JP5263531B2 - Power amplifier, transmission system, and power amplifier failure detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize a power amplifier for output of combined parallel outputs of a plurality of amplifying elements. <P>SOLUTION: A power amplifier 1041 amplifies digital broadcast signals. This power amplifier 1041 includes a plurality of amplifying elements 11 to 1n connected in parallel between a distributer 4 and a combiner 5, a current detector 3, and an irregular current detecting circuit 7. The current detector 3 is connected between the plurality of amplifying elements 11 to 1n and a power supply 6 to detect a total amount of current flowing into the plurality of amplifying elements 11 to 1n. The irregular current detecting circuit 7 determines occurrence of a fault in the plurality of amplifying elements 11 to 1n based on the total amount of current detected with the current detector 3. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a power amplifier that combines and outputs a plurality of amplified signals, and a failure detection method for the power amplifier.

  2. Description of the Related Art As an amplifying apparatus used for a broadcasting transmission apparatus, a power amplifier that amplifies a distributed broadcast signal by a plurality of amplifying elements and then combines and outputs the power is known. FIG. 1 is a diagram illustrating an example of a configuration of a conventional power amplifier. Referring to FIG. 1, the conventional power amplifier includes amplification elements 111 and 112, current detectors 131 and 132, a distributor 140, a combiner 150, a power supply 160, and a current abnormality detection circuit 170.

  The distributor 140 distributes a signal (for example, a broadcast signal) input from the input terminal 110 to the plurality of amplifying elements 111 and 112. Each of the amplifying elements 111 and 112 amplifies the signal and outputs the amplified signal to the synthesizer 150. The combiner 150 combines the signals input from the amplification elements 111 and 112 and outputs the combined signals to the output terminal 120.

  Here, the current detectors 131 and 132 are connected between the corresponding amplifying elements 111 and 112 and the power source 160, respectively. The current detectors 131 and 132 detect the magnitude of the bias current flowing through the amplifying elements 111 and 112 (transistors) and output them to the current abnormality detection circuit 170. The current abnormality detection circuit 170 outputs a signal indicating that the transistor is abnormal when the bias current flowing through one of the amplifying elements 111 and 112 is lower than the threshold value.

  As described above, in the conventional power amplifier, it is possible to detect the abnormality (for example, damage) of the transistor in each amplification element by detecting the current value in each of the plurality of amplification elements and determining the presence or absence of abnormality.

  In the case of analog broadcasting, the average power of the broadcast signal changes depending on the contents of the program. In this case, it is necessary to set a normal current range for each amplifying element and detect the presence or absence of current abnormality for each amplifying element. For this reason, the above-mentioned power amplifier provided with a current detector for each amplifying element is suitably used for broadcasting equipment for analog broadcasting.

  A technique for detecting an abnormality of a transistor is described in, for example, Japanese Patent Laid-Open No. 56-143704 (see Patent Document 1). Further, techniques for detecting an abnormality in a power amplifier are described in, for example, Japanese Patent Application Laid-Open No. 2008-72157 and Japanese Patent Application Laid-Open No. 61-227410 (see Patent Documents 2 and 3).

JP 56-143704 A JP2008-72157 JP 61-227410

  In recent years, the output of power amplifiers has increased, and the number of amplifying elements connected in parallel tends to increase. In the above-described power amplifier, since a current detector is connected to each amplification element, the number of current detectors and connection lines increases as the number of amplification elements increases. This increases the size and product cost of the power amplifier. In the future, in a single transmission system for digital broadcasting, the number of power amplifiers will increase, while downsizing of the apparatus is strongly desired.

  From the above, an object of the present invention is to downsize a power amplifier that synthesizes and outputs parallel outputs of a plurality of amplifying elements.

  In order to solve the above problems, the present invention employs the means described below. In the description of technical matters constituting the means, in order to clarify the correspondence between the description of [Claims] and the description of [Mode for Carrying Out the Invention] The number / symbol used in [Form] is added. However, the added numbers and symbols should not be used to limit the technical scope of the invention described in [Claims].

  The power amplifier (1041) according to the present invention amplifies the digital broadcast signal. A power amplifier (1041) according to the present invention includes a plurality of amplifying elements (11 to 1n) connected in parallel between a distributor (4) and a combiner (5), a current detector (3), And an abnormality detection circuit (7). The plurality of amplification elements (11 to 1n) amplify the signal distributed by the distributor (4) and output the amplified signal to the combiner (5). The current detector (3) is connected between the plurality of amplifying elements (11 to 1n) and the power source (6), and detects the total amount of current flowing through the plurality of amplifying elements (11 to 1n). The current abnormality detection circuit (7) determines the presence or absence of abnormality of the plurality of amplification elements (11 to 1n) based on the total amount of current detected by the current detector (3).

  According to the present invention, since the currents of a plurality of transistors are collectively detected by one current detector, the number of current detectors and power supply connection lines can be reduced.

  The failure detection method for a power amplifier according to the present invention is a failure detection method for a power amplifier that amplifies a signal whose average power is constant for a time sufficiently longer than the envelope of the signal. The failure detection method according to the present invention includes a step of detecting a total amount of current flowing through a plurality of amplifying elements (11 to 1n) connected in parallel between a distributor (4) and a combiner (5). Determining whether or not there is an abnormality in the plurality of amplifying elements (11 to 1n) based on the total amount of current.

  According to the present invention, it is possible to reduce the size of a power amplifier that synthesizes and outputs parallel outputs of a plurality of amplifying elements.

FIG. 1 is a diagram showing a configuration of a power amplifier according to the prior art. FIG. 2 is a diagram illustrating an example of a configuration of a transmission system mounted on a broadcasting device according to the present invention. FIG. 3 is a diagram showing the configuration of the power amplifier according to the first embodiment of the present invention. FIG. 4 is a diagram showing the configuration of the power amplifier according to the second embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same or similar reference numerals indicate the same, similar, or equivalent components. In the present embodiment, a transmission system used for terrestrial digital broadcasting by ISDB-T (Integrated Service Digital Broadcasting-Terrestrial) will be described as an example.

1. First Embodiment (Configuration)
With reference to FIG.2 and FIG.3, the structure of the transmission system by this invention is demonstrated. FIG. 2 is a diagram illustrating an example of a configuration of a transmission system mounted on a broadcasting device according to the present invention. FIG. 3 is a diagram showing the configuration of the power amplifier according to the first embodiment of the present invention.

  Referring to FIG. 2, a transmission system 100 according to the present invention includes a modulator 102, an exciter 103, a plurality of power amplifiers 1041 to 104N (N is an integer of 1 or more), and a filter 105.

  The transmission system 100 receives a TS (Transport Stream) signal from a studio apparatus (not shown). The modulator 102 performs OFDM (Orthogonal Frequency Division Multiplexing) modulation on the TS signal input from the input terminal 101 and outputs the result to the exciter 103 as an OFDM signal in an IF (Intermediate Frequency) band. The exciter 103 converts the IF signal in the IF band into an RF (Radio Frequency) signal in a desired frequency band (for example, UHF band). The exciter 103 has a nonlinear distortion compensation function for suppressing the occurrence of IM (intermodulation distortion) in the subsequent power amplifiers 1041 to 104N and a linear distortion compensation function for compensating for a frequency tilt generated in the transmission system 100.

  The RF signal output from the exciter 103 is distributed to a plurality of power amplifiers 1041 to 104N by a distributor (not shown). Each of the power amplifiers 1041 to 104N amplifies the power of the input low-power RF signal to a predetermined value. The RF signals that have been power-amplified in each of the power amplifiers 1041 to 104N are combined by a combiner (not shown), band-limited by the filter 105 (bandpass filter), and output to the output terminal 106. The output terminal 106 is connected to an antenna (not shown), and the RF signal from the transmission system 100 is output as a broadcast signal from the antenna.

  With reference to FIG. 3, details of the configuration of the power amplifiers 1041 to 104N according to the present invention will be described. Here, although the power amplifier 1041 will be described, the other power amplifiers 1042 to 104N have the same configuration, and thus the description thereof is omitted.

  The power amplifier 1041 includes amplifying elements 11 to 1n (n is an integer of 2 or more), a current detector 3, a distributor 4, a combiner 5, a power source 6, a current abnormality detection circuit 7, and a current abnormality threshold generation unit 8. .

  The distributor 4 is connected to the exciter 103 (distributor (not shown)) via the input terminal 1. The distributor 4 distributes the RF signal input from the input terminal 1 to the plurality of amplifying elements 11 to 1n. The amplifying elements 11 to 1n are connected in parallel between the distributor 4 and the combiner 5, respectively. The amplifying elements 11 to 1n amplify the input RF signals and output the amplified RF signals to the combiner 5. Specifically, each of the amplifying elements 11 to 1n preferably includes an input side matching circuit, a field effect transistor (FET), and an output side matching circuit. The gate of the field effect transistor is connected to the distributor 4 via the input side matching circuit, and the drain is connected to the combiner 5 via the output side matching circuit. The RF signal input from the distributor 4 is input to the gates of the amplification elements 11 to 1n, and is output from the drain to the combiner 5. At this time, the power of the amplifying elements 11 to 1n is increased according to the drain voltage supplied from the power supply 6, the DC bias voltage applied to the gate terminal, and the RF signal. That is, each bias current increases according to the output level of the amplifying elements 11 to 1n. The synthesizer 5 synthesizes the signals input from the amplifying elements 11 to 1n and outputs them to the output terminal 2. The output terminal 2 is connected to the filter 105 through a combiner (not shown).

  The current detector 3 is connected between the respective sources of the amplifying elements 11 to 1n and the power supply 6, and detects a bias current flowing through the amplifying elements 11 to 1n. Specifically, the current detector 3 detects the total amount (total value) of the bias current flowing through each of the amplifying elements 11 to 1n. The detected bias current value (total value) is output as current information 30 to the current abnormality detection circuit 7.

  The current abnormality detection circuit 7 refers to the current information 30 and outputs information indicating that any of the amplification elements 11 to 1n is abnormal when the bias current flowing through the amplification elements 11 to 1n is lower than the threshold value 40. A threshold 40 for determining abnormality of the amplification elements 11 to 1n is generated in the current abnormality threshold generation unit 8. Specifically, the current abnormality threshold generation unit 8 is set with a current range indicating a normal value based on the output power information 9. The output power information 9 is information that defines the output power of the power amplifier 1041 or information that indicates what percentage of the power is the rated output power of the transmission system 100. The output power information 9 may be set in a setting unit (for example, a storage device, not shown) installed in the transmission system 100, or may be input from an external device (not shown).

(Operation)
Next, the operation in the embodiment of the transmission system 100 according to the present invention will be described with reference to FIGS.

  The TS signal input to the input terminal 101 of the transmission system is OFDM modulated by the modulator 102. The signal modulated by the modulator 102 is frequency-converted by the exciter 103, amplified by the power amplifiers 1041 to 104N, and output as an RF signal.

  In the power amplifiers 1041 to 104N, the RF signal input from the input terminal 1 is distributed by the distributor 4 to each of the amplification elements 11 to 1n. The power of each of the amplifiers 11 to 1n is increased according to the drain voltage supplied from the power supply 6, the DC bias voltage applied to the gate terminal, and the RF signal. The synthesizer 5 synthesizes the RF signals input from the amplifiers 11 to 1n and outputs them to the output terminal 2.

  In each of power amplifying devices 1041 to 104N, it is determined whether or not the bias current flowing through amplifying elements 11 to 1n is normal. In the present invention, a single current detector 3 detects the total value of the bias currents flowing through the amplifying elements 11 to 1n, and the current abnormality is determined.

  When an OFDM-modulated signal handled in a digital terrestrial broadcasting transmission system takes an average value of power in a time sufficiently longer than an envelope of a predetermined frequency in the modulated signal, a broadcast program (information transmitted by the signal) Regardless of the), the average power is constant. For example, in Japanese digital television broadcasting, in the case of 13CH, a signal (digital television broadcasting program) having a modulation wave width of 6 MHz is transmitted by a carrier wave of 473 MHz. At this time, the envelope is indicated by a time variation (Envelop) of the signal amplitude having a bandwidth of 6 MHz.

  An OFDM-modulated digital broadcast signal is a highly random signal. That is, the amplitude of the digital broadcast signal changes randomly regardless of the content of the broadcast program. For example, in the above example, the broadcast signal has thousands of carriers with different frequencies in a 6 MHz band, and has a combined waveform. Therefore, there is no periodicity of amplitude, and according to the overlap of a plurality of carriers. Since the synthesized amplitude also changes, the randomness increases. Not only OFDM modulation but a digital modulation signal having a plurality of carriers has such a tendency.

  Accordingly, the average power of the digital broadcast signal in a sufficiently long time (for example, 100 msec) than the envelope wavelength (the time between peak values at which the amplitude is maximum) is a constant value regardless of the displayed screen (broadcast program). Indicates. Further, the operating currents of the amplifying elements 11 to 1n change slowly without following the rapid change of the envelope because there is a capacitance (not shown) in the drain and power supply output of the transistor. For this reason, the operating current (average current for a predetermined time) of the amplification elements 11 to 1n shows a constant value regardless of the broadcast program. As described above, in the case of a terrestrial digital broadcast transmission system that operates with the average value of output power being constant, the operating currents of the amplifier elements 11 to 1n are also constant regardless of the broadcast program. Here, the operating current is an average value of operating currents for a sufficiently long time when a plurality of signal envelopes are included.

  On the other hand, in analog television broadcasting, the average power for a time sufficiently longer than the envelope of the modulated signal varies depending on the content of the broadcast program. For example, in analog television broadcasting, the signal power changes depending on whether the screen display is white or black, and therefore, even if averaged over a sufficiently long time, it shows a different value in each case (white or black). For this reason, the average current in the amplifying element also shows a different value depending on the screen display. When there are two amplifying elements (transistors), the average current for a given time is normal when both amplifying elements are normal and the black display is maximum, then one amplifying element is normal, one is black when a failure occurs, Two devices are normal and display white, one amplifying element is normal, one fault continues white display, and two amplifying elements fail and white display or black display is minimum. Thus, in order to detect the four states, it is necessary to detect a failure by detecting the operating current for each amplification element. That is, in analog broadcasting, it is necessary to provide a current detector for each amplification element in order to detect a failure of the amplification element. The above example illustrates the case where the current is the largest and the case where the current is the smallest. Needless to say, there are a plurality of (infinite) gradations between the black display and the white display.

However, in digital television broadcasting, as described above, the operating currents (average value for a predetermined time) of the amplification elements 11 to 1n are constant regardless of the broadcast program. For this reason, when there are two amplifying elements (transistors), the average current for a predetermined time does not depend on the change of the screen color or the like, and both of the amplifying elements are normal or one is faulty (one is normal). There are only two states. in this case,
A failure can be detected by detecting the total value of the operating currents of the two amplifying elements.

  As described above, the bias current flowing through each of the amplifying elements 11 to 1n has a constant value. For this reason, when any one of the amplifying elements 11 to 1n is damaged, the total value of the bias currents flowing through each of the amplifying elements 11 to 1n is reduced by the number of the amplifying elements that are damaged. For example, when the total value of bias currents when all of the amplifying elements 11 to 1n are normal is Is, the total of bias currents when x amplifying elements are damaged is Is × (nx) ) / N.

  The current detector 3 detects the total value of the bias currents flowing through each of the amplifying elements 11 to 1n. In the current abnormality detection circuit 7, it is preferable that the threshold value 40 is set to a value larger than Is × (n−1) / n and smaller than Is. If the allowable number of breakage is A, the threshold value 40 can be set to a value larger than Is × (n−A) / n and smaller than Is.

  For example, when the two amplifying elements 11 and 12 are mounted in each of the power amplifiers 1041 to 104N, a value larger than 50% and smaller than 100% of Is is set as the threshold value 40. Here, when one of the amplifying element 11 and the amplifying element 12 is damaged, the current value detected by the current detector 3 becomes 50% of the normal current value Is. The current abnormality detection circuit 7 outputs information indicating that an abnormality has been detected because the current value indicated by the current information 30 (here, 50% of Is) is equal to or less than the threshold value 40.

  Alternatively, when the three amplifying elements 11 to 13 are mounted on the power amplifiers 1041 to 104N, a value larger than 2/3 of Is and smaller than 100% is set as the threshold value 40. Here, if any of the amplifying elements 11 to 13 is damaged, the current value detected by the current detector 3 becomes 2/3 or less of the normal current value Is. The current abnormality detection circuit 7 outputs information indicating that an abnormality has been detected because the current value indicated by the current information 30 (here, 2/3 or less of Is) is equal to or less than the threshold value 40.

  As described above, according to the present invention, even if the number of current detectors is smaller than the number of amplifying elements, it is possible to detect breakage of the amplifying elements.

  In the present invention, in a power amplifier 1041 that amplifies a signal having a constant average power for a predetermined time, the current of a plurality of amplifying elements is collectively detected by a single current detector 3 to detect a breakage of the amplifying element. Can do. As a result, it is possible to reduce the number of current detectors and connecting lines that have been conventionally provided, and it is possible to reduce the size and cost of the apparatus.

  Next, a case where the output power of the power amplifiers 1041 to 104N is changed will be described. The output power of the power amplifiers 1041 to 104N may differ depending on the configuration of the transmission system 100 and the convenience of the user. Since the normal current value Is changes depending on the magnitude of the output power, the threshold value 40 needs to be changed. For this reason, the current abnormality threshold value generation unit 8 resets the threshold value 40 for determining current abnormality based on the changed output power information 9. Here, the threshold value 40 can be changed by changing Is, which is the total value of the bias voltage at the normal time. Further, the threshold value 40 may be changed by changing the allowable number A of damages. The threshold value 40 may be calculated using a polynomial obtained from an actual measurement value of output power versus transistor operating current constituting the amplifying elements 11 to 1n. Or you may take the system which switches the threshold value 40 with reference to the threshold value table preset in the memory | storage device which is not shown in figure. In this case, the threshold voltage table is recorded with the output voltage and the threshold 40 (normal current range) associated with each other, and the current abnormality threshold generation unit 8 extracts the threshold corresponding to the output power information 9 from the table.

  According to the present invention, the user of the transmission system 100 or the power amplifiers 1041 to 104N appropriately sets the threshold 40 for detecting the current abnormality by setting the output power information 9 according to the actual usage level. be able to. In addition, since it is not necessary to individually reset the thresholds for detecting current abnormalities in the amplifier elements 11 to 1n, the output power of the power amplifiers 1041 to 104N can be flexibly and easily handled. Therefore, even when the output power setting is changed or when the output power is switched at regular intervals, an optimum current abnormality threshold value corresponding to the current output power is set to prevent the amplifier element (transistor) from failing. It can be detected properly.

  Furthermore, the manufacturer of the transmission system 100 and the power amplifiers 1041 to 104N does not need to individually change the threshold value for detecting current abnormality according to the actual usage level for each amplification element. For this reason, this invention can mass-produce the same apparatus, and contributes to improvement in production efficiency.

2. Second Embodiment With reference to FIG. 4, a second embodiment of a power amplifier 1041 according to the present invention will be described. FIG. 4 is a diagram showing a configuration of the power amplifier 1041 according to the second embodiment of the present invention. In the following, description of the same configuration and operation as in the first embodiment will be omitted, and only the parts different from the first embodiment will be described.

  The power amplifier 1041 in the present embodiment includes a directional coupler 21, a detector 22, an output abnormality detection circuit 23, and an output abnormality setting unit 24 in addition to the configuration of the power amplifier 1401 in the first embodiment.

  The directional coupler 21 outputs an RF signal corresponding to the power in the direction from the combiner 5 toward the output terminal 2 to the detector 22. The detector 22 detects the power level of the RF signal input from the directional coupler 21 and outputs the detection result to the output abnormality detection circuit 23. The output abnormality setting unit 24 outputs output power information 9 ′ indicating a normal output power range (threshold value). The output abnormality detection circuit 23 determines whether or not the power level detected by the detector 22 is normal based on the output power information 9 '. Here, when the power level detected by the detector 22 is out of the power range indicated by the output power information 9 '(above or below the threshold), it is determined that the output is abnormal. If the result of determination is abnormal, the output abnormality detection circuit 23 outputs information indicating output power abnormality.

  Further, the current abnormality threshold value generation unit 8 sets the threshold value 40 based on the output power information 9 'as in the first embodiment. Here, it is preferable to set the normal output power (threshold value) set in the output power information 9 ′ at a constant ratio with respect to the rated power. Thereby, the current abnormality threshold value generation unit 8 can estimate the current output power level with reference to the output power information 9 ′, and set the threshold value 40 corresponding to the estimated output power level.

  As described above, in power amplifier 1041 in the present embodiment, threshold 40 for detecting current abnormality can be set using the condition (output power information 9 ') for detecting output abnormality. That is, by linking the output power information 9 'of the power amplifiers 1041 to 104N with the current abnormality setting (threshold 40), it is possible to detect a current abnormality according to the output power in the actual operation state. Usually, a power amplifier is equipped with a function for setting an output abnormality. In the present embodiment, this function can be used as the output abnormality setting unit 24 to detect a current abnormality.

  The embodiment of the present invention has been described in detail above, but the specific configuration is not limited to the above-described embodiment, and changes within a scope not departing from the gist of the present invention are included in the present invention. . For example, when the average value of power is taken in a sufficiently long time than the envelope of the signal modulated by the modulator 102, the average power is constant regardless of the content of video or audio or other information desired to be transmitted. The present invention can also be applied to modulation schemes. In the above-described embodiment, a transmission system used for a broadcasting device that performs television broadcasting is shown. However, the present invention can also be applied to a transmission system used for other communication devices and radars.

1: Input terminal 2: Output terminal 3: Current detector 4: Distributor 5: Synthesizer 6: Power supply 7: Current abnormality detection circuit 8: Current abnormality threshold generation unit 9, 9 ′: Output power information 11 to 1n: Amplification Element 21: Directional coupler 22: Detector 23: Output abnormality detection circuit 24: Output abnormality setting unit 30: Current information 40: Threshold value 100: Transmission system 101: Input terminal 102: Modulator 103: Exciters 1041-104N: Power amplifier 105: Filter 106: Output terminal

Claims (7)

In power amplifiers that amplify digital broadcast signals,
A current abnormality threshold generation unit that sets a normal current range based on output power information that defines the output power of the power amplifier;
A plurality of amplifying elements connected in parallel between a distributor and a combiner, amplifying the signal distributed by the distributor and outputting the amplified signal to the combiner;
A current detector connected between the plurality of amplifying elements and a power source and detecting a total amount of current flowing through the plurality of amplifying elements;
A current abnormality detection circuit for determining presence / absence of abnormality of the plurality of amplifying elements based on a total amount of current detected by the current detector;
Equipped with,
The current abnormality detection circuit is a power amplifier that determines that the plurality of amplifying elements are abnormal when the total amount of the detected current is a value out of the normal current range . In power amplifiers that amplify digital broadcast signals,
A current abnormality threshold generation unit that sets a normal current range based on a threshold for detecting an output abnormality of the power amplifier;
A plurality of amplifying elements connected in parallel between a distributor and a combiner, amplifying the signal distributed by the distributor and outputting the amplified signal to the combiner;
A current detector connected between the plurality of amplifying elements and a power source and detecting a total amount of current flowing through the plurality of amplifying elements;
A current abnormality detection circuit for determining presence / absence of abnormality of the plurality of amplifying elements based on a total amount of current detected by the current detector;
Comprising
The current abnormality detection circuit is a power amplifier that determines that the plurality of amplifying elements are abnormal when the total amount of the detected current is a value out of the normal current range . The power amplifier according to claim 1 or 2 ,
Each of the plurality of amplifying elements is a power amplifier that amplifies an orthogonal frequency division multiplex modulated signal. The power amplifier according to any one of claims 1 to 3 ,
A modulator for modulating the input signal;
An exciter that converts the modulated signal into a signal of a predetermined frequency band and outputs the signal to the power amplifier;
And a filter that performs band control on the signal amplified by the power amplifier. In a failure detection method for a power amplifier that amplifies a digital broadcast signal,
Setting a normal current range based on output power information defining the output power of the power amplifier;
Detecting a total amount of current flowing in a plurality of amplifying elements connected in parallel between a distributor and a combiner, amplifying the signal distributed by the distributor and outputting the amplified signal to the combiner;
Determining whether there is an abnormality in the plurality of amplifying elements based on the total amount of the detected current,
The step of determining the presence or absence of the abnormality includes a step of determining that the plurality of amplifying elements are abnormal when the total amount of the detected current is a value out of the normal current range . Fault detection method. In a failure detection method for a power amplifier that amplifies a digital broadcast signal,
Setting a normal current range based on a threshold for detecting an output abnormality of the power amplifier;
Detecting a total amount of current flowing in a plurality of amplifying elements connected in parallel between a distributor and a combiner, amplifying the signal distributed by the distributor and outputting the amplified signal to the combiner;
Determining whether or not there is an abnormality in the plurality of amplifying elements based on the total amount of the detected current;
Comprising
The step of determining the presence or absence of the abnormality includes a step of determining that the plurality of amplifying elements are abnormal when the total amount of the detected current is a value out of the normal current range . Fault detection method. In the power amplifier failure detection method according to claim 5 or 6 ,
Each of the plurality of amplifying elements amplifies a signal subjected to orthogonal frequency division multiplexing modulation.

Images