JP2005295536A - Frequency modulation apparatus, polar modulation transmission apparatus, radio transmission device, and radio communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a two-point modulation type frequency modulation apparatus capable of settling the spectrum of a transmission wave within a spectrum mask. <P>SOLUTION: The voltage corresponding to modulation data is supplied to a control voltage terminal of a VCO 1 via a noise shaper 101 having the characteristic that quantization noise is attenuated as a frequency increases, so that a signal level which is outputted from a PLL circuit, obtained by adding a modulation signal and quantization noise is reduced as away from a center frequency, thereby realizing the two-point modulation type frequency modulation apparatus 100 capable of settling the spectrum of an RF modulation signal within a spectrum mask. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

  Conventionally, a frequency 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 frequency modulation device, 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. 15 shows a configuration of a frequency modulation apparatus using a conventional two-point modulation PLL. The frequency 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 modulation signal output from the VCO 1, and a frequency division A phase comparator 3 that compares the phases of the output signal of the comparator 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 modulation data generated by the modulation signal generator 5 as the frequency division ratio of the frequency divider.

In addition, the frequency modulation apparatus 10 converts the modulation data into an analog voltage by a digital / analog converter (D / A converter) 6, and suppresses aliasing noise appearing at the output of the D / A converter 6 by a post filter 7. Later, this is added to the output of the loop filter 4 and supplied to the control voltage terminal of the VCO 1 to perform the second modulation.
US Pat. No. 4,308,508

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

First, the frequency characteristics when two-point modulation is used will be considered. FIG. 16 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 7 is applied to the control voltage terminal of the VCO 1 to apply a high-pass filter having a transfer function 1-H (s) as shown in FIG. That is, if the modulation data is Φ (s), the baseband component included in the RF modulation signal output from the VCO 1 is irrelevant to the PLL frequency characteristics as represented by the following equation.
H (s) Φ (s) + {1−H (s)} Φ (s) = Φ (s) (1)

  Thus, when two-point modulation is applied to the PLL, it is possible to output a wideband RF modulation signal extending from the VCO 1 to outside the PLL band. Note that fs is a sampling frequency (an operating frequency of the D / A converter 6).

  Incidentally, quantization noise as shown in FIG. 16 is generated at the output of the D / A converter 6. The post filter 7 is required to suppress this quantization noise. The post filter 7 has a low-pass characteristic as shown in FIG. If the bandwidth is too narrow, the modulated signal shown in FIG. 16 is suppressed. Conversely, if the bandwidth is too wide, the influence on the modulation signal can be avoided, but noise such as quantization noise cannot be sufficiently suppressed.

  FIG. 17 illustrates the spectrum of the RF modulation signal that appears at the output of the VCO 1. A waveform in which quantization noise is superimposed on the modulation signal is output from the VCO 1. The reason why the quantization noise near the center frequency (fvco) is suppressed is due to the characteristic of 1-H (s) in FIG. The reason why the quantization noise is suppressed away from fvco is due to the frequency characteristics of the post filter 7.

  By the way, the GSM (Global System for Mobile Communications) standard and the like stipulate that the spectrum of a transmission wave should not protrude from a spectrum mask as indicated by a dotted line in the figure.

  However, in the conventional two-point modulation type frequency modulation device, as shown in FIG. 17, the spectrum of the transmission wave may protrude from the spectrum mask due to the influence of quantization noise.

  The present invention has been made in view of this point, and provides a two-point modulation type frequency modulation device, a polar modulation transmission device, a wireless transmission device, and a wireless communication device that can store the spectrum of a transmission wave within a spectrum mask. The purpose is to do.

  In order to solve such a problem, one aspect of the frequency modulation device of the present invention includes a PLL circuit and a PLL circuit that is provided in the PLL circuit and sets a frequency division ratio of the PLL circuit based on a baseband modulation signal and a carrier frequency signal. Provided between the frequency divider, the loop 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 loop filter and supplies it to the control voltage terminal of the voltage controlled oscillator A configuration is adopted that includes an adder and a noise shaper that changes the frequency characteristics of quantization noise that is generated when the baseband signal is converted to analog and supplied to the adder.

  According to this configuration, in the two-point modulation type frequency modulation device, the frequency characteristic of the quantization noise generated when the voltage supplied to the control voltage terminal of the voltage controlled oscillator can be changed by the noise shaper. Therefore, it becomes easy to fit the transmission wave including the quantization noise in the spectrum mask.

  One aspect of the frequency modulation device of the present invention employs a configuration in which a noise shaper attenuates quantization noise in a higher frequency range.

  According to this configuration, the signal level output from the PLL circuit, which is the sum of the modulation signal and the quantization noise, decreases as the distance from the center frequency increases, so that the transmission wave can be easily contained in the spectrum mask. Note that the low frequency component of the quantization noise is not a problem because it can be suppressed by the characteristics of the PLL circuit.

  One aspect of the frequency modulation apparatus of the present invention employs a configuration in which the noise shaper has a transfer function obtained by adding integrated quantization noise to a baseband modulation signal.

  According to this configuration, since the integrated quantization noise has a low-pass characteristic, the quantization noise can be attenuated as the frequency is increased, and the transmission wave including the quantization noise is spectrum masked. It becomes easier to fit inside.

  According to one aspect of the frequency modulation device of the present invention, the noise shaper has a differentiator for differentiating the baseband modulation signal, a quantizer, and the output signal of the differentiator and the output signal of the quantizer in time. A configuration including a feedback circuit for adding and inputting to the quantizer is adopted.

  According to this configuration, the transfer function of the noise shaper can be obtained by adding the integrated quantization noise to the baseband modulation signal.

  One aspect of the frequency modulation device of the present invention employs a configuration in which the noise shaper is a band-pass delta sigma modulator.

  According to this configuration, quantization noise at a specific frequency can be suppressed, so that leakage of the transmitted wave outside the spectrum mask can be favorably avoided in combination with the characteristics of other filters (for example, a post filter). Will be able to.

  One aspect of the frequency modulation device of the present invention employs a configuration in which the noise shaper is a delta modulator.

  According to this configuration, the delta modulator can lower the absolute level of the quantization noise appearing in the output by increasing the operating frequency, so that the transmission wave including the quantization noise is contained in the spectrum mask. It becomes easy.

  One aspect of the frequency modulation device of the present invention further employs a configuration in which a low-pass filter is provided between the noise shaper and the adder.

  According to this configuration, it is possible to suppress the signal in the high frequency band by the low-pass filter (for example, the post filter) while changing the frequency characteristic of the quantization noise by the noise shaper. Is easily stored in the spectrum mask. For example, if the high frequency component of the quantization noise is suppressed by a noise shaper, the low pass characteristic of the low pass filter need not be so narrow that the modulation signal waveform for the baseband modulation signal is suppressed. As a result, the transmission wave including the quantization noise can be accommodated in the spectrum mask while maintaining the modulation signal waveform.

  One aspect of the polar modulation transmission apparatus of the present invention inputs an amplitude phase separation unit that forms a baseband phase modulation signal and an amplitude modulation signal based on the baseband modulation signal, and a baseband phase modulation signal. A PLL circuit that outputs an RF phase modulation signal, a high frequency power amplifier that varies the amplitude of the RF phase modulation signal output from the voltage controlled oscillator of the PLL circuit according to the amplitude modulation signal, and a PLL circuit, Based on the phase modulation signal of the band and the carrier frequency signal, provided between the frequency divider for setting the frequency division ratio of the PLL circuit, the loop filter of the PLL circuit, and the voltage controlled oscillator of the PLL circuit, and the output of the loop filter An adder that adds a voltage corresponding to the baseband phase modulation signal to the voltage and supplies it to the control voltage terminal of the voltage controlled oscillator, and a baseband phase The tone signal employs a configuration comprising a noise shaper to change the frequency characteristic of the quantization noise generated when supplied to the adder into analog.

  According to this configuration, it is possible to realize a two-point modulation type polar modulation transmission apparatus in which the transmission wave does not protrude from the spectrum mask due to the influence of quantization noise. As a result, in addition to the effect of improving the power efficiency by the polar modulation method and the effect of improving the modulation accuracy by the two-point modulation, it is possible to realize a polar modulation transmission apparatus that can securely fit the transmission wave in the spectrum mask.

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

  A wireless communication apparatus according to the present invention includes a transmission unit having any one of the above frequency modulation devices, a reception unit that demodulates a reception signal, an antenna, supply of a transmission signal from the transmission unit to the antenna, and transmission from the antenna to the reception unit. A configuration including a transmission / reception switching unit that switches between supply of reception signals is adopted.

  According to these configurations, high-accuracy frequency modulation by two-point modulation can be performed, so that a high-quality transmission signal can be obtained, and in addition, a transmission wave can be reliably contained in a spectrum mask. Therefore, it is possible to realize a wireless transmission device and a wireless communication device that can suppress interference with other wireless devices.

  According to the present invention, it is possible to realize a two-point modulation type frequency modulation device, polar modulation transmission device, wireless transmission device, and wireless communication device that can fit the spectrum of a transmission wave within a spectrum mask.

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

(Embodiment 1)
FIG. 1, in which parts corresponding to those in FIG. 15 are assigned the same reference numerals, shows the configuration of a two-point modulation type frequency modulation apparatus according to Embodiment 1 of the present invention. The frequency modulation device 100 of FIG. 1 is provided with a noise shaper 101 instead of the D / A converter 6 as compared with the frequency modulation device 10 of FIG.

  The noise shaper 101 has a function of forming an analog voltage value corresponding to modulation data (digital baseband modulation signal) and a function of changing the frequency characteristic of quantization noise generated at that time.

  The noise shaper 101 of this embodiment is configured as shown in FIG. In FIG. 2, the modulation data is indicated as X and the output analog voltage is indicated as Y. The noise shaper 101 is roughly divided into a differentiator 102 for differentiating modulated data, a quantizer 103, an output signal of the differentiator 102 and an output signal of the quantizer 103 (that is, an output analog voltage Y) at a timing. And a feedback circuit 104 that adds them and inputs them to the quantizer 103.

The differentiator 102 subtracts the input signal X delayed by the delay element 105 by Z ⁻¹ (that is, one clock of the operation clock of the noise shaper 101) and the current input signal X by the subtractor 106. To obtain a differential output. Incidentally, Z represents Z conversion. This differential output is input to the quantizer 103 via the adder 107.

The quantizer 103 obtains an output analog voltage Y by quantizing the input signal at a sampling frequency that is at least twice the sampling frequency of the modulation data X. Actually, the quantizer 103 obtains an output analog voltage Y by performing quantization at a sampling frequency several tens of times the sampling frequency of the modulation data X. The output of the quantizer 103 is sent to the adder 107 via a delay element 108 that gives a delay time of Z ⁻¹ minutes.

  Next, operations and characteristics of the noise shaper 101 and the frequency modulation device 100 according to the present embodiment will be described.

The transfer function of the differentiator 102 can be expressed by (1-z ⁻¹ ). Here, when the quantization noise generated in the quantizer 103 is Q, the relationship between the modulation data X and the output analog voltage Y can be expressed by the following equation.
Y = (1−z ⁻¹ ) X + z ⁻¹ Y + Q (2)

When formula (2) is expanded, the following formula is obtained.
Y = X + Q / (1-z ⁻¹ ) (3)

1 / (1-z ⁻¹ ) multiplied by the quantization noise Q in the equation (3) is an integral transfer function. That is, the input signal X added with the integrated quantization noise appears at the output. The frequency characteristic of integration has a low-pass characteristic.

FIG. 3 shows the frequency characteristics of the baseband region of the frequency modulation device 100. Compared to FIG. 16, the distribution of the quantization noise Q is different. This is due to the frequency characteristic of the integral 1 / (1-z ⁻¹ ) shown in the equation (3). As a result, the quantization noise Q becomes infinite at DC (0 Hz), but after that, a high-pass characteristic of {1-H (s)} is applied, and as a result, noise near DC is suppressed. The

  Specifically, if the PLL order is increased, the slope of attenuation of {1-H (s)} can be made steep, so the PLL order is set so as to cancel the rise of quantization noise in the vicinity of DC in FIG. do it. Alternatively, the cutoff frequency of the PLL may be increased to increase the attenuation near the DC of {1-H (s)}, and this may be used to suppress noise near the DC.

  FIG. 4 shows the spectrum of the RF modulation signal output from the VCO 1. A waveform in which the quantization noise Q is superimposed on the modulation signal is output from the VCO 1. As can be seen from FIG. 4, the quantization noise Q superimposed on the modulation signal has a noise level that is farther from the center frequency than that of FIG. 17 due to the action of the noise shaper 101. This satisfies the spectrum mask standard.

  Thus, according to the present embodiment, the noise is generated when the modulation data is converted to analog by the adder provided in the preceding stage of the VCO 1 through the noise shaper 101 having the characteristic that the quantization noise attenuates as the frequency increases. By changing the frequency characteristics of the quantization noise to be supplied, the two-point modulation type frequency modulation apparatus 100 that can fit the spectrum of the transmission wave (RF modulation signal) within the spectrum mask can be realized.

  In this embodiment, the order of the noise shaper 101 has been described as a first order. However, a second or higher order configuration may be used. The noise shaper 101 is not limited to that having the configuration shown in FIG. 2, but may be anything as long as the noise shaper 101 has a characteristic of attenuating the quantization noise as the frequency increases.

  In the above-described embodiment, the detailed configuration of the frequency divider 2 is not mentioned, but a generally known fractional type is preferable, for example. The same applies to the embodiments described below.

(Embodiment 2)
In the present embodiment, it is proposed to use a bandpass delta sigma modulator having a configuration as shown in FIG. 5 as a noise shaper. The noise shaper 110 is used in the frequency modulation device 100 instead of the noise shaper 101 of FIG.

  Similar to the noise shaper 101 of the first embodiment, the noise shaper 110 has a function of forming an analog voltage value corresponding to modulation data and a function of changing the frequency characteristics of quantization noise generated at that time. However, the method of changing the frequency characteristics of the quantization noise is different from that of the first embodiment.

The noise shaper 110 inputs the modulation data to the subtractor 111 and inputs the subtraction result to the filter (F (z)) 112 having resonance characteristics as shown in FIG. The filter output is quantized by the quantizer 113 to be an output analog voltage Y. The output analog voltage Y is delayed by z ⁻¹ by the delay element 114 and then fed back as a subtraction input of the subtractor 111.

  Next, the operation and characteristics of the noise shaper 110 of this embodiment and the frequency modulation apparatus 100 using the same will be described.

When the quantization noise generated in the quantizer 113 is Q, the relationship between the modulation data X and the output analog voltage Y can be expressed by the following equation.
Y = X + Q / F (z) (4)

  1 / F (z) multiplied by the quantization noise Q is a notch transfer function. That is, the input signal X to which the quantization noise Q including a notch is added appears at the output.

  FIG. 7 shows the frequency characteristics of the baseband region of the frequency modulation device 100 when the noise shaper 110 of the present embodiment is used. Compared to FIG. 16, the distribution of the quantization noise Q is different. This is due to the frequency characteristic of the notch 1 / F (z) shown in the equation (4). The notch is preferably set to a frequency that can suppress noise outside the modulation band within the band of the post filter 7 having band-pass (low-pass) filter characteristics.

FIG. 8 shows the spectrum of the RF modulation signal output from the VCO 1. A waveform in which the quantization noise Q is superimposed on the modulation signal is output from the VCO 1. As can be seen from FIG. 8, the quantization noise Q superimposed on the modulation signal has a noise level far from the center frequency f _{VCO as} compared to FIG. 17 due to the notch effect of the noise shaper 110. This satisfies the spectrum mask standard.

  Thus, according to the present embodiment, the voltage corresponding to the modulation data is supplied to the control voltage terminal of the VCO 1 via the noise shaper 110 having the bandpass delta sigma modulator configuration, so that the spectrum of the transmission wave Can be realized in the spectrum mask.

(Embodiment 3)
In the present embodiment, it is proposed to use a delta modulator configured as shown in FIG. 9 as a noise shaper. The noise shaper 120 is used in the frequency modulation device 100 in place of the noise shaper 101 of FIG.

  Similar to the noise shapers 101 and 110 of the first and second embodiments, the noise shaper 120 has a function of forming an analog voltage value according to modulation data and the frequency characteristics of quantization noise generated at that time. It has a function to change. However, the method of changing the frequency characteristics of the quantization noise is different from the first and second embodiments.

The noise shaper 120 inputs the modulation data to the quantizer 122 via the subtractor 121. The quantizer 122 obtains an analog voltage by quantizing the input signal at a sampling frequency that is at least twice the sampling frequency of the modulation data. In practice, the quantizer 122 obtains an analog voltage by performing quantization at a sampling frequency several tens of times the sampling frequency of the modulation data. The analog voltage obtained by the quantizer 122 is integrated by an integrator 123 to become an output analog voltage Y. Further, the output of the quantizer 122 is fed back as a subtraction input of the subtractor 121 via a delay element 124 and a integrator 125 that give a delay time of z ⁻¹ minutes in order.

  Next, the operation and characteristics of the noise shaper 120 of this embodiment and the frequency modulation apparatus using the same will be described.

The transfer functions of the integrators 123 and 125 can be expressed by 1 / (1-z ⁻¹ ). Therefore, when the signal level at point A in FIG. 9 is A and the quantization noise generated by the quantizer 122 is Q, the following equation holds.
A = X−z ⁻¹ A / (1-z ⁻¹ ) + Q
A = (1-z ⁻¹ ) (X + Q) (5)

Thus, the output analog voltage Y of the noise shaper 120 can be expressed by the following equation.
Y = A / (1-z ⁻¹ )
Y = X + Q (6)

  Here, as can be seen from the equation (6), the input signal X added with the quantization noise Q appears in the output. However, as shown in the equation (5), a signal obtained by differentiating the input signal X and the quantization noise Q appears at point A. This means that the DC component of the input signal X is not transmitted to the output.

  FIG. 10 shows the frequency characteristics of the baseband region of the frequency modulation apparatus 100 when the noise shaper 120 of this embodiment is used. Although the quantization noise Q is uniformly distributed as in FIG. 16, the absolute level of the quantization noise can be lowered by increasing the operating frequency of the noise shaper 120 as shown in FIG. .

FIG. 11 shows the spectrum of the RF modulation signal output from the VCO 1. A waveform in which the quantization noise Q is superimposed on the modulation signal is output from the VCO 1. As can be seen from FIG. 11, the quantization noise Q superimposed on the modulation signal has a noise level that is far from the center frequency f _{VCO as} compared with FIG. 17 due to the action of the noise shaper 120. This satisfies the spectrum mask standard.

  Further, since the delta modulator used as the noise shaper 120 of the present embodiment can be realized using a 1-bit quantizer, a multi-bit like the D / A converter 6 (FIG. 15) in the prior art. It is not necessary to use a quantizer. Incidentally, the 1-bit quantizer can also be applied to the quantizers 103 and 113 of the first and second embodiments. Thereby, highly accurate signal processing can be performed. When such a delta modulator is applied to the two-point modulation PLL, there is an advantage that the modulation accuracy characteristic of the RF modulation signal is improved. However, the delta modulator has a demerit that it does not pass a DC component, but a path having a high pass characteristic of {1-H (s)} of a two-point modulation type PLL essentially does not pass a DC component. There is no demerit when viewed in the entire system of the two-point modulation PLL.

  Thus, according to the present embodiment, the voltage corresponding to the modulation data is supplied to the control voltage terminal of the VCO 1 via the noise shaper 120 having a delta modulator configuration, so that the spectrum of the transmission wave is spectrum masked. A two-point modulation type frequency modulation apparatus 100 that can be accommodated in the apparatus can be realized.

  In this embodiment, the case where a primary delta modulator is used as the noise shaper 120 has been described. However, the delta modulator may be a secondary or higher order.

(Embodiment 4)
In the present embodiment, it is presented that the frequency modulation apparatus 100 described in the first to third embodiments is applied to a polar modulation transmission apparatus.

  FIG. 12 shows the configuration of polar modulation transmission apparatus 200 of the present embodiment. The frequency modulation device 100 is used as a frequency synthesizer 206 in the figure. In FIG. 12, only the peripheral portion of the frequency synthesizer 206 in which the frequency modulation device 100 is used is shown.

Polar modulation transmission apparatus 200 inputs baseband modulation signal 201 composed of an I (in-phase) component and a Q (quadrature) component to amplitude phase separation section 202. The amplitude phase separation unit 202 sends the amplitude component of the baseband modulation signal 201 (that is, √ (I ² + Q ² )) as the amplitude modulation signal 203 to the amplitude modulation signal amplifier 205 and also the phase component of the baseband modulation signal 201. (For example, the angle formed by the modulation symbol and the I axis) is sent to the frequency synthesizer 206 as the baseband phase modulation signal 204.

  The polar modulation transmission apparatus 200 uses the frequency modulation apparatus 100 of the first embodiment, the second embodiment, or the third embodiment described above as the frequency synthesizer 206. The baseband phase modulation signal 204 corresponds to the modulation data described in the first to third embodiments.

  The frequency synthesizer 206 generates a high frequency phase modulation signal (RF modulation signal) 207 by modulating the carrier frequency with the baseband phase modulation signal (phase data) 204, and sends this to the high frequency power amplifier 208.

  The high-frequency power amplifier 208 is a non-linear amplifier, and the power supply voltage value is set according to the amplitude modulation signal 203 amplified by the amplitude modulation signal amplifier 205. As a result, the high-frequency power amplifier 208 outputs a transmission signal 209 in which a signal obtained by multiplying the power supply voltage value and the high-frequency phase modulation signal 207 output from the frequency synthesizer 206 is amplified by the gain of the high-frequency power amplifier 208. . A transmission signal 209 is transmitted from the antenna 210.

  As described above, in the polar modulation transmission apparatus 200, the high-frequency phase modulation signal 207 input to the high-frequency power amplifier 208 can be a constant envelope signal having no fluctuation component in the amplitude direction. As a result, a highly efficient nonlinear amplifier can be used.

  In addition, by using the frequency modulation device 100 of the first embodiment, the second embodiment, or the third embodiment as the frequency synthesizer 206 of the polar modulation transmission device 200, the transmission signal 209 in which the quantization noise is contained in the spectrum mask is obtained. Can be obtained. As a result, in addition to the effect of improving the power efficiency by the polar modulation method and the effect of improving the modulation accuracy by the two-point modulation, it is possible to realize the polar modulation transmission apparatus 200 that can securely fit the transmission wave in the spectrum mask.

(Other embodiments)
In the above-described fourth embodiment, the case where the frequency modulation apparatus 100 according to the first, second, or third embodiment is applied to the frequency synthesizer 206 provided in the polar modulation transmission apparatus 200 has been described. The frequency modulation device of the invention is not limited to this, and can be widely applied to a wireless communication device and a wireless communication device that are required to have a transmission signal band within a predetermined frequency band.

  FIG. 13 shows a configuration of a wireless transmission device equipped with the frequency modulation device according to the first to third embodiments. Radio transmitting apparatus 300 includes frequency modulation apparatus 100 according to any one of Embodiments 1 to 3, amplifier 301 that amplifies an RF modulation signal obtained by frequency modulation apparatus 100, and antenna 302 that transmits the amplified signal. Have

  FIG. 14 shows a configuration of a wireless communication device equipped with the frequency modulation device according to the first to third embodiments. Radio communication apparatus 400 includes transmission section 401 including frequency modulation apparatus 100 and amplifier 301 according to any of Embodiments 1 to 3, reception section 402 that performs predetermined reception processing including demodulation processing on the received signal, and transmission A duplexer 403 for switching between a signal and a received signal and an antenna 302 are provided.

  As a result, the wireless transmission device 300 and the wireless communication device 400 can perform high-accuracy frequency modulation by two-point modulation, so that a high-quality transmission signal can be obtained, and a transmission wave can be reliably transmitted. Since it can be accommodated in the spectrum mask, interference with other wireless devices can be suppressed.

  The present invention is preferably applied to a mobile terminal such as a mobile phone and a wireless communication apparatus such as a base station thereof.

The block diagram which shows the structure of the frequency modulation apparatus of embodiment Block diagram showing the configuration of the noise shaper of the first exemplary embodiment Characteristic curve diagram showing a baseband signal spectrum in the first embodiment Characteristic curve diagram showing an RF signal spectrum in the first embodiment Block diagram showing the configuration of the noise shaper of the second exemplary embodiment Characteristic curve diagram showing characteristics of transfer function F (z) of the second embodiment Characteristic curve diagram showing a baseband signal spectrum in the second embodiment Characteristic curve diagram showing RF signal spectrum in the second embodiment Block diagram showing the configuration of the noise shaper of the third exemplary embodiment Characteristic curve diagram showing a baseband signal spectrum in the third embodiment Characteristic curve diagram showing RF signal spectrum in the third embodiment Block diagram showing a configuration of a polar modulation transmission apparatus according to a fourth embodiment The block diagram which shows the structure of the radio | wireless transmitter in other embodiment. The block diagram which shows the structure of the radio | wireless communication apparatus in other embodiment. Block diagram showing the configuration of a conventional two-point modulation type frequency modulation device Characteristic curve diagram showing a baseband signal spectrum in a conventional two-point modulation type frequency modulation device Characteristic curve diagram showing RF signal spectrum in a conventional two-point modulation type frequency modulation device

Explanation of symbols

1 Voltage controlled oscillator (VCO)
2 frequency divider 3 phase comparator 4 loop filter 7 post filter 100 frequency modulator 101, 110, 120 noise shaper 102 differentiator 103 quantizer 104 feedback circuit 200 polar modulation transmitter 300 wireless transmitter 400 wireless communication device

Claims (10)

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 loop 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 loop filter and supplies it to the control voltage terminal of the voltage controlled oscillator An adder to
A frequency modulation device comprising: a noise shaper that changes a frequency characteristic of quantization noise generated when the baseband modulation signal is converted into an analog signal and supplied to the adder. The frequency modulation device according to claim 1, wherein the noise shaper attenuates the quantization noise in a higher frequency range. The frequency modulation device according to claim 2, wherein the noise shaper has a transfer function obtained by adding integrated quantization noise to the baseband modulation signal. The noise shaper is
A differentiator for differentiating the baseband modulation signal;
A quantizer,
The frequency modulation device according to claim 3, further comprising: a feedback circuit that adds the output signal of the differentiator and the output signal of the quantizer at the same timing and inputs the added signal to the quantizer. . The frequency modulator according to claim 1, wherein the noise shaper is a band-pass delta sigma modulator. The frequency modulation device according to claim 1, wherein the noise shaper is a delta modulator. The frequency modulation device according to claim 1, further comprising a low-pass filter provided between the noise shaper and the adder. An amplitude phase separation unit that forms a baseband phase modulation signal and an amplitude modulation signal based on the baseband modulation signal;
A PLL circuit for inputting the baseband phase modulation signal and outputting an RF phase modulation signal;
A high-frequency power amplifier that varies the amplitude of the RF phase modulation signal output from the voltage controlled oscillator of the PLL circuit according to the amplitude modulation signal;
A frequency divider provided in the PLL circuit for setting a frequency division ratio of the PLL circuit based on the baseband phase modulation signal and the carrier frequency signal;
A control voltage terminal provided between the loop filter of the PLL circuit and the voltage controlled oscillator of the PLL circuit, and adding a voltage corresponding to the baseband phase modulation signal to the output voltage of the loop filter. An adder for supplying to
A polar modulation transmission apparatus comprising: a noise shaper that changes a frequency characteristic of quantization noise generated when the baseband phase modulation signal is converted into an analog signal and supplied to the adder. A frequency modulation device according to any one of claims 1 to 7,
An amplifier for amplifying an RF modulation signal output from the frequency modulation device. A transmitter having the frequency modulation device according to any one of claims 1 to 7,
A receiver for demodulating the received signal;
An antenna,
A wireless communication apparatus comprising: a transmission / reception switching unit 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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