JP5577843B2 - Phase detector, demodulator and phase detection method - Google Patents

Description

  The present invention relates to a phase detector used in a demodulator using quadrature amplitude modulation.

  In a digital radio transmission system, phase noise is added to a carrier wave by frequency conversion or the like in a demodulator. Specifically, the phase noise appears as a phase shift of the carrier wave. On the other hand, in a QAM (quadrature amplitude modulation, quadrature amplitude modulation) system, which is a system for digital radio transmission, the amount of communication is increased by increasing the number of multi-values during modulation. A carrier recovery PLL (phase locked loop) circuit of the QAM demodulator detects the phase difference of the carrier in the input quadrature modulation signal and performs phase compensation by PLL control. Patent Document 1 discloses a configuration of a QAM demodulator related to the present invention.

  However, in the QAM system, when the multi-value number becomes large, a signal point existing at the outer edge of the QAM grating may enter an adjacent grating area at the time of demodulation due to a phase shift of the carrier wave. As a result, the demodulator may output an incorrect signal.

  Thus, since the demodulator may output an erroneous signal due to the phase shift of the carrier wave, the phase detection range of the carrier wave recovery PLL circuit is generally narrower as the multi-value number becomes larger. For example, in the case of QPSK (quadrature phase shift keying), the range of the phase difference that can be detected is about ± 45 degrees, whereas in the case of 256 QAM, the range is about ± 3 degrees. Degree.

JP 2009-147522 A (FIG. 9, paragraph [0007])

  When the phase difference of the carrier wave exceeds the range that can be detected by the phase detector, the phase detector outputs an incorrect phase detection result. If the phase of the carrier wave is drawn based on the incorrect phase detection result, the phase of the demodulated carrier wave is greatly different from the original phase. As a result, communication is interrupted and there is a possibility that the service will be greatly affected.

  For this reason, the QAM signal demodulator needs to detect the correct phase even when the carrier phase greatly fluctuates due to phase noise. In other words, the QAM signal demodulator is required to stably reproduce the carrier wave by widening the detection range of the phase detector of the carrier wave reproducing PLL circuit as much as possible. As described above, in order to perform stable carrier wave recovery, a QAM signal demodulator is required to have a wide phase detection range.

  However, the carrier recovery circuit described in Patent Document 1 does not have a special configuration for expanding the phase detection range. Therefore, in the carrier recovery circuit described in Patent Document 1, the phase difference exceeds the detection range when the phase of the carrier changes greatly because the detection range of the phase difference cannot be expanded. was there. As a result, in the demodulator described in Patent Document 1, the phase of the carrier wave may not be correctly synchronized.

  An object of the present invention is to provide a technique for solving the problem that a phase difference exceeds a detection range when the phase of a carrier wave greatly changes in a demodulator.

Phase detector of the present invention, the input quadrature baseband signal, and phase rotation means for outputting by giving a phase rotation based on the angle signal, the phase and quadrature baseband of the quadrature baseband signal input from the phase rotation means comprising a phase comparator means for outputting a phase difference signal indicating the phase difference between the signal of the reference phase, calculation means based on the phase difference signal outputs the phase detection signal and the angle signal.

The phase detection method of the present invention, the input quadrature baseband signal, and outputs by giving a phase rotation based on the angle signal, the quadrature baseband signal given the phase rotation phase and the quadrature baseband signal A phase difference signal indicating a phase difference from the reference phase is output, and a phase detection signal and the angle signal are output based on the phase difference signal.

  The present invention has the effect of expanding the detection range of the phase difference in the demodulator.

It is a figure which shows the structure of the phase detector in the 1st Embodiment of this invention. It is a figure which shows the structure of 1st Embodiment which applied the phase detector of this invention to the carrier wave recovery PLL circuit. It is a figure which shows the input / output characteristic of the general phase comparator relevant to this invention. It is a figure which shows the input / output characteristic of the phase comparator which corrected the input / output characteristic using the offset value. It is a figure which shows distribution of the signal point of the input carrier wave, and the characteristic of a general phase detector in relation to each other. It is a figure which shows in relation to the distribution of the signal point of the input carrier wave, and the characteristic of a phase detector in the 1st Embodiment of this invention. It is a figure which shows the structure of the demodulator of the 2nd Embodiment of this invention. It is a figure which shows the modification of the phase detector of the 1st Embodiment of this invention. It is a figure which shows the structure of the phase detector of the 3rd Embodiment of this invention.

[First Embodiment]
FIG. 2 is a diagram showing the configuration of the first embodiment in which the phase detector of the present invention is applied to a carrier wave recovery PLL circuit. The carrier recovery PLL circuit is a circuit used for controlling the phase shift of the carrier wave from the reference phase when demodulating the QAM signal. In the carrier recovery PLL circuit shown in FIG. 2, a QAM-modulated modulated wave is converted to baseband I (inphase) and Q (quadture) signals by quasi-synchronous quadrature detection and input to the carrier recovery PLL circuit. And Quasi-synchronous quadrature detection is a method of detecting an input received signal using the output of a local oscillator having a fixed frequency. The multiplier 5 rotates the carrier phase of the input signal by a phase rotation signal from an NCO (Numerically Controlled Oscillator) 6 to determine the carrier phase.

  The output of the multiplier 5 is output to the outside as the output of the carrier wave recovery PLL circuit and also input to the phase detector 8. The phase detector 8 is determined from the coordinates of signal points determined by the I and Q signals output from the multiplier 5 (hereinafter referred to as “I / Q signals”) and the signal point arrangement of the QAM. The phase difference from the coordinates where the signal point should be is detected and output as a phase detection signal.

  The phase detection signal output from the phase detector 8 is input to the loop filter 7. The loop filter 7 removes the high frequency component of the phase detection signal, converts the phase information of the phase detection signal into frequency information, and outputs the frequency information.

  The output of the loop filter 7 is input to the NCO 6. The NCO 6 generates and outputs a phase rotation signal corresponding to the frequency information input from the loop filter 7. The phase rotation signal generated by the NCO 6 is input to the multiplier 5 and rotates the carrier phase of the I / Q signal input from the quadrature detector.

  Next, a specific operation of the carrier wave recovery PLL circuit shown in FIG. 2 will be described.

The phase detector 8 detects the phase shift amount of the received QAM signal point and outputs the phase shift amount as a phase detection signal. Then, the loop filter 7 with removing high frequency components from the phase detection signal is converted into frequency information omega _c. Here, the loop filter calculates the frequency signal ω _c by integrating the input phase detection signal. The NCO 6 generates a sine wave and a cosine wave (sin ω _c t, cos ω _c t) having the frequency indicated by the frequency signal ω _c . Then, the multiplier 5 calculates the following equation (1) and corrects the carrier phase.

Ich (Output) = Ich (input) × cosω _c t + Qch (input) × sinω _c t
Qch (Output) = - Ich (input) × sinω _c t + Qch _{(input) × cosω c t ··· (1} )
In Expression (1), Ich and Qch inputs and outputs indicate inputs and outputs to the multiplier 5 in FIG. Further, it is assumed that the angle ω _c t is positive in the direction of canceling out the phase shift output from the phase detector 8.

  The phase shift of the carrier wave is controlled by the PLL configured by the phase detector 8, the loop filter 7, the NCO 6, and the multiplier 5. The phase shift amount is integrated by a loop filter to generate a frequency signal. Based on the frequency signal, the sine wave and cosine wave generated by the NCO are multiplied by the I / Q signal to compensate for the phase shift of the carrier wave. The configuration to do is known. Therefore, a detailed description of the operations of the loop filter 7, the NCO 6, and the multiplier 5 is omitted.

  Next, the phase detector 8 in the first embodiment will be described in detail. FIG. 1 is a diagram showing the configuration of the phase detector 8 in the first embodiment of the present invention.

  In FIG. 1, the phase rotator 1 receives the I / Q signal input from the multiplier 5 in FIG. 2 and the angle signal φ input from the offset calculator 4. The phase rotator 1 rotates the carrier phase of the input I / Q signal by φ in the direction opposite to the input angle signal φ. Specifically, the phase rotator 1 rotates the phase of the carrier wave by multiplication represented by the following expression (2) with respect to the input I / Q signal.

Ich (output) = Ich (input) x cosφ + Qch (input) x sinφ
Qch (output) = -Ich (input) x sinφ + Qch (input) x cosφ (2)
In Expression (2), Ich and Qch inputs and outputs indicate inputs and outputs for the phase rotator 1 of FIG. That is, the output of the multiplier 5 in FIG. 2 becomes the input to the phase rotator 1 in FIG. 1 and the equation (2).

  The phase comparator 2 calculates the phase difference between the coordinates determined by the I / Q signal input from the phase rotator 1 and the original coordinates determined from the signal point arrangement of the QAM, and outputs it as a phase difference signal To do. The phase difference signal output from the phase comparator 2 is input to the adder 3.

  The adder 3 adds the phase difference signal output from the phase comparator 2 and the correction value α output from the offset calculator 4. The output of the adder 3 is input as a phase detection signal to the offset calculator 4 and the loop filter 7 of FIG.

  The offset calculator 4 obtains an average value of the phase detection signals output from the adder 3, outputs an angle signal φ to the phase rotator 1, and outputs an offset signal α to the adder 3.

  Subsequently, the operation of the phase detector 8 in the first embodiment of the present invention will be further described with reference to FIGS.

The phase comparator 2 generally detects a phase shift of a carrier wave and outputs a signal having an amplitude proportional to the phase shift amount. FIG. 3 is a diagram showing input / output characteristics of a general phase comparator related to the present invention. As shown in FIG. 3, a general phase comparator outputs a linear result within a range where the phase shift amount of the input carrier wave is ± θ ₀ . However, when the amount of phase shift of the carrier wave exceeds ± θ ₀ , the amplitude of the output signal suddenly decreases, and the linearity of the output of the phase comparator is lost. In such a case, the phase comparator cannot output a correct phase shift amount. This is because, in a general phase comparator, the phase detection of the QAM carrier is performed only within the QAM lattice to which a certain reception point belongs, so that the phase shift amount increases and the signal point overlaps the adjacent lattice. This is because incorrect phase shift information is output.

Normally, when the carrier phase fluctuates due to phase noise or the like, the phase does not change abruptly, and the phase changes with a relatively long time constant. That is, the average value of the output of the phase comparator 2 has a value of around 0 in the steady state, but has a positive or negative value when the phase starts to shift. When this value exceeds a certain value (the phase shift amount exceeds θ ₀ ), the output of the phase comparator 2 loses linearity. Therefore, before the output of the phase comparator 2 loses its linearity, the phase of the input signal of the phase comparator 2 is pre-rotated by the phase rotator 1 to keep the input of the phase comparator 2 within a range where linear operation is possible. The phase detection range of the phase comparator can be expanded. This is shown in FIG.

  FIG. 4 is a diagram illustrating the input / output characteristics of the phase comparator in which the input / output characteristics are corrected using the offset values (α and φ). In the following description, it is assumed that the initial values of the offset values α and φ output from the offset calculator 4 are both zero.

  When a large carrier phase fluctuation that is close to the limit of the tracking capability of the carrier recovery PLL circuit occurs due to phase noise or the like, the output of the phase comparator 2 is first biased to be positive or negative. Then, the offset calculator 4 detects the amount of this deviation. Furthermore, the offset calculator 4 removes a noise component by calculating the average of the outputs of the phase comparator 2 and detects the amount of phase shift. When the offset calculator 4 detects that the phase shift amount is φ, the offset calculator 4 notifies the phase rotator 1 of the phase shift amount φ. Further, the offset calculator 4 notifies the adder 3 of the offset amount α with respect to the output of the phase comparator 2.

  The phase rotator 1 rotates the carrier phase by φ in a direction that cancels out the phase shift amount φ according to the equation (1). As a result, the phase shift amount at the input of the phase comparator 2 is corrected to zero.

  Here, in this state, the output of the phase detector 8 becomes zero although the carrier phase of the input signal to the phase detector 8 is shifted by φ. Therefore, in order to reflect the actual phase shift in the output, the adder 3 adds α as the correction value of the phase comparator 2 and outputs the result. The amount of α is obtained from the following equation (3) from the slope β of the input / output characteristics of the phase comparator 2.

α = β × φ (3)
As a result, as shown in FIG. 4, even when the phase shift φ exceeds ± θ ₀ , among the characteristics (broken line) of the phase comparator 2 when φ = ₀ , It is possible to obtain a characteristic (solid line) obtained by extending the linear operation part of phase difference detection within the range.

FIG. 5 is a diagram showing the distribution of signal points of an input carrier wave and the characteristics of a general phase comparator in association with each other. Here, consider a case where the carrier phase is shifted by θ. In FIG. 5, the phase detector can correctly detect the phase in the range where the input / output characteristics are linear and the phase difference is ± θ ₀ , that is, in the figure that is not shaded. FIG. 5A shows a case where the distribution of the input signal is a normal distribution with respect to the phase of the carrier wave. FIG. 5B shows characteristics of a general carrier phase comparator related to the present invention. In FIG. 5, the shaded portion indicates a region where the linearity of the input / output characteristics of the phase detector is lost. For this reason, in FIG. 5A, correct phase detection cannot be performed for a signal having a phase shift amount applied to the shaded portion. FIG. 5 shows that a correct phase signal cannot be extracted from nearly half of the signal.

  FIG. 6 is a diagram showing the distribution of signal points of the input carrier wave and the characteristics of the phase detector in the first embodiment of the present invention. As in FIG. 5, the phase cannot be detected correctly in the shaded area. However, in FIG. 6, since the input / output characteristics of the phase comparator are corrected by the offset values φ and α, correct phase information can be extracted from more received signals.

  As described above, the phase detector and the carrier wave recovery PLL circuit described in the first embodiment have an effect that the detection range of the phase difference in the phase detector can be expanded. The phase detector and the carrier recovery PLL circuit described in the first embodiment also have an effect that the phase of the carrier can be correctly synchronized by expanding the detection range of the phase difference.

  In the above-described first embodiment, the offset calculator 4 has been described as obtaining the average of the outputs of the phase comparator 2. However, in order to obtain the above effect, it is not essential to obtain the average of the outputs of the phase comparator 2 in the offset calculator 4. That is, the offset calculator 4 may directly calculate the offset values α and φ from the output of the phase comparator 2.

  Further, FIG. 8 shows a modification of the phase detector according to the first embodiment of the present invention. In FIG. 8, the phase difference signal output from the phase comparator 2 is input to the offset calculator 4 without adding the offset value α by the adder 3. That is, the input of the offset calculator 4 in FIG. 8 is smaller by the offset value α than in the case of FIG. Therefore, the offset calculator 4 in FIG. 8 operates similarly to the offset calculator 4 described in FIG. 1 by correcting the input value by the offset value α. Therefore, the modification of the phase detector of the first embodiment shown in FIG. 8 also has the same effect as that of the first embodiment. Also in the modification of the phase detector of the first embodiment, it is not essential to obtain the average of the outputs of the phase comparator 2 in the offset calculator 4.

[Second Embodiment]
FIG. 7 is a diagram illustrating a configuration of a demodulator according to the second embodiment of the present invention.

  The carrier recovery PLL circuit described in the first embodiment has a configuration based on the quasi-synchronous detection method. That is, in the first embodiment, the I / Q input signal input to the multiplier 5 is converted into the IF (intermediate frequency) signal or the RF (radio frequency, radio frequency) signal carrier frequency in the previous stage. The signal is orthogonally demodulated using a local signal having a fixed frequency.

  FIG. 7 shows a configuration in which the phase detector of the present invention is applied to a synchronous detection type demodulator. In FIG. 7, the phase detector 8 has the same configuration and function as the phase detector 8 described in FIG. 2 of the first embodiment. The phase detector 8 detects the phase shift amount of the carrier wave from the output of the quadrature demodulator 8 and outputs it to the loop filter 7. The loop filter 7 removes a high frequency component of the phase detection signal output from the phase detector 8 and converts the phase detection signal into frequency information. The loop filter 7 outputs a signal for controlling the frequency of the voltage controlled oscillator 10. The voltage controlled oscillator 10 generates a local signal at a frequency corresponding to the output of the loop filter 7. The quadrature demodulator 9 performs quadrature demodulation on the IF signal or the RF signal using the local signal input from the voltage controlled oscillator 10. Here, the phase detector 8 expands the detection range of the phase difference of the input carrier wave using the offset signals α and φ by the same operation as the phase detector 8 described in FIG. The operation of enlarging the phase difference is the same as the description of FIG. 6 in the first embodiment.

  As described above, the demodulator according to the second embodiment of the present invention shown in FIG. 7 includes the phase detector 8, the loop filter 7, the quadrature demodulator 9, and the voltage controlled oscillator 10 described in FIG. The demodulator according to the second embodiment of the present invention feeds back a phase detection signal obtained from the I / Q output of the quadrature demodulator 9 to the voltage controlled oscillator 10 to perform quadrature demodulation. Therefore, the demodulator of the second embodiment of the present invention having the configuration shown in FIG. 7 also has the effect of expanding the detection range of the phase difference in the phase detector and the effect of correctly synchronizing the phase of the carrier wave. Play.

[Third Embodiment]
FIG. 9 is a diagram showing the configuration of the phase detector according to the third exemplary embodiment of the present invention. The phase detector 20 shown in FIG. 9 includes a phase rotator 21, a phase comparator 22, and a calculator 23.

The phase rotator 21 gives a phase rotation based on the angle signal to the input quadrature baseband signal and outputs it. The phase comparator 22 outputs a phase difference signal indicating a phase difference between the phase of the orthogonal baseband signal input from the phase rotator 21 and the reference phase of the orthogonal baseband signal . The computing unit 23 outputs a phase detection signal and an angle signal based on the phase difference signal input from the phase comparator 22.

That is, the phase detector 20 shown in FIG. 9 rotates the phase of the orthogonal baseband signal input to the phase rotator 21 based on the phase difference signal detected by the phase comparator 22. Then, the phase detector 20 outputs a phase detection signal based on the phase difference signal.

Here, even when the phase difference of the orthogonal baseband signals input to the phase detector 20 is large, the phase rotator 21 rotates the phase of the orthogonal baseband signals , thereby causing the orthogonal bases input to the phase comparator 22 to rotate. The phase difference of the band signal can be kept within the phase detection range of the phase comparator 22. The computing unit 23 outputs a phase detection signal based on the phase difference signal output from the phase comparator 22. The computing unit 23 corrects and outputs the phase difference signal output from the phase comparator 22 in accordance with the amount of phase rotation by the phase rotator 21.

  Thus, the phase detector according to the third embodiment of the present invention having the configuration shown in FIG. 9 also has the effect of expanding the detection range of the phase difference in the phase detector.

  A part or all of the above-described embodiment can be described as in the following supplementary notes, but is not limited thereto.

To (Supplementary Note 1) input quadrature baseband signal, and phase rotation means for outputting by giving a phase rotation based on the angle signal, the phase and the quadrature baseband signal of the quadrature baseband signal input from the phase rotation means A phase detector comprising: phase comparison means for outputting a phase difference signal indicating a phase difference from a reference phase; and arithmetic means for outputting a phase detection signal and the angle signal based on the phase difference signal.

  (Additional remark 2) The said calculating means adds the said phase difference signal and an amplitude signal, and outputs the said phase detection signal, The said angle signal and the said amplitude signal based on the said phase detection signal input The phase detector according to claim 1, further comprising: an offset calculation unit that outputs.

  (Additional remark 3) The said calculating means adds the said phase difference signal and an amplitude signal, and outputs it as a phase detection signal, and the said angle signal and said amplitude signal based on the inputted said phase difference signal The phase detector according to claim 1, further comprising: an offset calculation unit that outputs

  (Additional remark 4) The said phase rotation means is a phase detector in any one of Claim 1 thru | or 3 which performs the said phase rotation so that the absolute value of the said phase difference which the said phase difference signal shows becomes small.

  (Supplementary note 5) The phase detection according to any one of claims 2 to 4, wherein the offset calculation means outputs the amplitude of the phase difference signal when the phase rotation means does not perform phase rotation as the amplitude signal. vessel.

  (Additional remark 6) The said offset calculation means is a phase detector in any one of Claim 2 thru | or 5 which outputs the said angle signal and the said amplitude signal based on the average value of the said phase detection signal.

  (Supplementary note 7) The multiplication means for multiplying the input quadrature modulation signal and the oscillation signal and outputting a multiplication result signal, and outputting the phase detection signal based on the multiplication result signal A demodulator comprising: the described phase detector; loop filter means for outputting frequency information based on the phase detection signal; and oscillating means for outputting the oscillation signal based on the frequency information.

  (Supplementary note 8) The demodulator according to claim 7, wherein the oscillation means is a numerically controlled oscillator that oscillates at a frequency based on the frequency information.

  (Supplementary note 9) The quadrature demodulation means for demodulating the input quadrature modulation signal using the oscillation signal, and the phase detection signal according to any one of claims 1 to 6, wherein the phase detection signal is output based on the demodulation result And a demodulator comprising: loop filter means for outputting frequency information based on the phase detection signal; and oscillating means for outputting the oscillation signal at a frequency based on the frequency information.

  (Supplementary note 10) The demodulator according to claim 7, wherein the frequency information is a voltage signal corresponding to a frequency, and the oscillation means is a voltage controlled oscillator that oscillates at a frequency based on the voltage signal.

(Supplementary Note 11) A phase rotation based on an angle signal is applied to an input quadrature baseband signal and output, and the phase of the quadrature baseband signal given the phase rotation and the reference phase of the quadrature baseband signal A phase detection method for outputting a phase difference signal indicating a phase difference between them and outputting a phase detection signal and the angle signal based on the phase difference signal.

1, 21 Phase rotator 2, 22 Phase comparator 3 Adder 4 Offset calculator 5 Complex multiplier 6 NCO (Numerically controlled oscillator)
7 Loop filter 8, 20 Phase detector 9 Quadrature demodulator 10 VCO (voltage controlled oscillator)
23 Calculator

Claims (10)

Calculation means for calculating the input quadrature modulation signal and oscillation signal and outputting a quadrature baseband signal; a phase detector for outputting a phase detection signal based on the quadrature baseband signal; and based on the phase detection signal A phase detector used in a demodulator comprising loop filter means for outputting frequency information and oscillating means for outputting the oscillation signal based on the frequency information, wherein the phase detector comprises:
Phase rotation means for giving a phase rotation based on an angle signal to the orthogonal baseband signal output from the calculation means, and outputting the phase rotation;
Phase comparison means for outputting a phase difference signal indicating a phase difference between the phase of the orthogonal baseband signal input from the phase rotation means and the reference phase of the orthogonal baseband signal;
An operation for generating the phase detection signal to be supplied to the loop filter unit based on the phase difference signal and generating the angle signal to be supplied to the phase rotation unit by averaging the phase difference signal And a phase detector.   The calculation means adds the phase difference signal and the amplitude signal and outputs the phase detection signal, and outputs the angle signal and the amplitude signal based on the input phase detection signal. The phase detector according to claim 1, further comprising offset calculation means.   The computing means adds the phase difference signal and the amplitude signal and outputs the result as a phase detection signal, and an offset for outputting the angle signal and the amplitude signal based on the inputted phase difference signal The phase detector according to claim 1, comprising a calculation means.   4. The phase detector according to claim 1, wherein the phase rotation unit performs the phase rotation so that an absolute value of the phase difference indicated by the phase difference signal is small. 5.   5. The phase detector according to claim 2, wherein the offset calculation unit outputs the amplitude of the phase difference signal when the phase rotation unit does not perform phase rotation as the amplitude signal. 6.   The phase detector according to claim 2, wherein the offset calculation unit outputs the angle signal and the amplitude signal based on an average value of the phase detection signals.   7. The multiplying means for multiplying the input quadrature modulation signal and the oscillation signal to output a multiplication result signal, and a phase detection signal based on the multiplication result signal. 8. A demodulator comprising: a detector; loop filter means for outputting frequency information based on the phase detection signal; and oscillating means for outputting the oscillation signal based on the frequency information.   The quadrature demodulating means for demodulating the input quadrature modulation signal using an oscillation signal, the phase detector according to any one of claims 1 to 6 for outputting a phase detection signal based on the demodulation result, A demodulator comprising: loop filter means for outputting frequency information based on a phase detection signal; and oscillating means for outputting the oscillation signal at a frequency based on the frequency information.   9. The demodulator according to claim 8, wherein the frequency information is a voltage signal corresponding to a frequency, and the oscillation means is a voltage controlled oscillator that oscillates at a frequency based on the voltage signal. Calculation means for calculating the input quadrature modulation signal and oscillation signal and outputting a quadrature baseband signal; a phase detector for outputting a phase detection signal based on the quadrature baseband signal; and based on the phase detection signal A phase detection method of the phase detector used in a demodulator comprising loop filter means for outputting frequency information and oscillation means for outputting the oscillation signal based on the frequency information,
The quadrature baseband signal output from the calculation means is output by giving a phase rotation based on an angle signal,
Outputting a phase difference signal indicating a phase difference between a phase of the quadrature baseband signal given the phase rotation and a reference phase of the quadrature baseband signal;
Outputting the phase detection signal to be supplied to the loop filter means based on the phase difference signal , and generating the angle signal used for the phase rotation by averaging the phase difference signal ;
Phase detection method.

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