quadrature modulation circuit is the local oscillator instead of the local oscillator.
A communication device comprising the phase-locked loop, or at least a prescaler circuit in the phase-locked loop. 3. The oscillation frequency of the local oscillator according to claim 1 or 2,
And a mixer circuit for up-converting the frequency of a quadrature modulated signal signal output from the adder to a transmission frequency. 4. The reception system according to claim 1, further comprising a receiving system, wherein one of the first and second carrier waves output from the 90-degree phase shifter is a second intermediate signal received by the receiving system. A communication device characterized by using a carrier wave for converting into a frequency signal. 5. The reception system according to claim 3, further comprising: a frequency divider that divides the output signal of the local oscillator by two, and outputs the output signal of the frequency divider to the second reception signal of the reception system. A communication device, which uses a carrier wave for converting into an intermediate frequency signal. 6. In a communication device for providing a quadrature modulation circuit for generating a transmission signal in a transmission system and transmitting a signal by digital modulation, the quadrature modulation circuit generates a carrier signal having a frequency four times the IF frequency. Frequency of the local oscillator and the carrier wave output by the local oscillator,
A frequency divider that generates a carrier signal having a frequency twice the frequency, and a first frequency converter that is triggered by a rising edge of the carrier signal generated by the frequency divider to down-convert the frequency to ½.
Carrier and a second carrier which is triggered by a falling edge of the carrier signal generated by the frequency divider to down-convert the frequency to ½ and which is phase-shifted by 90 degrees with respect to the first carrier. And a 90-degree phase shifter for generating and outputting, a first mixer circuit for integrating the first carrier wave from the 90-degree phase shifter and the first input signal after differential encoding, and the 90-degree phase A second mixer circuit that integrates the second carrier wave from the shifter and the second input signal after the differential encoding and the output signals of the first and second mixer circuits are added, and the IF frequency And an adder that generates a quadrature modulated signal. 7. A signal by digital modulation, wherein a second reception system is added to a transmission / reception system including a transmission system and a first reception system, and the transmission system is provided with a quadrature modulation circuit for generating a transmission signal. In a communication device for transmitting / receiving and diversity receiving, the quadrature modulation circuit includes a local oscillator that generates a carrier signal having a frequency twice the IF frequency, and a frequency of 1 /
A first carrier downconverted to 2 and a second carrier triggered by the falling edge of the carrier signal to downconvert the frequency to 1/2 and phase-shift 90 degrees with respect to the first carrier. And a 90-degree phase shifter for generating and outputting, a first mixer circuit for integrating the first carrier wave from the 90-degree phase shifter and the first input signal after differential encoding, and the 90-degree phase A second mixer circuit that integrates the second carrier wave from the shifter and the second input signal after the differential encoding and the output signals of the first and second mixer circuits are added, and the IF frequency An adder for generating a quadrature modulation signal; and a third mixer circuit for up-converting the frequency of the quadrature modulation signal of the IF frequency output from the adder to a transmission frequency to generate a transmission signal, Output from 90 degree phase shifter First, of the second carrier, the received signal of one in the first receiving system second to
A communication device, characterized in that it is a carrier wave for converting into an intermediate frequency signal, and the other is a carrier wave for converting a signal received by the second receiving system into a second intermediate frequency signal. 8. A signal by digital modulation, wherein a second reception system is added to a transmission / reception system including a transmission system and a first reception system, and a quadrature modulation circuit for generating a transmission signal is provided in the transmission system. In a communication device for transmitting / receiving and diversity receiving, the quadrature modulation circuit divides a carrier wave from the local oscillator for generating a carrier signal having a frequency four times the IF frequency into two, A frequency divider that generates and outputs a carrier signal having a frequency twice that of the first carrier, and a first carrier whose frequency is down-converted to ½ by being triggered by the rising edge of the carrier signal output from the frequency divider. , A 90 degree phase that is triggered on the falling edge of the carrier signal to generate and output a second carrier whose frequency is down converted to 1/2 and which is phase shifted by 90 degrees with respect to the first carrier. A lid, a first mixer circuit that integrates the first carrier wave from the 90-degree phase shifter and the first input signal after differential encoding, and the second carrier wave from the 90-degree phase shifter. And a second mixer circuit for integrating the second input signal after differential encoding, and an adder for adding the output signals of the first and second mixer circuits to generate a quadrature modulation signal of IF frequency And a third mixer circuit that up-converts the frequency of the quadrature modulated signal of the IF frequency output from the adder to a transmission frequency, and outputs the 90-degree phase shifter. Of the first and second carrier waves, one of the first and second carrier waves is used as the second received signal in the first receiving system.
A communication device, characterized in that it is a carrier wave for converting into an intermediate frequency signal, and the other is a carrier wave for converting a signal received by the second receiving system into a second intermediate frequency signal. 9. The local oscillator according to claim 6, wherein the local oscillator is a voltage-controlled oscillator in a phase-locked loop, and the quadrature modulation circuit is replaced by the local oscillator.
A communication device comprising the phase-locked loop, or at least a prescaler circuit in the phase-locked loop.