Distortion compensation device and distortion compensation method

Abstract

To provide a distortion compensation device and a distortion compensation method that stably perform distortion compensation even when a compression level of a power amplifier decreases.SOLUTION: In a wireless communication device 1, a method for stably performing distortion compensation includes: adding distortion with opposite characteristics to distortion occurring in an output signal of a power amplifier 5 to an input signal using a DPD processing unit 3; calculating a VSWR value, a power supply voltage Vd, and power loss Ploss from the output signal using a PA status monitor 13 when compensating for the distortion that occurs in the output signal; calculating an amount of attenuation of the input signal using a transmission output level suppression unit 14 when at least one of the VSWR value, the power supply voltage Vd, and the power loss Ploss exceeds a preset threshold; and attenuating the input signal on the basis of the calculated attenuation amount.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a distortion compensation device and a distortion compensation method for compensating for distortion of an output signal such as a power amplifier.

Background Art

[0002] In a power amplifier used in a wireless communication device or the like, a digital distortion compensator (DPD: Digital Pre-Distortion) that compensates for distortion of an output signal is used by applying distortion (inverse distortion characteristic) to an input signal in advance so as to cancel a distortion component generated in the output signal (see, for example, Patent Document 1). The distortion compensator is used not only in a base station of a mobile phone operated in a stable environment but also in a wireless communication device operated in a harsh environment such as a coastal station or a ship station using the MF / HF band.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In coastal and marine stations, strong winds can cause antenna movement, leading to an increase in the VSWR (Voltage Standing Wave Ratio), disrupting the impedance matching of the output, causing gain fluctuations, and resulting in the saturated output power falling below the rated output power (hereinafter also referred to as a decrease in compression level). When the output of the power amplifier decreases due to a decrease in the compression level, the distortion compensator, which has a function to compensate for the output level, attempts to restore the output by increasing the gain. However, in such cases, the operating point of the power amplifier approaches the saturation region, and since the distortion compensator cannot perform distortion compensation in the saturation region, it is expected that specifications such as IMD (Intermodulation Distortion) and ACPR (Adjacent Channel Leakage Ratio) cannot be met.

[0005] Furthermore, while ship stations supply power to their radio communication equipment from batteries and generators, the power supply voltage of these devices can become unstable due to environmental changes. For example, if the power supply voltage falls below the design value, the compression level of the power amplifier will decrease, similar to the VSWR value, and it is expected that specifications such as IMD and ACPR will not be met. Conversely, if the power supply voltage rises above the design value, power loss will exceed the design value, and the power amplifier may overheat and be damaged beyond its intended design value.

[0006] Therefore, the present invention aims to provide a distortion compensation device and a distortion compensation method that can stably perform distortion compensation even when the compression level of a power amplifier decreases. [Means for solving the problem]

[0007] To solve the above problems, the invention described in claim 1 is a distortion compensation device that adds distortion with an inverse characteristic to the distortion occurring in the output signal of a power amplifier to an input signal and compensates for the distortion occurring in the output signal, comprising: an amplifier state value calculation means that calculates at least one of the following as a state value indicating the state of the power amplifier from the output signal: a VSWR value, the power supply voltage of the power amplifier, and the power loss of the power amplifier; and a transmission output level suppression means that calculates the attenuation amount of the input signal when at least one of the VSWR value, the power supply voltage, and the power loss exceeds a preset threshold, and attenuates the input signal based on the calculated attenuation amount. The transmission output level suppression means compares the attenuation amount based on the VSWR value, the attenuation amount based on the power supply voltage, and the attenuation amount based on the power loss to determine the maximum value of the attenuation amount, and attenuates the input signal based on the maximum value of the attenuation amount. It is characterized by the following:

[0009] Claim 2 The invention described in the claim 1 In the distortion compensation device described above, the transmission output level suppression means is characterized in that it calculates the attenuation amount such that the attenuation amount increases as the value of the state value exceeding the threshold increases.

[0010] Claim 3 The invention described herein is a distortion compensation method that adds distortion with an inverse characteristic to the distortion occurring in the output signal of a power amplifier to an input signal, and compensates for the distortion occurring in the output signal, wherein at least one of the following is calculated from the output signal as a state value indicating the state of the power amplifier: the VSWR value, the power supply voltage of the power amplifier, and the power loss of the power amplifier; if at least one of the VSWR value, the power supply voltage, and the power loss exceeds a preset threshold, the attenuation amount of the input signal is calculated; and the input signal is attenuated based on the calculated attenuation amount. Then, the maximum value of the attenuation is determined by comparing the attenuation amount based on the VSWR value, the attenuation amount based on the power supply voltage, and the attenuation amount based on the power loss, and the input signal is attenuated based on the maximum value of the attenuation. It is characterized by the following: [Effects of the Invention]

[0011] Claim 1 and 3According to the invention described above, when at least one of the power amplifier's state values—VSWR value, power supply voltage, and power loss—exceeds a preset threshold, the input signal attenuation is calculated, and the input signal is attenuated based on the calculated attenuation. This prevents the distortion compensation device from being used in the power amplifier's saturation region, and allows for stable distortion compensation even when the power amplifier's compression level decreases.

[0012] Furthermore, claims 1 and 3 According to the invention described above, the input signal is attenuated based on the maximum attenuation amount among the attenuation amounts determined from the VSWR value, power supply voltage, and power loss. Therefore, even if the compression level of the power amplifier is reduced due to any of the factors among the VSWR value, power supply voltage, and power loss, stable distortion compensation is possible.

[0013] Furthermore, claims 2 According to the invention described above, the attenuation amount is calculated such that the greater the value of the state value exceeding the threshold, that is, the greater the decrease in the compression level of the power amplifier, the greater the attenuation amount. Therefore, stable distortion compensation is possible regardless of the level of decrease in the compression level of the power amplifier. In particular, with respect to the VSWR value and power loss, the attenuation amount of the input signal is calculated such that the greater the value exceeding the threshold, the greater the attenuation amount, so negative feedback is applied and stable distortion compensation is possible. [Brief explanation of the drawing]

[0014] [Figure 1] This is a block diagram illustrating the schematic configuration of a wireless communication device according to an embodiment of the present invention. [Figure 2] This block diagram shows the schematic configuration of the transmission power level suppression unit shown in Figure 1. [Figure 3] This flowchart shows the procedure for attenuating an input signal based on the state value of a power amplifier. [Modes for carrying out the invention]

[0015] Hereinafter, the present invention will be described based on the illustrated embodiments.

[0016] FIG. 1 is a block diagram showing a schematic configuration of a wireless communication device 1 according to an embodiment of the present invention. The wireless communication device 1 is, for example, a shore station or a ship station that uses the MF / HF band, and executes the distortion compensation device and the distortion compensation method of the present invention, and can perform stable distortion compensation by reducing the level of the input signal in response to a decrease in the compression level (gain compression) of the power amplifier.

[0017] The wireless communication device 1 includes a first level adjustment unit 2, a DPD processing unit 3, a second level adjustment unit 4, and a power amplifier (PA) 5. Further, the wireless communication device 1 includes a third level adjustment unit 6 and a delay adjustment unit 7. Furthermore, the wireless communication device 1 includes a forward wave power detection unit 8, a reflected wave power detection unit 9, a drain voltage detection unit 10, a drain current detection unit 11, a sensor analog-to-digital converter (sensor ADC) 12, a PA state monitor 13, and a transmission output level suppression unit (transmission output level suppression means) 14.

[0018] The first level adjustment unit 2 is a variable attenuator installed at the input stage of the DPD processing unit 3, and attenuates the input signal to an input level suitable for the DPD processing unit 3. Further, the first level adjustment unit 2 also has a function of adjusting the level of the input signal based on the attenuation control signal Gd input from the transmission output level suppression unit 14 when the attenuation amount of the input signal is calculated by the transmission output level suppression unit 14 according to the operating state of the power amplifier 5.

[0019] The DPD processing unit 3 calculates the inverse distortion characteristic using polynomial approximation. Specifically, the DPD processing unit 3 compares the FBK signal (feedback signal) fed back from the output signal of the power amplifier 5 and the REF signal (reference signal) using polynomial approximation, calculates the distortion characteristic opposite to the distortion generated in the output signal, and adds the calculated inverse distortion characteristic to the input signal. The input signal to which the inverse distortion characteristic is added is input to the second level adjustment unit 4.

[0020] The second level adjustment unit 4 is an attenuator installed at the output stage of the DPD processing unit 3, and attenuates the input signal to an input level suitable for the power amplifier 5. The power amplifier 5 is, for example, a multi-stage amplifier composed of an isolator, a small signal amplifier, a driver amplifier, and a final-stage Doherty amplifier, etc., and amplifies the input input signal to a predetermined power.

[0021] The third level adjustment unit 6 attenuates the above-described FBK signal to an input level suitable for the delay adjustment unit 7 and the DPD processing unit 3. The delay adjustment unit 7 performs delay adjustment so that the timings of the level-adjusted FBK signal and the REF signal match. The delay-adjusted REF signal and FBK signal are input to the DPD processing unit 3 and the transmission output suppression unit 14.

[0022] The forward wave power detection unit 8, the reflected wave power detection unit 9, the drain voltage detection unit 10, the drain current detection unit 11, the sensor ADC 12, and the PA state monitor 13 correspond to the amplifier state value calculation means of the present invention, and calculate a state value indicating the state of the power amplifier 5 from the output signal of the power amplifier 5.

[0023] The forward wave power detection unit 8 detects the forward wave power from the output signal of the power amplifier 5 distributed by a power divider (not shown), averages it, and inputs it to the sensor ADC 12. Similar to the forward wave power detection unit 8, the reflected wave power detection unit 9 detects the reflected wave power from the output signal, averages it, and inputs it to the sensor ADC 12. The drain voltage detection unit 10 and the drain current detection unit 11 detect the drain voltage and the drain current from the final stage of the power amplifier 5, average them, and input them to the sensor ADC 12.

[0024] The sensor ADC12 converts the forward wave power input from the forward wave power detection unit 8, the reflected wave power input from the reflected wave power detection unit 9, the drain voltage input from the drain voltage detection unit 10, and the drain current input from the drain current detection unit 11 into digital signals. The sensor ADC12 then inputs the converted digital signals of the forward wave voltage Vf, reflected wave voltage Vr, drain voltage Vd, and drain current Id to the PA state monitor 13.

[0025] The PA status monitor 13 calculates the VSWR value, power supply voltage Vd, and power loss Ploss as status values ​​indicating the state of the power amplifier 5. The VSWR value (voltage standing wave ratio) is a measured value that indicates how efficiently radio frequency power is transmitted to the load, and in this embodiment, it is used as a measured value that indicates the transmission state from the power amplifier 5 to the antenna (not shown). For example, in coastal stations and ship stations using the MF / HF band, if the antenna is shaken by strong winds, the impedance matching of the output is disrupted, the VSWR value increases, the gain of the power amplifier 5 decreases, and the compression level decreases further. When the compression level decreases, the operating point of the power amplifier 5 approaches the saturation region, but because the DPD processing unit 3, which uses polynomial approximation, has a narrow dynamic range, distortion compensation cannot be performed in the saturation region. Therefore, it is expected that it will not be possible to meet specifications such as IMD and ACPR.

[0026] Furthermore, while the ship station supplies power to the radio communication device 1 from a battery or generator, the power supply voltage Vd of the battery or generator may become unstable due to changes in the environment. For example, if the power supply voltage Vd falls below the design value, it is expected that the compression level of the power amplifier 5 will decrease, similar to the VSWR value, and it will become impossible to meet specifications such as IMD and ACPR. Conversely, if the power supply voltage Vd rises above the design value, the power loss Ploss will become larger than the design value, and the power amplifier 5 may overheat and be damaged beyond the expected design value.

[0027] In this embodiment, the VSWR value and power supply voltage Vd are calculated as state values ​​indicating a decrease in the compression level of the power amplifier 5, and the power loss Ploss is calculated as a state value indicating the heat generation state of the power amplifier 5. The PA state monitor 13 calculates the VSWR value using the following formula 1. The PA state monitor 13 also calculates the power loss Ploss using the following formula 2. The power supply voltage Vd is the drain voltage input from the drain voltage detection unit 10 via the sensor ADC 12.

[0028] [Mathematics 1] VSWR=(Vf+Vr) / Vf-Vr) (1)

[0029] [Math 2] Ploss = Vd·Id - Vf 2 ...(2)

[0030] Figure 2 is a block diagram showing the functional configuration of the transmission power level suppression unit 14. The transmission power level suppression unit 14 includes a first attenuation calculation unit 141, a second attenuation calculation unit 142, a third attenuation calculation unit 143, a fourth attenuation calculation unit 144, a peak suppression amount calculation unit 145, and an attenuation control unit 146.

[0031] The first attenuation calculation unit 141 calculates the attenuation of the DPD input signal by the first level adjustment unit 2 based on the VSWR value input from the PA state monitor 13. Specifically, as shown in the graph in the figure, the first attenuation calculation unit 141 pre-sets a threshold (for example, 1.5) at which the compression level of the power amplifier 5 decreases due to an increase in the VSWR value, and calculates an attenuation att1 such that when VSWR ≥ 1.5, the level of the DPD input signal decreases by a slope of 3 dB for every 0.5 increase in the VSWR value.

[0032] The second attenuation calculation unit 142 calculates the attenuation of the DPD input signal by the first level adjustment unit 2 based on the power supply voltage Vd input from the PA state monitor 13. Specifically, as shown in the graph in the figure, the second attenuation calculation unit 142 pre-sets a threshold (for example, 22V) for when the compression level of the power amplifier 5 decreases due to a decrease in the power supply voltage Vd, based on a reference voltage (24V), and calculates an attenuation amount att2 such that when the power supply voltage Vd ≤ 22V, the level of the DPD input signal decreases by 3dB for every 1V decrease in the power supply voltage Vd.

[0033] The third attenuation calculation unit 143 calculates the attenuation of the DPD input signal by the first level adjustment unit 2 based on the power loss Ploss input from the PA state monitor 13. Specifically, as shown in the graph in the figure, the third attenuation calculation unit 143 pre-sets a threshold (for example, 54 dBm = 250 W) based on the reference power at which the amount of heat generated by the power amplifier 5 increases due to a decrease in power loss Ploss, and calculates an attenuation att3 such that when power loss Ploss ≥ 54 dBm, the level of the DPD input signal is reduced by a slope of 3 dB for every 1 dB increase in power loss Ploss.

[0034] The fourth attenuation calculation unit 144 and the peak suppression calculation unit 145 calculate a peak suppression amount corresponding to the compression level of the power amplifier 5, and calculate the attenuation of the DPD input signal based on the calculated peak suppression amount. That is, while the first attenuation calculation unit 141, the second attenuation calculation unit 142, and the third attenuation calculation unit 143 calculate the attenuation of the DPD input signal based on state values ​​(VSWR, Vd, and Ploss) that are affected when the compression level of the power amplifier 5 decreases, the fourth attenuation calculation unit 144 and the peak suppression calculation unit 145 directly calculate the peak suppression amount (compression level) to determine the attenuation. As a result, even in situations where it is difficult to quantitatively express the causal relationship between the compression level and the VSWR value, power supply voltage Vd, and power loss Ploss due to environmental changes or changes in transmission frequency, the level of the DPD input signal can be lowered in accordance with the decrease in the compression level, enabling stable distortion compensation.

[0035] The peak suppression amount calculation unit 145 determines the gain of the power amplifier 5 from the REF signal generated from the input signal and the FBK signal generated from the output signal, and calculates the peak suppression amount, which is the difference between the maximum gain and the gain at maximum amplitude, as a state value indicating the state of the power amplifier 5. More specifically, it determines the instantaneous gain of the power amplifier from the REF signal and the FBK signal, and using the FBK signal level at maximum gain as a reference, it considers the minimum gain within the instantaneous period when the gain is greater than that as the peak value, and calculates the peak suppression amount from the difference between the maximum gain and the peak value.

[0036] The peak suppression amount calculation unit 145 calculates the maximum value Gp of the gain of the power amplifier 5 as described in step S1 of the peak suppression amount calculation flow in the figure. Specifically, it compares the delay-adjusted REF signal and FBK signal, and calculates the gain G(FBK / REF) of the power amplifier 5 for all samples. Then, for the time waveform of the gain G, an exponentially weighted moving average Gp is obtained. At this time, as the smoothing coefficient Kp used for calculating the exponentially weighted moving average Gp, the smoothing coefficient Kpa during attack (rise of the gain G) and the smoothing coefficient Kpr during release (fall of the gain G) are set in advance. Then, depending on the magnitude relationship between the gain G of the previous sample and the exponentially weighted moving average Gp, the smoothing coefficient Kpa and the smoothing coefficient Kpr used when obtaining the exponentially weighted moving average Gp of the next sample are adaptively switched, so that an exponentially weighted moving average Gp close to the maximum value can be obtained.

[0037] For example, when the previous sample is G≧Gp, the exponentially weighted moving average Gp is calculated using Kpa as the smoothing coefficient Kp in the next sample. Also, when the previous sample is G<Gp, the exponentially weighted moving average Gp is calculated using Kpr as the smoothing coefficient Kp in the next sample. By setting Kpa and Kpr so that the time during attack (rise of the gain G) (for example, 1 ms) is sufficiently faster than the time during release (fall of the gain G) (for example, 1500 ms), the maximum value Gp of the gain can be calculated.

[0038] Also, as described in step S2 of the peak suppression amount calculation flow in the figure, the peak suppression amount calculation unit 145 calculates the minimum value Gm of the gain of the power amplifier 5. Specifically, during the calculation of the maximum value Gp of the gain in step S1, the signal level Lp of the FBK signal that becomes the maximum value Gp is stored. When the level of the time waveform of the FBK signal is L, the exponential moving average Gm of the gain G is obtained for the sample where L ≥ Lp. At this time, as the smoothing coefficient Km used for calculating the exponential moving average Gm, the smoothing coefficient Kma during attack (rise of the gain G) and the smoothing coefficient Kmr during release (fall of the gain G) are set in advance. Then, by adaptively switching the smoothing coefficient Kma and the smoothing coefficient Kmr used when obtaining the exponential moving average Gm of the next sample according to the magnitude relationship between the gain G of the previous sample and the exponential moving average Gm, the minimum value of the gain in the instantaneous component with a large amplitude can be obtained, and the gain Gm at the peak of the amplifier where substantial peak suppression occurs can be obtained.

[0039] For example, when the previous sample is G ≥ Gm, the exponential moving average Gm is calculated using Kma as the smoothing coefficient Km for the next sample. When the previous sample is G < Gm, the exponential moving average Gm is calculated using Kmr as the smoothing coefficient Km for the next sample. By setting Kma and Kmr such that the time during attack (rise of the gain G) (for example, 1500 ms) is sufficiently slower than the time during release (fall of the gain G) (for example, 1 ms), the minimum value Gm of the gain can be calculated.

[0040] Also, as shown in step S3, the peak suppression amount calculation unit 145 calculates the peak suppression amount Ga, which is the difference between the maximum value Gp and the minimum value Gm of the gain. As described above, the peak suppression amount Ga corresponds to the compression level of the power amplifier 5. The graph shown inside the peak suppression amount calculation unit 145 in FIG. 2 shows the AM / AM characteristics of the power amplifier 5, where the vertical axis represents the gain G of the power amplifier 5 and the horizontal axis represents the level L of the FBK signal, and the maximum value Gp of the gain, the minimum value Gm, and the FBK level Lp of the maximum value Gp have the relationship as shown in the figure.

[0041] The method for calculating the peak suppression amount Ga described above is just one example, and other calculation methods may be used. For example, the maximum and minimum values ​​of the time waveform of the gain G may be constantly maintained and updated, and the peak suppression amount Ga may be calculated from the difference between the maximum and minimum values.

[0042] The fourth attenuation calculation unit 144 calculates the attenuation of the DPD input signal by the first level adjustment unit 2 based on the peak suppression amount Ga input from the peak suppression amount calculation unit 145. Specifically, as shown in the graph in the figure, the fourth attenuation calculation unit 144 pre-sets a threshold value (e.g., 3dB) for the peak suppression amount Ga, and calculates an attenuation amount att4 such that when the peak suppression amount Ga ≥ 3dB, the level of the DPD input signal is reduced by a slope of 3dB for every 1dB increase in the peak suppression amount Ga.

[0043] The attenuation amounts att1, att2, att3, and att4 calculated by the first attenuation calculation unit 141, the second attenuation calculation unit 142, the third attenuation calculation unit 143, and the fourth attenuation calculation unit 144 are input to the attenuation control unit 146. The attenuation control unit 146 compares the input attenuation amounts att1, att2, att3, and att4 to determine the maximum attenuation amount. Based on the maximum attenuation amount, it generates an attenuation control signal Gd for attenuating the DPD input signal and inputs it to the first level adjustment unit 2. The first level adjustment unit 2 attenuates the DPD input signal based on the attenuation control signal Gd. For example, if the attenuation amount att2 calculated by the second attenuation calculation unit 142 is the maximum value, the attenuation control unit 146 attenuates the DPD input signal based on the attenuation amount att2. This prevents the DPD processing unit 3 from being used in the saturation region of the power amplifier 5, and enables stable distortion compensation even when the compression level of the power amplifier 5 decreases.

[0044] Next, the operation of attenuating the DPD input signal based on the state value of the power amplifier 5 in the above embodiment will be explained based on the flowchart in Figure 3. The PA state monitor 13 calculates the VSWR value, power supply voltage Vd, and power loss Ploss as the state values ​​of the power amplifier 5 (step S10).

[0045] The first attenuation calculation unit 141, the second attenuation calculation unit 142, and the third attenuation calculation unit 143 of the transmit output level suppression unit 14 calculate the attenuation amounts att1, att2, and att3 of the DPD input signal, respectively, when the VSWR value, power supply voltage Vd, and power loss Ploss exceed their respective thresholds (YES in step S11), such that the larger the value exceeding the threshold, the greater the attenuation (step S12). In addition, the peak suppression amount calculation unit 145 of the transmit output level suppression unit 14 calculates the peak suppression amount Ga, which corresponds to the compression level of the power amplifier 5, and the fourth attenuation calculation unit 144 calculates the attenuation amount att4 of the DPD input signal, such that the larger the calculated peak suppression amount Ga, the greater the attenuation.

[0046] The attenuation control unit 146 of the transmission output level suppression unit 14 compares the input attenuation amounts att1, att2, att3, and att4 to determine the maximum attenuation amount. Based on the maximum attenuation amount, it generates an attenuation control signal Gd for attenuating the DPD input signal and inputs it to the first level adjustment unit 2. The first level adjustment unit 2 attenuates the DPD input signal based on the attenuation control signal Gd (step S13).

[0047] According to the wireless communication device 1 of this embodiment, when at least one of the state values ​​of the power amplifier 5, namely the VSWR value, power supply voltage Vd, and power loss Ploss, exceeds a preset threshold, the attenuation amount of the DPD input signal is calculated, and the DPD input signal is attenuated based on the calculated attenuation amount. This prevents the DPD processing unit 3 from being used in the saturation region of the power amplifier 5, and enables stable distortion compensation even when the compression level of the power amplifier 5 decreases.

[0048] Furthermore, according to the wireless communication device 1 of this embodiment, the DPD input signal is attenuated based on the maximum attenuation amount among the attenuation amounts att1, att2, and att3 determined from the VSWR value, power supply voltage Vd, and power loss Ploss. Therefore, even if the compression level of the power amplifier 5 decreases due to any of the factors of the VSWR value, power supply voltage Vd, or power loss Ploss, stable distortion compensation is possible.

[0049] Furthermore, according to the wireless communication device 1 of this embodiment, the greater the value of the state value such as the VSWR value that exceeds the threshold, that is, the lower the compression level of the power amplifier 5, the greater the attenuation of the DPD input signal. Therefore, regardless of the level of the compression level of the power amplifier 5, stable distortion compensation is possible. In particular, with respect to the VSWR value and power loss, the attenuation of the DPD input signal reduces the values ​​of the VSWR value and power loss, so negative feedback is applied and stable distortion compensation is possible.

[0050] In the above embodiment, the DPD input signal is attenuated by the first level adjustment unit 2 installed at the input stage of the DPD processing unit 3. However, the DPD output signal may be attenuated by the second level adjustment unit 4 installed at the output stage of the DPD processing unit 3. In this case, the third level adjustment unit 6, which adjusts the level of the FBK signal fed back from the power amplifier 5, amplifies the level of the FBK signal by the amount attenuated by the second level adjustment unit 4. Specifically, if the input signal is attenuated by 3 dB in the second level adjustment unit 4, the third level adjustment unit 6 amplifies the level of the FBK signal by 3 dB. This allows the output after the DPD processing unit 3 to be reduced without changing the gain of the DPD processing unit 3, thereby reducing the overall device output and preventing the DPD processing unit 3 from being used in the saturation region of the power amplifier 5.

[0051] Furthermore, the strain compensation device and strain compensation method according to this invention are not limited to use in wireless communication equipment for coast stations and ship stations using the MF / HF band as described in the above embodiments, but can also be applied to wireless communication equipment using other bands and various power amplifiers. [Explanation of Symbols]

[0052] 1. Wireless communication device 2. First level adjustment unit 3 DPD Processing Unit 4. Second level adjustment unit 5 Power Amplifier 6. Third level adjustment unit 7. Delay Adjustment Section 8. Forward wave power detection unit 9 Reflected wave power detection unit 10 Drain voltage detection unit 11 Drain current detection unit 12 SensorADC 13 PA Status Monitor (Amplifier Status Value Calculation Means) 14. Transmission output level suppression unit (transmission output level suppression means) 141 First Attenuation Calculation Unit 142 Second Attenuation Calculation Unit 143 Third Attenuation Calculation Unit 144. Fourth Attenuation Calculation Unit 145 Peak Suppression Amount Calculation Unit 146 Damping Control Unit

Claims

1. A distortion compensation device that adds distortion with an inverse characteristic to the distortion occurring in the output signal of a power amplifier to the input signal, and compensates for the distortion occurring in the output signal, Amplifier state value calculation means calculates at least one of the following as a state value indicating the state of the power amplifier from the output signal: VSWR value, power supply voltage of the power amplifier, and power loss of the power amplifier. A transmission output level suppression means that calculates the attenuation amount of the input signal when at least one of the VSWR value, the power supply voltage, and the power loss exceeds a preset threshold, and attenuates the input signal based on the calculated attenuation amount. Equipped with, The transmission output level suppression means compares the attenuation amount based on the VSWR value, the attenuation amount based on the power supply voltage, and the attenuation amount based on the power loss to determine the maximum value of the attenuation amount, and attenuates the input signal based on the maximum value of the attenuation amount. A distortion compensation device characterized by the following features.

2. The distortion compensation device according to claim 1, characterized in that the transmission output level suppression means calculates the attenuation amount such that the attenuation amount increases as the value of the state value exceeding the threshold increases.

3. A distortion compensation method that adds distortion with an inverse characteristic to the distortion occurring in the output signal of a power amplifier to the input signal, and compensates for the distortion occurring in the output signal, From the output signal, at least one of the following is calculated as a state value indicating the state of the power amplifier: the VSWR value, the power supply voltage of the power amplifier, and the power loss of the power amplifier. If at least one of the VSWR value, the power supply voltage, and the power loss exceeds a preset threshold, the attenuation amount of the input signal is calculated. Based on the calculated attenuation amount, the input signal is attenuated. The maximum value of the attenuation is determined by comparing the attenuation amount based on the VSWR value, the attenuation amount based on the power supply voltage, and the attenuation amount based on the power loss, and the input signal is attenuated based on the maximum value of the attenuation. A distortion compensation method characterized by the following features.

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