JP2009094721A - Polar modulation transmitter and radio communication equipment, and polar modulation transmission method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress a rise of a case body temperature while maintaining antenna emission power equal to a transmitter of an orthogonal modulation system or larger with respect to the impedance fluctuation of an antenna. <P>SOLUTION: The polar modulation transmitter 100 is provided with a power amplifier 105 for separating an amplitude modulation component and a phase modulation component included in an input signal from the input signal to be transmitted and for performing power amplification of the amplitude modulation component and the phase modulation component in channels independent from each other, a current detection part 112 for detecting the current consumption of the power amplifier 105; an output power switch 108 capable of switching two or more kinds of the output power of the power amplifier 105; and a power-down control unit 113 for giving a prescribed power-down signal to the output power switch 108 when the magnitude of power consumption detected by the current detection part 112 exceeds a prescribed threshold. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polar modulation transmission apparatus and a radio communication apparatus that can be used in a radio communication system such as a mobile phone, and a polar modulation transmission method.

  In a wireless communication device, for example, in the case of a mobile phone terminal, it is often used in the state where a human body or other conductor exists in the vicinity of the antenna used for the transmission. It changes frequently with changes. In such a situation, the impedance of the antenna varies greatly. Since the antenna is connected as a load to the output of the high-frequency power amplifier for transmission, when the impedance of the antenna varies, the output load of the high-frequency power amplifier varies, and there is a concern about deterioration of transmission characteristics. Specific transmission characteristics that are assumed to deteriorate include adjacent channel leakage power and modulation accuracy.

  That is, as a wireless communication device, an antenna whose impedance varies is directly connected to the output of the high-frequency power amplifier, so that distortion (harmonic component) occurs in the output signal of the high-frequency power amplifier as the impedance of the antenna varies. As a result, the transmission characteristics are degraded. As a method for solving such a problem, generally, one of the two types of methods described below has been conventionally used.

  In the first method, a linear power amplifier having high linearity is used as the power amplifier, and an isolator is inserted between the antenna and the power amplifier output. By inserting an isolator, even if the impedance of the antenna fluctuates, the output load of the power amplifier does not fluctuate, so that distortion of the output signal can be prevented.

  Since this method uses a low-distortion linear power amplifier, linear modulation signals such as Quadrature Phase Shift Keying (QPSK), Hybrid Phase Shift Keying (HPSK), and Quadrature Amplitude Modulation (QAM) are reduced. Can be amplified by distortion. However, it is necessary to increase the output power of the power amplifier in order to compensate for the power loss caused by the inserted isolator, resulting in an increase in power consumption. Moreover, since an isolator is added, the scale and cost of the apparatus increase.

  In the second method, a nonlinear power amplifier is used as the power amplifier. Nonlinear power amplifiers generally do not increase distortion due to fluctuations in output load (since they are used in a saturated state, impedance changes do not affect the waveform), so transmission characteristics do not deteriorate. However, when a non-linear operation power amplifier is used, it is used only for amplification of a specific modulation signal in which the level of the envelope of the modulation waveform does not change, such as FM (Frequency Modulation) and GMSK (Gaussian filtered Minimum Shift Keying). Is limited. When a linear modulation signal with varying amplitude is amplified, the waveform changes, and modulation information cannot be transmitted correctly.

  On the other hand, when the known polar modulation is employed, the advantages of both of the above two methods can be obtained. In a transmitter employing polar modulation, a modulation signal (input signal) is separated into phase information and amplitude information, and phase information of a constant envelope is input to a nonlinear power amplifier for amplification, and at the same time, for example, to the power amplifier By modulating the voltage of the supplied power supply using the amplitude information, a modulation signal in which phase information and amplitude information are combined can be obtained at the output of the power amplifier. A specific operation will be described below.

  FIG. 7 is a block diagram showing a configuration example of a conventional polar modulation transmission apparatus. The conventional polar modulation transmission apparatus 700 includes an I signal input terminal 701, a Q signal input terminal 702, a polar coordinate conversion unit 703, a phase modulation unit 704, a power amplifier 705, an antenna 706, and a transmission power setting signal. An input terminal 707, a multiplier 709, an amplitude modulation unit 710, and a power input terminal 711 are provided.

  Of the baseband IQ signal that is the signal to be transmitted, the I component is applied to the I signal input terminal 701 and the Q component is applied to the Q signal input terminal 702. Therefore, the baseband IQ signal is input to the polar coordinate conversion unit 703 via the I signal input terminal 701 and the Q signal input terminal 702.

  The polar coordinate conversion unit 703 performs polar coordinate conversion on the baseband IQ signal input from the I signal input terminal 701 and the Q signal input terminal 702, thereby separating the phase component and the amplitude component included in this signal, respectively. Take out. Of the signals separated and extracted from the baseband IQ signal by the polar coordinate conversion unit 703, the phase component signal is input to the phase modulation unit 704, and the amplitude component signal is input to the multiplier 709.

  The phase modulation unit 704 modulates the phase of the carrier signal generated therein using the phase component signal input from the polar coordinate conversion unit 703, and outputs the modulation result to the power amplifier 705. On the other hand, the multiplier 709 multiplies the amplitude component signal input from the polar coordinate conversion unit 103 by the transmission power setting signal indicating the transmission power input from the transmission power setting signal input terminal 707, and the multiplication result is amplitude. The data is output to the modulation unit 710.

  The amplitude modulation unit 710 amplitude-modulates the power supply voltage supplied from a predetermined DC power supply via the power input terminal 711 with the output signal of the multiplier 709. Therefore, the amplitude-modulated power supply voltage is supplied to the power supply line of the power amplifier 705. This power supply voltage is used as a drain voltage, a collector voltage, and the like inside the power amplifier 705.

  Since the power amplifier 705 operates in a non-linear mode (saturated state), the power of the signal output from the power amplifier 705 is proportional to the magnitude of the power supply voltage supplied to the power amplifier 705. Therefore, the signal output from the power amplifier 705 is phase-modulated and amplitude-modulated according to the baseband IQ signal input to the I signal input terminal 701 and the Q signal input terminal 702, and the signal power is further input to the transmission power setting signal input. It is determined according to the transmission power setting signal input from the terminal 707.

  In this way, the power amplifier 705 amplifies only the phase modulation signal that does not change the envelope level, and amplitude modulation is performed by controlling the power supply voltage supplied at the same time. A linear modulation signal can be output. At this time, since the power amplifier 705 is always operating in saturation, the power efficiency is high and amplitude modulation can be performed, so that a transmission output can be obtained regardless of the linear modulation method or the non-linear modulation method. In addition, since the power amplifier 705 is a non-linear operation that is resistant to output load fluctuations, transmission characteristics do not deteriorate even if the impedance of the antenna 706 changes.

For example, in Patent Document 1 which is a prior art, in order to reduce the influence of impedance fluctuations of antennas used for transmission, a plurality of antennas are provided and selectively used, and the current flowing into the transmission amplifier is large. It is disclosed that the optimum antenna is automatically selected based on this current.
JP 2001-102844 A

  However, in the polar modulation transmission apparatus, when the impedance of an antenna connected as a load to the output of the power amplifier changes, that is, when a load change occurs, the operating efficiency of the power amplifier is lowered. As a result, the power loss inside the power amplifier increases, so the amount of heat generation increases and the casing temperature of the apparatus also rises. And an excessive housing temperature rise may lead to a failure of the apparatus.

  The present invention has been made in view of the above circumstances, and a polar modulation transmission apparatus and a radio communication apparatus capable of suppressing an increase in casing temperature while maintaining an antenna radiation power equivalent to or higher than that of a transmission apparatus using an orthogonal modulation method An object is to provide a polar modulation transmission method.

The polar modulation transmission apparatus of the present invention is a polar modulation transmission apparatus including a power amplifier that amplifies power by separating an amplitude modulation component and a phase modulation component included in an input signal to be transmitted, and consumes current of the power amplifier A current detection unit that detects the output power, an output power switching unit that can switch the output power of the power amplifier between two or more types, and the current consumption detected by the current detection unit exceeds a predetermined threshold And a power-down control unit that provides a predetermined power-down signal to the output power switching unit.
As a result, when the amount of current consumption exceeds a predetermined threshold value, a predetermined power-down signal is output and the output power of the power amplifier is switched. It is possible to suppress an increase in the casing temperature while maintaining power.

The present invention is the polar modulation transmission apparatus described above, wherein the power-down control unit holds a predetermined first threshold value and a second threshold value, respectively, and the output power of the power amplifier is a predetermined amount. When the magnitude of the consumption current detected by the current detection unit in the normal state exceeds the first threshold, the output power is switched to a power-down state smaller than the normal state, and the output power of the power amplifier is It includes a device that cancels the power-down state when the current consumption detected by the current detection unit in the power-down state is less than or equal to the second threshold value.
As a result, it is possible to switch between a predetermined normal state and a power-down state in accordance with the amount of current consumed by the power amplifier.

Further, the present invention is the polar modulation transmission apparatus described above, wherein the power-down control unit is connected to the output power switching unit every time a predetermined timing arrives in synchronization with a periodically generated timing signal. After canceling the power-down signal to be applied, the magnitude of the consumption current detected by the current detection unit is grasped, and when the magnitude of the consumption current exceeds the predetermined threshold, the output power of the power amplifier Is set to a power-down state that is smaller than a predetermined amount of the normal state, and the output power of the power amplifier is set to the normal state when the magnitude of the consumption current is equal to or less than the threshold value.
As a result, it is possible to switch between a predetermined normal state and a power-down state in accordance with the amount of current consumed by the power amplifier. In addition, since the magnitude of the current consumption is detected in a state where the power-down is always canceled, it is not necessary to use a plurality of threshold values, and it is possible to reduce the adjustment process at the time of shipment and to reduce the manufacturing cost.

Further, the present invention is the polar modulation transmission apparatus described above, wherein the power down control unit includes a plurality of operations representing a state in which at least one of an operating frequency, a modulation method, and a communication system mode of the power amplifier is different. Holds multiple types of threshold values that match each of the conditions, and executes control using a set of threshold values selected from the held types of threshold values according to the input signal that specifies the operating conditions Including what to do.
As a result, optimal power-down control is performed for each power amplifier operating frequency, modulation method, and communication system mode, and the amount of reduction in transmission power can be kept to a minimum and communication quality degradation is suppressed. Can do.

Further, the present invention is the polar modulation transmission apparatus described above, wherein the output power switching unit includes a power designation value that defines a target value of output power of the power amplifier, and a power down signal output by the power down control unit Including an amplitude modulator that generates a modulation signal based on a result of multiplying the amplitude modulation component by the output of the adder.
Thereby, based on the result of multiplying the result of adding (or subtracting) the reduction amount corresponding to the power-down signal and the amplitude modulation component based on the power designation value (for example, a constant) that determines the output power in the normal state, The amplitude (power) of the output signal of the power amplifier is determined. For this reason, the amount of reduction in output power can be easily adjusted.

  The present invention also provides a wireless communication device including any one of the polar modulation transmission devices described above.

  The polar modulation transmission method of the present invention is a polar modulation transmission method for controlling a polar modulation transmission apparatus including a power amplifier that separates an amplitude modulation component and a phase modulation component contained in an input signal to be transmitted and amplifies the power. A current detection step for detecting a current consumption of the power amplifier, an output power switching step for switching the output power of the power amplifier between two or more types, and a magnitude of the detected current consumption being predetermined. A power-down control step of generating a predetermined power-down signal and controlling the switching of the output power when the threshold value of the power-off threshold is exceeded.

  Further, the present invention is the polar modulation transmission method described above, wherein in the power-down control step, a predetermined first threshold value and a second threshold value are respectively held, and the output power of the power amplifier is a predetermined amount. When the magnitude of the current consumption detected in the normal state exceeds the first threshold, the output power is switched to a power-down state smaller than the normal state, and the output power of the power amplifier is in the power-down state When the detected current consumption is equal to or smaller than the second threshold, the power-down state is canceled.

  Further, the present invention is the polar modulation transmission method described above, wherein, in the power down control step, the power down signal is canceled every time a predetermined timing arrives in synchronization with a periodically generated timing signal. After that, the magnitude of the current consumption is grasped, and when the magnitude of the current consumption exceeds the predetermined threshold, the output power of the power amplifier is set to a power down state smaller than a predetermined amount of the normal state. And determining that the output power of the power amplifier is in the normal state when the magnitude of the current consumption is equal to or less than the threshold value.

  The present invention is the polar modulation transmission method described above, wherein in the power-down control step, a plurality of operations representing a state in which at least one of an operating frequency, a modulation method, and a communication system mode of the power amplifier is different. Holds multiple types of threshold values that match each of the conditions, and executes control using a set of threshold values selected from the held types of threshold values according to the input signal that specifies the operating conditions Including what to do.

  According to the present invention, there are provided a polar modulation transmission apparatus, a radio communication apparatus, and a polar modulation transmission method capable of suppressing an increase in casing temperature while maintaining an antenna radiation power equal to or higher than that of an orthogonal modulation transmission apparatus. it can.

(First embodiment)
FIG. 1 is a block diagram showing a configuration of a polar modulation transmission apparatus according to the first embodiment of the present invention.

  A polar modulation transmission apparatus 100 according to the first embodiment includes an I signal input terminal 101, a Q signal input terminal 102, a polar coordinate conversion unit 103, a phase modulation unit 104, a power amplifier 105, an antenna 106, and transmission power. Setting signal input terminal 107, adder 108, multiplier 109, amplitude modulation unit 110, power input terminal 111, current detection unit 112, power-down control unit 113, and power-down release threshold storage unit 114 , A power-down threshold value storage unit 115 and a power-down value storage unit 116 are provided.

  Of the baseband IQ signal that is the signal to be transmitted, the I component is applied to the I signal input terminal 101 and the Q component is applied to the Q signal input terminal 102. Therefore, the baseband IQ signal is input to the polar coordinate conversion unit 103 via the I signal input terminal 101 and the Q signal input terminal 102.

  The polar coordinate conversion unit 103 performs polar coordinate conversion on the baseband IQ signal input from the I signal input terminal 101 and the Q signal input terminal 102 to separate the phase component and the amplitude component included in this signal, respectively. Take out. Of the signals separated and extracted from the baseband IQ signal by the polar coordinate conversion unit 103, the phase component signal is input to the phase modulation unit 104, and the amplitude component signal is input to the multiplier 109.

  The phase modulation unit 104 modulates the phase of the carrier signal generated by a carrier oscillation unit (not shown) existing therein using the phase component signal input from the polar coordinate conversion unit 103, and the modulation result is converted into the power amplifier 105. Output to.

  On the other hand, the multiplier 109 multiplies the amplitude component signal input from the polar coordinate conversion unit 103 by the output of the adder 108 and outputs the multiplication result to the amplitude modulation unit 110. A transmission power setting signal (that is, a setting value) corresponding to a target value of transmission power in a normal state is input to the transmission power setting signal input terminal 107. The adder 108 realizes the function of the output power switching unit, and the power down value (normally output from the power down control unit 113 based on the value of the transmission power setting signal input from the transmission power setting signal input terminal 107) In this state, the result of subtracting 0) is input to the multiplier 109. Then, the output of the multiplier 109, that is, the result of multiplying the amplitude component signal output from the polar coordinate conversion unit 103 and the output of the adder 108 is input to the amplitude modulation unit 110.

  The amplitude modulation unit 110 amplitude-modulates the power supply voltage supplied from a predetermined DC power supply via the power supply input terminal 111 with the output signal of the multiplier 109. Therefore, the amplitude-modulated power supply voltage is supplied to the power supply line of the power amplifier 105. This power supply voltage is used as a drain voltage, a collector voltage, and the like inside the power amplifier 105.

  Since the power amplifier 105 operates in a non-linear mode (saturated state), the power of the signal output from the power amplifier 105 is proportional to the magnitude of the power supply voltage supplied to the power amplifier 105. Therefore, the signal output from the power amplifier 105 is phase-modulated and amplitude-modulated according to the baseband IQ signal input to the I signal input terminal 101 and the Q signal input terminal 102, and the signal power is further input to the transmission power setting signal input. It is determined according to the transmission power setting signal input from the terminal 107.

  In addition, by controlling the power-down value output by the power-down control unit 113, the power of the signal output from the power amplifier 105 can be switched by switching the modulation amplitude in the amplitude modulation unit 110. That is, in a specific situation different from the normal state, the transmission power can be reduced compared to the transmission power setting signal input from the transmission power setting signal input terminal 107.

  Specifically, when the state near the antenna 106 changes and impedance variation (load variation) of the antenna 106 occurs, the operating efficiency of the power amplifier 105 decreases, and the amount of heat generated by the power amplifier 105 increases. The body temperature may rise abnormally. In order to suppress such an abnormal temperature rise, the power-down control unit 113 automatically controls transmission power.

  In order to investigate whether or not the operating efficiency of the power amplifier 105 is lowered, in the present embodiment, the current detection is performed based on the magnitude of the consumption current flowing from the power input terminal 111 to the power line of the power amplifier 105 via the amplitude modulation unit 110. This is detected by the unit 112. That is, since there is a large correlation between the operating efficiency of the power amplifier 105 and the change in the amount of heat generated due to the impedance variation (load variation) of the antenna 106 and the consumption current, in order to investigate the heat generation state of the power amplifier 105 Check the current consumption.

  Actually, the power-down control unit 113 has a power-down threshold value (first threshold value: constant) held by the power-down threshold value storage unit 115 in the normal state. ) To identify whether or not to transition from the normal state to the power-down state. Further, in the power-down state, by comparing the magnitude of the current consumption with the power-down cancellation threshold (second threshold: constant) held by the power-down cancellation threshold storage unit 114, Identifies whether to transition to the state. When transitioning to the power-down state, the power-down control unit 113 outputs the power-down value (constant) held by the power-down value storage unit 116 and inputs this to the adder 108. When transitioning from the power-down state to the normal state, the power-down value input to the adder 108 is switched to zero.

  FIG. 2 is a graph showing operating characteristics of the polar modulation transmission apparatus 100 shown in FIG. A specific example of the operating characteristics of the polar modulation transmission apparatus 100 according to the first embodiment will be described with reference to FIG.

  In FIG. 2, the characteristic 201 of the polar modulation transmission apparatus of this embodiment is shown on the upper side, and the characteristic 220 of the conventional transmission apparatus is shown on the lower side. As for the conventional transmission apparatus, a transmission apparatus using a general quadrature modulation scheme is assumed, and an apparatus in which an isolator is inserted between a power amplifier and an antenna is assumed.

  When the impedance of the antenna fluctuates, impedance mismatch occurs between the output circuit of the transmission device and the antenna, and as a result, a reflected wave that returns without being emitted from the antenna is generated, and a standing wave is generated. Therefore, in order to represent the state of impedance variation of the antenna, the characteristics are shown in FIG. 2 using VSWR (Voltage Standing Wave Ratio).

That is, the characteristic 201 shown on the upper side of FIG. 2 shows the relationship between the current consumption of the power amplifier 105 and the VSWR characteristic of the antenna 106. Further, a characteristic 220 shown on the lower side of FIG. 2 indicates a relationship between the antenna loss (loss caused by mismatch between the isolator and the antenna) of the conventional transmission apparatus and the antenna VSWR characteristic. Details of each characteristic and parameter shown in FIG. 2 are as follows.
202: Current consumption of power amplifier 105 with transmission power set to 24 dBm (during normal transmission) vs. VSWR characteristic of antenna 106 203: Current consumption of power amplifier 105 with transmission power set to 24 dBm (during power down) vs. VSWR characteristic of antenna 106 Current consumption of power amplifier 105 vs. VSWR characteristic of antenna 106 at transmission power 22 dBm setting (during normal transmission) 205: Current consumption of power amplifier 105 vs. VSWR characteristic of antenna 106 at transmission power 22 dBm setting (during power down) 206: Transmission power Current consumption of power amplifier 105 at 20 dBm setting (during normal transmission) vs. VSWR characteristic of antenna 106 207: Power-down threshold (when transmission power is 24 dBm)
208: Power-down release threshold (when transmission power is 24 dBm)
209: Power-down threshold (when transmission power is 22 dBm)
210: Power-down release threshold (when transmission power is 22 dBm)

  Further, as shown in FIG. 2, when the polar modulation transmission apparatus 100 transits to the power-down state at the time of 24 dBm transmission, the antenna VSWR of (b)-(b ′) is X1, and in the conventional transmission apparatus, the antenna VSWR When X is X1, the antenna loss 211 is Y1. Further, the antenna VSWR when the polar modulation transmission apparatus 100 transitions to the power-down state during 22 dBm transmission is X2, and in the conventional transmission apparatus, the antenna loss 212 when the antenna VSWR is X2 is Y2.

  The amount of reduction in output power when the polar modulation transmission apparatus 100 transitions from the normal state to the power-down state is determined to be equal to or smaller than the antenna loss (Y1, Y2) in the conventional transmission apparatus. is there.

  FIG. 3 is a time chart showing an operation example of the polar modulation transmission apparatus 100 shown in FIG. In FIG. 3, a current consumption 301 during normal transmission of the power amplifier 105, a change in the current consumption 302 of the power amplifier 105 during power down, a power down threshold 303 and a power down cancellation threshold 304 are shown.

  In FIG. 3, for the current consumptions 301 and 302, the waveforms when the power-down and power-down cancel processing are actually performed are represented by thick solid lines, and the other waveform portions are represented by thin solid lines. . In this example, it is assumed that a transition from the normal state to the power-down state and a transition from the power-down state to the normal state (state indicated by a thick solid line) are performed in the load fluctuation section 305 shown in FIG. .

  In the polar modulation transmission apparatus 100 of the present embodiment, the output power during normal operation is variable (24 dBm, 22 dBm) by switching the transmission power setting signal input to the transmission power setting signal input terminal 107 as shown in FIG. Can be.

  When the output power during normal operation changes, it is necessary to change the threshold and power down value used in the power down control and the power down release control in the power down control unit 113. Therefore, a plurality of threshold values (corresponding to 207 to 210 shown in FIG. 2) are stored in advance in the power-down threshold storage unit 115 and the power-down release threshold storage unit 114, respectively. The power-down value is stored. The power down control unit 113 selects an appropriate threshold or power down value according to the value of the transmission power setting signal input to the transmission power setting signal input terminal 107. Therefore, it is possible to transition from the normal state to the power-down state under an appropriate condition, or to cancel the power-down state, and appropriately determine the amount of output power reduction (corresponding to the power-down value) in the power-down state. it can.

  Actually, the power-down value when the transmission power is 24 dBm is set to a value smaller than the antenna loss (Y1 shown in FIG. 2) of the conventional transmission device under the same conditions, and the power-down value when the transmission power is 22 dBm is the same. It is set to a value smaller than the antenna loss (Y2 shown in FIG. 2) of the conventional transmitter in the condition. Therefore, even in the power-down state, the polar modulation transmission apparatus 100 can realize a larger transmission output than the conventional transmission apparatus.

  Next, a specific operation of the polar modulation transmission apparatus 100 of the present embodiment will be described in time series using FIG. 2 and FIG. 3 by taking 24 dBm transmission as an example. 2 and 3, (a), (b), (b '), (c), (c'), and (d) each show the operation status at the same time. In this example, a situation will be described in which the VSWR of the antenna changes from VSWR = 1 to X1 (> 1) and returns to VSWR = 1 again.

(A) to (b): When VSWR increases due to load fluctuation during transmission, the current consumption of the power amplifier 105 increases according to the characteristic 202.
(B) to (b ′): When the current consumption of the power amplifier 105 exceeds the power-down threshold value 207, a power-down process is executed and the power-down value held by the power-down value storage unit 116 (Y1 or less) Only reduce the transmission power.
(B ′) to (c): When the load fluctuation is reduced and the VSWR is reduced, the current consumption of the power amplifier 105 decreases according to the characteristic 203.
(C) to (c ′): When the current consumption of the power amplifier 105 falls below the power-down cancellation threshold 208, the power-down cancellation processing is executed, and normal transmission is resumed.
(C ′) to (d): Load fluctuation is settled and the initial state (a) is restored.

  As described above, in the present embodiment, the load fluctuation is monitored by detecting the current consumption of the power amplifier 105, and when the set threshold value is exceeded, the transmission power is reduced by the power down control unit 113, thereby reducing the power amplifier. The amount of heat generated at 105 is suppressed. Further, the amount of transmission power reduction is set to a value smaller than the antenna loss (= power amplifier output power−antenna radiation power) due to the antenna impedance change in the conventional orthogonal modulation method. Accordingly, it is possible to reduce the casing temperature rise while maintaining the antenna radiation power equal to or higher than that of the orthogonal modulation transmission device.

  As described above, according to the first embodiment, the output power of the power amplifier 105 is output by outputting a power-down signal when the amount of heat generated in the power amplifier 105 increases with the impedance fluctuation of the antenna. The amount of heat generated can be reduced by switching between the two. It has been found that when the antenna impedance fluctuates and the amount of heat generated inside the power amplifier increases, the current consumed by the power amplifier 105 increases more than usual. Therefore, by detecting the current consumption of the power amplifier 105 and comparing the magnitude with a threshold value, it is possible to identify whether or not a large amount of heat is generated. Therefore, when the heat generation is large, the power-down control unit 113 outputs a power-down signal. To reduce the output power of the power amplifier 105, the amount of heat generated can be reduced.

  Here, in order to keep the antenna radiated power equal to or higher than that of a conventional orthogonal modulation transmission device used with an isolator inserted between the output of the power amplifier and the antenna, a power down signal is used. What is necessary is just to determine the reduction amount of the transmission power controlled by outputting as follows. That is, the reduction amount of the transmission power is set to a value smaller than the antenna loss (= power amplifier output power−antenna radiation power) in the orthogonal modulation method accompanying the antenna impedance change. Accordingly, it is possible to reduce the casing temperature rise while maintaining the antenna radiation power equal to or higher than that of the orthogonal modulation transmission device.

  Further, in response to a change in the current consumption of the power amplifier 105, that is, a change in the impedance of the antenna, when the amount of heat generation exceeds the power down threshold and the amount of heat generation becomes excessive, the output power of the power amplifier is switched from the normal state to the power down state. When returning to a state where the amount of heat generation is low after falling below the down release threshold, the output power of the power amplifier can be switched from the power down state to the normal state. The condition for switching the state at this time can be freely determined by two threshold values.

  Also, the result of adding (or subtracting) a reduction amount corresponding to the power-down signal with reference to a power designation value (transmission power setting signal) that defines the output power in the normal state input to the transmission power setting signal input terminal 107 Based on the result of multiplication by the amplitude modulation component, the amplitude modulation unit 110 generates a modulation signal and drives the power amplifier 105. In this case, since the amplitude (power) of the output signal of the power amplifier 105 is determined based on the multiplication result input to the amplitude modulation unit 110, the reduction amount of the output power can be easily adjusted.

(Second Embodiment)
FIG. 4 is a block diagram showing a configuration of a polar modulation transmission apparatus according to the second embodiment of the present invention. The second embodiment is a modification of the first embodiment, and elements corresponding to those of the first embodiment are denoted by the same reference numerals.

  A polar modulation transmission apparatus 400 according to the second embodiment includes an I signal input terminal 101, a Q signal input terminal 102, a polar coordinate conversion unit 103, a phase modulation unit 104, a power amplifier 105, an antenna 106, and transmission power. A setting signal input terminal 107, an adder 108, a multiplier 109, an amplitude modulation unit 110, a power input terminal 111, a current detection unit 112, a power down control unit 413, a power down threshold storage unit 415, A power-down value storage unit 416 and a power-down control timing signal input terminal 401 are provided.

  That is, as compared with the first embodiment, the power down cancellation threshold value storage unit 114 is omitted, and a power down control timing signal input terminal 401 is provided instead. In addition, the operation of the power-down control unit 413 is changed. Details of the operation will be described later.

  FIG. 5 is a time chart showing an operation example of the polar modulation transmission apparatus 400 shown in FIG. In FIG. 5, the current consumption 301 during normal transmission of the power amplifier 105, the change in the current consumption 302 of the power amplifier 105 during power down, the power down threshold 303, the power down control start timings 501 to 503, and the power A down control period 504 is shown. In FIG. 5, for the current consumptions 301 and 302, the waveforms when the power-down and power-down cancel processing are actually performed are represented by thick solid lines, and the other waveform portions are represented by thin solid lines. .

  In this example, it is assumed that a transition from the normal state to the power-down state and a transition from the power-down state to the normal state (state indicated by a thick solid line) are performed in the load fluctuation section 305 shown in FIG. . Further, details in the vicinity of the power-down control start timing 503 in the load fluctuation section 305 are shown as an enlarged waveform 510. Further, as shown in the enlarged waveform 510, a power-down cancellation section 505 is provided.

  Since the basic operation of the polar modulation transmission apparatus 400 according to the second embodiment shown in FIG. 4 is the same as that of the first embodiment, only the characteristic operation of the polar modulation transmission apparatus 400 will be described below. explain.

  A pulse signal whose level changes periodically at a constant cycle (corresponding to the power-down control cycle 504 shown in FIG. 5 or a half cycle thereof) is input to the power-down control timing signal input terminal 401 of the polar modulation transmitter 400. Is applied as a power-down control timing signal.

  Therefore, the power-down control unit 413 recognizes the power-down control start timings 501 to 503 that periodically appear from the level change of the power-down control timing signal, and performs control periodically in synchronization with these timings.

  At this time, the power-down control unit 413 performs processing described below in synchronization with each of the power-down control start timings (501 to 503) appearing at each power-down control cycle 504.

  That is, power down is first canceled (maintains the same state during normal transmission), then a current consumption detection value (monitor value) output from the current detection unit 112 is obtained, and the current consumption detection value and power The power-down threshold stored in the down-threshold storage unit 415 is compared, and a power-down process or a power-down cancellation process is performed according to the comparison result. That is, if the detected current consumption value exceeds the power-down threshold, the power-down value stored in the power-down value storage unit 416 is applied to the adder 108 to transition to the power-down state, and the detected current consumption value is If it is less than or equal to the power-down threshold, the power-down is canceled and the normal state is entered.

  In any case, when the power-down control unit 413 performs processing in synchronization with each power-down control start timing (501 to 503), only a certain section, such as the power-down cancellation section 505 shown in FIG. Cancel power down and detect current consumption in that state. Therefore, the threshold value for identifying whether or not to transition from the normal state to the power-down state and the threshold value for identifying whether or not to transition from the power-down state to the normal state can be made common. The power-down cancellation threshold storage unit 114 as in the embodiment is not necessary.

  Thereby, in 2nd Embodiment, the adjustment process at the time of shipment can be reduced, and manufacturing cost can be reduced. Further, since the power-down cancellation period is sufficiently short with respect to the entire transmission time, the influence on the casing temperature rise is small.

  Note that the actual power-down cancellation interval 505 is desirably an integral multiple of the transmission power control minimum interval of the wireless communication system (eg, 1 slot = 667 μs in the case of W-CDMA (Release 99)).

  As described above, according to the second embodiment, the output power of the power amplifier is changed from the normal state to the power state when the amount of heat generation becomes excessive according to the change in the current consumption of the power amplifier 105, that is, the change in the impedance of the antenna. When switching to the down state and returning to a state where the amount of heat generation is small, the output power of the power amplifier can be switched from the power down state to the normal state. In addition, since the magnitude of the current consumption is detected in a state where the power-down is always canceled, it is not necessary to use a plurality of threshold values, and the adjustment process at the time of shipment of the apparatus can be reduced and the manufacturing cost can be reduced.

(Third embodiment)
FIG. 6 is a block diagram showing a configuration of a polar modulation transmission apparatus according to the third embodiment of the present invention. The third embodiment is a modification of the first embodiment, and elements corresponding to the first embodiment are denoted by the same reference numerals.

  A polar modulation transmission apparatus 600 according to the third embodiment includes an I signal input terminal 101, a Q signal input terminal 102, a polar coordinate conversion unit 103, a phase modulation unit 104, a power amplifier 105, an antenna 106, and transmission power. Setting signal input terminal 107, adder 108, multiplier 109, amplitude modulation unit 110, power input terminal 111, current detection unit 112, power-down control unit 613, and power-down release threshold storage unit 614 A power-down threshold storage unit 615, a power-down value storage unit 616, and an operation condition signal input terminal 601.

  Since the basic operation of the polar modulation transmission apparatus 600 of the third embodiment shown in FIG. 6 is the same as that of the first embodiment, only the characteristic operation of the polar modulation transmission apparatus 600 will be described below. explain.

  Here, with respect to the signal input to the operation condition signal input terminal 601 provided in the polar modulation transmission apparatus 600, an operation condition signal representing at least one difference between the operation frequency of the power amplifier, the modulation method, the communication system mode, and the like. Is assumed to be entered.

  That is, the operating conditions of the power amplifier, the modulation method, the communication system mode, and the like change depending on the application and environment in which the polar modulation transmitter 600 is actually used. The threshold and power down value also change. Therefore, in the power-down cancellation threshold storage unit 614, the power-down threshold storage unit 615, and the power-down value storage unit 616 shown in FIG. is there.

  Then, the power-down cancellation threshold storage unit 614 selects an optimal power-down cancellation threshold according to the operation condition signal input to the operation condition signal input terminal 601, and provides this power-down cancellation threshold to the power-down control unit 613. . Similarly, the power-down threshold storage unit 615 selects an optimal power-down threshold according to the input operation condition signal, and gives this power-down threshold to the power-down control unit 613. In addition, the power-down value storage unit 616 selects an optimal power-down value according to the input operation condition signal, and gives this power-down value to the power-down control unit 613. And the power-down control part 613 controls transmission power by controlling the power-down value output according to these input values.

  Therefore, in the polar modulation transmission apparatus 600 of the third embodiment, power down control is performed using optimum parameters that match the operating frequency of the power amplifier, the modulation method, and the actual operating conditions for each communication system mode. Therefore, it is possible to always minimize the amount of reduction in transmission power, and to suppress deterioration in communication quality.

  In any of the first to third embodiments described above, it is assumed that various electric circuits such as an adder and a multiplier are used as components, but hardware such as a microprocessor and a memory is used. Needless to say, a similar control function can be realized by combining the software and software that operates the software and performs predetermined processing.

  Further, the polar modulation transmission apparatus of the first to third embodiments can be applied to various wireless communication apparatuses, and a wireless communication apparatus provided with the polar modulation transmission apparatus of the present embodiment can be configured. In this case, similarly to the above-described embodiment, abnormal heat generation due to the impedance variation of the antenna can be suppressed, and an increase in the housing temperature can be suppressed. For example, by mounting the polar modulation transmission device of the present embodiment on a mobile wireless communication device that is small and portable, and has a wireless transmission function and a wireless reception function, such as a mobile phone terminal, the state near the antenna Even if the impedance fluctuates in accordance with the change, the rise in the housing temperature can be suppressed. Moreover, since it is not necessary to insert an isolator, an increase in power consumption can be suppressed. In particular, when there is a human body or other conductor near the antenna, such as a mobile phone terminal, and it is used in an environment where the state of the antenna changes, the housing that generates heat even if the impedance of the antenna fluctuates. Because it can suppress the temperature rise of the body, etc., it helps to increase safety.

  It should be noted that the present invention is not limited to those shown in the above-described embodiments, and those skilled in the art can also make changes and applications based on the description in the specification and well-known techniques. Yes, included in the scope of protection.

  INDUSTRIAL APPLICABILITY The present invention has an effect of suppressing an increase in casing temperature while maintaining an antenna radiation power equivalent to or higher than that of a quadrature modulation transmitter, and can be used in a wireless communication system such as a mobile phone. It is useful as a polar modulation transmission apparatus, a radio communication apparatus, a polar modulation transmission method, and the like.

The block diagram which shows the structure of the polar modulation transmission apparatus which concerns on the 1st Embodiment of this invention. The graph which shows the operating characteristic of the polar modulation transmission apparatus of 1st Embodiment Time chart showing an operation example of the polar modulation transmission apparatus of the first embodiment The block diagram which shows the structure of the polar modulation transmission apparatus which concerns on the 2nd Embodiment of this invention. Time chart showing an operation example of the polar modulation transmission apparatus of the second embodiment The block diagram which shows the structure of the polar modulation transmission apparatus which concerns on the 3rd Embodiment of this invention. Block diagram showing a configuration example of a conventional polar modulation transmitter

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Polar modulation transmission apparatus 101 I signal input terminal 102 Q signal input terminal 103 Polar coordinate conversion part 104 Phase modulation part 105 Power amplifier 106 Antenna 107 Transmission power setting signal input terminal 108 Adder 109 Multiplier 110 Amplitude modulation part 111 Power input terminal 112 Current detection unit 113 Power down control unit 114 Power down release threshold storage unit 115 Power down threshold storage unit 116 Power down value storage unit 400 Polar modulation transmitter 401 Power down control timing signal input terminal 413 Power down control unit 415 Power down threshold storage Unit 416 power down value storage unit 600 polar modulation transmitter 601 operation condition signal input terminal 613 power down control unit 614 power down release threshold storage unit 615 power down threshold storage unit 616 Wardown value storage

Claims (10)

A polar modulation transmission apparatus comprising a power amplifier that separates an amplitude modulation component and a phase modulation component contained in an input signal to be transmitted and amplifies the power,
A current detection unit for detecting current consumption of the power amplifier;
An output power switching unit capable of switching the magnitude of the output power of the power amplifier between two or more types;
A power-down control unit that provides a predetermined power-down signal to the output power switching unit when the magnitude of the consumption current detected by the current detection unit exceeds a predetermined threshold;
A polar modulation transmitter. The polar modulation transmission apparatus according to claim 1,
The power down control unit holds a predetermined first threshold value and a second threshold value, respectively, and the magnitude of the consumption current detected by the current detection unit when the output power of the power amplifier is in a normal state of a predetermined amount. Exceeds the first threshold, the output power is switched to a power-down state smaller than the normal state, and the current consumption detected by the current detector when the output power of the power amplifier is in the power-down state is large. A polar modulation transmitter that cancels the power-down state when the power falls below the second threshold. The polar modulation transmission apparatus according to claim 1,
The power-down control unit detects the current detection unit after releasing the power-down signal given to the output power switching unit every time a predetermined timing arrives in synchronization with a periodically generated timing signal Ascertaining the magnitude of the current consumption, if the magnitude of the current consumption exceeds the predetermined threshold, the output power of the power amplifier is set to a power-down state smaller than the normal state of a predetermined amount, A polar modulation transmitter that determines the output power of the power amplifier in the normal state when the magnitude of current consumption is equal to or less than the threshold value. The polar modulation transmission apparatus according to any one of claims 1 to 3,
The power-down control unit holds a plurality of types of thresholds adapted to each of a plurality of operating conditions representing a state in which at least one of an operating frequency, a modulation method, and a communication system mode of the power amplifier is different, and the operation A polar modulation transmission apparatus that performs control using a set of threshold values selected from a plurality of types of threshold values held in accordance with an input signal that specifies a condition. The polar modulation transmission apparatus according to claim 1,
The output power switching unit includes an adder that outputs an addition result obtained by adding a power specified value that defines a target value of output power of the power amplifier and a power down signal output by the power down control unit,
A polar modulation transmission apparatus including an amplitude modulation unit that generates a modulation signal based on a result obtained by multiplying the amplitude modulation component by the output of the adder.   A wireless communication apparatus comprising the polar modulation transmission apparatus according to claim 1. A polar modulation transmission method for controlling a polar modulation transmission apparatus including a power amplifier that separates an amplitude modulation component and a phase modulation component contained in an input signal to be transmitted and amplifies the power,
A current detection step of detecting current consumption of the power amplifier;
An output power switching step capable of switching the output power of the power amplifier between two or more types;
A power-down control step of generating a predetermined power-down signal to control switching of the output power when the detected current consumption exceeds a predetermined threshold; and
A polar modulation transmission method. The polar modulation transmission method according to claim 7,
In the power-down control step, a predetermined first threshold value and a second threshold value are respectively held, and the magnitude of the consumed current detected when the output power of the power amplifier is in a normal state of a predetermined amount is the first threshold value. When the threshold value is exceeded, the output power is switched to a power-down state smaller than the normal state, and the amount of current consumption detected when the output power of the power amplifier is in the power-down state is less than or equal to the second threshold value. A polar modulation transmission method for canceling the power-down state. The polar modulation transmission method according to claim 7,
In the power-down control step, every time a predetermined timing arrives in synchronization with the periodically generated timing signal, the power-down signal is canceled, and then the magnitude of the current consumption is determined. When the magnitude exceeds the predetermined threshold, the output power of the power amplifier is set to a power-down state smaller than a predetermined amount of the normal state, and when the current consumption is equal to or smaller than the threshold A polar modulation transmission method for determining output power of the power amplifier in the normal state. The polar modulation transmission method according to any one of claims 7 to 9,
In the power-down control step, a plurality of types of threshold values that are adapted to each of a plurality of operating conditions in which at least one of an operating frequency, a modulation scheme, and a communication system mode of the power amplifier are different are held, and the operation A polar modulation transmission method in which control is executed using a set of threshold values selected from a plurality of types of threshold values held in accordance with an input signal for specifying a condition.

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