JP2001298496A - Frequency band limiting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a frequency band limiting method for a transmission output waveform of a wireless transmitter, on which a modulator and an amplifier represented by a digital phase shift keying(PSK) system are mounted. SOLUTION: This method executes a 1st processing where digital phase shift keying is applied to a carrier with a base band signal without band limit, to obtain a modulation wave whose frequency spectrum is spread and a 2nd processing, where phase shift keying is applied to a carrier whose phase is delayed by 180-degrees with a base band signal from which a main signal component is eliminated to obtain a carrier with the same level as and an opposite phase to those of a side lobe component of the carrier obtained in the 1st processing. Then the carrier obtained by the 1st processing and the carrier obtained in the 2nd processing are coupled as a 3rd processing, to transmit a transmission signal, the spread of the frequency spectrum of which is suppressed is sent to an antenna.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for limiting a frequency band of a transmission output waveform in a radio transmitter equipped with a modulator represented by a digital phase shift keying (PSK) system and an amplifier.

[0002]

2. Description of the Related Art PSK modulation will be described below as a typical example of this type of modulation system. Note that this type of modulation scheme includes DPSK modulation and the like. The PSK modulator is a method of transmitting information by shifting the phase of a carrier by a certain amount according to data.

However, in the modulator, there is a disadvantage that when the phase is shifted by a certain amount, the frequency spectrum is widened. Moreover, since the spread of the frequency spectrum affects other communications, the spread of the spectrum must be minimized.

Conventionally, the spread of such a spectrum is suppressed by using an equalizer for data. In addition, by using an amplifier having a good linear characteristic for the amplifier at the subsequent stage, the influence of the spread of the spectrum by the amplifier is reduced.

However, when the amplifier is used in a state where the linear characteristics are good, there occurs a problem that the power efficiency is remarkably deteriorated. For this reason, a method with higher power efficiency has been studied conventionally. As an example, what is shown in the following literature will be described.

Document title: 1992 IEICE Autumn Conference "C-40 800 MHz band 10 W ultra-low distortion feedforward amplifier" FIG. 2 shows the configuration of the feedforward amplifier described in this document. As shown in FIG. 2, the spectrum-suppressed signal W1 output from the modulation unit 1 is branched into a path 1 and a path 2. Here, the path 1 is a main signal system, and the path 2 is a distortion detection loop system. The signal that has proceeded to the path 1 is provided to the first amplifier 4 through the phase shifter 2 and the variable attenuator 3, and is amplified at a predetermined amplification factor. The amplified signal W4 is branched, and a part thereof is provided to the path 2 via the variable attenuator 6. The difference between the signal W2 and the signal W4, which has been delayed by the delay unit 5, is obtained at the connection with the path 2. This difference information is detected as a distortion component. This distortion component proceeds to a distortion removal loop system. In the distortion removal loop,
First, the phase of the distortion component is inverted by the phase shifter 7. After this,
The phase-inverted distortion component passes through the variable attenuator 8 and the second amplifier 9 and is recombined with the main signal system.
Is synthesized with the main signal W4 delayed. At this time,
Since the phase of the distortion component W6 merged from the second amplifier 9 is opposite in phase to the distortion component included in the main signal, the distortion component canceled out is output to the antenna (antenna). .

[0007]

As described above, in the circuit having the configuration shown in FIG. 2, although the power efficiency is improved, there is a disadvantage that the circuit scale becomes large and it becomes difficult to miniaturize the device. Therefore, in practice, it is necessary to sacrifice linearity to some extent or to use the circuit with a large circuit scale, and there is a disadvantage that the side lobe cannot be completely suppressed.

[0008]

Means for Solving the Problems (A) In order to solve this problem, in the first invention corresponding to claim 1,
In the frequency band limiting method in the wireless transmitter, a method having the following processing method is adopted.

That is, (1) a first process of digitally modulating a carrier with a baseband signal without band limitation to obtain a modulated wave having a spread frequency spectrum, and (2) a phase of 180 degrees with respect to the carrier. A second process of phase-modulating the delayed signal with a baseband signal from which the main signal component has been removed to obtain a modulated wave having the same level and opposite phase as the side lobe component of the modulated wave obtained in the first process; 3) combining the modulated wave obtained in the first processing and the modulated wave obtained in the second processing, and transmitting the transmission signal, in which the spread of the frequency spectrum is suppressed to the antenna, to the antenna. I do.

(B) According to a second aspect of the present invention, a method for limiting a frequency band in a wireless transmitter, which includes the following processing method, is employed.

That is, (1) a first process of digitally phase-modulating a carrier with a baseband signal without band limitation to obtain a modulated wave having a spread frequency spectrum, and (2) a carrier having the same phase as the carrier. A second process of performing phase modulation with the baseband signal from which the main signal component has been removed and further inverting and amplifying to obtain a modulated wave having the same level and opposite phase as the side lobe component of the modulated wave obtained in the first process; (3)
A third process of combining the modulated wave obtained in the first process with the modulated wave obtained in the second process and transmitting a transmission signal whose frequency spectrum is suppressed from being spread to an antenna is provided.

(C) According to a third aspect of the present invention, a method for limiting a frequency band in a wireless transmitter, which includes the following processing method, is employed.

That is, (1) a first process of digitally phase-modulating a carrier with a baseband signal without band limitation to obtain a modulated wave having a spread frequency spectrum; and (2) a carrier having the same phase as the carrier. A second process of performing phase modulation with a signal obtained by removing a main signal component from a logically inverted output of a baseband signal to obtain a modulated wave having the same level and opposite phase as a side lobe component of a modulated wave obtained in the first process; , (3)
A third process of combining the modulated wave obtained in the first process with the modulated wave obtained in the second process and transmitting a transmission signal whose frequency spectrum is suppressed from being spread to an antenna is provided.

(D) In a fourth aspect of the present invention, a method for limiting a frequency band in a radio transmitter, which includes the following processing method, is employed.

That is, (1) a carrier is branched into two, and one carrier is subjected to digital amplitude modulation by being input to a switch means controlled by a baseband signal input without band limitation, and The carrier is delayed by 180 ° in phase with respect to one of the carriers, and then input to switch means controlled by a logically inverted baseband signal to be digitally amplitude-modulated.
A first process for obtaining a modulated wave having a spread frequency spectrum by combining two modulated waves; and (2) a modulated wave having the same level and opposite phase as the side lobe component of the modulated wave obtained in the first process. And (3) combining the modulated wave obtained in the first processing and the modulated wave obtained in the second processing,
And a third process of transmitting, to the antenna, the transmission signal in which the spread of the frequency spectrum is suppressed.

(E) In a fifth aspect of the present invention, a method for limiting a frequency band in a wireless transmitter, which includes the following processing method, is employed.

That is, (1) a carrier is branched into two, and one carrier is subjected to digital amplitude modulation by being input to an amplifier whose power supply is controlled by a baseband signal input without band limitation. , The other carrier is delayed by 180 ° in phase with respect to the one carrier, and then input to an amplifier whose power supply is controlled by a logically inverted baseband signal, thereby performing digital amplitude modulation. A first process for obtaining a modulated wave in a state where the frequency spectrum is widened by coupling;
(2) second processing for obtaining a modulated wave having the same level and opposite phase as the side lobe component of the modulated wave obtained in the first processing; (3)
A third process of combining the modulated wave obtained in the first process with the modulated wave obtained in the second process and transmitting a transmission signal whose frequency spectrum is suppressed from being spread to an antenna is provided.

(F) In a sixth aspect of the present invention, a method for limiting a frequency band in a radio transmitter, which includes the following processing method, is employed.

That is, (1) a carrier is branched into two, and one carrier is subjected to digital amplitude modulation by being input to an amplifier whose power supply is controlled by a baseband signal input without band limitation. The other carrier is digitally amplitude-modulated by input to an inverting amplifier whose power supply is controlled by a logically-inverted baseband signal, and the two modulated waves are combined to modulate the spread of the frequency spectrum. A first process for obtaining a wave, (2) a second process for obtaining a modulated wave having the same level and opposite phase as a side lobe component of the modulated wave obtained in the first process, and (3) a first process. A third process of combining the obtained modulated wave with the modulated wave obtained in the second process and transmitting a transmission signal whose frequency spectrum is suppressed from being spread to the antenna is provided.

(G) According to a seventh aspect of the present invention, in the frequency band limiting method in the wireless transmitter, the method includes the following processing method.

That is, (1) a carrier is branched into two, and one of the carriers is subjected to digital amplitude modulation by being input to an amplifier having a base band signal inputted as a bias signal without band limitation, and The carrier is digitally amplitude-modulated by inputting it to an inverting amplifier that uses a logically inverted baseband signal as a bias signal, and a first modulated wave having a spread frequency spectrum is obtained by combining these two modulated waves. Processing and (2) First
(2) a second process for obtaining a modulated wave having the same level and opposite phase as the side lobe component of the modulated wave obtained in the process (3), and (3) a modulated wave obtained in the first process and a modulated wave obtained in the second process And a third process of transmitting to the antenna a transmission signal in which the spread of the frequency spectrum is suppressed.

(H) According to an eighth aspect of the present invention, in the frequency band limiting method according to any one of the first to seventh aspects, the following processing is employed. That is, in the first process, the main amplifier is used in the saturation region.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (A) First Embodiment (A-1) Device Configuration FIG. 1 shows a first embodiment of a radio transmitter to which a frequency band limiting method according to the present invention is applied. This wireless transmitter
Two in-phase and out-of-phase carriers are prepared, and the in-phase carrier is modulated by a baseband signal including a main signal and a side lobe component, and the in-phase carrier is modulated by a baseband signal having only a side lobe component. Are synthesized.

As shown in FIG. 1, the radio transmitter includes an oscillator 11, a distributor 12, an amplifier 13, a phase modulator 14, a 180 ° phase shifter 15, a delay unit 16, a high-pass filter 17, a phase modulator 18, an amplifier 19,
It comprises a level adjuster 20 and a coupler 21.

Here, the oscillator 11 is a circuit for generating a carrier wave. The distributor 12 is a circuit element that splits the carrier output from the oscillator 11 into a path 1 and a path 2.

On the path 1, an amplifier 13, a phase modulator 1
There are four. Here, the amplifier 13 is a circuit that amplifies the input carrier to a specified level and outputs the amplified carrier. Further, the phase modulator 14 has a NRZ (Non Return to Zero).
This is a circuit for phase-modulating a carrier with a baseband signal.
The output of the phase modulator 14 is output to the combiner 21.

On the other hand, a 180 ° phase shifter 1
5, delay unit 16, high-pass filter 17, phase modulator 1
8, an amplifier 19, and a level adjustment circuit 20. Here, the 180 ° phase shifter 15 is a circuit for obtaining a carrier wave that is 180 ° out of phase (ie, out of phase) with the path 1 system.

The delay unit 16 is a circuit for adjusting a delay generated on the subsequent line. High pass filter 17
Is a circuit for passing only the high frequency component of the NRZ baseband signal, that is, for obtaining the signal component of only the side lobe component excluding the main signal component.

The phase modulator 18 includes a high-pass filter 17
Is a circuit for obtaining a carrier (opposite phase) with a signal from which a main signal component has been removed by passing through the signal. Amplifier 19
This is a circuit for amplifying the modulated wave of the path 2 so that the signal level is almost the same as the modulated wave of the path 1 when the modulated wave of the path 1 is coupled.

The level adjustment circuit 20 is a circuit for finely adjusting the level of the modulated wave on the path 1 and the level of the modulated wave on the path 2 to be the same.

The coupler 21 is a circuit that combines the modulated wave of the path 1 and the modulated wave of the path 2 and outputs the combined wave to the antenna (antenna). The modulated wave combined by the combiner 21 is adjusted to the opposite phase and the same level except for the main signal, so that the side lobe component is canceled.

(A-2) Transmission Operation Next, the transmission operation of the PSK transmitter according to the first embodiment will be described. The carrier generated by the oscillator 11 is branched into a path 1 and a path 2 in the distributor 12.

In the path 1, after amplifying the carrier signal, PSK modulation is performed with a baseband signal that is not band-limited. At this time, the amplifier 13 is used in a saturation region. As a result, the modulated wave becomes a modulated wave in a state where the spectrum is spread.

On the other hand, in the path 2, the phase of the carrier input by the 180 ° phase shifter 15 is shifted by 180 °, and a carrier signal having a phase opposite to the carrier signal in the path 1 is obtained. The delay difference due to the subsequent line is adjusted by the delay unit 16. Next, phase modulation is performed using the baseband signal from which the main signal component has been removed, that is, the baseband signal having only the side lobe component.

Thereafter, the side lobe component of the path 1 and the side lobe component of the path 2
The signals are amplified by the amplifier 19 so as to be at the same level when they are combined at 1. The fine adjustment of the level is performed by the level adjuster 20.

Thus, in the coupler 21, the path 1
The phase-modulated signal input from the path 2 and the phase-modulated signal input from the path 2 are coupled in a state in which the phases are shifted by 180 °, that is, in a state where they are mutually canceled. As a result, the side lobe components cancel each other and are reduced.

(A-3) Effect of First Embodiment As described above, according to the frequency band limiting method according to the first embodiment, the main amplifier (the amplifier 13 in the path 1) is placed in the saturation region (non-linear operation). Region), the spread of the frequency spectrum can be suppressed. In addition, since the main amplifier is operated in the saturation region, power efficiency is improved and power consumption can be reduced.

(A-4) Other Embodiments In FIG. 1, a variable resistance type attenuator is used for the level adjustment circuit 20 as the band limiting means.
The level adjustment may be performed by changing the gain of the amplifier. In this case, an amplifier for level adjustment may be prepared separately from the amplifier 19, or the amplifier 19 may be a variable gain amplifier.

As the coupler 21, a directional coupler, a Wilkinson coupler, or the like can be used.

(B) Second Embodiment (B-1) Device Configuration FIG. 3 shows a second embodiment of a radio transmitter to which the frequency band limiting method according to the present invention is applied. In the first embodiment, the case where the side lobe component is suppressed using two carriers of the same phase and the opposite phase has been described. In the present embodiment, a case where only one carrier is used will be described.

As shown in FIG. 3, the radio transmitter includes an oscillator 11, a distributor 12, an amplifier 13, a phase modulator 14, a delay unit 16, a high-pass filter 17, a phase modulator 18, , Inverting amplifier 19 'and level adjustment circuit 2
0 and a coupler 21. Here, in FIG. 3, the portions corresponding to those in FIG. 1 are denoted by the same reference numerals, and the same portions are denoted by the same reference numerals.

As is clear from FIG. 3, the second embodiment differs from the first embodiment in that the signal branched to the path 2 by the distributor 12 is directly input to the delay unit 16 and the output (modulation) of the phase modulator 18 is changed. This is different from the wireless transmitter according to the first embodiment in that the wave is inverted by an inverting amplifier 19 ′. That is,
In the second embodiment, the 180 according to the first embodiment is used.
The difference is that the function of the phase shifter 15 is provided to the inverting amplifier 19 '.

(A-2) Transmission Operation Next, the transmission operation of the PSK transmitter according to the second embodiment will be described. The carrier generated by the oscillator 11 is branched into a path 1 and a path 2 in the distributor 12.

In the path 1, as in the case of the first embodiment, after amplifying the carrier signal, PSK modulation is performed with a baseband signal that is not subjected to band limitation. At this time, amplifier 1
3 is used in the saturation region. As a result, the modulated wave becomes a modulated wave in a state where the spectrum is spread.

On the other hand, in the path 2, a carrier having the same phase as that of the path 1 branched by the distributor 12 is provided to the phase modulator 18 via the delay unit 16. Of course, the delay device 16 has a function of adjusting a delay difference generated in a subsequent line.

The phase modulator 18 performs the phase modulation with the baseband signal from which the main signal component has been removed by the high-pass filter 17, that is, the baseband signal having only the side lobe component. Thereafter, the phase-modulated signal subjected to the phase modulation by the phase modulator 18 is inverted by the inverting amplifier 19 ′ so that the side lobe component of the path 1 and the side lobe component of the path 2 become the same level when they are combined in the coupler 21. Invert and amplify. The level is finely adjusted by the level adjustment circuit 20.

Thus, in the coupler 21, the path 1
The phase-modulated signal input from the path 2 and the phase-modulated signal input from the path 2 are coupled in a state in which the phases are shifted by 180 °, that is, in a state where they are mutually canceled. As a result, the side lobe components cancel each other and are reduced.

(B-3) Effects of the Second Embodiment As described above, according to the frequency band limiting method according to the second embodiment, the functions equivalent to those of the 180 ° phase shifter in the first embodiment. By the inverting amplifier 19 ′,
The circuit scale can be further reduced as compared with the first embodiment.

(C) Third Embodiment (C-1) Apparatus Configuration FIG. 4 shows a third embodiment of a radio transmitter to which the frequency band limiting method according to the present invention is applied. In the second embodiment, the 180 ° phase shifter 1 is used by using the inverting amplifier 19 ′.
Although the fifth function is realized, in the present embodiment, the same function is realized by inputting a baseband signal to be given to the path 2 via the inverter 22.

As shown in FIG. 4, the radio transmitter includes an oscillator 11, a distributor 12, an amplifier 13, a phase modulator 14, a delay unit 16, a high-pass filter 17, a phase modulator 18, , An amplifier 19, a level adjustment circuit 20,
It comprises a coupler 21 and an inverter 22. Here, in FIG. 4, the portions corresponding to those in FIG. 3 are denoted by the same reference numerals, and the same portions are denoted by the same reference numerals.

As is apparent from FIG. 4, the third embodiment differs from the first embodiment in that the function of the 180 ° phase shifter 15 according to the first embodiment is provided to the inverter 22.

(C-2) Transmission Operation Next, the transmission operation of the PSK transmitter according to the third embodiment will be described. The carrier generated by the oscillator 11 is branched into a path 1 and a path 2 in the distributor 12.

In path 1, as in the case of the first embodiment, after amplifying the carrier signal, PSK modulation is performed with a baseband signal that is not band-limited. At this time, amplifier 1
3 is used in the saturation region. As a result, the modulated wave becomes a modulated wave in a state where the spectrum is spread.

On the other hand, in the path 2, a carrier having the same phase as that of the path 1 branched by the distributor 12 is supplied to the phase modulator 18 via the delay unit 16. Of course, the delay device 16 has a function of adjusting a delay difference generated in a subsequent line.

Now, in the phase modulator 18, the inverter 2
Then, phase modulation is performed with the baseband signal from which only the side lobe component is extracted by the high-pass filter 17. Thereafter, the phase-modulated signal subjected to the phase modulation by the phase modulator 18 is amplified by the amplifier 19 so that the side lobe component of the path 1 and the side lobe component of the path 2 become the same level when they are combined in the coupler 21. .
The level is finely adjusted by the level adjustment circuit 20.

Thus, in the coupler 21, the path 1
The phase-modulated signal input from the path 2 and the phase-modulated signal input from the path 2 are coupled in a state in which the phases are shifted by 180 °, that is, in a state where they are mutually canceled. As a result, the side lobe components cancel each other and are reduced.

(C-3) Effect of Third Embodiment As described above, according to the frequency band limiting method according to the third embodiment, the function equivalent to that of the 180 ° phase shifter in the first embodiment. In the baseband frequency band,
The circuit scale can be further reduced as compared with the first embodiment.

(D) Fourth Embodiment (D-1) Apparatus Configuration FIG. 5 shows a fourth embodiment of a radio transmitter to which the frequency band limiting method according to the present invention is applied. In this embodiment,
A configuration in which the phase modulator on path 1 is replaced with two switches is proposed. The configuration of the path 2 is based on the configuration described in the third embodiment, that is, the configuration using an inverter. However, as the configuration of the route 2, the same configuration as in the first embodiment can be applied.
The same one as in the second embodiment can be applied.

As shown in FIG. 5, the radio transmitter includes an oscillator 11, a distributor 12, an amplifier 13, and a distributor 23.
, A first switch 24, a 180 ° phase shifter 25, a second switch 26, an inverter 27, and a combiner 28.
, A delay unit 16, an inverter 22, a high-pass filter 17, a phase modulator 18, an amplifier 19, a level adjuster 20, and a coupler 21. Here, in FIG. 5, the portions corresponding to those in FIG. 4 are denoted by the same reference numerals, and the same portions are denoted by the same reference numerals.

Here, the distributor 23 is connected to the amplifier 1
3 is a circuit for splitting the carrier wave amplified in 3 into two. The first switch 24 is a switch element that is on / off controlled by a baseband signal, and the carrier is subjected to digital amplitude modulation (ASK) by the on / off control.

The 180 ° phase shifter 25 is a circuit for shifting the phase of the carrier wave split by the distributor 23 by 180 °, ie, inverting the phase of the carrier wave to the opposite phase. The second switch 26 is a switch element that is on / off controlled by a baseband signal logically inverted by the inverter 27, and the carrier is subjected to digital amplitude modulation (ASK) by the on / off control.

The coupler 28 includes the first and second switches 2
This is a circuit that combines carrier waves that have been amplitude-modulated by each of 4 and 26. This combination provides an output having the same wavelength as the PSK-modulated wave.

(D-2) Transmission Operation Next, the transmission operation of the PSK transmitter according to the fourth embodiment will be described. Here, two switches 24 and 26
It is clarified that the PSK modulator configured as follows operates in the same manner as the phase modulator 14 on the path 1 in the third embodiment.

The carrier wave generated by the oscillator 11 is
In 2, the path branches to path 1 and path 2.

In path 1, the branched carrier signal is amplified to a specified level. At this time, the amplifier 13 operates in the saturation region. Therefore, the output of the amplifier 13 is branched at the distributor 23, and the first switch 24 and the second switch 2
6 is output.

At this time, the carrier inputted to the second switch 26 has a phase difference of 180 ° with respect to the carrier inputted to the first switch 24 by the 180 ° phase shifter 25.

The carrier signal after branching is supplied to the first switch 24.
And the second switch 26 performs amplitude modulation (ASK modulation).

FIG. 6 shows the modulation timing at this time. FIG. 6 illustrates an example in which the switch is turned on when the baseband signal (FIG. 6A) is “1” and the switch is turned off when the baseband signal is “0”.

Accordingly, from the first switch 24, FIG.
As shown in (B), the carrier is output during the period when the baseband signal is “1”. On the other hand, from the second switch 26, as shown in FIG.
The carrier is output during the period of “0” of the baseband signal.

[0070] These two ASK modulated waves are input to the combiner 28 and combined. The waveform after the combination is as shown in FIG. This waveform is the PSK modulation wave itself. The modulation waveform at this time is a waveform in which the band is not limited.

On the other hand, in the path 2, a carrier having the same phase as that of the path 1 branched by the distributor 12 is provided to the phase modulator 18 via the delay unit 16. Here, the delay unit 16 has a function of adjusting a delay difference generated in a subsequent line.

This carrier is converted by the phase modulator 18
After being logically inverted by the inverter 22 and passing through the high-pass filter 17, only the side lobe component is phase-modulated with the extracted base band signal. The phase modulated signal output from the phase modulator 18 has the side lobe component of the path 1 and the side lobe component of the path 2
, Are amplified by the amplifier 19 so as to have the same level when they are combined, and the level is finely adjusted by the level adjusting circuit 20.

Thus, in the coupler 21, the path 1
The phase-modulated signal input from the path 2 and the phase-modulated signal input from the path 2 are coupled in a state in which the phases are shifted by 180 °, that is, in a state where they are mutually canceled. As a result, the side lobe components cancel each other and are reduced.

(D-3) Effect of Fourth Embodiment As described above, according to the frequency band limiting method according to the fourth embodiment, in addition to the same effect as in the third embodiment, PS
By configuring the K modulator with two switches, the transmission output can be increased.

(E) Fifth Embodiment (E-1) Apparatus Configuration FIG. 7 shows a fifth embodiment of a radio transmitter to which the frequency band limiting method according to the present invention is applied. In this embodiment,
A configuration is proposed in which the phase modulator provided on the path 1 is replaced with two amplifiers. Note that the same configuration as that of the fourth embodiment, that is, a configuration using an inverter is applied to the configuration of the path 2. However, in this case as well, the configuration of the route 2 can be the configuration of the first embodiment or the configuration of the second embodiment.

As shown in FIG. 7, the radio transmitter includes an oscillator 11, a distributor 12, an amplifier 13, and a distributor 23.
, A first amplifier 32, a 180 ° phase shifter 25, and a second
, A coupler 28, an inverter 29, a first power switch 30, a second power switch 31,
Delay device 16, inverter 22, high-pass filter 1
7, a phase modulator 18, an amplifier 19, a level adjustment circuit 20, and a coupler 21. Here, in FIG. 7, the portions corresponding to those in FIG. 5 are denoted by the same reference numerals, and the same portions are denoted by the same reference numerals.

Here, the first and second amplifiers 32 and 3
Reference numeral 3 denotes a circuit for setting the output to a saturation region. That is, in this embodiment, three amplifiers 13, 32, and 33 operate in the saturation region. The inverter 29 is a circuit that inverts the logic of the baseband signal and outputs the inverted signal.

The first power switch 30 is a switch element which is turned on / off by the baseband signal itself. This switch is on (closed)
During the period, power is supplied to the first amplifier 32. On the other hand,
The second power switch 31 is a switch element that is turned on and off by a baseband signal logically inverted by the inverter 29. Power is supplied to the second amplifier 33 while the switch is turned on (closed).

However, it is assumed that all the power switches are turned on when the input is logic “1”. Therefore, when the power switch is set to be turned on when the input is “0”, the insertion position of the inverter 29 may be arranged in front of the first switch 30.

(E-2) Transmission Operation Next, the transmission operation of the PSK transmitter according to the fifth embodiment will be described. Here, it is clarified that the PSK modulator composed of the two amplifiers 32 and 33 operates in the same manner as the PSK modulator composed of the two switches 24 and 26 described in the fourth embodiment.

The carrier wave generated by the oscillator 11 is
In 2, the path branches to path 1 and path 2.

In path 1, the branched carrier signal is amplified to a specified level. At this time, the amplifier 13 operates in the saturation region. Accordingly, the output of the amplifier 13 is branched in the distributor 23 and output to each of the first amplifier 32 and the second amplifier 33.

At this time, the carrier wave input to the second amplifier 33 is converted by the 180 ° phase shifter 25 into the first amplifier 3.
2 has a phase difference of 180 ° with respect to the carrier wave input to 2.

The carrier signal after the branch is subjected to amplitude modulation (AS) in each of the first amplifier 32 and the second amplifier 33.
K modulation).

The modulation timing at this time is the same as that of the first and second switches shown in FIG. Therefore, as shown in FIG. 6B, a carrier is output from the first amplifier 32 during the period when the baseband signal is “1”. On the other hand, as shown in FIG. 6C, a carrier is output from the second amplifier 33 during a period of “0” of the baseband signal at which the inverter output is “1”.

[0086] These two ASK modulated waves are input to the combiner 28 and combined. The waveform after the combination is as shown in FIG. This waveform is the PSK modulation wave itself. The modulation waveform at this time is a waveform in which the band is not limited.

On the other hand, in the path 2, a carrier having the same phase as that of the path 1 branched by the distributor 12 is supplied to the phase modulator 18 via the delay unit 16. Here, the delay unit 16 has a function of adjusting a delay difference generated in a subsequent line.

This carrier is converted by the phase modulator 18
After being logically inverted by the inverter 22 and passing through the high-pass filter 17, only the side lobe component is phase-modulated with the extracted base band signal. The phase modulated signal output from the phase modulator 18 has the side lobe component of the path 1 and the side lobe component of the path 2
, Are amplified by the amplifier 19 so as to have the same level when they are combined, and the level is finely adjusted by the level adjusting circuit 20.

Thus, in the coupler 21, the path 1
The phase-modulated signal input from the path 2 and the phase-modulated signal input from the path 2 are coupled in a state in which the phases are shifted by 180 °, that is, in a state where they are mutually canceled. As a result, the side lobe components cancel each other and are reduced.

(E-3) Effect of Fifth Embodiment As described above, according to the frequency band limiting method according to the fifth embodiment, the AS effect in addition to the effect of the fourth embodiment is obtained.
By realizing K modulation with an amplifier, the final-stage amplifiers (amplifiers 32 and 33) can be replaced by amplifiers with low saturation output due to the insertion loss due to the switch and the increase in output due to two amplifiers. As a result, the cost of parts can be reduced.

(F) Sixth Embodiment (F-1) Device Configuration FIG. 8 shows a sixth embodiment of a radio transmitter to which the frequency band limiting method according to the present invention is applied. In this embodiment,
A description will be given of a configuration for achieving further miniaturization while keeping the basic configuration of the wireless transmitter described in the fifth embodiment.

As shown in FIG. 8, the radio transmitter includes an oscillator 11, a distributor 12, an amplifier 13, and a distributor 23.
, An amplifier 32, an inverting amplifier 33 ', and a combiner 28.
, An inverter 29, a first power switch 30, a second power switch 31, the delay unit 16, the inverter 2
2, a high-pass filter 17, a phase modulator 18, an amplifier 19, a level adjustment circuit 20, and a coupler 21. Here, in FIG. 8, the portions corresponding to those in FIG. 7 are denoted by the same reference numerals, and the same portions are denoted by the same reference numerals.

As is apparent from a comparison between FIG. 8 and FIG.
The sixth embodiment is characterized in that the 180 ° phase shifter 25 and the second amplifier 33 in the fifth embodiment are replaced with an inverting amplifier 33 ′. The output of the inverting amplifier 33 'also operates in the saturation region.

(F-2) Transmission Operation Next, the transmission operation of the PSK transmitter according to the sixth embodiment will be described. In this transmission operation, the function of the 180 ° phase shifter 25 described in the fifth embodiment is the same as that of the inverting amplifier 3.
It is the same except that it is realized by 3 '.

That is, from the amplifier 32, FIG.
As shown in FIG. 6, a carrier is output during the period when the baseband signal is "1", and the inverting amplifier 33 outputs "0" of the baseband signal whose inverter output is "1" as shown in FIG. Are outputted.

Accordingly, the output of the combiner 28 is the waveform itself obtained by PSK-modulating the carrier with the baseband signal, and the waveform is a waveform which is not subjected to the band limitation. Thus, in the coupler 21, the phase modulation signal input from the path 1 and the phase modulation signal input from the path 2 are coupled in a state of being shifted by 180 °, that is, in a state of canceling each other. The side lobe components cancel each other and are reduced.

(F-3) Effects of the Sixth Embodiment As described above, according to the frequency band limiting method of the sixth embodiment, the fifth embodiment has the same advantages as the fifth embodiment, in addition to the fifth embodiment.
By realizing the function of the 180 ° phase shifter 25 used in the embodiment by the inverting amplifier 33 ′, it is possible to further reduce the circuit size.

(G) Seventh Embodiment (G-1) Device Configuration FIG. 9 shows a seventh embodiment of a radio transmitter to which the frequency band limiting method according to the present invention is applied. In the sixth embodiment, the case where the power switch type amplifiers 32 and 33 'are used has been described. In the seventh embodiment, a case where these are used as bias voltage control type amplifiers will be described. With this configuration, the power switches 30 and 31 used in the sixth embodiment become unnecessary.

As shown in FIG. 9, the radio transmitter includes an oscillator 11, a distributor 12, an amplifier 13, and a distributor 23.
, An amplifier 32 ", an inverting amplifier 33", and a coupler 28 ".
, An inverter 29, a first power switch 30, a second power switch 31, the delay unit 16, the inverter 2
2, a high-pass filter 17, a phase modulator 18, an amplifier 19, a level adjustment circuit 20, and a coupler 21. Here, in FIG. 9, the portions corresponding to those in FIG. 8 are denoted by the same reference numerals, and the same portions are denoted by the same reference numerals.

Here, the amplifier 32 "and the inverting amplifier 33"
For example, a bias voltage control type amplifier as shown in FIG. 10 is used. As shown in FIG. 10, a carrier signal is provided as an input signal, and a baseband signal is provided as a bias voltage to a gate electrode of a field effect transistor (FET). Here, the baseband signal is the impedance element R
Given through. In FIG. 10, the output terminal is a connection point between the drain of the FET and the inductance L. However, the connection configuration shown in FIG. 10 is only an example, and various specific circuit configurations are conceivable.

(G-2) Transmission Operation Next, the transmission operation of the PSK transmitter according to the seventh embodiment will be described. This transmission operation is the same as the transmission operation of the sixth embodiment except that both the amplifier 32 "and the inverting amplifier 33" are directly controlled by the baseband signal. That is, ASK modulation is performed by turning on / off the bias voltage by the baseband signal.

The modulated waveform at this time is a waveform for which no band limitation is performed. By combining the modulated wave with the modulated wave of the opposite phase from which the main signal component from the path 2 has been removed, the side lobe components are canceled out and removed in this embodiment also.

(G-3) Effects of the Seventh Embodiment As described above, according to the frequency band limiting method of the seventh embodiment, in addition to the same effects as in the sixth embodiment, the AS
Since K modulation is performed by bias voltage control, the power switch can be omitted from the circuit, and the circuit size can be reduced.
As a result, the cost can be further reduced.

(G-4) Other Embodiments In the description of the above embodiment, the ASK modulator is FE
Although the description has been made using the T gate modulator, a base modulator of a bipolar transistor or the like can also be used. Further, another method can be applied to the grounding method.

[0105]

(A) According to the first aspect of the present invention, as described above, a carrier is digitally phase-modulated with a baseband signal without band limitation to obtain a modulated wave having a widened frequency spectrum. Processing and phase-modulating a signal whose phase is delayed by 180 ° with respect to a carrier with a baseband signal from which a main signal component has been removed, and a modulated wave having the same level and opposite phase as the side lobe component of the modulated wave obtained in the first processing. And the third process of combining the modulated wave obtained in the first process and the modulated wave obtained in the second process to transmit a transmission signal in which the spread of the frequency spectrum is suppressed to the antenna.
And so on. As a result, even if the main amplifier is operated in the saturation region (non-linear operation region), the side lobe component can be surely suppressed, and the spread of the frequency spectrum can be suppressed.

(B) As described above, according to the second aspect,
A first process of digitally modulating a carrier with a baseband signal without band limitation to obtain a modulated wave in a state where a frequency spectrum is widened, and a phase of a carrier having the same phase as the carrier with a baseband signal from which a main signal component is removed. Modulate,
A second process for obtaining a modulated wave having the same level and an opposite phase as the side lobe component of the modulated wave obtained in the first process by further inverting and amplifying the modulated wave obtained in the first process and the second process; And a third process of transmitting to the antenna a transmission signal in which the spread of the frequency spectrum has been suppressed. Thus, the same effect as that of the first invention can be realized with a smaller circuit.

(C) As described above, according to the third aspect,
A first process of digitally modulating a carrier with a baseband signal without band limitation to obtain a modulated wave having a spread frequency spectrum, and a carrier having the same phase as the carrier is converted from a logically inverted output of the baseband signal to a main signal. A second process for performing phase modulation with the signal from which the component has been removed to obtain a modulated wave having the same level and opposite phase as the side lobe component of the modulated wave obtained in the first process, and a modulated wave obtained in the first process. Second
And the third process of transmitting the transmission signal, in which the spread of the frequency spectrum has been suppressed, to the antenna. Thereby, the first
In the baseband frequency band, a modulated wave having a phase opposite to that of the modulated wave obtained by the above process can be realized, and the same effects as those of the first and second inventions can be realized by a smaller circuit.

(D) As described above, according to the fourth aspect,
A carrier is branched into two, and one carrier is digitally amplitude-modulated by inputting to a switch means controlled by a baseband signal input without band limitation, and the other carrier is applied to one carrier with respect to one carrier. Phase 18
After delaying by 0 °, digital amplitude modulation is performed by inputting to a switch means controlled by a logically inverted base band signal, and a modulated wave having a spread frequency spectrum is obtained by combining these two modulated waves. 1
, A second process for obtaining a modulated wave having the same level and opposite phase as the side lobe component of the modulated wave obtained in the first process, and a second process for obtaining the modulated wave obtained in the first process and the second process. And a third process of combining the modulated waves with each other and transmitting a transmission signal whose frequency spectrum has been suppressed to an antenna. As a result, not only the size of the circuit can be reduced but also the transmission output can be increased.

(E) As described above, according to the fifth aspect,
A carrier is branched into two, and one carrier is digitally amplitude-modulated by inputting to an amplifier whose power supply is controlled by a baseband signal input without band limitation, and the other carrier is used for one carrier. After delaying the phase by 180 ° with respect to the carrier, digital amplitude modulation is performed by input to an amplifier whose power supply is controlled by a logically inverted baseband signal, and the frequency spectrum is spread by combining these two modulated waves. A first process for obtaining a modulated wave in a shifted state, a second process for obtaining a modulated wave having the same level and opposite phase as a side lobe component of the modulated wave obtained in the first process, and a first process A third method of combining the modulated wave and the modulated wave obtained in the second processing, and transmitting a transmission signal with a spread of the frequency spectrum suppressed to the antenna.
And so on. As a result, not only the size of the circuit can be reduced but also the transmission output can be increased.

(F) According to the sixth aspect, as described above,
A carrier is branched into two, and one carrier is subjected to digital amplitude modulation by inputting to an amplifier whose power supply is controlled by a baseband signal input without band limitation, and the other carrier is logically inverted. A first process of performing digital amplitude modulation by inputting to an inverting amplifier whose power supply is controlled by the baseband signal and combining these two modulated waves to obtain a modulated wave having a spread frequency spectrum. A second process for obtaining a modulated wave having the same level and opposite phase as the side lobe component of the modulated wave obtained in the first process, a modulated wave obtained in the first process, and a modulated wave obtained in the second process And a third process of transmitting to the antenna a transmission signal in which the spread of the frequency spectrum is suppressed is executed. As a result, not only the size of the circuit can be reduced but also the transmission output can be increased.

(G) As described above, according to the seventh aspect,
A carrier is branched into two, and one carrier is digitally amplitude-modulated by being input to an amplifier that uses a baseband signal input as a bias signal without band limitation, and the other carrier is a logically inverted baseband. Digital amplitude modulation is performed by inputting the signal to an inverting amplifier that uses the signal as a bias signal, and these two modulated waves are combined to obtain a modulated wave having a spread frequency spectrum. A second process for obtaining a modulated wave having the same level and opposite phase as the side lobe component of the obtained modulated wave, and a modulated wave obtained in the first process and a modulated wave obtained in the second process are combined to obtain a frequency spectrum. And a third process of transmitting to the antenna a transmission signal whose spread has been suppressed. As a result, not only the size of the circuit can be reduced but also the transmission output can be increased.

(H) As described above, according to the eighth aspect,
In the frequency band limiting method according to any one of the first to seventh inventions described above, power efficiency can be improved by using the main amplifier used in the first process in a saturation region.

[Brief description of the drawings]

FIG. 1 is a functional block diagram illustrating a first embodiment of a wireless transmitter.

FIG. 2 is a functional block diagram showing a configuration of a conventional device.

FIG. 3 is a functional block diagram illustrating a second embodiment of the wireless transmitter.

FIG. 4 is a functional block diagram showing a third embodiment of the wireless transmitter.

FIG. 5 is a functional block diagram showing a fourth embodiment of the wireless transmitter.

FIG. 6 is a diagram showing a time waveform of a baseband signal and a modulated wave.

FIG. 7 is a functional block diagram showing a fifth embodiment of the wireless transmitter.

FIG. 8 is a functional block diagram showing a sixth embodiment of the wireless transmitter.

FIG. 9 is a functional block diagram showing a seventh embodiment of the wireless transmitter.

FIG. 10 is a diagram illustrating a configuration example of an amplifier used for modulating a carrier wave.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Modulation part, 2, 7 ... Phase shifter, 3, 6, 8 ... Variable attenuator, 4, 9, 13, 19, 19 ', 32, 32 ", 3
3, 33 ', 33 "... amplifier, 5, 10, 16 ... delay unit, 11 ... oscillator, 12, 23 ... distributor, 14, 18 ...
Phase modulator, 15, 25 180-degree phase shifter, 17 high-pass filter, 20 level adjustment circuit, 21, 28 coupler, 22, 27, 29 inverter, 24, 26, 3
0, 31 ... Switch.

Claims (8)

[Claims] 1. A frequency band limiting method in a radio transmitter, comprising: a first process of digitally modulating a carrier with a baseband signal without band limiting to obtain a modulated wave having a widened frequency spectrum; In contrast, a second signal whose phase is delayed by 180 ° is phase-modulated with a baseband signal from which a main signal component has been removed to obtain a modulated wave having the same level and opposite phase as the side lobe component of the carrier obtained in the first processing. And a third process of combining the modulated wave obtained in the first process with the modulated wave obtained in the second process, and transmitting a transmission signal in which the spread of the frequency spectrum is suppressed to the antenna. A frequency band limiting method comprising: 2. A frequency band limiting method in a wireless transmitter, comprising: a first process of digitally modulating a carrier with a baseband signal without band limiting to obtain a modulated wave having a widened frequency spectrum; A carrier wave in phase with the baseband signal from which the main signal component has been removed is phase-modulated and further inverted and amplified to obtain a modulated wave having the same level and opposite phase as the side lobe component of the modulated wave obtained in the first processing. A second process for combining the modulated wave obtained in the first process with the modulated wave obtained in the second process, and transmitting a transmission signal in which the spread of the frequency spectrum is suppressed to the antenna; And a process for limiting the frequency band. 3. A frequency band limiting method in a radio transmitter, comprising: a first process of digitally modulating a carrier with a baseband signal without band limiting to obtain a modulated wave having a widened frequency spectrum; And phase-modulate the carrier in phase with a signal obtained by removing the main signal component from the logically inverted output of the baseband signal,
A second process for obtaining a modulated wave having the same level and opposite phase as the side lobe component of the modulated wave obtained in the first process, and a modulated wave obtained in the first process and obtained in the second process A third process of combining a modulated wave and transmitting a transmission signal in which a spread of a frequency spectrum is suppressed to an antenna. 4. A frequency band limiting method in a wireless transmitter, wherein a carrier is branched into two, and one carrier is input to a switch means controlled by a base band signal input without band limiting. Digital amplitude modulation is performed, and the other carrier is delayed by 180 ° in phase with respect to the one carrier, and then input to switching means controlled by a logically inverted baseband signal to perform digital amplitude modulation. A first process for obtaining a modulated wave having a spread frequency spectrum by combining the waves, and a second process for obtaining a modulated wave having the same level and opposite phase as the side lobe component of the modulated wave obtained in the first process. And the modulation wave obtained in the first processing and the modulation wave obtained in the second processing are combined to expand the frequency spectrum. Frequency band limiting process, characterized in that it comprises but a third process of transmitting the transmission signal is suppressed to the antenna. 5. A frequency band limiting method in a wireless transmitter, wherein a carrier is branched into two, and one of the carriers is input to an amplifier whose power supply is controlled by a baseband signal input without band limiting. Digital amplitude modulation, and the other carrier is delayed by 180 ° in phase with respect to the one carrier, and then input to an amplifier whose power supply is controlled by a logically inverted baseband signal. A first process for obtaining a modulated wave having a spread frequency spectrum by combining the two modulated waves; and a side wave component having the same level and opposite phase as the side lobe component of the modulated wave obtained in the first process. A second process for obtaining a modulated wave, and combining the modulated wave obtained in the first process with the modulated wave obtained in the second process, and Third processing and the frequency band limiting process characterized in that it comprises the transmitting a transmission signal ram spread is suppressed to the antenna. 6. A frequency band limiting method in a wireless transmitter, wherein a carrier is split into two, and one of the carriers is input to an amplifier whose power supply is controlled by a baseband signal input without band limiting. The other carrier is digitally amplitude-modulated by inputting it to an inverting amplifier whose power supply is controlled by a logically inverted baseband signal, and the frequency is obtained by combining these two modulated waves. A first process for obtaining a modulated wave having a spread spectrum; a second process for obtaining a modulated wave having the same level and opposite phase as a side lobe component of the modulated wave obtained in the first process; The modulated wave obtained by the above-mentioned processing and the modulated wave obtained by the above-mentioned second processing are combined, and the transmission signal in which the spread of the frequency spectrum is suppressed is used as an antenna. And a third process of transmitting to the frequency band limiting device. 7. A frequency band limiting method in a radio transmitter, wherein a carrier is branched into two, and one of the carriers is input to an amplifier that uses a base band signal input without band limiting as a bias signal. Digital amplitude modulation is performed, and the other carrier is digitally amplitude-modulated by inputting it to an inverting amplifier that uses a logically inverted baseband signal as a bias signal, and by combining these two modulated waves, the frequency spectrum is expanded. A first process for obtaining a modulated wave; a second process for obtaining a modulated wave having the same level and opposite phase as a side lobe component of the modulated wave obtained in the first process; and a modulation obtained in the first process. A third method of combining the wave and the modulated wave obtained in the second processing, and transmitting a transmission signal in which the spread of the frequency spectrum is suppressed to the antenna. And a frequency band limiting method. 8. The frequency band limiting method according to claim 1, wherein in the first processing, the main amplifier is used in a saturation region.