JP2005304007A - Phase modulation apparatus, polar modulation transmission apparatus, radio transmission apparatus and radio communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an excellent RF phase modulation signal even if a modulation sensitivity of a voltage controlled oscillator is varied. <P>SOLUTION: The phase modulation apparatus is provided with: a phase detector 105 for detecting a phase of an RF phase modulation signal outputted from a voltage controlled oscillator 101; a comparator 106 for comparing the detected signal with a phase of a baseband phase modulation signal and outputting a difference therebetween; and a variable gain amplifier 107 which controls a gain of the baseband phase modulation signal based on the output of the comparator 106 and supplies the gain controlled baseband phase modulation signal to the voltage controlled oscillator 101. Thus, a phase modulation apparatus 100 can be realized, in which a signal level of the baseband phase modulation signal supplied to the voltage controlled oscillator 101 can be changed in accordance with a modulation sensitivity of the voltage controlled oscillator 101, so that even if the modulation sensitivity of the voltage controlled oscillator 101 is varied, an excellent RF phase modulation signal can be obtained. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention particularly relates to a phase modulation device, a polar modulation transmission device, a wireless transmission device, and a wireless communication device that perform phase modulation using a PLL (Phase Locked Loop).

  Conventionally, a phase modulation device using a PLL is widely used to form a transmission signal by modulating a carrier signal with a baseband modulation signal (that is, upconverting a baseband modulation signal to a radio frequency). In this type of phase modulation apparatus, generally, low cost, low power consumption, good noise characteristics and modulation accuracy are required. When modulation is performed using a PLL, it is desirable to make the frequency band (PLL band) of the PLL wider than the frequency band (modulation band) of the modulation signal in order to improve the modulation accuracy.

  However, widening the PLL bandwidth leads to degradation of noise characteristics. Therefore, a technique called two-point modulation is proposed in which the PLL bandwidth is set narrower than the modulation bandwidth and the modulation within the PLL band and the modulation outside the PLL band are applied at two different locations (see, for example, Patent Document 1).

  FIG. 11 shows a configuration of a phase modulation apparatus using a conventional two-point modulation PLL. The phase modulation device 10 includes a voltage controlled oscillator (VCO) 1 whose oscillation frequency changes according to the voltage at the control voltage terminal, a frequency divider 2 that divides the frequency of the RF phase modulation signal output from the VCO 1, and a frequency divider A phase comparator 3 that compares the phases of the output signal of the frequency divider 2 and the reference signal and outputs a signal corresponding to the phase difference, and a loop filter 4 that averages and outputs the output signal of the phase comparator 3. The first modulation is performed by giving the carrier frequency data obtained by adding the phase modulation signal generated by the modulation signal generator 5 as the frequency division ratio of the frequency divider.

  In addition, the phase modulation device 10 passes the phase modulation signal through the post filter 6 and then adds it to the output of the loop filter 4 to supply it to the control voltage terminal of the voltage controlled oscillator 1, thereby performing the second modulation. To do.

  When such a two-point modulation technique is used, even if the PLL bandwidth is set to be narrower than the modulation bandwidth, it is possible to output a broadband RF phase modulation signal extending beyond the PLL band. As a result, it is possible to suppress the deterioration of noise characteristics due to the PLL.

  FIG. 12 is a diagram showing the frequency characteristics of the baseband region for explaining the operation of the two-point modulation PLL. Here, a transfer function representing the frequency characteristic of the PLL is H (s) (where s = jω). H (s) has a low-pass characteristic as shown in FIG. The modulation signal added to the frequency division ratio set in the frequency divider 2 is subjected to a low-pass filter having a transfer function H (s) by the PLL. On the other hand, the modulation signal output from the post filter 6 is applied to the control voltage terminal of the voltage controlled oscillator 1 to apply a high-pass filter having a transfer function 1-H (s) as shown in FIG. That is, when the modulation signal is set to Φ (s), the baseband component included in the RF modulation signal output from the voltage controlled oscillator 1 is irrelevant to the frequency characteristics of the PLL as expressed by the following equation.

H (s) Φ (s) + {1−H (s)} Φ (s) = Φ (s) (1)
As described above, when two-point modulation is applied to the PLL, it is possible to output a broadband RF modulation signal extending from the voltage controlled oscillator 1 to the outside of the PLL band. Note that fs is a sampling frequency.

  However, when the configuration as in Patent Document 1 is used, if the voltage controlled oscillator 1 is integrated in an LSI, the element value varies during manufacturing. Thereby, the modulation sensitivity of the voltage controlled oscillator 1 varies individually in each LSI. This modulation sensitivity varies with temperature. If the modulation sensitivity of the voltage controlled oscillator 1 varies, it becomes difficult to obtain a desired output signal (RF modulation signal). FIG. 13 shows an ideal VCO output signal, and FIG. 14 shows a VCO output signal when the modulation sensitivity changes.

  As one method for solving such a problem, there is a phase modulation device disclosed in Patent Document 2 conventionally. This phase modulation device is also a two-point modulation PLL, but differs from the configuration of Patent Document 1 shown in FIG. 11 in that the first modulation is performed by modulating the reference signal.

  FIG. 15 shows the configuration of the phase modulation apparatus disclosed in Patent Document 2. The phase modulation device 20 is down-converted with a voltage controlled oscillator (VCO) 21 whose oscillation frequency changes according to the voltage at the control voltage terminal, and a down converter 25 including a mixer 22, a synthesizer 23, and a low pass filter (LPF) 24. A frequency divider 26 that divides the frequency of the RF phase modulation signal, a phase comparator (PD) 27 that compares the output signal of the frequency divider 26 with the phase of the reference signal, and outputs a signal corresponding to the phase difference; A loop filter (LPF: low-pass filter) 28 that averages and outputs the output signal of the phase comparator 27;

  In addition, the phase modulation device 20 includes a direct digital synthesizer (DDS) 30. The direct digital synthesizer 30 forms a phase modulation signal having a reference frequency as a center frequency based on the baseband input phase modulation signal, and applies this to the phase comparator 27 as a reference signal to perform the first point modulation. .

  In addition, the phase modulation device 20 adds the input phase modulation signal to the output of the loop filter 28 by the adder 31 and supplies the added signal voltage to the control voltage terminal of the voltage controlled oscillator 21. Modulation is performed.

  Furthermore, the phase modulation device 20 includes a phase detector 32 that detects the phase of the phase modulation signal output from the low-pass filter 24, and a comparator that compares the detected signal with the baseband phase modulation signal and outputs a difference between them. 33 and a variable gain amplifier 34 that controls the gain of the baseband phase modulation signal based on the output of the comparator 33 and supplies the gain-controlled baseband phase modulation signal to the voltage controlled oscillator 21 at the subsequent stage of the loop filter 28. And have. In practice, the baseband phase modulation signal gain-controlled by the variable gain amplifier 34 is added to the output of the loop filter 28 by the adder 31 and supplied to the voltage controlled oscillator 21.

  In the above configuration, the variable gain amplifier 34 increases the gain by the difference value when the comparator 33 obtains a comparison result in which the signal level of the phase modulation signal is larger than the signal level of the phase detection signal. When the comparator 33 obtains a comparison result in which the signal level of the phase modulation signal is smaller than the signal level of the phase detection signal, the gain is lowered by the difference value.

As a result, even when the modulation sensitivity of the voltage controlled oscillator 21 varies, the modulation degree can be automatically adjusted.
U.S. Pat. No. 4,308,508 US Pat. No. 5,952,895

  However, in order to obtain good modulation accuracy characteristics in the phase modulation device 20 having the configuration shown in FIG. 15, it is necessary to increase the resolution in the DDS 30. In order to increase the resolution, a high-speed clock is required, which causes another problem of increased power consumption.

  In addition, in order to increase the clock, there is a tradeoff with power consumption and a limitation due to the operation limit frequency of the circuit. Therefore, in reality, the DDS output frequency cannot be increased so much. As a result, the bandwidth of the PLL has to be narrowed, and there has been another problem that the lock-up time of the PLL is increased accordingly.

  The present invention has been made in view of such a point, and even when the modulation sensitivity of the voltage controlled oscillator varies, a phase modulation device, a polar modulation transmission device, a wireless transmission device, and a An object is to provide a wireless communication device.

  In order to solve such a problem, one aspect of the phase modulation device of the present invention is provided in a PLL circuit and a PLL circuit, and a division ratio of the PLL circuit is set based on a baseband modulation signal and a carrier frequency signal. Provided between the frequency divider, the low-pass filter of the PLL circuit, and the voltage-controlled oscillator of the PLL circuit, and adds a voltage corresponding to the baseband modulation signal to the output voltage of the low-pass filter and supplies it to the control voltage terminal of the voltage-controlled oscillator An adder, a phase detector that detects the phase of the RF phase modulation signal output from the voltage controlled oscillator, a comparator that compares the phase detected RF phase modulation signal and the baseband modulation signal, and outputs a difference between them. Gain control means for controlling the gain of the baseband modulation signal based on the output of the comparator and outputting the gain-controlled baseband modulation signal to the adder. Employs a configuration in which Bei.

  According to this configuration, since the gain of the baseband modulation signal is controlled in accordance with the modulation sensitivity of the actual voltage controlled oscillator, a good RF modulated signal is output from the voltage controlled oscillator.

  One aspect of the phase modulation apparatus of the present invention employs a configuration further including a down converter that down-converts an RF phase modulation signal output from a voltage controlled oscillator and supplies the signal to a phase detector.

  According to this configuration, the phase detector detects the phase of the modulated signal that has been down-converted and has a low frequency, so that the configuration of the phase detector can be simplified and the detection accuracy can be improved.

  One aspect of the phase modulation apparatus of the present invention includes a second frequency divider that divides the RF phase modulation signal output from the voltage controlled oscillator and supplies it to the phase detector, and a bandwidth of the baseband modulation signal. A bandwidth conversion unit that converts the frequency division ratio of the second frequency divider according to the frequency division ratio and supplies it to the comparator is adopted.

  According to this configuration, the phase detector detects the phase of the modulated signal that has been frequency-divided and lowered in frequency, so that the configuration of the phase detector can be simplified and the detection accuracy can be improved. Further, since the baseband modulated signal converted into the bandwidth matched to the frequency division ratio by the bandwidth converter is input to the comparator, the comparator can compare signals of the same bandwidth.

  According to one aspect of the phase modulation apparatus of the present invention, the phase detector phase-detects the signal output from the frequency divider instead of the RF phase modulation signal, and also divides the bandwidth of the baseband modulation signal. A configuration is further provided that further includes a bandwidth conversion unit that converts the frequency division ratio and supplies it to the comparator.

  According to this configuration, it is possible to detect a low-frequency signal after frequency division without down-converting the RF modulation signal. Therefore, it is easy to eliminate the need for a down converter such as a mixer or a synthesizer. The detection accuracy can be improved with a simple configuration and low power consumption. Further, since the baseband modulated signal converted into the bandwidth matched to the frequency division ratio by the bandwidth converter is input to the comparator, the comparator can compare signals of the same bandwidth.

  One aspect of the polar modulation transmission apparatus of the present invention includes an amplitude phase separation unit that forms a phase modulation signal and an amplitude modulation signal based on transmission data, and a PLL that inputs the phase modulation signal and outputs an RF phase modulation signal Circuit, a frequency divider provided in the PLL circuit and setting a frequency division ratio of the PLL circuit based on the phase modulation signal and the carrier frequency signal, a low pass filter of the PLL circuit, and a voltage controlled oscillator of the PLL circuit An adder that adds a voltage according to the phase modulation signal to the output voltage of the low-pass filter and supplies the voltage to the control voltage terminal of the voltage controlled oscillator, and amplitude modulates the amplitude of the RF phase modulation signal output from the voltage controlled oscillator A high-frequency power amplifier that varies according to the signal, a coupler that detects the output signal of the high-frequency power amplifier, and the amplitude of the signal detected by the coupler is limited. Based on the width limiter, the phase detector that detects the phase of the signal output from the amplitude limiter, the comparator that compares the phase-detected signal with the phase-modulated signal, and outputs the difference between them, and the output of the comparator And a gain control means for controlling the gain of the phase modulation signal and supplying the gain-controlled phase modulation signal to the adder.

  According to this configuration, the amplitude modulation component of the transmission signal output from the high frequency power amplifier is removed by the amplitude limiting unit. The signal is phase-detected, compared with the baseband phase modulation signal, and based on the result, the signal level of the baseband phase modulation signal supplied immediately before the voltage controlled oscillator is controlled by the gain control means. In addition to the deterioration in modulation accuracy caused by the modulation sensitivity of the oscillator, it is possible to realize a polar modulation transmission apparatus capable of simultaneously compensating for AM-PM distortion generated in the amplitude modulation section.

  One aspect of the polar modulation transmission apparatus of the present invention employs a configuration further including a down converter that down-converts a signal input to the phase detector.

  According to this configuration, since the phase detector detects the phase of the down-converted signal, the configuration of the phase detector can be simplified and the detection accuracy can be improved.

  One aspect of the polar modulation transmission apparatus of the present invention includes an amplitude phase separation unit that forms a phase modulation signal and an amplitude modulation signal based on transmission data, and a PLL that inputs the phase modulation signal and outputs an RF phase modulation signal Circuit, a frequency divider provided in the PLL circuit and setting a frequency division ratio of the PLL circuit based on the phase modulation signal and the carrier frequency signal, a low pass filter of the PLL circuit, and a voltage controlled oscillator of the PLL circuit An adder that adds a voltage according to the phase modulation signal to the output voltage of the low-pass filter and supplies the voltage to the control voltage terminal of the voltage controlled oscillator, and amplitude modulates the amplitude of the RF phase modulation signal output from the voltage controlled oscillator A high-frequency power amplifier that varies according to the signal, a coupler that detects the output signal of the high-frequency power amplifier, and a phase detection by dividing the signal detected by the coupler. A second frequency divider to be supplied to the frequency divider, a phase detector for phase-detecting the signal output from the second frequency divider, and the bandwidth of the phase modulation signal to the frequency divider ratio of the second frequency divider Bandwidth conversion means for converting together, a comparator that compares the signal detected by the phase detector and the phase modulation signal that has been bandwidth-converted by the bandwidth conversion means, and outputs the difference between them, and the output of the comparator Based on this, the gain of the phase modulation signal is controlled, and gain control means for supplying the gain-controlled phase modulation signal to the adder is adopted.

  According to this configuration, since the frequency divider has an amplitude limiting function in addition to the frequency dividing function, the frequency divider outputs a transmission signal in which the frequency is reduced and the amplitude modulation component is removed. The signal is phase-detected, compared with the baseband phase modulation signal, and based on the result, the signal level of the baseband modulation signal supplied immediately before the voltage control oscillator is controlled by the gain control means. In addition to the deterioration of modulation accuracy caused by the modulation sensitivity, it is possible to realize a polar modulation transmission apparatus that can simultaneously compensate for AM-PM distortion generated in the amplitude modulation section.

  A radio transmission apparatus according to the present invention employs a configuration including any one of the phase modulation apparatuses described above and an amplifier that amplifies an RF phase modulation signal output from the phase modulation apparatus.

  A wireless communication apparatus according to the present invention includes a transmitter having any one of the above-described phase modulation apparatuses, a receiver that demodulates a received signal, an antenna, supply of a transmission signal from the transmitter to the antenna, and transmission from the antenna to the receiver. A configuration including a duplexer that switches between supply of received signals is adopted.

  According to these configurations, a good RF phase modulation signal can be obtained even when the modulation sensitivity of the voltage-controlled oscillator of the phase modulation device varies, so that a high-quality signal can be transmitted. For example, even when the phase modulator is placed in various temperature environments due to heat generated from the amplifier or an external temperature, and the modulation sensitivity of the voltage controlled oscillator varies due to this temperature change, a high-quality signal can be transmitted.

  Thus, according to the present invention, it is possible to realize a phase modulation apparatus that can obtain a satisfactory RF phase modulation signal even when the modulation sensitivity of the voltage controlled oscillator varies. In addition, it is possible to realize a polar modulation transmission device, a wireless transmission device, and a wireless communication device that can transmit a high-quality signal even when the amplifier generates heat or changes in external temperature.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 shows the configuration of a phase modulation apparatus according to Embodiment 1 of the present invention. The phase modulation apparatus 100 includes a voltage controlled oscillator (VCO) 101 whose oscillation frequency changes according to the voltage at the control voltage terminal, and a frequency divider 102 that divides the frequency of the RF phase modulation signal output from the voltage controlled oscillator 101. A phase comparator (PD) 103 that compares the phases of the output signal of the frequency divider 102 and the reference signal and outputs a signal corresponding to the phase difference, and a loop filter that averages and outputs the output signal of the phase comparator 103 (LPF: low-pass filter) 104. The first modulation is performed by giving the VCO output frequency setting signal (carrier frequency data) added with the baseband input phase modulation signal as the frequency division ratio of the frequency divider 102.

  Further, the phase modulation apparatus 100 performs the second modulation by supplying the signal voltage obtained by adding the input phase modulation signal to the output of the loop filter 104 by the adder 108 to the control voltage terminal of the voltage controlled oscillator 101. It has become.

  By the way, instead of adding the baseband phase modulation signal to the reference signal in this way, the frequency division ratio is changed temporally by inputting the baseband phase modulation signal to the frequency divider, and the average value is calculated. A method of setting a desired frequency division ratio is generally called a Fractional-N method. When this Fractional-N method is used, compared with a method of adding a baseband phase modulation signal to the reference signal, the comparison frequency in the phase comparator can be set higher, and the lock-up time of the PLL can be shortened accordingly. .

  When a signal obtained by adding a baseband phase modulation signal to a reference signal is used as an input of a phase comparator, for example, a direct digital synthesizer (DDS) may be used. However, in order to increase the resolution in DDS, Since a high-speed clock is required, power consumption increases. In fact, there is a limit to raising the clock, so the DDS output frequency cannot be so high. As a result, since the bandwidth of the PLL must be narrowed, the PLL lock-up time is increased accordingly. The Fractional-N method adopted in the present embodiment is a very effective method in these respects.

  In addition to such a configuration, the phase modulation apparatus 100 according to the present embodiment includes a phase detector 105 that detects an RF phase modulation signal output from the voltage controlled oscillator 101, a detected signal, and a baseband phase modulation signal. And a comparator 106 that outputs the difference between them, and the gain of the baseband phase modulation signal is controlled based on the output of the comparator 106, and the gain-controlled baseband phase modulation signal is output after the loop filter 104. And a variable gain amplifier 107 that supplies the voltage controlled oscillator 101. Actually, the baseband phase modulation signal gain-controlled by the variable gain amplifier 107 is added to the output of the loop filter 104 by the adder 108 and supplied to the voltage controlled oscillator 101.

  In the above configuration, when the modulation sensitivity (Hz / V) of the voltage controlled oscillator 101 is low, the signal level output from the phase detector 105 is lower than the desired signal level. When the comparator 106 performs a comparison operation for subtracting the phase detection signal from the phase modulation signal, a positive difference value is obtained from the comparator 106. At this time, the variable gain amplifier 107 increases the gain of the phase modulation signal by this positive difference value and outputs it.

  On the other hand, when the modulation sensitivity of the voltage controlled oscillator 101 is high, the phase modulation apparatus 100 causes the signal level output from the phase detector 105 to be higher than the desired signal level. When a comparison operation for subtracting the phase detection signal from the modulation signal is performed, a negative difference value is output from the comparator 106. At this time, the variable gain amplifier 107 lowers the gain of the phase signal by this negative difference value and outputs it.

  That is, in the variable gain amplifier 107, when the comparator 106 obtains a comparison result in which the signal level of the phase modulation signal is larger than the signal level of the phase detection signal, the gain is increased by the difference value. Thus, when a comparison result is obtained in which the signal level of the phase modulation signal is smaller than the signal level of the phase detection signal, the gain is lowered by the difference value.

  As a result, even when the modulation sensitivity of the voltage controlled oscillator 101 varies, a good RF phase modulation signal as shown in FIG. 13 can be obtained.

  Thus, according to the present embodiment, the phase detector 105 for detecting the phase of the RF phase modulation signal output from the voltage controlled oscillator 101, the detected RF phase modulation signal and the original phase modulation signal are compared, and the difference is obtained. By providing a comparator 106 for outputting, and a variable gain amplifier 107 for controlling the gain of the phase modulation signal based on the output of the comparator 106 and supplying the gain-controlled phase modulation signal to the voltage controlled oscillator 101, a voltage is provided. Even when the modulation sensitivity of the control oscillator 101 varies, the phase modulation device 100 that can obtain a good RF phase modulation signal can be realized.

  In the above-described embodiment, the variable gain amplifier 107 is used as a gain control unit that controls the gain of the phase modulation signal based on the output of the comparator 106 and supplies the gain-controlled phase modulation signal to the voltage controlled oscillator 101. However, the gain control means is not limited to the variable gain amplifier, and any circuit may be used as long as it can control the gain.

  In the above-described embodiment, the phase modulation signal is described as an example of the baseband modulation signal input to the phase modulation device. However, the present invention is not limited to this, and another modulation signal may be input. The same applies to Embodiments 2 to 4 described later. Incidentally, the reason why the phase modulation signal is taken as an example is that it is assumed that the phase modulation device of the present invention is applied to a polar modulation transmission device, as will be described later in Embodiment 5 and Embodiment 6. . However, the phase modulation device of the present invention can be applied to devices other than the radio transmission device using the polar modulation method, and even in that case, the same effect as the above-described embodiment can be obtained.

(Embodiment 2)
The phase modulation apparatus of this embodiment is shown in FIG. 2, in which parts corresponding to those in FIG. Compared with phase modulation apparatus 100 of the first embodiment, phase modulation apparatus 200 includes down converter 201 that down-converts the RF phase modulation signal and sends it to the phase detector.

  For example, as shown in FIG. 2, the down converter 201 includes a mixer 202, a synthesizer 203, and a low-pass filter (LPF) 204, and inputs the RF phase modulation signal and the frequency generated by the synthesizer 203 to the mixer 202. Thus, the frequency of the RF phase modulation signal is lowered to the frequency generated by the synthesizer. The configuration of the down converter is not limited to this, and in short, any circuit may be used as long as the frequency of the RF phase modulation signal can be lowered.

  The signal whose frequency is lowered by the down converter 201 is input to the phase detector 105. Subsequent processing is the same as in the first embodiment, and a description thereof will be omitted.

  As described above, according to the present embodiment, in addition to the configuration of the first embodiment, the down-converter 201 that down-converts the RF phase modulation signal output from the voltage-controlled oscillator 101 and supplies it to the phase detector 105. In addition to the effects of the first embodiment, the configuration of the phase detector 105 can be simplified and the detection accuracy can be improved.

(Embodiment 3)
The phase modulation apparatus of this embodiment is shown in FIG. 3 in which parts corresponding to those in FIG. Compared with the phase modulation apparatus 100 of the first embodiment, the phase modulation apparatus 300 divides the RF phase modulation signal output from the voltage controlled oscillator 101 and supplies it to the phase detector 105; A bandwidth conversion circuit 302 that converts the bandwidth of the phase modulation signal in accordance with the frequency division ratio of the frequency divider 301 and supplies the converted signal to the comparator 106;

  Thus, by providing the frequency divider 301 and lowering the frequency of the RF phase modulation signal input to the phase detector 105, the configuration of the phase detector 105 can be simplified and the detection accuracy can be improved. .

  By the way, when the RF phase modulation signal passes through the frequency divider 301, the bandwidth becomes 1 / D (where D is the frequency division ratio of the frequency divider 301). Therefore, in the phase modulation apparatus 300, a bandwidth conversion circuit 302 is provided, and the bandwidth conversion circuit 302 sets the bandwidth of the phase modulation signal to 1 / D and then inputs it to the comparator 106. Signals of the same bandwidth can be compared with each other.

  For example, the bandwidth conversion circuit 302 may shift the frequency of the input signal by 1 / D and output it. FIG. 4 shows the phase shift operation by the bandwidth conversion circuit 302 in this case. As shown in FIG. 5, the bandwidth conversion circuit 302 can be realized by an amplifier having a gain of 1 / D, for example.

  The frequency dividing ratio of the frequency divider 301 may be a fixed value. Since an asynchronous circuit can be used when it is raised to a power of 2, a low power consumption frequency divider can be realized.

  As described above, according to the present embodiment, in addition to the configuration of the first embodiment, the frequency divider that divides the RF phase modulation signal output from the voltage controlled oscillator 101 and supplies the frequency detector 105 to the phase detector 105 301 and the bandwidth conversion circuit 302 that converts the bandwidth of the baseband phase modulation signal in accordance with the frequency division ratio of the frequency divider 301 and supplies it to the comparator 106 are provided. In addition, the configuration of the phase detector 105 can be simplified and the detection accuracy can be improved.

(Embodiment 4)
FIG. 6 showing the parts corresponding to those in FIG. 1 with the same reference numerals shows the phase modulation apparatus of the present embodiment. Compared with the phase modulation device 100 of the first embodiment, the phase modulation device 400 does not input the RF phase modulation signal output from the voltage controlled oscillator 101 to the phase detector 105, but instead of the frequency divider 102. The output is input. The phase modulation apparatus 400 includes a bandwidth conversion circuit 302 that converts the bandwidth of the phase modulation signal in accordance with the frequency division ratio of the frequency divider 102 and supplies the converted signal to the comparator 106.

  Thereby, in phase modulation apparatus 400, the low frequency signal output from frequency divider 102 is detected by phase detector 105, so down converter 201 that down-converts the RF phase modulation signal as in the second embodiment. In addition, since it is not necessary to provide another frequency divider 301 as in the third embodiment, the phase detection accuracy can be improved with a simple configuration.

  By the way, when the RF phase modulation signal passes through the frequency divider 102, the bandwidth becomes 1 / N (where N is the frequency division ratio of the frequency divider 102). Therefore, in the phase modulation apparatus 400, the bandwidth conversion circuit 302 is provided, and the bandwidth 106 of the modulation signal is set to 1 / N by the bandwidth conversion circuit 302 and then input to the comparator 106. Bandwidth signals can be compared with each other.

  As described above, according to the present embodiment, the signal output from frequency divider 102 is input to phase detector 105 in place of the RF phase modulation signal, as compared with the configuration of the first embodiment. In addition, by providing a bandwidth conversion circuit 302 that converts the bandwidth of the baseband phase modulation signal in accordance with the frequency division ratio of the frequency divider 102 and supplies it to the comparator 106, the effect of the first embodiment is achieved. In addition, the configuration of the phase detector 105 can be simplified and the detection accuracy can be improved. Further, the configuration can be simplified as compared with the second and third embodiments.

(Embodiment 5)
In this embodiment, a preferred configuration when the phase modulation apparatus of the present invention is applied to a polar modulation transmission apparatus is presented. FIG. 7 in which the same reference numerals are assigned to the parts corresponding to those in FIG. 1 shows the configuration of polar modulation transmission apparatus 500 of the present embodiment.

  The polar modulation transmission apparatus 500 forms an amplitude phase separation unit 510, a high frequency power amplifier (hereinafter referred to as a power amplifier (PA)) 501, and a power supply voltage that amplifies the amplitude modulation signal and supplies the amplified signal to the power amplifier 501. A power supply voltage control unit 511.

  Polar modulation transmission apparatus 500 inputs baseband transmission data to amplitude phase separation section 510. The amplitude phase separation 510 forms a baseband amplitude modulation signal and a baseband phase modulation signal based on the transmission data, and sends the amplitude modulation signal to the power supply voltage control unit 511 and the phase modulation signal to the PLL circuit. Note that the amplitude / phase separation unit 510, the power supply voltage control unit 511, and the power amplifier 501 need not be described in detail because they may use known configurations used in conventional polar modulation transmission apparatuses.

  The RF phase modulation signal output from the voltage controlled oscillator 101 is sent to a power amplifier (PA) 501. The power amplifier 501 obtains an RF phase amplitude modulation signal (transmission signal) by changing the amplitude of the constant envelope RF phase modulation signal based on the amplitude modulation signal.

  The polar modulation transmission apparatus 500 includes a coupler 502 that detects an output signal of the power amplifier 501 and a limiter amplifier 503 as an amplitude limiting unit that limits the amplitude of the signal detected by the coupler 502. As a result, the amplitude modulation component of the transmission signal (RF phase amplitude modulation signal) output from the power amplifier 501 is removed by the limiter amplifier 503.

  The signal from which the amplitude modulation component has been removed is transmitted to the phase detector 105 after the frequency is lowered by a down converter 504 including a mixer 505, a synthesizer 506, and a low pass filter (LPF) 507. The subsequent configuration and operation are the same as those in the first embodiment.

  As described above, according to the present embodiment, the coupler 502 that detects the phase amplitude modulation signal output from the power amplifier 501, the limiter amplifier 503 that limits the amplitude of the signal detected by the coupler 502, and the limiter amplifier A phase detector 105 that performs phase detection on the signal output from 503; a comparator 106 that compares the detected signal with a baseband phase modulation signal and outputs a difference between them; and phase modulation based on the output of the comparator By providing a variable gain amplifier 107 that controls the gain of the signal and supplies the voltage-controlled oscillator 101 with a gain-controlled baseband phase-modulated signal, the modulation accuracy is degraded due to variations in the modulation sensitivity of the voltage-controlled oscillator 101. In addition to the polar, the AM-PM distortion generated in the power amplifier 501 can be compensated simultaneously. It is possible to realize a control transmitter device 500.

  In this embodiment, the limiter amplifier 503 is used as the amplitude limiting unit. However, the amplitude limiting unit is not limited to this, and any circuit may be used as long as the signal amplitude can be a constant envelope. . Further, the down converter 504 may be omitted. Further, the present invention can be applied to a configuration in which a linear mixer or a gain control amplifier is used instead of the power amplifier 501. In short, a signal after the amplitude modulation unit that varies the amplitude of the RF phase modulation signal in accordance with the amplitude modulation signal may be detected by the coupler.

(Embodiment 6)
The polar modulation transmission apparatus of this embodiment is shown in FIG. 8 in which the same reference numerals are assigned to the parts corresponding to those in FIG. Polar modulation transmission apparatus 600 is different from polar modulation transmission apparatus 500 of the fifth embodiment in that frequency divider 601 is provided instead of limiter amplifier 503 and down converter 504, and frequency division of frequency divider 601 is performed. Polar modulation transmission apparatus 500 according to the fifth embodiment, except that bandwidth conversion circuit 602 that converts the bandwidth of the baseband phase modulation signal to 1 / D and supplies the same to comparator 106 in accordance with ratio D is provided. It has the same configuration as

  Since the frequency divider 601 has an amplitude limiting function in addition to the frequency dividing function, amplitude limiting means such as a limiter amplifier can be omitted. Thereby, in polar modulation transmission apparatus 600, the same effect as in the fifth embodiment can be obtained with a simpler configuration.

(Other embodiments)
FIG. 9 shows a configuration of a wireless transmission device on which the phase modulation device according to the first to fourth embodiments is mounted. Radio transmission apparatus 700 amplifies an RF phase modulation signal obtained by phase modulation apparatus 100 (200, 300, 400) of any of Embodiments 1 to 4 and phase modulation apparatus 100 (200, 300, 400) And an antenna 702 for transmitting the amplified signal. Thereby, in the wireless transmission device 700, a good RF phase modulation signal can be obtained even when the modulation sensitivity of the voltage controlled oscillator 101 of the phase modulation device 100 (200, 300, 400) varies. The signal can be transmitted. For example, even when the phase modulation device 100 (200, 300, 400) is placed in various temperature environments due to heat generated from the amplifier 701 or an external temperature, and the modulation sensitivity of the voltage controlled oscillator 101 varies due to this temperature change. High quality signal can be transmitted.

  FIG. 10 shows a configuration of a wireless communication apparatus equipped with the phase modulation apparatus according to the first to fourth embodiments. Radio transmitting apparatus 800 includes transmitting section 801 including phase modulation apparatus 100 (200, 300, 400) and amplifier 701 according to any one of Embodiments 1 to 4, and predetermined reception processing including demodulation processing on a received signal A receiving unit 802 that performs switching, a duplexer 803 that switches between a transmission signal and a reception signal, and an antenna 702. As a result, the radio communication apparatus 800 can transmit a high-quality signal even when the modulation sensitivity of the voltage controlled oscillator 101 of the phase modulation apparatus 100 (200, 300, 400) varies. In particular, in a portable terminal such as a cellular phone, the temperature change of the voltage controlled oscillator increases along with transmission power control and external temperature variation. Therefore, the present invention is very suitable when applied to a portable terminal such as a cellular phone.

  The present invention can obtain a good RF phase modulation signal even when the modulation sensitivity of the voltage controlled oscillator varies, and is suitable for application to a mobile terminal such as a mobile phone and a radio communication device such as a base station thereof. It is.

1 is a block diagram showing the configuration of a phase modulation apparatus according to Embodiment 1 of the present invention. FIG. 3 is a block diagram showing a configuration of a phase modulation apparatus according to a second embodiment. FIG. 4 is a block diagram showing a configuration of a phase modulation apparatus according to a third embodiment. Diagram for explaining operation of bandwidth conversion circuit The figure which shows the structural example of the bandwidth conversion circuit A block diagram showing a configuration of a phase modulation apparatus according to a fourth embodiment. Block diagram showing a configuration of a polar modulation transmission apparatus according to a fifth embodiment Block diagram showing a configuration of a polar modulation transmission apparatus according to a sixth embodiment The block diagram which shows the structure of the radio | wireless transmitter of other embodiment The block diagram which shows the structure of the radio | wireless communication apparatus of other embodiment. Block diagram showing the configuration of a conventional two-point modulation type phase modulation apparatus Characteristic curve diagram showing a baseband signal spectrum in a two-point modulation type phase modulation apparatus Characteristic diagram showing ideal VCO output Characteristic diagram showing VCO output when modulation sensitivity changes Block diagram showing the configuration of a conventional two-point modulation type phase modulation apparatus

Explanation of symbols

100, 200, 300, 400 Phase modulator 101 Voltage controlled oscillator (VCO)
102, 301, 601 Frequency divider 103 Phase comparator (PD)
104 Loop filter (LPF)
DESCRIPTION OF SYMBOLS 105 Phase detector 106 Comparator 107 Variable gain amplifier 108 Adder 201,504 Down converter 302,602 Bandwidth conversion circuit 500,600 Polar modulation transmitter 501 High frequency power amplifier (power amplifier)
502 coupler 503 limiter amplifier 510 amplitude phase separation unit 511 power supply voltage control unit 700 wireless transmission device 701 amplifier 800 wireless communication device 801 transmission unit 802 reception unit

Claims (9)

A PLL circuit;
A frequency divider provided in the PLL circuit for setting a frequency division ratio of the PLL circuit based on a baseband modulation signal and a carrier frequency signal;
Provided between the low-pass filter of the PLL circuit and the voltage-controlled oscillator of the PLL circuit, and adds a voltage corresponding to the baseband modulation signal to the output voltage of the low-pass filter and supplies it to the control voltage terminal of the voltage-controlled oscillator An adder to
A phase detector for detecting a phase of an RF phase modulation signal output from the voltage controlled oscillator;
A comparator that compares the phase-detected RF phase modulation signal and the baseband modulation signal and outputs a difference between them;
Gain control means for controlling the gain of the baseband modulation signal based on the output of the comparator and outputting the gain-controlled baseband modulation signal to the adder. Phase modulator. The phase modulation apparatus according to claim 1, further comprising a down converter that down-converts an RF phase modulation signal output from the voltage controlled oscillator and supplies the RF phase modulation signal to the phase detector. A second frequency divider that divides the RF phase modulation signal output from the voltage controlled oscillator and supplies it to the phase detector;
2. A bandwidth conversion unit that further converts a bandwidth of the baseband modulation signal in accordance with a frequency division ratio of the second frequency divider and supplies the converted bandwidth to the comparator. The phase modulation device according to 1. The phase detector, instead of the RF phase modulation signal, phase-detects the signal output from the frequency divider,
2. The phase according to claim 1, further comprising: a bandwidth conversion unit that converts a bandwidth of the baseband modulation signal in accordance with a division ratio of the frequency divider and supplies the converted bandwidth to the comparator. Modulation device. An amplitude phase separation unit that forms a phase modulation signal and an amplitude modulation signal based on transmission data;
A PLL circuit that inputs the phase modulation signal and outputs an RF phase modulation signal;
A frequency divider provided in the PLL circuit for setting a frequency division ratio of the PLL circuit based on the phase modulation signal and the carrier frequency signal;
Provided between the low-pass filter of the PLL circuit and the voltage-controlled oscillator of the PLL circuit, adds a voltage corresponding to the phase modulation signal to the output voltage of the low-pass filter and supplies the voltage to the control voltage terminal of the voltage-controlled oscillator An adder;
A high frequency power amplifier that varies the amplitude of the RF phase modulation signal output from the voltage controlled oscillator in accordance with the amplitude modulation signal;
A coupler for detecting an output signal of the high-frequency power amplifier;
Amplitude limiting means for limiting the amplitude of the signal detected by the coupler;
A phase detector for phase detection of the signal output from the amplitude limiting means;
A comparator that compares the phase-detected signal with the phase-modulated signal and outputs a difference between them;
A polar modulation transmission apparatus comprising: gain control means for controlling a gain of the phase modulation signal based on an output of the comparator and outputting the gain-controlled phase modulation signal to the adder. The polar modulation transmission apparatus according to claim 5, further comprising a down converter that down-converts a signal input to the phase detector. An amplitude phase separation unit that forms a phase modulation signal and an amplitude modulation signal based on transmission data;
A PLL circuit for inputting the phase modulation signal and outputting an RF phase modulation signal;
A frequency divider provided in the PLL circuit for setting a frequency division ratio of the PLL circuit based on the phase modulation signal and the carrier frequency signal;
Provided between the low-pass filter of the PLL circuit and the voltage-controlled oscillator of the PLL circuit, adds a voltage corresponding to the phase modulation signal to the output voltage of the low-pass filter and supplies the voltage to the control voltage terminal of the voltage-controlled oscillator An adder;
A high frequency power amplifier that varies the amplitude of the RF phase modulation signal output from the voltage controlled oscillator in accordance with the amplitude modulation signal;
A coupler for detecting an output signal of the high-frequency power amplifier;
A second divider for dividing the signal detected by the coupler and supplying the divided signal to the phase detector;
A phase detector for detecting a phase of a signal output from the second frequency divider;
Bandwidth conversion means for converting the bandwidth of the phase modulation signal in accordance with the frequency division ratio of the second frequency divider;
A comparator that compares the signal detected by the phase detector with the phase modulation signal bandwidth-converted by the bandwidth converter and outputs a difference between them;
A polar modulation transmission apparatus comprising: gain control means for controlling a gain of the phase modulation signal based on an output of the comparator and outputting the gain-controlled phase modulation signal to the adder. A phase modulation device according to any one of claims 1 to 4,
An amplifier for amplifying an RF phase modulation signal output from the phase modulation device. A transmitter having the phase modulation device according to any one of claims 1 to 4,
A receiver for demodulating the received signal;
An antenna,
A wireless communication apparatus comprising: a duplexer that switches between supply of a transmission signal from the transmission unit to the antenna and supply of a reception signal from the antenna to the reception unit.

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