JPH0983587A - Modulator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compensate offset by using an analog quadrature modulator and quadrature detector at the time of the envelope detection-type distortion compensating of a digital communication equipment. SOLUTION: A transmission base band signal from an arithmetic/control part 13 is converted into an analog signal and it is added to the quadrature modulator 18. A transmission modulation wave generated by quadrature modulating a reference carrier is branched and is added to the quadrature detector 35. A reception base band signal obtained by converting a demodulation signal obtained by quadrature detection by the reference carrier into a digital signal is fed back to the arithmetic/control part 13, and the transmission base band signal is predistortion-processed in accordance with the transmission base band signal and a compared result. At the time of removing the waveform distortion of the transmission modulation wave, a lacking carrier based on the offsetting of the quadrature modulator 18 is detected and the reference points (offsetting) of amplifiers 16 and 17 for the input of the quadrature modulator is changed in accordance with a signal which is made into direct current. Then, an input signal value for the quadrature modulator 18 is shifted. Then, the offsetting of the quadrature modulator 18 is controlled to become a minimum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distortion compensation system for a transmitter of a digital communication radio apparatus, and more particularly to an analog quadrature modulator and quadrature detection in an envelope detection type distortion compensation system of a digital nonlinear distortion compensation system. The purpose is to enable the use of vessels.

[0002]

2. Description of the Related Art In recent years, a high efficiency transmission system based on digitalization has come into wide use due to a tight frequency resource in wireless communication. In wireless communication,
When applying the multi-valued amplitude modulation method, it is important to linearize the amplification characteristics of the transmission side, especially the transmission power amplifier to suppress non-linear distortion, and to prevent leakage to adjacent channels due to the spread of the band. In order to improve the power efficiency, when using an amplifier having a poor linearity, a technique for compensating for the distortion caused by it has been essential.

A distortion compensation technique in such a case is L
INC (Lnear Amplification By Combination Of C-Cl
Ass Amplification), feed forward method, analog Cartesian method, polar loop method, predistortion method using non-linear elements, and many other types of analog distortion compensation methods have already been proposed and are actually used.

However, these distortion compensation methods generally have a complicated circuit structure, and have drawbacks such as an obstacle to downsizing and cost reduction of the apparatus, and complicated adjustment of the apparatus. .

On the other hand, in recent years, the processing speed of the signal processing processor (DSP) has been remarkably improved by the progress of the LSI technology, so that the distortion compensation method using the digital signal processing technology can be realized. . As a digital nonlinear distortion compensation method, many papers have been published, such as the adaptive linearization method ^* using predistortion proposed by the University of Victoria (Australia), which is well known in theory. . ^* Michael Fsulkner & Mats Johanson; "Adaptive Linea
risation Using Predistortion-Experimental Result
s ", IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, VOL.4
3, NO.2, MAY 1994

However, no envelope detection type distortion compensation system based on such a digital nonlinear type distortion compensation system has hitherto been put to practical use.

[0007]

DISCLOSURE OF THE INVENTION An envelope detection type distortion compensation system detects a sending signal by feedback detection, compares the amplitudes of the sending signal and the feedback signal by digital conversion, and detects the envelope of an input signal. Since the amount of distortion compensation is determined from this envelope, if there is an offset at the operating point in the quadrature modulator on the transmission side and the quadrature detector in the feedback system, an error will occur in the magnitude of the amplitude, and distortion compensation will be normal. There is an essential problem that it will not be carried out at. That is, if there is an offset, even if the amplitude is the same,
Since the amplitude values are observed differently in the first quadrant and the second quadrant, the distortion compensation amounts are different.

Since the analog type quadrature modulation circuit and quadrature detection circuit which are generally used at present are composed of Gilbert cell differential amplifiers and the like as well known, variations in element performance and temperature environment. Change or the like may cause an offset, or may be affected by an offset variation of a DC amplifier used after digital-analog (D / A) conversion of a baseband signal. These offsets are unavoidable in the current technology, but this problem causes the practical use of the envelope detection type distortion compensation method.
It is a major technical barrier.

As a method of solving this problem, by constructing the quadrature modulation circuit and the quadrature detection circuit with a D / A converter, there is no offset (or even if there is an offset, the resolution of the D / A converter is present). Within), a method of constructing a digital quadrature modulation circuit and a quadrature detection circuit is conceivable, but a high-speed D / A converter of several tens of MHz to several hundreds of MHz is required, and the recent advances in LSI technology Even if it is considered, it is expected that it will take some time before it reaches a practical level in terms of cost.

Further, in order to enable use of a D / A converter having a low operating frequency, when the up-conversion method is adopted, it is necessary to adopt the triple conversion method at present, so that spurious emission of the transmitter can be reduced. This will cause another technical difficulty.

Further, a method has been proposed in which the baseband signal is stored in a rectangular coordinate system to remove the influence of the offset, but in this method, it is necessary to store all the signal space matrices, so it is enormous. Since it requires a RAM capacity, it is still not practical in terms of cost at present.

The present invention is intended to solve such a problem of the prior art, and detects the carrier leak energy due to the offset of the quadrature modulator, and inputs it to the quadrature modulator so as to minimize it. By adjusting the level, cancel the offset of the quadrature modulator, or give a frequency difference or a phase difference to the reference carrier of the quadrature modulator and the quadrature detector, the offset of the quadrature modulator and the offset of the quadrature detector, It is an object of the present invention to provide a distortion compensation method that more surely removes the distortion of a transmission signal by making each calculation possible and eliminating the influence of offset.

[0013]

In order to solve the above-mentioned problems, the following means are used in the present invention. In each of the following means, each component is shown with the same number as that in the corresponding embodiment in the drawings.

(1) A transmission baseband signal composed of digital signals of I and Q components from the arithmetic / control section 13 is converted into an analog signal, which is added to a quadrature modulator 18 via amplifiers 16 and 17, respectively, The carrier wave is quadrature-modulated to generate a transmission modulation wave, and the transmission modulation wave is branched and added to the quadrature detector 35, and the demodulated signals of the I component and the Q component obtained by the quadrature detection with the reference carrier are converted into digital signals. The reception baseband signal obtained by the conversion is fed back to the arithmetic / control unit 13, and the arithmetic / control unit 13 compares the feedback baseband signal with the transmission baseband signal to predistort the transmission baseband signal. In the digital radio device of the envelope detection type distortion compensation system that removes the waveform distortion of the transmission modulation wave, the offset of the quadrature modulator 18 is By detecting a leak carrier based on the output and applying a DC-converted signal to the control unit 45,
The control unit 45 outputs a control signal to change the operation reference points (offsets) of the amplifiers 16 and 17, and the quadrature modulator 18
The offset of the quadrature modulator 18 is controlled to be the minimum by adjusting the input signal values of the I component and the Q component with respect to.

(2) I component and Q from operation / control section 13A
The transmission baseband signal composed of the component digital signal is converted into an analog signal and applied to the quadrature modulator 18, the reference carrier wave is quadrature-modulated to generate a transmission modulation wave, and the transmission modulation wave is branched to obtain the quadrature detector 35. In addition, the received baseband signals obtained by converting the demodulated signals of the I component and the Q component obtained by quadrature detection using the reference carrier into digital signals are fed back to the arithmetic / control unit 13A, and the arithmetic / control unit 1
In 3A, in a digital radio apparatus of an envelope detection type distortion compensation system that removes the waveform distortion of a transmission modulated wave by comparing the feedback baseband signal and the transmission baseband signal and predistorting the transmission baseband signal, The arithmetic / control unit 13A is composed of a signal processor, detects a leak carrier based on the offset of the quadrature modulator 18, converts it into a direct current, and then converts it into a digital signal to add to the arithmetic / control unit 13A. The section 13A outputs I to the quadrature modulator 18.
The quadrature modulator 18 is adjusted by adjusting the signal input values of the component and the Q component.
The offset is controlled to be the minimum.

(3) In the case of (1) or (2), the circuit for detecting the leak carrier based on the offset of the quadrature modulator 18 is also used as the input circuit of the transmission modulated wave to the quadrature detector 35.

(4) In the case of (1) or (2), the leakage carrier based on the offset of the quadrature modulator 18 is detected and converted into a direct current, which is output as the RSSI of the input circuit of the transmission modulated wave to the quadrature detector 35. Use output.

(5) In the case of (1) or (2), the circuit for detecting the leak carrier based on the offset of the quadrature modulator 18 is provided with a narrow band bandpass filter for removing the modulation component.

(6) In any one of (1) to (3), a circuit for detecting the leak carrier based on the offset of the quadrature modulator 18 is provided with a multiplier 51, and the leak carrier and the modulation component based on the offset are included. And degenerate to the same phase.

(7) In any one of (1) to (3), the circuit for detecting the leak carrier based on the offset of the quadrature modulator 18 inversely modulates the leak carrier by the input signal to the quadrature modulator 18. And an inverse modulator 52 for removing the modulation component.

(8) In any of the cases (1) to (4), a carrier based on the offset of the quadrature modulator is detected from any point from the output side of the quadrature modulator 18 to the input side of the antenna 29. A means is provided for detecting the branch and disconnecting the power supply or the antenna system of the amplifier after the branch detection point of this carrier, and the offset of the quadrature modulator 18 at the time other than the transmission interruption or the self-slot in the time division multiplexing system. Enables compensating action.

(9) In any one of (1) to (8), the offset compensating operation of the quadrature modulator 18 is performed by the perturbation principle, and the perturbation width is gradually reduced as the offset carrier amount is reduced. Such a perturbation algorithm is used.

(10) In any of the cases (1) to (3), the differential derivative of the change curve of the electric energy when the arithmetic means inputs the unit circle as the modulated baseband signal becomes 0. The offset angle is determined from the point, and the I component and the Q component of the offset are calculated from the offset angle and the offset amount determined by the carrier power based on the offset of the quadrature modulator 18, and the offset compensation operation for the quadrature modulator is performed. I do.

(11) In any one of (1) to (3), the calculating means obtains the offset angle by the angle at which the power becomes maximum when the unit circle is input as the modulation baseband signal, and the offset angle is calculated. From the angle and the offset amount determined by the carrier power based on the offset of the quadrature modulator 18, the I component and Q of the offset of the quadrature modulator 18 are calculated.
The component is estimated and the offset compensation operation for the quadrature modulator is performed.

(12) In the case of (9), the calculating means determines the offset angle from the point where the differential derivative of the change curve of the electric energy when the unit circle is input as the modulated baseband signal becomes 0. The power when the calculation for determining the I component and the Q component of the offset from the offset angle and the offset amount determined by the carrier power based on the offset of the quadrature modulator 18 is completed, or when the unit circle is input as the modulation baseband signal. The offset angle is obtained from the maximum angle, and this offset angle and the quadrature modulator 18
The perturbation operation is started from the state in which the control for calculating the I component and the Q component of the offset of the quadrature modulator 18 is finished based on the offset determined by the carrier power based on the offset.

(13) A transmission baseband signal composed of digital signals of I component and Q component is converted into an analog signal and added to a quadrature modulator 18, and a reference carrier wave is quadrature modulated to generate a transmission modulation wave, and the transmission signal is transmitted. The modulated base wave is added to the quadrature detector 35, the demodulated signals of the I component and the Q component obtained by quadrature detection by the reference carrier are converted into digital signals, respectively, and a feedback baseband signal and a transmission baseband signal are obtained. In the digital radio apparatus of the envelope detection type distortion compensation system that removes the waveform distortion of the transmission modulation wave by performing the predistortion processing on the transmission baseband signal by comparing the reference carrier of the quadrature modulator 18 with 0.
The offset of the quadrature detector 35 is obtained from the average value of the maximum value and the minimum value of the I component and the average value of the maximum value and the minimum value of the Q component of the detection output of the quadrature detector 35 when the phase is shifted by 360 ° to 360 °. At the same time, the average value of the maximum value and the minimum value of the I component of the detection output when a unit circle is drawn in the detection output of the quadrature detector 35 by changing the I component and the Q component of the input of the quadrature modulator 18 The total offset of the quadrature modulator 18 and the quadrature detector 35 is obtained from the maximum value and the average value of the minimum values of the Q component, and the offset of the quadrature modulator 18 is complexly subtracted from the total offset to obtain the quadrature modulator. Eighteen offsets are obtained and stored, and compensation is performed at the quadrature modulator input and the quadrature detector output according to each offset, thereby compensating the distortion correction error based on the offset. (14) In the case of (13), an arbitrary offset is forcibly added to the quadrature modulator 18 during the calculation period for obtaining the offset amount of the quadrature detector 35.

(15) In the case of (13), the means for shifting the reference carrier wave of the quadrature modulator 18 by 0 ° to 360 ° is constructed by mounting a variable capacitance diode on a branch line hybrid or by infinite. It is composed of a phase shifter (four-phase modulator).

(16) In the case of (13), the means for phase-shifting the reference carrier wave of the quadrature modulator 18 by 0 ° to 360 ° is used for the offset calculation, and at the same time when performing the envelope detection type distortion compensation operation. , Shared for delaying the sending signal and adjusting the phase.

(17) In the case of (13), the quadrature modulator 18 and the quadrature detector 35 are respectively provided with the reference carrier from the first PLL 22 and the second PLL 62 controlled by the common reference frequency generator 63. Is supplied to the quadrature modulator 1
Means for phase-shifting the 8 reference carriers by 0 ° to 360 °
It is formed by making the reference carrier frequencies generated in the PLL 22 and the second PLL 62 different from each other.

(18) In the case of (13), a plurality of transmitters 74 to 76, to which reference carrier waves are respectively supplied from a plurality of PLLs 71 to 73 controlled by a common reference frequency, are set at the time of offset calculation. As the reference carrier of the internal quadrature modulator and the quadrature detector, P of other transmitters are mutually
The wireless base station device is configured so that the LL reference carrier can be supplied.

(19) In the case of (13), a plurality of transmitters 8
0 and 81 respectively supply the reference carrier from the internal PLL 82 to the quadrature modulator 85 (or the quadrature detector 86), and are equipped with the switch 84 to provide the reference carrier from the internal PLL and the internal PLL of the partner device. The quadrature detector 86 (or the quadrature modulator 8)
The wireless base station device is configured so that the wireless base station device can be supplied to 5).

In the cases of (20) and (13), the modulation signal is branched from any point from the output side of the quadrature modulator 18 to the antenna 29, and from the input side of the quadrature detector 35 to the input of the receiving system. With means to return to any part of
A means for disconnecting the power supply or the antenna system of the amplifier after the branching feedback point of the modulation signal is provided, and the compensation operation of the distortion correction error based on the offset is possible at the time other than the transmission interruption or the self-slot in the time division multiplexing system. To

(21) In any one of (1) to (20), the carrier frequency, the transmission power, and the temperature of the transmitting device are detected, and the offset is set for all or some of the conditions. The measured values are stored as a table, and at the time of transmission, the calculation is started from the offset at the time of the previous calculation, or the calculation is omitted when the offset is small, for each corresponding condition.

(22) In any one of (1) to (21), the offset adjustment is performed within the preamble period preceding the self-allocation slot.

(23) In the cases of (22), the offset adjustment is performed within the preamble period preceding the self-assigned slot, and the offset is adjusted after a plurality of times.

(24) In the case of (22) or (23), the offset due to the leakage carrier of the quadrature modulator is firstly received within the preamble period preceding the self-assigned slot or within the plurality of preamble periods. The adjustment or measurement calculation is performed, the offset measurement of the quadrature detector is calculated second, and the distortion correction parameter is set third.

The operation of the distortion compensation method of the present invention will be described below. FIG. 1 shows the concept of the envelope detection type distortion compensation method.

In FIG. 1, the baseband signal sent from the arithmetic / control unit 1 is quadrature-modulated by the reference carrier 3 in the quadrature modulator 2 to be a modulated wave, which is amplified by the amplifier 4 to the required power and the antenna 5 is transmitted. Sent from.

On the other hand, the modulated wave signal detected by the directional coupler 6 is quadrature-detected by the quadrature detector 7 by the same reference carrier 3 as that on the transmitting side to generate a baseband signal.

The demodulated baseband signal is input to the arithmetic / control section 1 and internally compared and calculated with the transmitted baseband signal. By performing the distortion processing, the waveform distortion due to the nonlinearity of the modulator and the power amplifier is improved. The predistortion type distortion compensation method is well known for both analog type and digital type, and there are many publicly known examples, papers, etc., and detailed description thereof will be omitted.

As described above, in the case of the method of separating the baseband signal into the phase and the amplitude and comparing the magnitudes thereof, if there is an amplitude error due to the offset of the quadrature modulator and the quadrature detector, an error will occur in the calculation. As a result, proper distortion compensation cannot be performed.

FIG. 2 shows a QPSK modulated wave on a complex plane, in which the phase is represented by the vector direction and the amplitude is represented by the length. If the quadrature modulator has an offset as shown by the dotted line, the offset is superimposed on the amplitude a, and therefore the arithmetic / control unit 1 recognizes the illustrated b in which the offset is superimposed on the amplitude a as the amplitude. Therefore, in the case of the envelope detection type distortion compensation method in which the amplitude components of modulated waves are compared, an error occurs in the distortion compensation, and proper distortion compensation cannot be performed.

FIG. 3 shows the output on the complex plane when there is no modulation. In the case of a digital modulation wave, there should be no output at the time of non-modulation, but if there is an offset in the quadrature modulator, as indicated by c, carriers proportional to the offset amount leak.

Therefore, in the system of the present invention, the leak side carrier is detected, and control means for finely adjusting the I and Q input levels of the quadrature modulator is provided so that the value thereof is minimized, and the transmission side offset is adjusted. To do.

Further, in the present invention, distortion compensation is performed by separately measuring the offset of the quadrature modulator on the transmission side and the offset of the quadrature detector on the reception side.

FIG. 4 illustrates the offset in which the quadrature detector and the quadrature modulator are superimposed in the distortion compensation system.
FIG. 4 shows a baseband output obtained by detecting the output of the quadrature modulator by the quadrature detector when the input of the quadrature modulator is not modulated in the distortion compensation system on the complex plane. When the input of the quadrature modulator is non-modulated, in the baseband signal whose output is detected by the quadrature detector, as shown in the figure, the offset component a of the quadrature modulator and the offset component b of the quadrature detector are Although they appear as offsets such as c when they are superposed, it is impossible to separate the two offset components and measure their respective magnitudes by the usual means.

Now, in the quadrature modulator, by the phase shifting means installed between the reference carrier generator and the quadrature modulator,
When the phase of the reference carrier is changed in the range of 0 ° to 360 °, the carrier phase is rotated due to the offset of the quadrature modulator. Therefore, the baseband output detected by the quadrature detector is based on the offset of the quadrature modulator. The output phase rotates.

FIG. 5 shows the phase rotation of the baseband output in the quadrature detector. The output based on the offset of the quadrature modulator is on the I and Q planes with the offset point of the quadrature detector as the center. It has been shown to rotate at.

If such a unit circle on the complex plane can be observed, the maximum values Vimax and Vqmax and the minimum values Vimin and Vqmin of the I and Q channels at this time are determined.

[Equation 1] By measuring over the offset ΔVi, Δ
Vq can be calculated by the following equation. ΔVi = (Vimax + Vimin) / 2 (2) ΔVq = (Vqmax + Vqmin) / 2 (3)

By performing the calculation of the above equation, the offset of the quadrature detector shown by the broken line in FIG. 5 can be recognized.

Further, by forcibly changing the I and Q inputs on the side of the quadrature modulator and performing modulation so as to output a unit circle, the same calculation as the above equations (1) to (3) is performed. Thus, the total offset of the modulation system and the detection system can be measured.

FIG. 6 illustrates the total offset of the modulation system and the detection system. In the figure, the broken line indicates the offset output of the detection system, b indicates the offset output of the modulation system, and a indicates the output that generates the unit circle.

From FIG. 6, as in the case of FIG.
By performing the same operations as the expressions (1) to (3),
It is known that the total offset with respect to the quadrature modulator and the quadrature detector shown by the thin line in the figure can be measured.

If the total offset of the quadrature modulator and the quadrature detector can be measured, the offset of the quadrature detector is known as described above. Therefore, the offset of the quadrature detector can be calculated from the total offset of the quadrature modulator and the quadrature detector. The offset of the quadrature modulator can be separately obtained by subtracting the quadrature modulator.

After measuring the offsets of the quadrature modulator and the quadrature detector, distortion compensation operation is performed. In the envelope detection type distortion compensation method, since the magnitudes of the transmitted signal and the feedback signal are compared, the magnitude a of the demodulated signal shown in FIG. 6 is measured on the I and Q coordinates. Since the offset b of the quadrature modulator and the offset c of the quadrature detector are superimposed, it is necessary to correct them. Since the offset of the quadrature modulator and the offset of the quadrature detector are measured in advance and are known as described above, correction can be performed by calculation.

Therefore, according to the present invention, even if an analog quadrature modulator and a quadrature detector having an offset are used,
It is possible to realize the distortion compensation method in which the error due to the offset is removed.

[0057]

FIG. 7 shows an embodiment (1) of the present invention, and proposes a distortion compensation method having a function of reducing the offset of a quadrature modulator.

In FIG. 7, the data group sent from the voice CODEC 11 is burst processed in the TDMA unit 12 and sent to the arithmetic / control unit 13. The input data is separated into an I signal and a Q signal in the arithmetic / control unit 13, and each of them is digital-analog converter (DA) 1
It is converted to an analog baseband signal via 4, 15,
After being amplified through amplifiers (AMPs) 16 and 17, they are input to a quadrature modulator 18.

In the quadrature modulator 18, the AMP 16,
Quadrature modulation is performed on the input from 17 by multiplying the reference carrier wave and the signal obtained by 90 ° phase shift by the 90 ° phase shifter 21 in multipliers 19 and 20, respectively. The reference carrier wave is supplied from a first PLL frequency synthesizer (hereinafter, simply referred to as PLL) 22 via a hybrid (HYB) 23. The modulated output is amplified by an amplifier (AMP) 24 and is transmitted to a transmission mixer (MI
X) 25 is up-converted by a local oscillation signal from a second PLL frequency synthesizer (hereinafter simply referred to as PLL) 26, and a power amplifier (P-A)
After being amplified to a required power via MP) 27, it is coupled to antenna (ANT) 29 via directional coupler (HYB) 28 and transmitted.

The transmission signal branched through the directional coupler 28 is input through the hybrid (HYB) 30, amplified by the amplifier (AMP) 31, and then received by the reception mixer (M).
IX) 32, down-converted by the local oscillation signal from the second PLL 26, and the amplifier 33
Amplified by (AMP) and band pass filter (BPF)
After being band-limited by 34, it is input to the quadrature detector 35.

In the quadrature detector 35, with respect to the input from the BPF 34, in the multipliers 36 and 37, the reference carrier wave from the first PLL 22 and the reference carrier wave from
The quadrature detection is performed by multiplying the 90 ° phase-shifted signal by the 90 ° phase shifter 38 to reproduce the baseband signal on the transmitting side. This baseband signal is
It is converted into a digital signal through the analog-digital converters (AD) 39, 40 and input to the arithmetic / control section 13.

The operation / control section 13 compares the amplitude of the fed-back baseband signal with the amplitude of the transmission baseband signal, and performs an operation of predistorting the transmission baseband signal until both are the same. Because I will
Finally, the distortion caused by the non-linearity of the quadrature modulator and the power amplifier can be compensated.

In the distortion compensation system of the present invention, prior to the operation, the transmission operation is performed in the non-modulation state to compensate the offset of the quadrature modulator. That is, the quadrature modulator 18
The leaky carrier due to the offset of is extracted through the HYB 30, the band is limited through the bandpass filter (BPF) 41, amplified by the amplifier (AMP) 42, detected by the detector (DET) 43, and converted into a DC signal. , Is converted into a digital signal through an analog-digital converter (AD) 44 and input to a control unit (CPU) 45.

The CPU 45 generates two kinds of control signals by this, and the digital-analog converter (D
A) AMP1 converted to an analog signal via 46 and 47
6 and 17 to adjust the operation reference points (offsets) of the quadrature modulator 18,
Fine tune the input level so that its leaky carrier value is minimized. The PLL 26 is C
By being controlled by the PU 45, the local oscillation frequency can be switched according to the used channel.

As described above, according to the embodiment (1), the means for detecting the energy of the offset carrier of the quadrature modulator and converting it into the DC component, and the function of controlling the offset voltage of the quadrature modulator by the detection signal are provided. By providing the control means, it is possible to realize distortion compensation without the influence of the offset of the quadrature modulator on the transmission side.

FIG. 8 shows a specific circuit configuration example of the embodiment (1), and the same components as those in FIG. 7 are designated by the same numbers. In FIG. 8, reference numeral 100 is a microphone (MIC) for inputting a voice signal. Reference numeral 101 is an IC that constitutes a quadrature modulator, and is composed of multipliers 102 and 103 and a π / 4 shift circuit 104 that shifts the phase of a reference carrier wave. Reference numerals 105 and 106 denote bandpass filters (BPF) that limit the band of the transmission signal.

Reference numeral 107 denotes an IC which constitutes a receiving section,
Reference numeral 108 is an amplifier (AMP). Reference numeral 109 denotes an IC constituting a quadrature detector, which includes multipliers 110 and 111, and is externally provided with a π / 4 shift circuit 112 for shifting the phase of a reference carrier wave. Reference numerals 113 and 114 denote low-pass filters (LPFs) that limit the band of the detection output. Reference numeral 115 is a diode, and 116 is a smoothing capacitor, which constitutes a detector for leak carriers.

In FIG. 8, the arithmetic / control unit 13 is composed of a signal processor (DSP) and has the functions of baseband waveform generation and linearizer.
Further, the AMPs 16 and 17 are composed of differential amplifiers, and by connecting the DAs 14 and 15 to one input and adding an offset to each output level according to the analog signals of the DAs 46 and 47 at the other input, Finely adjust the I and Q input levels to the quadrature modulator.

FIG. 9 shows an embodiment (2) of the present invention, which proposes a distortion compensation method having a function of reducing the offset of the quadrature modulator. The same components as those in FIG. 7 are designated by the same reference numerals, and 46 is a control unit (CPU).
That is, the PLL 26 is controlled to switch the local oscillation frequency according to the used channel. In the present embodiment, the arithmetic / control unit 13A is composed of a DSP.

In FIG. 9, the leakage carrier due to the offset of the quadrature modulator 18 is extracted through the hybrid 30, band-limited through the BPF 41, amplified by the AMP 42, detected by the DET 43, converted into a DC signal, and AD.
Operation / control unit 1
Input to 3A.

By this, the arithmetic / control section 13A
The I and Q input levels are finely adjusted, converted into analog signals via the DAs 14 and 15 and input to the quadrature modulator 18, so that the amount of leaked carriers from the quadrature modulator 18 is minimized.

As described above, according to the embodiment (2), the DSP for distortion compensation has a built-in offset compensation function, so that the distortion compensation without the influence of the offset of the quadrature modulator on the transmission side is realized. In addition, since the control unit (CPU) for removing the offset is not required, it is possible to reduce the size and cost.

FIG. 10 shows a specific circuit configuration example of the embodiment (2), in which the same components as those in FIGS. 8 and 9 are designated by the same reference numerals. In FIG. 10, calculation /
The control unit 13A is composed of a DSP, has a function of baseband waveform generation and a linearizer, and
It also has the function of compensating for the offset of the quadrature modulator.

FIG. 11 shows an embodiment (3) of the present invention, which proposes a distortion compensation method having a function of reducing the offset of the quadrature modulator. The same parts as those in FIG. 8 are shown by the same numbers, 47 is a hybrid (HYB), and 48 is a switch (SW).

In the embodiment of FIG. 11, the means for detecting the leakage carrier energy due to the offset of the quadrature modulator 18 is also used as the means for feeding back the output for distortion compensation.

The transmission signal branched through the directional coupler 28 is amplified by the amplifier 31, then down-converted by the local oscillation signal from the second PLL 26 in the reception mixer 32, and amplified by the amplifier 33. After being band-limited by the band-pass filter (BPF) 34, it is input to the quadrature detector 35 to reproduce the baseband signal on the transmission side, thereby performing distortion compensation operation.

During the offset removing operation of the quadrature modulator 18, the output of the BPF 34 is branched by the HYB 47, and the DET 4
The signal detected by 3 and converted into a DC signal is switched by the switch 48, converted into a digital signal through the AD converter 40, and input to the arithmetic / control unit 13A. By this, the arithmetic / control unit 13A finely adjusts the I and Q input levels, and inputs them to the quadrature modulator 18 via the digital-analog (DA) converters 14 and 15 to leak carrier from the quadrature modulator 18. Try to minimize the amount of.

As described above, according to the embodiment (3), in front of the quadrature detector 35, a means for branching the energy component due to the leakage carrier due to the offset of the quadrature modulator 18 and the calculation / control by switching this energy component. By providing the means for inputting to the unit 13A, it is possible to realize distortion compensation that eliminates the influence of the offset of the quadrature modulator on the transmission side. At this time, the control unit (CPU) for removing the offset is not required, and the means for detecting the energy of the leak carrier caused by the offset of the quadrature modulator 18 is also used as the means for feeding back the output for the distortion compensation. Therefore, further downsizing and cost reduction can be achieved.

FIG. 12 shows an embodiment (4) of the present invention, which proposes a distortion compensation method having a function of reducing the offset of the quadrature modulator. 9 are the same as those in FIG. 9, and 49 is an RSSI (Radi
Signal strength indicator) output generator 50 is a reception IF IC including a quadrature detector.

In the embodiment shown in FIG. 12, when the means for feeding back the transmission output for compensating for the distortion has the RSSI output function, the energy of the leaked carrier caused by the offset of the quadrature modulator 18 is detected. The RSSI output function is used as a means for doing so.

The transmission signal branched via the directional coupler 28 is amplified by the AMP 31, then down-converted by the local oscillation signal from the second PLL 26 in the reception mixer 32, amplified by the AMP 33, and then amplified by the AMP 33.
After the band is limited by the PF 34, the quadrature detector 35
And the baseband signal on the transmitting side is reproduced, and the distortion compensation operation is performed.

During the offset removing operation of the quadrature modulator 18, the RSSI output generated by comparing the input and output of the AMP 33 in the RSSI output generating section 49 is
It is converted into a digital signal via AD44 and input to the arithmetic / control unit 13A. By this, the arithmetic / control unit 13A finely adjusts the I and Q input levels and inputs them to the quadrature modulator 18 via the DAs 14 and 15 so that the amount of leakage carriers from the quadrature modulator 18 is minimized. To

As described above, according to the embodiment (4), the RSS
By including the I output means and the AD means for converting the RSSI output into a digital signal, it is possible to realize distortion compensation that eliminates the influence of the offset of the quadrature modulator on the transmission side, and control for offset removal. Since the RSSI output function of the reception IF IC is used as a means for detecting the energy of the leaking carrier caused by the offset of the quadrature modulator 18 without requiring a unit (CPU), an energy detecting means is not required separately. Further, it is possible to further reduce the size and reduce the cost.

Since the RSSI function has high energy detection accuracy and a wide detection level dynamic range, it is possible to improve compensation accuracy for offset removal of the quadrature modulator.

FIG. 13 shows a specific circuit configuration example of the embodiment (4), in which the same components as those in FIGS. 8 and 12 are designated by the same reference numerals. In FIG. 13, I
The RSSI output of C107 is used as a means for detecting the energy of the leaky carrier caused by the offset of the quadrature modulator 18.

In the case of the time division multiplexing method, the offset adjustment in each of the above embodiments may be performed at the time of preamble of the transmission burst or during the self-assigned slot.

As an embodiment (5) of the present invention, an embodiment
The BPF used to extract the carrier component in the means for detecting the energy of the leaky carrier caused by the offset of the quadrature modulator 18 in (1) and (2).
By setting 41 as a narrow band, the carrier component based on the offset and the modulation component can be separated.

As described above, according to the embodiment (5), by providing the narrow band filter, it becomes possible to perform offset compensation of the quadrature modulator even during normal modulation. In the case of the embodiments (1) and (2), the BPF
Since 41 is not a particularly narrow band, the carrier component and the modulation component based on the offset cannot be separated. Therefore, the offset compensation of the quadrature modulator cannot be performed unless there is no modulation.

FIG. 14 shows an embodiment (6) of the present invention, which proposes a distortion compensation system having a function of reducing the offset of the quadrature modulator. The same components as those in FIG. 9 are designated by the same reference numerals, and 51 is a multiplier.

In FIG. 14, the leak carrier caused by the offset of the quadrature modulator 18 is extracted through the hybrid 30 and multiplied by, for example, 8 times by the multiplier 51, and then the BPF.
After limiting the band through 41, it is amplified by AMP42 and D
The signal is detected by the ET43, converted to a DC signal, converted to a digital signal via the AD44, and input to the arithmetic / control unit 13A. By this, the I and Q input levels of the quadrature modulator 18 are finely adjusted to prevent leakage carriers. Try to minimize the amount of.

FIG. 15 illustrates degeneration to the same phase by multiplication. 8 signals for each phase shown in the figure
When multiplied, for example,

[Equation 2]

(Equation 3) , All phase components degenerate to the same phase.

Therefore, since all the modulation components of the QPSK signal and the carrier based on the offset have the same phase, the carrier size is controlled to be the minimum in this state to reduce the offset carrier. ,
Offset compensation of the quadrature modulator can be performed.

According to the embodiment (6), by providing the multiplication means, it is possible to realize distortion compensation which eliminates the influence of the offset of the quadrature modulator on the transmission side, and at the time of normal modulation, the quadrature modulator. Offset compensation can be performed. Compared with the case of the embodiment (5),
It is cost-effective because it does not require a narrow band filter which is technically difficult and expensive.

FIG. 16 shows an embodiment (7) of the present invention, which proposes a distortion compensation method having a function of reducing the offset of a quadrature modulator. The same components as those in FIG. 9 are designated by the same reference numerals, and 52 is a quadrature modulator, which is composed of multipliers 53 and 54 and a 90 ° phase shifter 55. 56 is a polarity reversal device.

In FIG. 16, the carrier based on the offset of the quadrature modulator 18 extracted by the BPF 34 is
While adding to one multiplier 53 of the quadrature modulator 52,
This is shifted by 90 ° through the 90 ° phase shifter 55, added to the other multiplier 54, the I component of the transmission signal is added to the multiplier 53, and the Q component is inverted via the polarity inverter 56 to be multiplied. 54
In addition, the carrier based on the offset is inversely modulated with the transmission signal to remove the modulation component.

The carrier component from which the modulation component has been removed is
The band is limited through the PF 41, detected by the DET 43 and converted into a DC signal, converted into a digital signal through the AD 44, and input to the arithmetic / control unit 13A.

The calculation / control section 13A thereby
The I and Q input levels are finely adjusted and input to the quadrature modulator 18 via the DAs 14 and 15, so that the quadrature modulator 18
Minimize the value of carrier leakage.

As described above, according to the embodiment (7), by providing the inverse modulation means, it is possible to realize the distortion compensation without the influence of the offset of the quadrature modulator on the transmission side, and also during the normal modulation. Offset compensation can be performed. Compared with the case of the embodiment (5), a narrow band filter which is technically difficult and expensive is not required, which is advantageous in cost.

FIG. 17 shows an embodiment (8) of the present invention, which proposes a distortion compensation system having a function of reducing the offset of the quadrature modulator. The same parts as those in FIG. 9 are shown by the same numbers, and 57 is a switch (S
W), which acts to disconnect the ANT 29.

In FIG. 17, the carrier based on the offset of the quadrature modulator 18 is branched from any one of the output side of the quadrature modulator 18, the input side of the transmission mixer 25, and the input side of the P-AMP 27, and passes through the BPF 41. After the band is limited, the signal is amplified by the AMP 42, detected by the DET 43, converted into a DC signal, converted into a digital signal through the AD 44, and input to the arithmetic / control unit 13A.

The arithmetic / control section 13A thereby
The I and Q input levels are finely adjusted and input to the quadrature modulator 18 via the DAs 14 and 15, so that the quadrature modulator 18
Minimize the amount of carrier leakage.

On the other hand, by turning off the power supply of the AMP 24 or the P-AMP 27 or turning off the antenna system, the above-mentioned leakage occurs in the state of the transmission interruption or the time other than the self-slot in the time division multiplex communication. To be able to perform carrier compensation operation.

As described above, according to the embodiment (8), by providing the antenna output cutoff means such as the antenna system disconnection means or the amplifier power supply disconnection means, the transmission interruption state or the time slot multiplex in the idle slot, Offset compensation of the quadrature modulator can be performed. Therefore, the time required for offset compensation can be shortened.

As the embodiment (9) of the present invention, in each of the above-mentioned embodiments (1) to (8), the offset control function of the quadrature modulator can operate according to the well-known perturbation principle. Further, the perturbation width in this case gradually decreases as the offset carrier amount decreases.
Perturbation algorithms can also be used.

FIG. 18 shows an example of a flowchart of offset compensation by the perturbation algorithm. In the figure, V _{i and} V _q are input voltages of the I component and the Q component to the quadrature modulator, and V _R is a carrier energy detection voltage based on the offset of the quadrature modulator. Further, FIG. 19 illustrates the setting of the perturbation amount, where (a) shows the case where the perturbation amount is constant, and (b) shows the case where the perturbation amount is inversely proportional to the offset carrier.

According to the embodiment (9), by providing the perturbation algorithm, high-speed and highly accurate offset compensation operation can be realized.

As the embodiment (10), the embodiments (1) to (1) to
In the case of (3), the offset control function of the quadrature modulator is set to the carrier leak power (offset amount) at the time of no signal output.
By using an arithmetic algorithm that estimates the offset of the quadrature modulator using the power measurement value when the unit circle is input as the modulation baseband signal, it is possible to enable offset compensation faster than perturbation operation. .

The calculation algorithm in this case is as follows. Now, _let v _{x and} v _y be DC offsets,
When outputting the unit circle of amplitude r, the power p to be detected is expressed by ^{p = x 2 + y 2 (} x-v x) 2 + (y-v y) 2 = r 2. From this, the power p is represented by the rotation angle θ of r,
Find the maximum and minimum values.

Substituting x−v _x = r cos θ y−v _y = r sin θ, the electric power p is calculated as follows: p = (r cos θ + v _x ) ² + (r sin θ + v _y ) ² = r ² + v _x ² + v _y ² + 2rv _x cos θ + 2rv _y sin θ = r ² + p _L + 2r (v _x cos θ + v _y sin θ) (4) where p _L = v _x ² + v _y ² is the power measurement value at the time of no signal output.

Since dp / dθ = −2rv _x sin θ + 2rv _y cos θ = 0, v ₀ / v _x = sin θ ₀ / cos θ ₀ (5) Equation (4), where θ ₀ is the θ at which the derivative becomes ₀ . When obtaining the v _x, v _y from _{(5), v x = (} 1 / 2rcosθ 0) (p 0 -p L -r 2) v Y = (1 / 2rsinθ 0) (p 0 -p L -r ² ) Here, p ₀ is the value of the power p when dp / dθ = 0.

That is, the DC offsets v _x, v _y can be calculated if the power p _L at the time of no signal output and the minimum power p ₀ at the time of outputting the unit circle of the amplitude r and θ giving this can be measured. . Maximum offset angle (p ₀ , θ ₀ )
Is the same as the minimum offset angle (p ₀ , θ ₀ ).

According to the embodiment (10), by providing the carrier leak detecting means of the quadrature modulator and the calculating means, high-speed offset compensation is possible and offset compensation faster than the perturbation operation is performed. be able to. As the calculation means in this case, for example, in the case of the embodiment (1),
The control unit 45 corresponds, and in the case of the embodiment (2), the arithmetic / control unit 13A corresponds.

As an embodiment (11) of the present invention, an embodiment
In (1) to (3), the offset amount and offset angle are measured from the measured value of the carrier leak power when there is no signal output and the measured value of the power when the unit circle is input as the modulation baseband signal. By inferring the offset point from the measured value, offset compensation can be performed.

FIG. 20 is a diagram for explaining the estimation of the offset point. (A) shows the relationship between the offset point recognized by the DSP and the offset by the quadrature modulator, and (b) shows the unit circle input state. Changes in the measured power value, (c) show the estimation of the offset point.

The DSP outputs the zero point that it recognizes. The power P of the offset carrier based on the offset of the quadrature modulator at that time is measured by the detecting means.
(At this time, the power is known, but the offset direction is unknown.)

The DSP outputs a unit circle. There is a power difference in the signal direction due to the presence of the offset, the direction at Pmax is the direction of the offset, and the angle at that time is θ. (The DSP recognizes θ because it outputs the unit circle by itself.)

From θ and the offset power P obtained by the term, r ² = p = v _x ² + v _y ² where r = P ^1/2 v _x = r sin θ v _y = r cos θ

Therefore, if θ and r are known, the offset amounts v _x and v _y can be derived by a simple calculation.

According to the embodiment (11), the carrier leak detection means and the arithmetic means can perform offset compensation of the quadrature modulator at high speed. According to the present embodiment, offset compensation can be performed faster than in the case of perturbation operation, and since the amount of calculation is smaller than in the case of the embodiment (10), offset compensation can be performed even faster. As the arithmetic means in this case, for example, in the case of the embodiment (1), the control unit 45 corresponds to the embodiment.
In the case of (2), the arithmetic / control unit 13A corresponds.

As the embodiment (12) of the present invention, the embodiment (1
The offset point obtained in 0) or (11) can be used as the start point of the perturbation operation to perform offset compensation of the quadrature modulator.

According to the embodiment (12), the offset compensation of the quadrature modulator can be performed at high speed and with high accuracy by the carrier leak detecting means, the calculating means and the perturbation operation. This is because the offset amount is roughly found by the calculation method and then the accurate offset amount is obtained by the perturbation operation.

In each of the above-described embodiments, as the arithmetic means for performing the offset compensation process, for example, the control unit 45 corresponds to the case of the embodiment (1), and the arithmetic operation / operation of the embodiment (2). The control unit 13A corresponds.

FIG. 21 shows an embodiment (13) of the present invention, in which the offsets of the quadrature modulator and the quadrature detector are individually calculated, and the function of compensating for the distortion correction error due to each offset is shown. It proposes a distortion compensation method with. The same parts as those in FIG.
Is a digital-to-analog converter (DA), and 61 is a phase shifter.

In the embodiment (13), as described with reference to FIG. 9, the quadrature modulation signal from the quadrature modulator 18 is
By branching at the output side, inputting to the quadrature detector 35, performing quadrature detection and inputting to the arithmetic / control unit 13A, the amplitude of the fed back baseband signal is compared with the amplitude of the transmission baseband signal. Then, the envelope detection type distortion compensation is performed by performing an operation of predistorting the transmission baseband signal until both are the same.

Further, when the transmission is interrupted, at the time of preamble of the transmission burst of the time division multiplex transmission system or at the time of the self-allocation slot, the DA converter 60 converts the output signal from the arithmetic / control unit 13A into an analog signal and outputs it. Phase shifter 61
Changes the phase of the reference carrier wave added from the PLL 22 by 0 ° to 360 ° according to this output signal.

As a result, the phase rotation of the leaky carrier caused by the offset of the quadrature modulator 18 in the non-modulation state causes the phase shift of the baseband output of the quadrature detector 35 to draw a unit circle on the complex plane. , Arithmetic / control unit 1
In 3A, observing this unit circle, (1) ~
As described above, the offset of the quadrature detector can be obtained by performing the calculation of equation (3).

Next, with the phase change of the reference carrier wave set to 0, the arithmetic / control unit 13A forcibly changes the I and Q inputs to the quadrature modulator 18 to perform modulation such that a unit circle is output. Let me do it. The modulated wave signal is branched and input to the quadrature detector 35, and the quadrature detected signal is processed by the arithmetic / control unit 13A in the above (1) to (1).
By performing the same calculation as the equation (3), the total offset of the modulation system and the detection system can be obtained as described above.

The arithmetic / control section 13A separates the offset of the quadrature modulator by a complex operation from the total offset of the modulation system and the detection system thus obtained and the offset of the quadrature detector. Ask for. Calculation/
The control unit 13A stores the offset of the quadrature detector and the offset of the quadrature modulator obtained in this way, and compensates the modulation input and the demodulation output.
Removes distortion due to offset of quadrature detector and quadrature modulator.

Therefore, according to the embodiment (13), by providing the phase shift means for the quadrature modulator, it is possible to perform the distortion compensation in which the distortion correction error due to the offset between the quadrature modulator and the quadrature detector is compensated. , Embodiment (1) ~
As in the case of (12), the means for detecting the offset carrier of the quadrature modulator becomes unnecessary.

In the embodiment (13), the offset compensation process is performed by the arithmetic / control unit 1 including a DSP for generating a baseband waveform, as shown in the embodiment (1).
It may be performed in the control unit 45 different from the control unit 3 or in the operation / control unit 13A including the DSP for generating the baseband waveform as shown in the embodiment (2).

In the embodiment (14) of the present invention, in the embodiment (13), a means for forcibly adding the offset is provided to the quadrature modulator 18 during the calculation period for obtaining the offset of the quadrature detector 35.

As a result, when the offset of the quadrature detector 35 is obtained, the carrier due to the offset of the quadrature modulator 18 increases, and the phase rotation of the baseband output of the quadrature detector 35 based on the phase rotation causes Since the unit circle drawn on the complex plane expands, the calculation / control unit 1
In 3A, observing this unit circle, (1) ~
It is possible to improve the calculation accuracy when the offset of the quadrature detector is calculated by calculating the formula (3).

According to the embodiment (14), the offset of the quadrature detector can be calculated more accurately by providing the quadrature modulator with the phase shift means and the offset giving means.

As an embodiment (15) of the present invention, the embodiment (1
In 3), the phase of the reference carrier with respect to the quadrature modulator is set to 0.
As the phase shift means 61 for changing the angle from ° to 360 °, use is made of a type in which a variable capacitance diode is mounted on a branch line hybrid, or a type configured by an infinite phase shifter (four phase modulator). You can

As an embodiment (16) of the present invention, a phase shift means 61 for changing the phase of the reference carrier wave by 0 ° to 360 °.
Is used to calculate the offset amount of the quadrature modulator, and at the same time, in the envelope detection type distortion compensation operation,
It can be commonly used for phase adjustment by delaying a transmission signal to both multipliers 19 and 20.

According to the embodiment (16), by providing a phase adjusting means (not shown) in addition to the phase shifting means 61, this phase adjusting means is commonly used for offset calculation in the distortion compensation system having the phase adjusting means by delay. This can contribute to downsizing and cost reduction.

FIG. 22 shows an embodiment (17) of the present invention, in which the offsets of the quadrature modulator and the quadrature detector are individually calculated, and the function of compensating the distortion correction error due to each offset is shown. It proposes a distortion compensation method with. The same parts as those in FIG.
2 is a third PLL frequency synthesizer (hereinafter simply referred to as PL
Reference numeral 63 is a reference frequency generator (TCXO).

In the embodiment (17), the quadrature modulator 18
The phase shift means for varying the phase of the reference carrier wave for 0 ° to 360 ° is configured by using a plurality of PLL frequency synthesizers. As shown in FIG. 22, the reference carrier for the quadrature modulator 18 is supplied from the PLL 22, and the local oscillation signal for the transmitting mixer 25 and the receiving mixer 32 is supplied to the PL.
It is supplied from L26, the reference carrier for the quadrature detector 35 is supplied from PLL62,
The reference frequency signal given to L62 is supplied from TCXO63.

At the time of offset measurement, the output frequency of either PLL 22 or PLL 62 is set to N.
(N is an integer) The baseband output of the quadrature detector 35 can be phase-shifted by the frequency difference between the two PLLs by shifting by a channel or by making the frequencies apart by a frequency that can be set by the PLL. Therefore, the arithmetic / control unit 13A can obtain the offset of the quadrature detector by observing the unit circle drawn on the complex plane and performing the operations of the above equations (1) to (3).

As described above, the arithmetic / control unit 13A further obtains the total offset of the modulation system and the detection system, and separately obtains the offset of the quadrature modulator by calculation, thereby obtaining the quadrature detector and the quadrature modulation. Remove distortion due to instrument offset.

According to the embodiment (17), a plurality of PLLs and P
By including the LL control means, it is possible to draw the unit circle at an accurate rotation speed and execute the calculation of the offset amount with high accuracy. The present embodiment has an advantage that it can be realized without expanding the circuit scale in the case of a device that originally uses a plurality of PLLs, for example, when the transmitting and receiving devices are separated.

FIG. 23 shows an embodiment (18) of the present invention, in which the offsets of the quadrature modulator and the quadrature detector are individually calculated and the distortion correction error due to each offset is compensated. It proposes a distortion compensation method with. In the figure, reference numeral 70 is a reference oscillator, 71 to 73 are PLL frequency synthesizers (hereinafter simply referred to as PLL), and 74 to 76 are transmitters (TX).

The embodiment (18) is configured such that a plurality of transmitters are installed close to each other, and each PLL is supplied with a reference frequency signal from a common reference oscillator, such as a base station radio apparatus. It is applied in the case of the device. In this embodiment, a plurality of reference carrier waves are input to each of the transmitters 74 to 76, and selected and used.

At the time of offset calculation, the reference carrier frequency of the quadrature modulator or quadrature detector in the transmitter is switched by the switching means so that the reference carrier frequencies of the quadrature modulator and the quadrature detector are N (N is an integer) channels. Be different. With this, similarly to the case of the embodiment (17), the baseband output of the quadrature detector 35 is phase-rotated at the frequency of the difference between the two reference carrier frequencies, and the offset of the quadrature detector can be obtained.

Further, as described above, the total offset of the modulation system and the detection system is obtained, and the offset of the quadrature modulator is separately obtained by calculation, so that the distortion based on the offset of the quadrature detector and the quadrature modulator is obtained. Remove.

In the embodiment (18), each transmitter is provided with the input means and the switching means for the reference carrier wave so that the unit circle is drawn at an accurate rotation speed and the offset calculation is executed with high accuracy. You can According to the present embodiment, there is an advantage that it is not necessary to install a new PLL when a plurality of transmitters are used and PLLs of adjacent devices can be mutually used.

FIG. 24 shows an embodiment (19) of the present invention, in which the offsets of the quadrature modulator and the quadrature detector are individually calculated, and the function of compensating for the distortion correction error due to each offset is shown. It proposes a distortion compensation method with. In the figure, 80 and 81 are transmitting devices. In each transmitting device, 82 is a PLL frequency synthesizer (hereinafter simply referred to as PLL), 83 is a distributor, and 84 is a switch (S).
W), 85 is a quadrature modulator, and 86 is a quadrature detector.

The embodiment (19) is applied to a case where a plurality of transmitters are installed close to each other, such as a base station radio apparatus. In this embodiment, in each of the transmitters 80 and 81, the reference carrier signal of the PLL 82 is supplied to the quadrature modulator 85 and the partner transmitter via the distributor 83, and the reference carrier of the PLL of its own device or the P of the partner device is supplied.
The LL reference carrier is switched via the switch 84 and supplied to the quadrature detector 86. Switch 84
Always selects the PLL 82 side of its own device.

At the time of offset calculation, the PLL of the partner device
Of the reference carrier of the quadrature detector and the quadrature detector 86 by supplying the quadrature detector 86 with the reference carrier frequency of N (N is an integer), or the same frequency. Also by being asynchronous, the baseband output of the quadrature detector 35 can be phase-rotated at the frequency of the difference between the reference carrier frequencies to obtain the offset of the quadrature detector, as in the case of the embodiment (17). it can.

Further, as described above, the total offset of the modulation system and the detection system is obtained, and the offset of the quadrature modulator is separately obtained by calculation, so that the distortion based on the offset of the quadrature detector and the quadrature modulator is obtained. Remove.

In the embodiment (19), each transmitting device is provided with the input / output means and switching means for the reference carrier wave so that the unit circle is drawn at an accurate rotation speed and the offset calculation is executed with high accuracy. be able to. According to this embodiment,
There is an advantage that it is not necessary to install a new PLL when a plurality of transmitters are provided and the PLLs of adjacent devices can be mutually used.

FIG. 25 shows an embodiment (20) of the present invention, in which the offsets of the quadrature modulator and the quadrature detector are individually calculated and the function of compensating the distortion correction error due to each offset is shown. It proposes a distortion compensation method with. In the figure, the same parts as those in FIG. 21 are indicated by the same numbers, and 64 and 65 are switches (SW), respectively.

In the embodiment (20), the modulated signal is branched from any part from the output of the quadrature modulator to the input of the antenna system, and any part from the input of the quadrature detector to the input of the antenna system is branched. Return to. In FIG. 25, SW
It is shown that 64 is provided to connect from the output of AMP 24 to the input of BPF 34. Also, the antenna output is turned off during the offset calculation. In FIG. 25, S
Although it is shown that W65 is provided to disconnect ANT29, instead of disconnecting ANT29, P-AMP2
The power of 7 may be turned off.

In the embodiment (20), SW64 is turned on and SW65 is turned off, thereby
In addition, the offset compensation operation can be performed by performing the offset calculation at the time other than the self-slot of the time division multiplexing system (at the idle slot).

As described above, according to the embodiment (20), by providing the antenna output cutoff means, it is possible to perform offset compensation even in the state of transmission interruption. Further, in the time division multiplexing method, offset compensation can be performed during idle slots. Therefore, the time required for offset compensation can be shortened.

As an embodiment (21) of the present invention, when the offset compensation operation of each of the above embodiments is performed, a carrier frequency of the transmitter, a transmission power, and a device temperature detection means are provided to perform transmission during the offset compensation operation. The offsets for all or some of the equipment carrier frequency, transmission power, and equipment temperature conditions are stored as a table. Then, at the time of transmission, the offset at the previous compensation operation is obtained from the table based on the above conditions at that time, and the offset calculation is started from this value. If the offset is small from the previous data, the offset calculation is omitted.

According to the embodiment (21), by providing means for tabulating the offset and storage means for storing this value, the data at the previous compensation operation is used as the calculation start point of the offset compensation. The time required for calculation can be shortened. In the case of the perturbation operation, high-speed convergence can be achieved by starting the perturbation from the previous offset point. Further, when the offset calculation can be omitted, the distortion compensation operation can be started immediately, so that the distortion compensation time can be shortened.

As an embodiment (22) of the present invention, the offset compensating operation of each of the above embodiments is performed within the preamble period preceding the self-assigned slot in the time division multiplexing system.

As an embodiment (23) of the present invention, the offset compensating operation of each of the above embodiments is performed within the preamble period preceding the self-assigned slot in the time division multiplexing method, and the preamble is performed a plurality of times. Try to converge over a period of time.

According to an embodiment (24) of the present invention, when performing distortion compensation of a transmitting apparatus, the first orthogonal modulation is performed within a preamble period preceding a self-allocation slot or within a plurality of preamble periods. The offset adjustment or measurement calculation is performed by the leak carrier of the detector, the offset measurement calculation of the quadrature detector is performed second, and the distortion correction parameter is set third.

[0161]

As described above, according to the present invention, the carrier leak energy due to the offset of the quadrature modulator is detected, and the input level of the quadrature modulator is adjusted so as to minimize it. It is possible to eliminate the offset of the modulator and remove the waveform distortion of the transmitted modulated wave.

Further, a frequency difference or a phase difference is given to the reference carrier of the quadrature modulator and the quadrature detector, a unit circle is drawn at the output of the quadrature detector to find the offset of the quadrature detector, and the input of the quadrature modulator is adjusted. Draw the unit circle with the output of the quadrature detector to find the total offset of the quadrature modulator and the quadrature detector, and calculate the offset of the quadrature modulator from this, and then calculate the quadrature modulator input and quadrature detector output. Can compensate for the influence of the offset of the quadrature modulator and the quadrature detector.

Therefore, according to the distortion compensation method of the present invention, when performing envelope detection type distortion compensation,
It is possible to remove distortion of the transmission signal.

[Brief description of drawings]

FIG. 1 is a diagram showing a concept of an envelope detection type distortion compensation system.

FIG. 2 is a diagram showing a QPSK modulated wave on a complex plane.

FIG. 3 is a diagram showing an output on a complex plane when there is no modulation.

FIG. 4 is a diagram illustrating an offset in which a quadrature detector and a quadrature modulator are superimposed in a distortion compensation system.

FIG. 5 is a diagram showing phase rotation of a baseband output in a quadrature detector.

FIG. 6 is a diagram illustrating a total offset of a modulation system and a detection system.

FIG. 7 is a diagram showing an embodiment (1) of the present invention.

FIG. 8 is a diagram showing a specific circuit configuration example of the embodiment (1).

FIG. 9 is a diagram showing an embodiment (2) of the present invention.

FIG. 10 is a diagram showing a specific circuit configuration example of the embodiment (2).

FIG. 11 is a diagram showing an embodiment (3) of the present invention.

FIG. 12 is a diagram showing an embodiment (4) of the present invention.

FIG. 13 is a diagram showing a specific circuit configuration example of the embodiment (4).

FIG. 14 is a diagram showing an embodiment (6) of the present invention.

FIG. 15 is a diagram for explaining degeneration to the same phase by multiplication.

FIG. 16 is a diagram showing an embodiment (7) of the present invention.

FIG. 17 is a diagram showing an embodiment (8) of the present invention.

FIG. 18 is a diagram showing an example of a flowchart of offset compensation by a perturbation algorithm.

FIG. 19 is a diagram illustrating a change in perturbation amount.

FIG. 20 is a diagram illustrating estimation of an offset point.

FIG. 21 is a diagram showing an embodiment (13) of the present invention.

FIG. 22 is a diagram showing an embodiment (17) of the present invention.

FIG. 23 is a diagram showing an embodiment (18) of the present invention.

FIG. 24 is a diagram showing an embodiment (19) of the present invention.

FIG. 25 is a diagram showing an embodiment (20) of the present invention.

[Explanation of symbols]

 13 Computation / control section 13A Computation / control section 16 Amplifier 17 Amplifier 18 Quadrature modulator 22 PLL 29 Antenna 35 Quadrature detector 45 Control section 51 Multiplier 52 Quadrature modulator 62 PLL 63 Reference frequency generator 71 PLL 72 PLL 73 PLL 74 Transmitter 75 Transmitter 76 Transmitter 80 Transmitter 81 Transmitter 82 PLL 84 Switch 85 Quadrature modulator 86 Quadrature detector

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuyuki Oishi 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor, Ninya Osaki 3-22-8, Hakata Station, Hakata-ku, Fukuoka City, Fukuoka Prefecture, Fujitsu Limited Kyushu Digital Technology Co., Ltd. (72) Inventor Yuji Kaneko 3-22-8 Hakataekimae, Hakata-ku, Fukuoka City, Fukuoka Prefecture Fujitsu Kyushu Digital Technology Co., Ltd. (72) Inventor ▲ Taka ▼ Takashi Fukuoka 3-22-8 Hakataekimae, Hakata-ku, Fukuoka City, within Fujitsu Kyushu Digital Technology Co., Ltd. (72) Inventor Yu Kabashima 3-22-8 Hakataekimae, Hakata-ku, Fukuoka City, Fukuoka Prefecture Fujitsu Kyushu Digital Technology Co., Ltd. Within

Claims (24)

[Claims] 1. A transmission baseband signal composed of digital signals of I and Q components from an arithmetic / control unit is converted into an analog signal, which is added to a quadrature modulator via an amplifier and a reference carrier wave is quadrature-modulated. The transmission modulated wave is generated, the transmission modulated wave is branched and added to a quadrature detector, and the demodulated signals of the I component and the Q component obtained by the quadrature detection by the reference carrier are converted into digital signals. The received baseband signal is fed back to the calculation / control unit, and the calculation / control unit compares the feedback baseband signal and the transmission baseband signal to perform predistortion processing on the transmission baseband signal, thereby performing transmission modulation. In a digital radio apparatus of an envelope detection type distortion compensation system that removes waveform distortion of a wave, leakage caused by offset of the quadrature modulator By adding detect and direct current signal of the Yaria the control unit,
The control unit outputs a control signal to change the operation reference point of the amplifier and adjust the input signal values of the I component and the Q component to the quadrature modulator, thereby minimizing the offset of the quadrature modulator. Distortion compensation method characterized by controlling so that 2. A transmission baseband signal composed of digital signals of I component and Q component from an arithmetic / control unit is converted into an analog signal and added to a quadrature modulator, and a reference carrier wave is quadrature modulated to generate a transmission modulation wave. At the same time, the transmitted modulated wave is branched and added to the quadrature detector, and the demodulated signals of the I component and the Q component obtained by the quadrature detection by the reference carrier are respectively converted into digital signals to obtain received baseband signals. By returning to the calculation / control unit, the calculation / control unit compares the feedback baseband signal and the transmission baseband signal to perform predistortion processing on the transmission baseband signal, thereby suppressing the waveform distortion of the transmission modulation wave. In a digital radio apparatus of an envelope detection type distortion compensation system to be removed, the arithmetic / control unit is composed of a digital signal processor, A leak carrier based on the offset of the quadrature modulator is detected, converted into a direct current, converted into a digital signal and added to the calculation / control unit, whereby the calculation / control unit causes the I component and the Q component for the quadrature modulator. Distortion compensation method characterized in that the signal input value of is adjusted so that the offset of the quadrature modulator is minimized. 3. The distortion compensation system according to claim 1, wherein a circuit for detecting a leak carrier based on an offset of the quadrature modulator is used as an input circuit of a transmission modulation wave to the quadrature detector. Characteristic distortion compensation method. 4. The distortion compensation system according to claim 1 or 2, wherein a leaky carrier based on an offset of the quadrature modulator is detected and converted into a direct current, and an output of a transmission modulated wave to the quadrature detector is input. Distortion compensation method characterized by using RSSI output. 5. The distortion compensation system according to claim 1, wherein a circuit for detecting a leak carrier based on the offset of the quadrature modulator is provided with a narrow band bandpass filter for removing a modulation component. Distortion compensation method. 6. The distortion compensation method according to claim 1, wherein a circuit for detecting a leak carrier based on the offset of the quadrature modulator is provided with a multiplier, and the leak carrier and the modulation component based on the offset are provided. Distortion compensation method characterized by degenerating and in the same phase. 7. The distortion compensation method according to any one of claims 1 to 3, wherein a circuit for detecting a leak carrier based on an offset of the quadrature modulator is provided with the leak carrier by an input signal to the quadrature modulator. A distortion compensation method characterized by comprising an inverse modulator for inverse modulation to remove a modulation component. 8. The distortion compensation system according to any one of claims 1 to 4, wherein a carrier based on an offset of the quadrature modulator is provided from any point from the output side of the quadrature modulator to the input side of the antenna. A means for branch detection and a means for disconnecting the power supply or antenna system of the amplifier after the branch detection point of the carrier is provided, and the offset of the quadrature modulator is provided at the time other than the transmission interruption or the self-slot in the time division multiplexing system. Distortion compensation method characterized by enabling compensation operation. 9. The distortion compensating method according to claim 1, wherein the offset compensating operation of the quadrature modulator is performed based on the perturbation principle, and the perturbation width is sequentially increased as the offset carrier amount decreases. Distortion compensation method characterized by using a perturbation algorithm that decreases. 10. The distortion compensation method according to any one of claims 1 to 3, wherein the calculating means sets the differential derivative of the change curve of the electric energy to 0 when the unit circle is input as the modulation baseband signal. Determine the offset angle from
An offset compensation operation for the quadrature modulator is performed by performing an operation for determining an I component and an Q component of the offset from the offset angle and an offset amount determined by a carrier power based on the offset of the quadrature modulator. Distortion compensation method. 11. The distortion compensation method according to any one of claims 1 to 3, wherein the computing means obtains an offset angle by an angle that maximizes power when a unit circle is input as a modulated baseband signal, From the offset angle and the offset amount determined by the carrier power based on the offset of the quadrature modulator, control for estimating the I component and the Q component of the offset of the quadrature modulator is performed to perform the offset compensation operation for the quadrature modulator. Distortion compensation method characterized by performing. 12. The distortion compensating method according to claim 9, wherein the calculating means sets the offset angle from the point where the differential derivative of the change curve of the electric energy when the unit circle is input as the modulation baseband signal becomes zero. I component and Q of the offset determined from the offset angle and the offset amount determined by the carrier power based on the offset of the quadrature modulator.
The offset angle is determined by the angle that maximizes the power when the unit circle is input as the modulation baseband signal after the calculation to determine the component is determined, and is determined by the carrier power based on the offset angle and the offset of the quadrature modulator. A distortion compensating method, wherein the perturbation operation is started from a state in which a control for calculating an I component and a Q component of the offset of the quadrature modulator is completed based on the offset. 13. A transmission baseband signal composed of digital signals of I component and Q component is converted into an analog signal and added to a quadrature modulator, and a reference carrier wave is quadrature modulated to generate a transmission modulation wave, and the transmission modulation is performed. I obtained by branching the wave and applying it to the quadrature detector and performing quadrature detection with the reference carrier
By comparing the feedback baseband signal obtained by converting the demodulated signals of the Q component and the Q component with the transmission baseband signal and predistorting the transmission baseband signal, the waveform distortion of the transmission modulation wave is reduced. In the digital radio apparatus of the envelope detection type distortion compensation system for removing, the maximum value and the minimum value of the I component of the detection output of the quadrature detector 35 when the reference carrier of the quadrature modulator is phase-shifted by 0 ° to 360 ° The offset of the quadrature detector is obtained from the average value and the average value of the maximum and minimum values of the Q component, and the I and Q components of the input of the quadrature modulator are changed to detect the detection output of the quadrature detector. In Fig. 2, the quadrature modulator and the quadrature detector are calculated from the average values of the maximum and minimum values of the I component and the maximum and minimum values of the Q component of the detection output when the unit circle is drawn. The offset of the quadrature modulator is calculated by complexly subtracting the offset of the quadrature modulator from the total offset of the quadrature modulator, and the offset is calculated and stored according to each offset. Distortion compensation method characterized by compensating for distortion correction error based on offset by performing compensation at the output of the quadrature detector. 14. The distortion compensation method according to claim 13, wherein an arbitrary offset is forcibly added to the quadrature modulator during a calculation period for obtaining an offset amount of the quadrature detector. method. 15. The distortion compensation method according to claim 13, wherein the reference carrier wave of the quadrature modulator 18 is 0 ° to 360 °.
The means for phase shifting comprises a variable capacitance diode mounted on a branch line hybrid, or an infinite phase shifter (4
Distortion compensation method characterized by being configured with a phase modulator. 16. The distortion compensation method according to claim 13, wherein the reference carrier wave of the quadrature modulator 18 is 0 ° to 360 °.
Distortion characterized in that the means for phase shifting is used for the offset calculation, and at the same time, it is used for delaying the transmission signal and performing phase adjustment during the envelope detection type distortion compensation operation. Compensation method. 17. The distortion compensating method according to claim 13, wherein the quadrature modulator and the quadrature detector are controlled by a common reference frequency generator.
When the reference carrier waves are respectively supplied from L and L, the means for phase-shifting the reference carrier wave of the quadrature modulator 18 by 0 ° to 360 ° is a reference carrier wave frequency generated in the first PLL and the second PLL. Distortion compensation method characterized in that it is formed by making different. 18. The distortion compensating method according to claim 13, wherein a plurality of PLLs controlled by a common reference frequency.
From multiple transmitters, each supplied with a reference carrier from
A base station radio characterized in that, at the time of the offset calculation, the reference carrier of the PLL of another transmitter can be mutually supplied as the reference carrier of the quadrature modulator and the quadrature detector inside each transmitter. apparatus. 19. The distortion compensation method according to claim 13, wherein each of the plurality of transmitters supplies a reference carrier from an internal PLL to a quadrature modulator (or a quadrature detector), and includes a switch. The base station radio apparatus is characterized in that the reference carrier from the PLL and the reference carrier from the PLL inside the partner apparatus can be switched and supplied to the quadrature detector (or the quadrature modulator). 20. The distortion compensation method according to claim 13, wherein the modulation signal is branched from any point from the output side of the quadrature modulator to the antenna, and the modulation signal is branched from the input side of the quadrature detector 35 to the reception system. A means for feeding back to any part up to the input is provided, and a means for cutting off the power supply or the antenna system of the amplifier after the branch feedback point of the modulated signal is provided.
A distortion compensating method capable of compensating for a distortion correction error based on the offset except when transmission is interrupted or at the time of self-slot in time division multiplexing. 21. The distortion compensation method or base station radio apparatus according to claim 1, wherein the carrier frequency, the transmission power, and the temperature of the transmission apparatus are detected, and all or part of each condition is detected. The offset measurement values are stored as a table for each condition, and at the time of transmission, the calculation is started from the offset at the previous calculation for each applicable condition, or
Alternatively, the distortion compensation method is characterized in that the calculation is omitted when the offset is small. 22. The distortion compensation method or base station radio apparatus according to claim 1, wherein offset adjustment is performed within a preamble period preceding the self-assigned slot. method. 23. The distortion compensation method according to claim 22, wherein offset adjustment is performed within a preamble period preceding the self-assigned slot, and the offset is adjusted after a plurality of times. Distortion compensation method. 24. The distortion compensation method according to claim 22 or 23, wherein the offset due to a leaky carrier of a quadrature modulator is firstly placed within a preamble period preceding a self-assigned slot or within a plurality of such periods. The distortion compensation method is characterized by performing the adjustment or measurement calculation of, the second measurement calculation of the offset of the quadrature detector, and the third parameter setting of distortion correction.