JPH06303042A - Linear modulation wave envelope control method and linear transmitter - Google Patents

Abstract

PURPOSE:To amplify power of a modulation wave at a high efficiency while a distortion factor of the modulation wave is always reduced in an excellent way by controlling variably a delay based on a frequency error between a linear modulation wave subjected to envelope control and a setting reference frequency component. CONSTITUTION:An envelope signal is delayed at a variable delay circuit 7 by a desired value and obtained as a power amplifier control signal via a D/A converter circuit 8 and received by an envelope control circuit 9 as an envelope control signal to control an envelope of the modulation wave from a quadrature modulation circuit 5 in a desired way with respect to the envelope signal. As a result, a less distortion modulation wave is obtained as an object to be power-amplified from the circuit 9 and outputted from the circuit 9 to the power amplifier. The modulated wave from the circuit 9 is detected frequency components at the frequency error detection circuit 12 via an A/D conversion circuit 15 then its frequency components is compared with reference frequency components stored in a memory 14 in advance. Thus, the frequency error signal is obtained and the delay of the circuit 7 is controlled based on the frequency error signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear modulation wave envelope control method for a linear transmission device and the linear transmission device itself, and particularly to a linear modulation wave suitable for reducing the distortion factor of the linear modulation wave. The present invention relates to an envelope control method and a linear transmission device.

[0002]

2. Description of the Related Art Hitherto, in a high frequency band linear transmitter, various devices have been devised for amplifying a modulated wave with high power efficiency and transmitting it, assuming that it is used as a mobile communication device. However, at that time, as a method for reducing the distortion rate of the modulated wave, for example, Japanese Patent Laid-Open No. 3-347
The one described in Japanese Patent Publication No. 09 is known. In this case, in order to reduce the distortion rate of the (linear) modulated wave, the in-phase envelope component and the quadrature envelope component generated in the baseband processing unit of the modulator cause the modulated wave by the quadrature modulator and further The drain control signal to the high frequency amplifier is generated by digital operation processing of the base band, and the modulated wave is power-amplified with a saturation characteristic based on the drain control signal.

[0003]

However, in the case of the above publication, the time waveform of the drain control signal and the envelope waveform of the modulation wave from the quadrature modulator do not coincide with each other in time, and this is why modulation is performed. Not only is the effect of reducing the distortion factor of the waves insufficient, but in order to make their waveforms coincide in time,
Even if the drain control signal or the envelope waveform of the modulation wave from the quadrature modulator is delayed in time, it is difficult to adjust the delay amount with a delay circuit for that purpose, and even after the delay amount is once adjusted, The distortion factor of the modulated wave is deteriorated with the temperature change in each of the circuit and the element. An object of the present invention is to provide a linear modulation wave envelope control method and a linear transmission device capable of performing power amplification on a modulation wave with high efficiency in a state where the distortion factor of the modulation wave is always favorably reduced without requiring delay adjustment for temperature changes. To serve.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an envelope signal as a power amplification control signal in a state where at least one of a linear modulation wave and an envelope signal is delayed by varying a delay amount. The linearly modulated wave is subjected to envelope control in order to reduce distortion of the linearly modulated wave, and the linearly modulated wave subjected to the envelope control is used as a power amplification target, and is set between the set reference frequency component of the linearly modulated wave. This is achieved by variably controlling the delay amount based on the frequency error, and is also achieved by configuring the linear transmission device as such.

[0005]

Operation: In a state where at least one of the linear modulation wave and the envelope signal is delayed by varying the delay amount, the modulation wave is envelope-controlled by the envelope signal, and then the envelope-controlled linear modulation wave is set. When the delay amount is variably controlled based on the frequency error between the reference frequency component and the relative frequency between the modulation wave and the envelope signal, the distortion of the envelope-controlled linear modulation wave should be reduced. The delay time can be optimally controlled.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to FIGS. As described above, in the linear modulation wave envelope control method according to the present invention, at least one of the linear modulation wave and the envelope signal is delayed as a variable delay amount, and the envelope signal is subjected to the power amplification control signal. As the linear modulation wave by the envelope signal, the envelope control is performed to reduce the distortion of the linear modulation wave, and the linear modulation wave with the envelope control is subjected to power amplification, and the set reference frequency component of the linear modulation wave is set. The amount of delay is variably controlled on the basis of the frequency error between and, but FIGS. 1 to 4 each show various configurations of the linear transmission device according to the present invention. First, referring to FIG. 1, the baseband signal from the input terminal 1 is subjected to digital signal processing by an I / Q signal generation circuit (complex envelope generation circuit) 2 to generate an in-phase envelope component I (t ) And the orthogonal envelope component Q (t) are generated. If you explain the process in more detail,
Assuming that the carrier angular frequency of the modulated wave is ω _C , the envelope signal is R (t), and the modulation phase is φ (t), the modulated wave e (t) is generally expressed as Equation 1 below. Has become.

[0007]

[Equation 1]

However, in Expression 1, Re [f] represents the real part of the function f, and E (t) represents the complex envelope represented by Expressions 2 and 3, respectively.

[0009]

[Equation 2]

[0010]

[Equation 3]

As described above, in the I / Q signal generation circuit 2, the in-phase envelope component I (t) and the quadrature envelope component Q (t) are generated by digital signal processing.
Furthermore, the in-phase envelope component I (t) and the quadrature envelope component Q
(t) is converted into an analog signal waveform through each of the D / A conversion circuits 3 and 4, and the quadrature modulation circuit 5 uses the carrier oscillator 13
Is multiplied by the carrier wave from the modulated wave e (t)
Is obtained. In the quadrature modulation circuit 5, the carrier wave from the carrier wave oscillator 13 oscillating at the frequency ω _C is used, the in-phase carrier wave is in the in-phase envelope component I (t), and the quadrature envelope component Q (t) is in the quadrature. The modulated waves e (t) are obtained as their outputs by multiplying and adding the respective carrier waves.

On the other hand, in the envelope signal generating circuit 6, the I / Q
Using the in-phase envelope component I (t) and the quadrature envelope component Q (t) from the signal generating circuit 2, the envelope signal R (t) is generated by the following equation 4.

[0013]

[Equation 4]

This envelope signal R (t) is delayed by the variable delay circuit 7 by a desired amount (this delay amount will be described later), and then D
While being obtained as a power amplification control signal via the A / A conversion circuit 8, it is input to the envelope control circuit 9 as an envelope control signal, so that the envelope of the modulated wave e (t) from the quadrature modulation circuit 5 becomes The envelope signal R (t) is controlled as desired. As a result, the envelope control circuit 9 obtains a modulated wave e (t) as a power amplification target with little distortion and outputs the modulated wave e (t) from the output terminal 16 to the power amplifier.

On the other hand, the modulated wave e from the envelope control circuit 9
(t) is the frequency error detection circuit 1 through the A / D conversion circuit 15.
The frequency error signal is obtained by detecting the frequency component in 2 and comparing it with the reference frequency component stored in advance in the memory 14, and based on this, the delay amount in the variable delay circuit 7 is determined. It is controlled. In this example, the frequency error signal is once converted into an analog signal by the LPF 11 and then acts on the variable delay circuit 7 as a digital delay control signal via the A / D circuit 10. The variable delay circuit 7 is configured as, for example, a shift register (serial-in / parallel-out type) having a plurality of stages, and a parallel output at a stage corresponding to a digital delay control signal from the A / D circuit 10 is selectively output. Thus, the envelope signal R (t) from the envelope signal generation circuit 6
Can be delayed by a desired amount. As a result, the modulated wave e (t) obtained from the envelope control circuit 9 has a frequency component that always has a desired spectrum, so that the modulated wave e (t) from the quadrature modulation circuit 5 is relative to the envelope control signal. The delay time is controlled. As a method of detecting the frequency component of the modulated wave e (t) obtained from the envelope control circuit 9, for example, the fast Fourier transform method or the like can be used. As the range of the reference frequency component stored and set in the memory 14 in advance, a frequency range according to the memory capacity may be set.

Next, referring to FIG. 2, the general operation and effects are almost the same as those in FIG. That is, in this example, as shown in the figure, the envelope signal R (t) from the envelope signal generating circuit 6 is converted into an analog signal by the D / A circuit 8, and its delay time is changed by the variable delay circuit 7. Although controlled, the variable delay circuit 7 can be configured using a charge transfer element such as a CCD. The frequency error signal from the frequency error detection circuit 12 is L
The delay time for the envelope signal R (t) is controlled by being generated as a clock signal having a frequency corresponding to the frequency error signal from the VCO 17 via the PF 11 and being input as a shift clock to the variable delay circuit 7. It is what

Further, when the one shown in FIG. 3 is described, the schematic operation and effect thereof are almost the same as those in the case of FIG. As shown in the figure, in this example, the variable delay circuit 7 is provided at the subsequent stage of the I / Q signal generation circuit 2, so that the in-phase envelope component I (t) and the quadrature envelope component Q to the quadrature modulation circuit 5 are provided. The delay time of (t) is digitally controlled by the frequency error signal.

Further, when the one shown in FIG. 4 is explained, the general operation and effect are almost the same as in the case of FIG. As shown in the figure, in this example, the modulated wave e (t) from the quadrature modulation circuit 5 is delayed by the variable delay circuit 7 by a desired amount and then input to the envelope control circuit 9, but the frequency error detection circuit The frequency error signal from 12 is generated from the VCO 17 via the LPF 11 as a clock signal having a frequency corresponding to the frequency error signal, and is input to the variable delay circuit 7 as a shift clock.
The delay time for (t) is controlled.

[0019]

As described above, according to the first aspect of the present invention, it is not necessary to adjust the delay with respect to the temperature change, and the modulated wave is highly efficiently power-amplified while the distortion rate of the modulated wave is always favorably reduced. In the case where the linearly modulated wave envelope control method that can be performed is according to claims 2 to 4, it is not necessary to adjust the delay with respect to the temperature change, and the modulated wave is highly efficient with the distortion factor of the modulated wave constantly reduced. A linear transmitter that can be power-amplified is obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a first example of a linear transmission device according to the present invention.

FIG. 2 is a diagram showing a configuration of a second example of a linear transmission device according to the present invention.

FIG. 3 is a diagram showing a configuration of a linear transmission device according to a third example of the present invention.

FIG. 4 is a diagram showing a configuration of a linear transmission device according to a fourth example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Input terminal, 2 ... I / Q signal generation circuit (complex envelope generation circuit), 3, 4, 8 ... D / A conversion circuit, 5 ... Quadrature modulation circuit, 6 ... Envelope signal generation circuit, 7 ... Variable Delay circuit, 9 ... Envelope control circuit, 10, 15 ... A / D conversion circuit, 11 ... LPF (low-pass filter), 12 ... Frequency error detection circuit, 13 ... Carrier wave oscillator, 14 ... Memory, 16 ... Output terminal, 17 ... VCO (voltage controlled oscillator).

Claims (4)

[Claims] 1. An in-phase envelope component and a quadrature envelope component of the modulated wave are generated from an input modulated wave, and a linear modulated wave generated from the in-phase envelope component and the quadrature envelope component is converted into the in-phase envelope. A linear modulated wave envelope control method for linear power amplification with a saturation characteristic based on an envelope signal separately generated from a component and a quadrature envelope component,
In the state where at least one of the linear modulation wave and the envelope signal is delayed by varying the delay amount, the envelope signal is used as a power amplification control signal, the linear modulation wave is generated by the envelope signal, and the distortion of the linear modulation wave is generated. The envelope amount is controlled to reduce the power consumption of the envelope-controlled linear modulation wave, and the delay amount is variably controlled based on a frequency error between the linear modulation wave and the set reference frequency component of the linear modulation wave. Method for controlling linearly modulated wave envelope. 2. A complex envelope generating means for generating an in-phase envelope component and a quadrature envelope component of the modulated wave from the input modulated wave, and the quadrature modulating means for producing the in-phase envelope component and the quadrature envelope component. The generated linearly modulated wave is linearly power-amplified with a saturation characteristic by a saturation type power amplifier based on the envelope signal generated by the envelope signal generating means separately from the in-phase envelope component and the quadrature envelope component. A linear transmission device, wherein variable delay means delays the envelope signal from the envelope signal generating means by varying the delay amount, and the envelope signal from the variable delay means as a power amplification control signal. Envelope control means for controlling the envelope of the linear modulation wave to reduce distortion of the linear modulation wave from the quadrature modulation means using a line signal, and memory means for setting and storing a reference frequency component. The amount of delay in the variable delay means, after detecting the frequency error between the frequency component of the envelope-controlled linearly modulated wave and the reference frequency component from the memory means, which is the power amplification target from the envelope control means. And a frequency error detecting means for variably controlling the frequency difference. 3. An in-phase envelope component and a quadrature envelope component of the modulated wave are generated from the input modulated wave by the complex envelope generating means, and then the in-phase envelope component and the quadrature envelope component are processed by the quadrature modulating means. The generated linearly modulated wave is linearly power-amplified with a saturation characteristic by a saturation type power amplifier based on the envelope signal generated by the envelope signal generating means separately from the in-phase envelope component and the quadrature envelope component. A linear transmission device configured as described above, including variable delay means for variably delaying the in-phase envelope component and the quadrature envelope component from the complex envelope generating means to the quadrature modulating means with the same delay amount, and the envelope signal generating means. Envelope control means for controlling the envelope of the linear modulation wave from the quadrature modulation means by using the envelope signal as the power amplification control signal A frequency error between the frequency component of the envelope-controlled linearly modulated wave and the reference frequency component from the memory unit, which is a power amplification target from the envelope control unit, and the memory unit in which the reference frequency component is set and stored. And a frequency error detection means for variably controlling the amount of delay in each of the variable delay means. 4. A complex envelope generating means for generating an in-phase envelope component and a quadrature envelope component of the modulated wave from the input modulated wave, and the quadrature modulating means for producing the in-phase envelope component and the quadrature envelope component. The generated linearly modulated wave is linearly power-amplified with a saturation characteristic by a saturation type power amplifier based on the envelope signal generated by the envelope signal generating means separately from the in-phase envelope component and the quadrature envelope component. In the linear transmitter, the variable delay means delays the linearly modulated wave from the quadrature modulating means by varying the delay amount, and the envelope signal from the envelope signal generating means is used as a power amplification control signal. An envelope control means for controlling the envelope of the linearly modulated wave to reduce distortion of the linearly modulated wave from the variable delay means using a signal; a memory means for setting and storing a reference frequency component; The amount of delay in the variable delay means, after detecting the frequency error between the frequency component of the envelope-controlled linearly modulated wave and the reference frequency component from the memory means as the power amplification target from the envelope control means. And a frequency error detecting means for variably controlling the frequency difference.