JP2008098830A - Transmission circuit and portable terminal equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission circuit and portable terminal equipment capable of improving the power efficiency of a power amplifier. <P>SOLUTION: A wave detector 25 detects the envelope waveform of output signals outputted from the power amplifier 23. A BPF 26 has such characteristics that at least a transmission frequency becomes a stop band and extracts the adjacent channel frequency components of signals detected by the wave detector 25. An ADC 28b converts the signals outputted from the BPF 26 to digital signals. Thus, the measured value of adjacent channel leakage power is outputted from the ADC 28b. A distortion characteristic control part 16 controls the power supply voltage of the power amplifier 23 on the basis of the measured value of the adjacent channel leakage power. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a transmission circuit and a portable terminal device.

  As an example of a transmission power control method in a wireless device or the like equipped with a transmission circuit, there is a method of measuring transmission power and performing feedback control based on the result.

  For example, in Patent Document 1, in a transmission circuit having a variable gain power amplifier composed of a variable gain drive amplifier and a power amplifier, when the output signal level is reduced, current consumption is further reduced, and deterioration of power efficiency is suppressed. A transmitter circuit for this purpose is described.

  This transmission circuit extracts a part of the output signal of the variable gain power amplifier, and extracts the signal smoothed and output by DC smoothing, and the variable gain power amplifier so that the current consumption of the variable gain power amplifier is always minimized. A control circuit that generates a voltage source control signal according to a reference voltage that determines an output signal level, and a variable voltage power source that supplies a power supply voltage and a bias voltage to a power amplifier according to the voltage source control signal output from the control circuit. It is to be prepared.

JP-A-7-170202

  For example, when a large number of wireless devices are manufactured such as mobile phone terminals, the distortion characteristics of individual wireless devices vary due to individual differences among devices such as a power amplifier. Since the yield is taken into account at the time of manufacture, a radio device very close to 100% must satisfy the specification of distortion characteristics. For example, the operating point of the power amplifier in the transmission circuit is set in consideration of the characteristic variation for each individual transmission circuit.

  Due to the above-described variations, in order to satisfy the specifications even in a radio device having a distortion characteristic lower than the average, the average distortion characteristic needs to be designed to have a sufficient margin with respect to the originally required value. . Therefore, some wireless devices have an excessive margin, and there are cases where the optimum operating point of the power amplifier cannot be set in response to the excessive margin. Since the power amplifier of the transmission circuit is a part of high power consumption in the wireless device, insufficient optimization of the operating point leads to an increase in the power consumption of the wireless device, leading to a decrease in call time, etc. There are circumstances that will end up.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a transmission circuit and a portable terminal device capable of improving the power efficiency of a power amplifier.

  The present invention provides, firstly, a power amplifier that amplifies and outputs a transmission signal having a predetermined transmission frequency, a detector that detects an envelope waveform of the output signal output from the power amplifier, and Based on the output, the adjacent channel leakage power measuring unit that measures the adjacent channel leakage power indicating the power outside the transmission frequency band, and the power supply voltage of the power amplifier is controlled based on the measured adjacent channel leakage power A band-pass filter for extracting an adjacent channel frequency component from a signal output from the detector, wherein the adjacent channel leakage power measurement unit has a characteristic that at least the transmission frequency is a stop band. A first A / D converter that converts the signal output from the bandpass filter into a digital signal and outputs the digital signal, and an output from the first A / D converter. The signal in which the transmission circuit and a power value converting circuit for converting the measured value of the adjacent channel leakage power is provided.

  A second aspect of the present invention is the transmission circuit according to the first aspect, wherein a low-pass filter that smoothes a waveform indicating instantaneous signal power output from the detector, and the low-pass filter A second A / D converter that converts the output signal into a digital signal and outputs the signal, and a second A / D converter that converts the signal output from the second A / D converter into a measured value of average transmission power An average power measurement unit having a power value conversion circuit; and the distortion characteristic control unit has a function of subtracting the measurement value of the average power from the measurement value of the adjacent channel leakage power to obtain an adjacent channel leakage power ratio. A transmission circuit is provided.

  With this configuration, by measuring the adjacent channel leakage power ratio and controlling the power supply voltage of the power amplifier, it is possible to suppress variations in distortion characteristics among individual transmission circuits. Therefore, it is possible to satisfy the specifications even if the distortion characteristic setting margin is reduced, so it is possible to increase the operating point of the power amplifier by reducing the margin, improving the power efficiency and reducing the power consumption of the transmission circuit can do.

  The third aspect of the present invention is the transmission circuit according to the second aspect, wherein the first input unit is connected to the output of the low-pass filter and the second input unit is connected to the output of the band-pass filter. A first switching unit that selects one of the input units and connects to the input of the first A / D converter, and the first switching unit selects the first input unit Sometimes when the first output unit connected to the input of the first power value conversion circuit is selected, and when the first switching unit selects the second input unit, the second power value conversion circuit Select a second output unit connected to the input, and a second switching unit connected to the output of the first A / D converter, adjacent to the output of the first A / D converter A first power value conversion circuit that converts and outputs a measured value of channel leakage power, and an average power measurement from the output of the first A / D converter. A second power value conversion circuit that converts the value into a value and outputs the value, and the distortion characteristic control unit subtracts the measured value of the average power from the measured value of the adjacent channel leakage power to obtain an adjacent channel leakage power ratio. Thus, a transmission circuit for controlling the power supply voltage of the power amplifier according to the adjacent channel leakage power ratio is provided.

  With this configuration, the first A / D converter can be shared in time division for the measurement of the adjacent channel leakage power and the average power, so that the transmission circuit can be reduced in size.

  Fourthly, the present invention provides the transmission circuit according to any one of the second to third aspects, wherein the variable gain amplifier is connected in front of the power amplifier, and the transmission controls the gain of the variable gain amplifier. A transmission circuit for controlling a gain of the variable gain amplifier based on a difference between the measured value of the average power and a predetermined set value. is there.

  With this configuration, the transmission power in the transmission circuit can be controlled so as to approach a desired set value.

  Fifth, the present invention provides the transmission circuit according to any one of the first to fourth aspects, wherein the distortion characteristic control unit generates a control signal according to an adjacent channel leakage power ratio. And a DC / DC converter that changes a power supply voltage supplied to the power amplifier based on the control signal.

  With this configuration, the power supply voltage of the power amplifier can be controlled using a DC / DC converter.

  Sixth, the transmission circuit according to the fifth aspect, wherein the distortion characteristic control unit further includes a D / A converter that converts an output signal of the control signal generation circuit into an analog signal. The DC / DC converter is provided with a transmission circuit having a DC / DC converter that changes a power supply voltage supplied to the power amplifier based on an output of the D / A converter.

  With this configuration, an arbitrary power supply voltage can be supplied to the power amplifier by analog control.

  Seventhly, the present invention provides the transmission circuit according to the fifth aspect, wherein the DC / DC converter includes a DC / DC converter that can be controlled by a digital signal. A transmission circuit for changing a power supply voltage supplied to the power amplifier based on a control signal is provided.

  With this configuration, an arbitrary power supply voltage can be supplied to the power amplifier without the need to D / A convert the control signal from the control signal generation circuit.

  Eighthly, the present invention provides the transmission circuit according to the sixth or seventh aspect, wherein the DC / DC converter includes a transmission / reception type DC / DC converter.

  With this configuration, an arbitrary voltage can be supplied to the power amplifier by the step-up / step-down DC / DC converter.

  The ninth aspect of the present invention is the transmission circuit according to the sixth or seventh aspect, wherein the DC / DC converter includes a step-down DC / DC converter.

  With this configuration, the step-down DC / DC converter having a relatively simple configuration is applied to the DC / DC converter, whereby the transmission circuit can be reduced in size.

  Tenthly, the present invention provides a mobile terminal device including the transmission circuit according to any one of the first to ninth aspects.

  With this configuration, by measuring the adjacent channel leakage power and controlling the power supply voltage of the power amplifier, it is possible to suppress variations in distortion characteristics among individual transmission circuits. Therefore, it is possible to satisfy the specifications even if the distortion characteristic setting margin is reduced, so it is possible to increase the operating point of the power amplifier by reducing the margin, improving the power efficiency and reducing the power consumption of the transmission circuit can do.

  ADVANTAGE OF THE INVENTION According to this invention, the transmission circuit and portable terminal device which can improve the power efficiency of a power amplifier can be provided.

(First embodiment)
FIG. 1 is a block diagram showing a main configuration of a transmission circuit according to the first embodiment of the present invention. As shown in FIG. 1, the transmission circuit of this embodiment includes a baseband signal processing unit 10 and a radio signal processing unit 20.

  The baseband signal processing unit 10 includes a signal processing unit 11, an output power setting unit 12, a transmission power control circuit 13, a target ACPR setting unit 14, a calculator 15, a distortion characteristic control circuit 16, and a power value conversion. Circuits 17a and 17b.

  The radio signal processing unit 20 includes a modulator 21, a variable gain amplifier 22, a power amplifier 23, a coupler 24, a detector 25, a band-pass filter (hereinafter referred to as BPF) 26, and a low-pass filter. (Hereinafter referred to as LPF) 27, A / D converters (hereinafter referred to as ADC) 28a and 28b, D / A converters (hereinafter referred to as DAC) 29, and step-up / step-down DC / DC converter (hereinafter referred to as DC). 30).

  The signal processing unit 11 processes information to be transmitted and outputs a baseband signal. The modulator 21 modulates the baseband signal output from the signal processing unit 11 and outputs a transmission signal in a predetermined transmission frequency band (radio frequency band).

  The variable gain amplifier 22 is controlled in gain based on the control signal from the transmission power control circuit 13 and amplifies the transmission signal output from the modulator 21 with the controlled gain. The power amplifier 23 amplifies the signal output from the variable gain amplifier 22 with a predetermined gain and outputs the amplified signal.

  The coupler 24 extracts a part of the signal output from the power amplifier 23. The detector 25 detects the envelope waveform of the signal extracted from the coupler 24.

  The LPF 27 functions as an example of a low-pass filter, and smoothes the waveform indicating the instantaneous power of the signal output from the detector 25. The ADC 28a functions as an example of a second A / D converter, and converts the signal output from the LPF 27 into a digital signal and outputs the digital signal. The power value conversion circuit 17a functions as an example of a second power value conversion circuit, converts the signal output from the ADC 28a, and outputs a measured value of average power. The LPF 27, the ADC 28a, and the power value conversion circuit 17a function as an example of an average power measurement unit.

  The BPF 26 has a characteristic that at least the transmission frequency is a stop band and the adjacent channel frequency band is a pass band, and extracts an adjacent channel frequency component from the signal output from the detector 25. The ADC 28b functions as an example of a first A / D converter, and converts the signal output from the BPF 26 into a digital signal. The power value conversion circuit 17b functions as an example of a first power value conversion circuit, converts the signal output from the ADC 28b, and outputs a measurement value of adjacent channel leakage power. The BPF 26, the ADC 28b, and the power value conversion circuit 17b function as an example of an adjacent channel leakage power measurement unit that measures adjacent channel leakage power based on the output from the detector 25.

  The output power setting unit 12 stores a set value of transmission power of the transmission circuit. The transmission power control unit 13 generates a control signal based on the average power measurement value output from the ADC 28a and the setting value stored in the output power setting unit 12, and outputs the control signal to the variable power amplifier 22. The gain of the amplifier 22 is controlled. For example, the transmission power control unit 13 refers to the setting value stored in the output power setting unit 13 and generates a control signal according to a predetermined conversion law until a measurement value from the ADC 28a is obtained. Then, after the measurement value is obtained from the ADC 28a, a control signal for controlling the gain of the variable power amplifier 22 is generated so that the difference between the measurement value and the set value is minimized.

  The target ACPR setting unit 14 stores a target value of the adjacent channel leakage power ratio. The calculator 15 subtracts the average power measurement value output from the power value conversion circuit 17a from the measurement value of the adjacent channel leakage power output from the power value conversion circuit 17b. By this calculation, the adjacent channel leakage power ratio is obtained.

  The distortion characteristic control unit 16 generates a control signal based on the measured value of the adjacent channel leakage power ratio output from the computing unit 15 and the target value stored in the target ACPR setting unit 14 and outputs the control signal to the DC / DC 30. The power supply voltage of the power amplifier 23 is controlled. For example, the distortion characteristic control unit 16 refers to the target values stored in the output power setting unit 12 and the target ACPR setting unit 14 and obtains a predetermined conversion law until a measurement value from the computing unit 15 is obtained. Therefore, a control signal is generated. Then, after the measurement value from the computing unit 15 is obtained, a control signal is generated so that the difference between the measurement value and the target value is minimized.

  The DAC 29 converts the digital control signal output from the distortion characteristic control unit 16 into an analog signal and outputs the analog signal to the DC / DC 30. The DC / DC 30 controls the DC voltage Vbat supplied from a power supply unit (not shown) based on the analog control signal output from the DAC 29, and outputs the power supply voltage of the power amplifier 23.

  The processing performed by the power value conversion circuits 17a and 17b is not limited to this circuit. For example, the processing may be performed inside the transmission power control unit 13, the arithmetic unit 15, and the distortion characteristic control unit 16. Is possible.

  FIG. 2 is an explanatory diagram showing the operation of the transmission circuit according to the first embodiment of the present invention, and FIG. 2A is a diagram showing time waveforms before and after signal conversion by the detector and the low-pass filter, (B) is a figure which shows the frequency spectrum waveform before and behind signal conversion by a detector.

  As shown in FIG. 2A, the output signal 101 of the power amplifier 23 is converted by the detector 25 into an envelope signal 102 indicating instantaneous power. When this portion is represented by a frequency spectrum, as shown in FIG. 2B, the output signal spectrum 111 of the power amplifier 23 in the radio frequency band is equal to the DC frequency band in the envelope signal after detection by the detector 25. A spectrum 112 is obtained. Among them, the BPF 26 has a frequency characteristic as shown by the characteristic 126 in order to extract the adjacent channel band component 112b.

  According to the first embodiment of the present invention, the operating point of the power amplifier is controlled by the feedback loop so that the difference between the measured value of the adjacent channel leakage power ratio and the target value is minimized, Adjacent channel leakage power ratio is kept constant regardless of individual differences.

  In other words, by measuring the adjacent channel leakage power and controlling the power supply voltage of the power amplifier, it is possible to suppress variations in distortion characteristics among individual transmission circuits. Therefore, it is possible to satisfy the specifications even if the distortion characteristic setting margin is reduced, so it is possible to increase the operating point of the power amplifier by reducing the margin, improving the power efficiency and reducing the power consumption of the transmission circuit can do.

(Second Embodiment)
FIG. 3 is a block diagram showing a main configuration of a transmission circuit according to the second embodiment of the present invention. In FIG. 3, portions that are the same as those in FIG. 1 described in the first embodiment are denoted by the same reference numerals.

  As shown in FIG. 3, the transmission circuit of the present embodiment includes a baseband signal processing unit 50 and a radio signal processing unit 60. The baseband signal processing unit 50 includes a signal processing unit 11, an output power setting unit 12, a transmission power control unit 13, a target ACPR setting unit 14, a calculator 15, a distortion characteristic control unit 16, and power value conversion circuits 17a and 17b. The switching circuit 51 is included. The radio signal processing unit 60 includes a switching circuit 61 and an ADC 62 in addition to the modulator 21, variable gain amplifier 22, power amplifier 23, coupler 24, detector 25, BPF 26, LPF 27, DAC 29, DC / DC 30. .

  The switching circuit 61 functions as an example of a first switching unit, and selects one of a terminal a that is an example of a first input unit and a terminal b that is an example of a second input unit. And connected to the input of the ADC 62. The LPF 27 is connected to the terminal a, and the BPF 26 is connected to the terminal b. The switching circuit 61 is switched based on, for example, a control signal from a control unit (not shown). This control unit may be provided in the transmission circuit of the present embodiment, or when the transmission circuit of the present embodiment is applied to a mobile terminal device or the like, is included in the control unit that controls the operation of the mobile terminal device. It may be.

  The ADC 62 has the same function as the ADC 28a and ADC 28b described in the first embodiment, converts the signal output from the switching circuit 61 into a digital signal, and outputs measured values of transmission power and adjacent channel leakage power. To do.

  The switching circuit 51 functions as an example of a second switching unit, and selects and outputs either the output from the ADC 62 or the terminal c and the terminal d. The terminal c is connected to one input of the transmission power control unit and the calculator 15 via the power value converter circuit 17a, and the terminal d is connected to the other input of the calculator 15 via the power value converter circuit 17b. Is done. The switching circuit 51 operates in synchronization with the switching circuit 61, and the terminal c is selected at the timing when the measured value when the terminal a is selected in the switching circuit 61 is output from the ADC 62. The terminal d is selected at the timing when the measured value when the terminal b is selected in the circuit 61 is output from the ADC 62.

  That is, when the terminal a is selected in the switching circuit 61, the switching circuit 51 provides a measured value of average power obtained by the signal output from the detector 25 passing through the path through the LPF 27 and the ADC 62. output from c. Further, when the terminal b is selected in the switching circuit 61, the measured value of the adjacent channel leakage power obtained when the signal output from the detector 25 passes through the path through the BPF 26 and the ADC 62 is output from the terminal d. To do.

  According to the second embodiment of the present invention as described above, the switching circuits 51 and 61 are switched in a time division manner as described above, whereby the average power and the adjacent channel leakage power are shared by the ADC 62. It becomes possible to measure.

  In the first and second embodiments, the case where a step-up / step-down DC / DC converter is used as an example of the DC / DC 30 used in the transmission circuit has been described. The step-up / step-down DC / DC converter can supply an arbitrary voltage to the power amplifier 23. However, the DC / DC 30 used in the transmission circuit is not limited to the step-up / step-down DC / DC converter.

  For example, a step-down DC / DC converter may be used for the DC / DC 30. Since the step-down DC / DC converter has a relatively simple configuration, the transmission circuit can be reduced in size.

  The DC / DC 30 may be a step-up / step-down (or step-down) DC / DC converter that can be controlled by a digital signal. The DC / DC converter changes the power supply voltage supplied to the power amplifier 23 based on the control signal from the distortion characteristic control unit 16. With this configuration, an arbitrary power supply voltage can be supplied to the power amplifier 23 without the need to D / A convert the control signal from the distortion characteristic control unit 16. Therefore, the DAC 29 is not necessary, and the transmission circuit can be reduced in size.

  The transmission circuit and the mobile terminal device of the present invention have an effect of improving the power efficiency of the power amplifier, and are useful for mobile terminal devices and the like.

The block diagram which shows the main structures of the transmission circuit which concerns on the 1st Embodiment of this invention Explanatory drawing which shows operation | movement of the transmission circuit which concerns on the 1st Embodiment of this invention. The block diagram which shows the main structures of the transmission circuit which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 50 Baseband signal processing part 11 Signal processing part 12 Output power setting part 13 Transmission power control part 14 Target ACPR setting part 15 Calculator 16 Distortion characteristic control part 17a, 17b Power value conversion circuit 20, 60 Wireless signal processing part 21 Modulator 22 Variable gain amplifier 23 Power amplifier 24 Coupler 25 Detector 26 Band pass filter (BPF)
27 Low-pass filter (LPF)
28a, 28b, 62 A / D converter (ADC)
29 D / A converter (DAC)
30 Buck-Boost DC / DC Converter (DC / DC)
51, 61 Switching circuit 101 Time waveform of radio frequency band signal before detection 102 Time waveform of radio frequency band signal after detection 111 Spectrum waveform of radio frequency band signal before detection 112 Spectrum waveform of radio frequency band signal after detection 112a Transmission frequency band of spectrum waveform 112b Adjacent channel frequency band of spectrum waveform 126 Frequency characteristics of band pass filter

Claims (10)

A power amplifier that amplifies and outputs a transmission signal of a predetermined transmission frequency;
A detector for detecting an envelope waveform of an output signal output from the power amplifier;
Based on the output from the detector, an adjacent channel leakage power measurement unit that measures adjacent channel leakage power indicating power outside the transmission frequency band;
A distortion characteristic control unit that controls a power supply voltage of the power amplifier based on the measured adjacent channel leakage power, and
The adjacent channel leakage power measurement unit
A bandpass filter that has a characteristic that at least the transmission frequency is a stopband, and extracts an adjacent channel frequency component from a signal output from the detector;
A first A / D converter that converts a signal output from the bandpass filter into a digital signal and outputs the digital signal;
A first power value converting means for converting the signal output from the first A / D converter into a power value to obtain adjacent channel leakage power; The transmission circuit according to claim 1,
A low-pass filter for smoothing a waveform indicating the signal instantaneous power output from the detector, and a second A / D conversion for converting the signal output from the low-pass filter into a digital signal and outputting the digital signal And an average power measurement unit having a second power value conversion means for converting the signal output from the second A / D converter into a power value to obtain an average transmission power,
The distortion characteristic control unit obtains an adjacent channel leakage power ratio by subtracting the measured value of the average power from the measured value of the adjacent channel leakage power, and determines a power supply voltage of the power amplifier according to the adjacent channel leakage power ratio. Transmitter circuit to control. The transmission circuit according to claim 1,
The first A / D is selected by selecting one of a first input connected to the output of the low-pass filter and a second input connected to the output of the band-pass filter. A first switching unit connected to the input of the converter;
When the first switching unit selects the first input unit, an output obtained from the first A / D converter is output as a signal when measuring the average power, and the first switching unit A second switching unit that outputs an output obtained from the first A / D converter when the second input unit is selected as a signal when measuring the adjacent channel leakage power, and
The distortion characteristic control unit outputs the first A / D converter from the measured value of the adjacent channel leakage power output from the first A / D converter and converted by the first power value conversion means. The adjacent channel leakage power ratio is obtained by subtracting the measured average power value output from the second power value conversion means and the power supply voltage of the power amplifier is controlled according to the adjacent channel leakage power ratio. Transmitter circuit to do. A transmission circuit according to any one of claims 2 to 3,
A variable gain amplifier connected in front of the power amplifier;
A transmission power control unit for controlling the gain of the variable gain amplifier,
The transmission power control unit is a transmission circuit that controls a gain of the variable gain amplifier based on a difference between the measured value of the average power and a predetermined set value. The transmission circuit according to any one of claims 1 to 4,
The distortion characteristic control unit
A control signal generation circuit for generating a control signal according to the adjacent channel leakage power ratio;
A DC / DC converter that changes a power supply voltage supplied to the power amplifier based on the control signal. The transmission circuit according to claim 5, wherein
The distortion characteristic control unit further includes a D / A converter that converts an output signal of the control signal generation circuit into an analog signal,
The DC / DC converter includes a DC / DC converter that changes a power supply voltage supplied to the power amplifier based on an output of the D / A converter. The transmission circuit according to claim 5, wherein
The DC / DC converter includes a DC / DC converter that can be controlled by a digital signal, and changes a power supply voltage supplied to the power amplifier based on a control signal from the control signal generation circuit. The transmission circuit according to claim 6 or 7,
The DC / DC converter is a transmission circuit having a step-up / step-down DC / DC converter. The transmission circuit according to claim 6 or 7,
The DC / DC converter is a transmission circuit having a step-down DC / DC converter.   A portable terminal device comprising the transmission circuit according to claim 1.

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