JP2008048052A - Transmitter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmitter in which the timing difference of amplitude signals and phase signals is accurately adjusted and the distortion of vector modulated wave signals is eliminated. <P>SOLUTION: A phase/frequency conversion part 11 converts delay phase signals p1(t), outputted from a delay adjustment part 18, into frequency signals f1(t), and a frequency modulation part 12 modulates the frequency signals f1(t) and generates phase modulated wave signals Sc(t). A multiplication part 14 multiplies delay amplitude signals r1(t), outputted from a delay adjustment part 17 and the frequency signals f1(t) outputted from the phase/frequency conversion part 11, and calculates multiplied signals m(t), a band filter 15 outputs distorted extraction signals n(t) in which the distortion frequency components are extracted from the multiplied signals m(t), and a control part 16 controls the delay amount to be adjusted by the delay adjustment part 17 and 18 that the distorted extraction signals n(t) becomes a prescribed level or lower. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a transmission apparatus using a polar modulation scheme.

The polar modulation method is a method of individually processing the amplitude signal r (t) and the phase signal p (t) separated from the input signal as shown in FIG. In FIG. 13, a phase modulation unit 101 phase-modulates a carrier wave signal having an angular frequency ωc with a phase signal p (t) to generate a phase modulated wave signal Sc (t). The amplifying unit 102 amplifies the phase modulation wave signal Sc (t) with a gain based on the amplitude signal r (t), gives an amplitude modulation component to the phase modulation wave signal Sc (t), and generates the vector modulation wave signal Srf (t ) Is generated. The phase modulation wave signal Sc (t) and the vector modulation wave signal Srf (t) are expressed by the following <Expression 1> and <Expression 2>.
Sc (t) = cos [ωc · t + p (t)] (Formula 1)
Srf (t) = r (t) · Sc (t) (Formula 2)

  Since the signal input to the amplifying unit 102 is a phase-modulated wave signal having no fluctuation component in the amplitude direction, it becomes a constant envelope signal. Therefore, since an efficient nonlinear amplifier can be used as the amplifying unit 102, a highly efficient transmission device can be provided.

  However, in this polar modulation method, the difference (delay time) between the timing when the component of the amplitude signal r (t) reaches the amplifying unit 102 and the timing when the component of the phase signal p (t) reaches the amplifying unit 102. ) Causes a problem that distortion occurs in the vector modulated wave signal Srf (t). This distortion causes the spread of the frequency spectrum ((b) of FIG. 14).

  Therefore, in order to solve the above problem, the following technique has been proposed (for example, see Patent Document 1). FIG. 15 is a diagram illustrating a configuration example of a conventional transmission apparatus. This conventional transmission device further includes an amplitude detection unit 111, a phase detection unit 112, delay comparison units 113 and 114, and delay adjustment units 115 and 116, in addition to the phase modulation unit 101 and the amplification unit 102. Yes.

In this conventional transmission device, the amplified vector modulation wave signal Srf (t) is detected using the amplitude detection unit 111 and the phase detection unit 112, and the detection amplitude signal r2 (t) and the detection are detected from the actual output signal. Each of the phase signals p2 (t) is extracted. The delay comparison unit 113 compares the detected amplitude signal r2 (t) with the input amplitude signal r (t), and the delay adjustment unit 115 matches the amplitude signal r so that the timings of both signals coincide according to the comparison result. The delay amount of (t) is adjusted. Similarly, the delay comparator 114 compares the detected phase signal p2 (t) with the input phase signal p (t), and the delay adjuster 116 adjusts the phase so that the timings of both signals coincide according to the comparison result. The delay amount of the signal p (t) is adjusted.
JP 2005-203960 A

  However, in the above-described conventional transmission device, a detection error always occurs in the amplitude detection unit 111 and the phase detection unit 112, so that the waveform of the detection amplitude signal r2 (t) completely matches the waveform of the amplitude signal r (t). do not do. For this reason, the comparison result between the detection amplitude signal r2 (t) and the amplitude signal r (t) in the delay comparison unit 113 includes a comparison error. Similarly, since the waveform of the detection phase signal p2 (t) and the waveform of the phase signal p (t) do not completely match, the detection phase signal p2 (t) and the phase signal p (t) in the delay comparison unit 114 are The comparison result includes a comparison error. Because of these comparison errors, the timing difference between the amplitude signal and the phase signal cannot be sufficiently absorbed only by adjusting the delay amount in the delay adjustment units 115 and 116, and the vector modulated wave signal Srf (t) is distorted. Will remain.

  Therefore, an object of the present invention is to provide a transmission device that can accurately adjust a timing difference between an amplitude signal and a phase signal and eliminate distortion of a vector modulation wave signal.

  The present invention is directed to a transmission apparatus using a polar modulation scheme. In order to achieve the above object, the transmitting apparatus of the present invention includes a phase-frequency converter that converts an input phase signal into a frequency signal, and a frequency that generates a phase-modulated wave signal by frequency-modulating the frequency signal. A modulation unit, an amplification unit that amplifies the phase-modulated wave signal according to the input amplitude signal, a multiplication unit that multiplies the amplitude signal and frequency signal input to the amplification unit, and a predetermined band from the signal multiplied by the multiplication unit Band filter for extracting the distortion frequency component of the signal, and the phase signal input to the phase-frequency converter and the amplitude signal input to the amplifier so that the distortion frequency component extracted by the band filter is below a predetermined level. A delay adjustment / control unit that adjusts at least one of the delay amounts.

  Or it further includes an amplitude detection unit for detecting the amplitude of the signal output from the amplification unit, and a frequency detection unit for detecting the frequency of the signal output from the amplification unit, and in the multiplication unit, the amplitude detection unit detects the signal. The signal for extracting the distortion frequency component may be generated by multiplying the amplitude signal and the frequency signal detected by the frequency detection unit.

Preferably, the phase-frequency conversion unit includes a differentiator that performs time differentiation processing on the input phase signal. Alternatively, the phase-frequency conversion unit outputs a frequency-divided signal of the phase-modulated wave signal fed back from the frequency modulation unit in accordance with the input phase signal, and a reference frequency signal source that generates a reference frequency signal The phase comparator compares the phase of the frequency-divided signal with the phase of the reference frequency signal, and a low-pass filter that generates a frequency signal from the comparison result of the phase comparator.
Preferably, the bandpass filter is configured by a digital filter that digitally processes the signal multiplied by the multiplication unit or a discrete Fourier transformer that performs a discrete Fourier transform.

  According to the present invention, there is no influence of the detection error and the comparison error that existed in the past. Therefore, the timing difference between the amplitude signal and the phase signal can be adjusted with high accuracy, and distortion of the vector modulation wave signal can be eliminated.

(First embodiment)
FIG. 1 is a block diagram showing a configuration of a transmission apparatus according to the first embodiment of the present invention. In FIG. 1, the transmission apparatus according to the first embodiment includes a phase-frequency conversion unit 11, a frequency modulation unit 12, an amplification unit 13, a multiplication unit 14, a band filter 15, a control unit 16, and a delay. Adjustment units 17 and 18 are provided. The phase-frequency conversion unit 11 and the frequency modulation unit 12 correspond to a phase modulation unit.

First, an outline of each configuration of the transmission apparatus according to the first embodiment of the present invention will be described.
The delay adjusting unit 18 adjusts the delay amount of the input phase signal p (t) according to the control of the control unit 16 and outputs it as a delayed phase signal p1 (t). The phase-frequency converter 11 converts the delayed phase signal p1 (t) output from the delay adjuster 18 into a frequency signal f1 (t). This conversion is performed by time-differentiating the delayed phase signal p1 (t) as shown in FIG. The converted frequency signal f1 (t) is input to the frequency modulation unit 12 and the multiplication unit 14. The frequency modulation unit 12 frequency-modulates the frequency signal f1 (t) converted by the phase-frequency conversion unit 11 to generate a phase-modulated phase modulated wave signal Sc (t). The delay adjustment unit 17 adjusts the delay amount of the input amplitude signal r (t) according to the control of the control unit 16 and outputs it as a delay amplitude signal r1 (t). The amplification unit 13 amplifies the phase modulation wave signal Sc (t) output from the frequency modulation unit 12 in accordance with the delay amplitude signal r1 (t) output from the delay adjustment unit 17, and the vector modulation wave signal Srf (t) Is generated.

  The multiplication unit 14 multiplies the delay amplitude signal r1 (t) output from the delay adjustment unit 17 and the frequency signal f1 (t) output from the phase-frequency conversion unit 11 to obtain the multiplication signal m (t). calculate. At this time, if there is no or small timing difference (time difference) between the delay amplitude signal r1 (t) and the frequency signal f1 (t), the delay amplitude signal r1 (t) is limited at the peak of the frequency signal f1 (t). Since it becomes zero, a flat multiplication signal m (t) is obtained (FIG. 3A). On the other hand, when the timing difference (time difference) between the delay amplitude signal r1 (t) and the frequency signal f1 (t) is large, the delay amplitude signal r1 (t) is not zero at the peak of the frequency signal f1 (t). A distortion signal m (t) with distortion is obtained (FIG. 3B). As a result, the frequency spectrum of the multiplication signal m (t) is spread (FIG. 4). This spread of the frequency spectrum tends to appear prominently at a high frequency (for example, an arrow portion in FIG. 4).

  Since the frequency signal f1 (t) is a signal that is generated based on the phase signal p (t) and transmits information held by the phase signal p (t), the frequency signal f1 (t) and the amplitude signal r The act of detecting and adjusting the timing difference from (t) has the same effect as the act of detecting and adjusting the timing difference between the phase signal p (t) and the amplitude signal r (t).

  3A and 3B show an example in which the amplitude signal approaches infinitely zero and the frequency signal has a particularly large peak. There are various modulation schemes applied by the radio communication system in which the transmission apparatus is used, and the degree of the amplitude signal approaching zero and the degree of the peak of the frequency signal differ depending on the modulation scheme. However, in the transmission device according to the first embodiment, even if the degree of the amplitude signal approaching zero or the degree of the peak of the frequency signal is different from the example of FIGS. A slight distortion of the time waveform caused in the multiplication signal due to the timing difference appears as a spread of the frequency spectrum in the frequency domain.

  The band filter 15 extracts a distortion frequency component of a predetermined band from the multiplication signal m (t) calculated by the multiplication unit 14 and outputs the distortion frequency component as a distortion extraction signal n (t). In addition, what is necessary is just to set this predetermined band to the frequency band etc. which the breadth of the frequency spectrum mentioned above appears notably, for example. The control unit 16 suppresses the spread of the frequency spectrum of the multiplication signal m (t) within a predetermined range so that the distortion extraction signal n (t) output from the band filter 15 becomes a predetermined level or less. In addition, the delay amount of the amplitude signal r (t) adjusted by the delay adjustment unit 17 and the delay amount of the phase signal p (t) adjusted by the delay adjustment unit 18 are respectively controlled. An example of the delay amount control method will be described later.

Next, a detailed circuit example of each configuration will be described.
5 and 6 are diagrams illustrating detailed circuit examples of the phase-frequency conversion unit 11 and the frequency modulation unit 12. FIG. 5 shows an example in which the phase-frequency converter 11 is configured by a differentiator 11a and the frequency modulator 12 is configured by a voltage controlled oscillator (VCO) 12a. In this example, the frequency signal f1 (t) is generated by time-differentiating the delayed phase signal p1 (t) using the differentiator 11a.

  Further, FIG. 6 shows that the phase-frequency conversion unit 11 outputs a frequency-divided signal of the phase-modulated wave signal Sc (t) fed back from the frequency modulation unit 12 according to the delayed phase signal p1 (t). A reference frequency signal source 11b that generates a reference frequency signal, a phase comparator 11c that compares the phase of the divided signal with the phase of the reference frequency signal, and a frequency signal f1 (t) generated from the comparison result of the phase comparator 11c. This is an example in which the low-pass filter 11d is configured and the frequency modulation unit 12 is configured by a voltage controlled oscillator (VCO) 12a. In this example, the frequency signal f1 (t) is generated by performing PLL processing on the output of the voltage controlled oscillator 12a. Accordingly, when this circuit example is used, a feedback path from the frequency modulation unit 12 to the phase-frequency conversion unit 11 is added to the circuit shown in FIG.

7 and 8 are diagrams illustrating circuit examples of the bandpass filter 15. FIG. 7 shows an example in which the band filter 15 is constituted by a digital filter 15a. FIG. 8 shows an example in which the band filter 15 is configured by a discrete Fourier transformer (DFT) 15b.
Here, when the digital filter 15a and the discrete Fourier transformer 15b are used, the input multiplication signal m (t) needs to be a digital signal. Therefore, in this case, the signal must be converted from analog to digital before being input to the band filter 15. FIG. 9 is a circuit example in which an analog-digital conversion configuration (AD converter 19a) and a digital-analog conversion configuration (DA converter 19b) are added to the transmission apparatus according to the first embodiment.

  FIG. 10 is a diagram illustrating a detailed circuit example of the control unit 16. FIG. 11 is a flowchart illustrating the processing operation performed by the control unit 16 of FIG. In FIG. 10, the control unit 16 includes a signal level calculation unit 16a, a first memory 16b, a second memory 16c, a comparator 16d, a counter 16e, and a selector 16f.

  First, the selector 16f selects the output of the counter 16e (step S101). Further, the counter 16e sets a count value (delay amount adjustment value) to an initial value (step S102). The value to be initialized is −127, for example, when 8-bit digital control is performed. The set initial value is stored in the second memory 16c (step S103). Further, a value (signal level proportional to the distortion extraction signal n (t)) output from the signal level calculation unit 16a at the initial stage is stored in the first memory 16b (step S104).

  Next, the counter 16e increments the count value by 1, that is, changes the delay amount of the phase signal p (t) and the amplitude signal r (t) (step S105). Then, the comparator 16d compares the output value of the signal level calculation unit 16a after the change with the previous value stored in the first memory 16b (step S106). As a result of the comparison, if the output value of the signal level calculation unit 16a after the change is larger, it is determined that the delay amount is small (No in step S107), and the counter 16e further increments the count value by one. Then, the processing after step S105 is repeated. On the other hand, when the output value of the signal level calculation unit 16a after the change is smaller, it is determined that the delay amount is appropriate at the present time (step S107, Yes), and the second memory 16c uses the current count value of the counter 16e. At the same time, the first memory 16b stores the output value (steps S108 and S109).

  This iterative process is performed up to the upper limit of the count value of the counter 16e (step S110). When performing the above-described 8-bit digital control, the upper limit is +127. Through the above processing, the delay amount that minimizes the output value of the signal level calculation unit 16a, that is, the optimal delay amount within the adjustable range is stored in the second memory 16f. When the count reaches the upper limit, the selector 16f selects the output of the second memory 16f (step S111). Normally, this process is performed independently of the control of the amplitude signal r (t) and the control of the phase signal p (t).

  As described above, according to the transmission apparatus according to the first embodiment of the present invention, the delay amount is adjusted without using the detection signal, so that there is no influence of the detection error and the comparison error that existed in the past. Therefore, the timing difference between the amplitude signal and the phase signal can be adjusted with high accuracy, and distortion of the vector modulation wave signal can be eliminated.

In the present embodiment, an example of a control method in which the counter 16e operates so as to count up the count value to the upper limit of the count value has been described. However, a predetermined level is set in advance, and the output value of the signal level calculation unit 16a The counter 16e may be controlled to operate so as to stop counting up when the value becomes smaller than a predetermined level.
Further, in the operation in which the counter 16e counts up the count value to the upper limit of the count value, a state where the output value of the signal level calculation unit 16a is minimized is searched, and based on the result, the distortion of the vector modulation wave signal is minimized. be able to.
Further, a predetermined level is set in advance, and when the output value of the signal level calculation unit 16a becomes smaller than the set predetermined level, the counter 16e performs an operation of stopping the count-up so that the vector modulated wave signal Distortion can be suppressed below a predetermined level.
The distortion of the vector modulated wave signal is most desirably a minimum value, but even if it is not the minimum value, it may be sufficient to satisfy the performance (distortion level) required of the transmission apparatus. In such a case, the control is performed by searching for a state where the output value of the signal level calculation unit 16a is smaller than a predetermined level without searching for a state where the output value of the signal level calculation unit 16a is the minimum value. It can be simplified. In this case, since the output value of the signal level calculation unit 16a has a correlation with the distortion level of the vector modulation wave signal, the output of the signal level calculation unit 16a is based on the performance (distortion level) required of the transmission apparatus. What is necessary is just to obtain | require and set beforehand the predetermined level used as the reaching target value of a value.

(Second Embodiment)
FIG. 12 is a block diagram showing a configuration of a transmission apparatus according to the second embodiment of the present invention. In FIG. 12, the transmission apparatus according to the second embodiment includes a phase-frequency conversion unit 11, a frequency modulation unit 12, an amplification unit 13, a multiplication unit 14, a band filter 15, a control unit 16, and a delay. Adjustment units 17 and 18, amplitude detection unit 21, and frequency detection unit 22 are provided. As can be seen from FIG. 12, the configuration of the transmission device according to the second embodiment is different in the amplitude detection unit 21 and the frequency detection unit 22 from the configuration of the transmission device according to the first embodiment. Hereinafter, the transmission apparatus according to the second embodiment will be described focusing on this different configuration.

  The amplitude detector 21 detects the vector modulated wave signal Srf (t) amplified and output by the amplifier 13 and extracts the detected amplitude signal r2 (t). The frequency detector 22 detects the vector modulated wave signal Srf (t) amplified and output by the amplifier 13 and extracts the detected frequency signal f2 (t). The multiplication unit 14 multiplies the detection amplitude signal r2 (t) output from the amplitude detection unit 21 and the detection frequency signal f2 (t) output from the frequency detection unit 22 to calculate a multiplication signal m (t). To do.

  As described above, according to the transmission apparatus according to the second embodiment of the present invention, the detection signal is used, but the delay amount is not adjusted based on the comparison between the detection signal and the input signal. There is no influence of detection error and comparison error. Therefore, the timing difference between the amplitude signal and the phase signal can be adjusted with high accuracy, and distortion of the vector modulation wave signal can be eliminated. Further, since the signal detected from the vector modulation wave signal is used, the influence of the delay difference generated in the frequency modulation unit and the amplification unit can be avoided.

  In the first and second embodiments, the configuration has been described in which the delay adjustment of the amplitude signal r (t) and the phase signal p (t) is performed to control the timing difference between both signals. However, as long as the timing difference between the two signals can be controlled, only one of the signals may be delay-adjusted.

  The present invention can be used for a polar modulation type transmission apparatus and the like, and is particularly suitable for a case where it is desired to accurately adjust a timing difference between an amplitude signal and a phase signal to eliminate distortion of a vector modulation wave signal.

The block diagram which shows the structure of the transmitter which concerns on the 1st Embodiment of this invention. The figure explaining the concept of the conversion process performed in the phase-frequency conversion part 11 The figure explaining the concept of the multiplication process performed in the multiplication part 14 The figure explaining the concept of the multiplication process performed in the multiplication part 14 The figure explaining the influence by the difference between FIG. 3A and FIG. 3B The figure which shows the detailed circuit example of the phase-frequency conversion part 11 and the frequency modulation part 12 The figure which shows the other detailed circuit example of the phase-frequency conversion part 11 and the frequency modulation part 12 The figure which shows the circuit example of the bandpass filter 15 The figure which shows the other circuit example of the bandpass filter 15 Circuit example in which configurations of AD converter and DA converter are added to the transmission apparatus according to the first embodiment The figure which shows the detailed circuit example of the control part 16 A flowchart for explaining processing operations performed by the control unit 16 The block diagram which shows the structure of the transmitter which concerns on the 2nd Embodiment of this invention. Diagram explaining polar modulation system Diagram explaining the problems that exist in polar modulation system The block diagram which shows the structural example of the conventional transmitter

Explanation of symbols

11 Phase-frequency converter 11a Differentiator 11b Reference frequency signal source 11c, 16d, 113, 114 Comparator 11d Reduction filter 11e Variable frequency divider 12 Frequency modulator 12a Voltage controlled oscillator (VCO)
13, 102 Amplifier 14 Multiplier 15 Bandpass filter 15a Digital filter 15b Discrete Fourier Transform (DFT)
16 Control part 16a Signal level calculation part 16b, 16c Memory 16e Counter 16f Selector 17, 18, 115, 116 Delay adjustment part 19a Analog-digital converter (AD converter)
19b Digital-analog converter (DA converter)
21, 111 Amplitude detector 22 Frequency detector 101 Phase modulator 112 Phase detector

Claims (6)

A transmitter using a polar modulation scheme,
A phase-frequency converter for converting an input phase signal into a frequency signal;
Frequency modulating the frequency signal to generate a phase-modulated wave signal; and
An amplifier for amplifying the phase-modulated wave signal according to the input amplitude signal;
A multiplier that multiplies the frequency signal and the amplitude signal input to the amplifier;
A band filter for extracting a distortion frequency component of a predetermined band from the signal multiplied by the multiplier;
The delay amount of at least one of the phase signal input to the phase-frequency conversion unit and the amplitude signal input to the amplification unit is adjusted so that the distortion frequency component extracted by the bandpass filter is below a predetermined level. A transmission apparatus comprising: a delay adjustment / control unit configured to A transmitter using a polar modulation scheme,
A phase-frequency converter for converting an input phase signal into a frequency signal;
Frequency modulating the frequency signal to generate a phase-modulated wave signal; and
An amplifier for amplifying the phase-modulated wave signal according to the input amplitude signal;
An amplitude detector for detecting the amplitude of the signal output from the amplifier;
A frequency detection unit for detecting the frequency of the signal output from the amplification unit;
A multiplier for multiplying the amplitude signal detected by the amplitude detector by the frequency signal detected by the frequency detector;
A band filter for extracting a distortion frequency component of a predetermined band from the signal multiplied by the multiplier;
The delay amount of at least one of the phase signal input to the phase-frequency conversion unit and the amplitude signal input to the amplification unit is adjusted so that the distortion frequency component extracted by the bandpass filter is below a predetermined level. A transmission apparatus comprising: a delay adjustment / control unit configured to   The transmission apparatus according to claim 1, wherein the phase-frequency conversion unit includes a differentiator that performs time differentiation processing on the input phase signal. The phase-frequency converter is
A variable frequency divider that outputs a frequency-divided signal of a phase-modulated wave signal fed back from the frequency modulator according to the input phase signal;
A reference frequency signal source for generating a reference frequency signal;
A phase comparator that compares the phase of the divided signal with the phase of the reference frequency signal;
The transmission apparatus according to claim 1 or 2, comprising a low-pass filter that generates the frequency signal from a comparison result of the phase comparator.   The transmission device according to claim 1, wherein the band filter is configured by a digital filter that digitally processes the signal multiplied by the multiplication unit. The transmission device according to claim 1, wherein the bandpass filter includes a discrete Fourier transformer that performs a discrete Fourier transform on the signal multiplied by the multiplication unit.

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