Power amplifier evaluation method and measurement system

Abstract

The present invention provides a power amplifier evaluation method and a measurement system for measuring the characteristics of a power amplifier, which can shorten the measurement time. A high-frequency signal with a constant amplitude is modulated by a digital modulation signal to generate a high-frequency input signal with a step-like amplitude change. The high-frequency input signal is input to a power amplifier to be evaluated. The period during which the amplitude of the high-frequency input signal is constant is set as a measurement period, and the output signal from the power amplifier is measured in a plurality of measurement periods during which the amplitude of the high-frequency input signal is different.

Description

Technical Field

[0001] The present invention relates to a power amplifier evaluation method and a measurement system for measuring characteristics of a power amplifier. Background Art

[0002] As a technology for improving the power added efficiency of a power amplifier, a power amplifier using envelope tracking (ET) technology is known (for example, Patent Document 1). In order to evaluate the characteristics of a power amplifier operating in an ET manner, the power of a high-frequency input signal is scanned for a plurality of power supply voltages, and the high-frequency input signal, high-frequency output signal, power supply voltage, power supply current, etc. are measured. In addition, even in the evaluation of the characteristics of a power amplifier using average power tracking (APT) technology, the power of the high-frequency input signal is scanned and measured.

[0003] Prior Art Literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application No. 2015-511802 Summary of the invention

[0006] Problems to be solved by the invention

[0007] When evaluating the characteristics of a power amplifier, the power of a high frequency input signal is swept at each measurement point with a fixed power supply voltage, which increases the measurement time. The present invention aims to provide a power amplifier evaluation method and a measurement system that can shorten the measurement time.

[0008] Technical solutions to solve problems

[0009] According to one aspect of the present invention, a power amplifier evaluation method is provided, wherein:

[0010] A high-frequency signal with constant amplitude is modulated by a digital modulation signal to generate a high-frequency input signal with a step-like amplitude change.

[0011] The high frequency input signal is input to the power amplifier of the evaluation object,

[0012] A period during which the amplitude of the high-frequency input signal is constant is set as a measurement period, and an output signal from the power amplifier is measured in each of a plurality of measurement periods during which the amplitude of the high-frequency input signal is different.

[0013] According to another aspect of the present invention, there is provided a measurement system comprising:

[0014] An input signal generator modulates a high-frequency signal with a constant amplitude with a digital modulation signal to generate a high-frequency input signal with a step-like amplitude change, and inputs the high-frequency input signal to a power amplifier of an evaluation object;

[0015] A power supply for supplying a power supply voltage to the power amplifier;

[0016] a waveform measuring device for measuring waveforms of voltage and current supplied from the power supply to the power amplifier; and

[0017] The vector signal analyzer measures the power and phase of the output signal from the power amplifier.

[0018] Effects of the Invention

[0019] By changing the amplitude of the high-frequency input signal in steps, the characteristics of the power amplifier can be measured under various output power conditions. In addition, by modulating a high-frequency signal with a constant amplitude with a digital modulation signal to generate a high-frequency input signal, the measurement time can be shortened compared to a method of changing the amplitude by scanning the oscillation amplitude of an oscillator. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a block diagram of the measurement system according to the first embodiment.

[0021] Figure 2 : is a graph showing an example of the waveforms of the digital modulation signal DMS and the envelope signal Env.

[0022] Figure 3 The diagram shows a combination of pulses of the digital modulation signal DMS and pulses of the envelope signal Env using square grids.

[0023] Figure 4A , Figure 4B ,as well as Figure 4C The graphs respectively show the gain characteristic, the phase characteristic, and the power added efficiency characteristic of the power amplifier measured using the measurement system according to the first embodiment.

[0024] Figure 5A as well as Figure 5B Each of them is a graph showing a waveform of a digital modulation signal DMS used in a measurement system according to a modified example of the first embodiment.

[0025] Fig. 6A as well as Figure 6B The graphs respectively show the waveforms of the digital modulation signal DMS and the envelope signal Env used in the measurement system according to still another modified example of the first embodiment.

[0026] Figure 7This is a block diagram of a measurement system according to the second embodiment.

[0027] Description of Reference Numerals

[0028] 10: Input signal generator;

[0029] 11: Oscillator;

[0030] 12: Modulation signal generator;

[0031] 13: Modulator;

[0032] 20: Envelope signal generator;

[0033] 25: Power supply;

[0034] 30: Waveform measuring device;

[0035] 35: Vector signal analyzer;

[0036] 50: power amplifier;

[0037] DMS: digital modulation signal;

[0038] Env: envelope signal;

[0039] Icc: power supply current;

[0040] RFC: high frequency signal;

[0041] RFin: high frequency input signal;

[0042] RFout: high frequency output signal;

[0043] Vcc: power supply voltage. DETAILED DESCRIPTION

[0044] [First embodiment]

[0045] Reference Figures 1 to 4C The power amplifier evaluation method and measurement system based on the first embodiment are described with reference to the accompanying drawings.

[0046] Figure 1 The block diagram of the measurement system according to the first embodiment. The measurement system according to the first embodiment includes an input signal generator 10, an envelope signal generator 20, a power supply 25, a waveform measurement device 30, and a vector signal analyzer 35. The high-frequency input signal RFin output from the input signal generator 10 is input to the power amplifier 50 of the evaluation object. Figure 1 , an example of the waveform of the high-frequency input signal RFin is shown. Similarly, examples of the waveforms of other signals are also shown.

[0047] The input signal generator 10 includes an oscillator 11, a modulation signal generator 12, and a modulator 13. The oscillator 11 generates a high-frequency signal RFC with a constant frequency and amplitude. The modulation signal generator 12 generates a digital modulation signal DMS. The digital modulation signal DMS is composed of a plurality of pulses arranged intermittently on the time axis, for example, a plurality of pulses arranged periodically on the time axis, and each of the plurality of pulses has a peak value corresponding to any one of a plurality of pre-set evaluation levels.

[0048] The plurality of evaluation levels include a level higher than the reference level, a level lower than the reference level, and a level equal to the reference level. When the evaluation level is equal to the reference level, although a pulse waveform does not appear in the digital modulation signal DMS, it can be considered that the digital modulation signal DMS has a pulse whose peak value corresponds to the following level, which is the same as the reference level. The modulator 13 changes the amplitude of the high-frequency signal RFC through the digital modulation signal DMS to generate a high-frequency input signal RFin whose amplitude changes in a step-like manner.

[0049] The envelope signal generator 20 generates an envelope signal Env. For example, an arbitrary waveform generator (AWG) can be used as the envelope signal generator 20. The envelope signal Env is composed of a plurality of pulses intermittently arranged on the time axis, for example, a plurality of pulses periodically arranged on the time axis, similarly to the digital modulation signal DMS, and each of the plurality of pulses has a peak value corresponding to any one of a plurality of pre-set evaluation levels.

[0050] The power supply 25 changes the power supply voltage Vcc supplied to the power amplifier 50 based on the envelope signal Env. The power supply 25 can include a DC power supply and a power modulator. The power modulator changes (modulates) the constant voltage output from the DC power supply by the envelope signal Env. The output voltage of the power modulator is supplied to the power amplifier 50.

[0051] The waveform measuring device 30 measures the waveforms (time changes) of the power supply voltage Vcc and the power supply current Icc supplied from the power supply 25 to the power amplifier 50. As the waveform measuring device 30, for example, an oscilloscope, a synchronous oscilloscope, etc. can be used. Based on the voltage waveform and the current waveform measured by the waveform measuring device 30, the instantaneous value of the power supplied to the power amplifier 50 can be obtained.

[0052] The vector signal analyzer 35 measures the power and phase of the high frequency output signal RFout output from the power amplifier 50. As a phase reference, the high frequency signal RFC generated by the oscillator 11 of the input signal generator 10 is used. That is, the vector signal analyzer 35 measures the amount of change in the phase of the high frequency output signal RFout relative to the high frequency signal RFC.

[0053] Figure 2 : is a graph showing an example of the waveform of the digital modulation signal DMS and the envelope signal Env. The upper graph shows the waveform of the digital modulation signal DMS, and the lower graph shows the waveform of the envelope signal Env. The horizontal axis of the upper and lower graphs represents time, with a unit of "μs". The vertical axis of the upper graph represents the power (high-frequency input power) Pin of the high-frequency input signal RFin modulated by the digital modulation signal DMS, with a unit of "dBm". The vertical axis of the lower graph represents the power supply voltage Vcc supplied to the power amplifier 50, with a unit of "V".

[0054] The digital modulation signal DMS includes 11 pulses from M1 to M11 during each of a plurality of cycles Cm(i). Here, i is a positive integer indicating the order of the cycles. The peak values ​​of the 11 pulses from M1 to M11 within one cycle Cm(i) are all different. The level of the high-frequency input power Pin varies according to the peak values ​​of the pulses from M1 to M11. For example, the value of the high-frequency input power Pin is distributed at intervals of 2.5 dBm between -15 dBm and +10 dBm. The peak values ​​of the pulses from M1 to M11 are the same between a plurality of cycles Cm(i). The reference power level of the high-frequency input power Pin is set to 0 dBm, and the high-frequency input power Pin during a period when no pulses of the digital modulation signal DMS appear is 0 dBm.

[0055] The envelope signal Env includes 10 pulses E1 to E10 during each of a plurality of cycles Cv(j). Here, j is a positive integer indicating the order of the cycles. The peak values ​​of the 10 pulses E1 to E10 in one cycle Cv(j) are all different. The level of the power supply voltage Vcc varies according to the peak values ​​of the pulses E1 to E10. For example, the value of the power supply voltage Vcc is distributed at intervals of 0.5V between 0V and 5V. The peak values ​​of the pulses E1 to E10 are the same between a plurality of cycles Cv(j). The reference voltage level of the power supply voltage Vcc is set to 2.5V, and the power supply voltage Vcc is 2.5V during the period when no pulses appear in the envelope signal Env.

[0056] The repetition period of the pulses of the digital modulation signal DMS (the time interval width of the output pulses) is the same as the repetition period of the pulses of the envelope signal Env, for example, 2 μs. Therefore, on the time axis, the multiple pulses of the digital modulation signal DMS and the multiple pulses of the envelope signal Env correspond one-to-one. The timing of the digital modulation signal DMS and the envelope signal Env is adjusted so that the high-frequency input signal RFin and the power supply voltage Vcc modulated by the corresponding pulses of the digital modulation signal DMS and the envelope signal Env are simultaneously supplied to the power amplifier 50. The duty cycle is, for example, 1 / 2, where the duty cycle is the ratio of the pulse width to the repetition period of the pulse. The period in which the pulse is generated is called the "measurement period", and the other periods are called the "non-measurement period".

[0057] The total time of the 10-cycle repetition of Cm(1) to Cm(10) of the digital modulation signal DMS and the total time of the 11-cycle repetition of Cv(1) to Cv(11) of the envelope signal Env are equal to 220 μs. Within the total time of the 10-cycle repetition of Cm(1) to Cm(10) of the digital modulation signal DMS, all combinations of the 11 pulses M1 to M11 and the 10 pulses E1 to E10 appear, that is, 110 combinations.

[0058] Figure 3 The diagram shows a combination of pulses of the digital modulation signal DMS and pulses of the envelope signal Env using square grids. Figure 3 The rows of the square grid correspond to the 11 pulses M1 to M11 of the digital modulation signal DMS, respectively. That is, each of the rows corresponds to the level of the high-frequency input power Pin in one measurement period (hereinafter referred to as the evaluation power level). Figure 3 The plurality of columns of the square grid correspond to the ten pulses E1 to E10 of the envelope signal Env, respectively. That is, each of the plurality of columns corresponds to one level of the power supply voltage Vcc (hereinafter referred to as an evaluation voltage level).

[0059] The multiple grid points of the square grid correspond to the combination of the evaluation power level and the evaluation voltage level in one measurement period. It can be seen that all the combinations of 11 evaluation power levels and 10 evaluation voltage levels appear. In addition, the number of evaluation power levels and the number of evaluation voltage levels are not limited to 10 and 11, respectively. Figure 2 ) contains a number of pulses other than 11, and a cycle Cv(j)( Figure 2 ) is set to a plurality of pulses other than 10. That is, all combinations of a plurality of evaluation power levels and a plurality of evaluation voltage levels may be measured.

[0060] Figure 4A , Figure 4B ,as well as Figure 4C The graphs respectively show the gain characteristic, the phase characteristic, and the power added efficiency characteristic of the power amplifier 50 measured using the measurement system according to the first embodiment. Figure 4A , Figure 4B , Figure 4C The horizontal axis represents the power (output power) of the high-frequency output signal RFout, and one scale corresponds to 5dBm. Figure 4A The vertical axis represents gain, with one scale equal to 1 dB. Figure 4B The vertical axis represents the phase, with one scale equal to 5°. Figure 4C The vertical axis represents power added efficiency, with one scale equal to 10%.

[0061] The gain can be obtained from the measured values ​​of the power of the high-frequency output signal RFout and the power of the high-frequency input signal RFin in each measurement period. The power of the high-frequency output signal RFout is measured in each measurement period by the vector signal analyzer 35. The power of the high-frequency input signal RFin can be calculated in each measurement period based on the output power of the oscillator 11 and the peak value of the pulse of the digital modulation signal DMS.

[0062] The phase is obtained by the vector signal analyzer 35 detecting the phase of the high-frequency output signal RFout in each measurement period, using the phase of the high-frequency signal RFC output from the oscillator 11 as a reference.

[0063] The power added efficiency can be obtained based on the magnitude of the DC power supplied to the power amplifier 50, the power of the high-frequency output signal RFout, and the measured values ​​of the power of the high-frequency input signal RFin in each measurement period. The magnitude of the DC power can be calculated based on the instantaneous values ​​of the voltage waveform of the power supply voltage Vcc and the current waveform of the power supply current Icc measured by the waveform measuring device 30.

[0064] exist Figure 4A , Figure 4B ,as well as Figure 4C The numerical values ​​marked on the four curves of the graph represent the power supply voltage Vcc. In addition, in the measurement, the evaluation power level was set at 80 levels in the range of -15dBm to +10dBm at an interval of approximately 0.32dB. The evaluation voltage level was set at 81 levels in the range of 0.5V to 4.5V at an interval of 0.05V. Figure 4A , Figure 4B ,as well as Figure 4C , only four measurement results when the power supply voltage Vcc is 1 V, 2 V, 3 V, and 4 V among the 81 evaluation voltage levels are shown.

[0065] The frequency of the high frequency signal RFC is set to 1.950 GHz. The repetition period of the pulses of the digital modulation signal DMS and the envelope signal Env is set to 8 μs. The number of combinations of 80 evaluation power levels and 81 evaluation voltage levels is 6480, so all combinations can be measured in 51.8 ms.

[0066] Next, the excellent effects of the first embodiment will be described.

[0067] In the first embodiment, the power amplifier 50 ( Figure 1 ) is measured by setting the power supply voltage Vcc to a plurality of evaluation voltage levels. Figure 4A , Figure 4B , Figure 4C As shown, the gain characteristic, phase characteristic, and power added efficiency characteristic can be measured under a plurality of conditions with different magnitudes of the power supply voltage Vcc. Based on these measurement results, the power supply voltage condition that maximizes the power added efficiency when the power amplifier 50 is operated in an envelope tracking manner can be found. Furthermore, the power supply voltage condition that optimizes the gain characteristic and the phase characteristic can be found.

[0068] In the first embodiment, the high frequency signal RFC with a constant amplitude is modulated by the digital modulation signal DMS, thereby making the signal sent to the power amplifier 50 ( Figure 1 ) is used to measure the power change of the high-frequency input signal RFin. Compared with the conventional method of changing the power of the high-frequency input signal to the power amplifier by scanning the oscillation amplitude based on the oscillator, this method can change the power of the high-frequency input signal quickly. Therefore, the time required for measurement can be shortened.

[0069] Furthermore, in the first embodiment, the digital modulation signal DMS ( Figure 2 ) and the envelope signal Env( Figure 2 ) during the period other than the measurement period of the generated pulse (non-measurement period), the high-frequency input power Pin is set to the reference power level, and the power supply voltage Vcc is set to the reference voltage level. It is preferable to set the reference power level and the reference voltage level to be substantially equal to the average input power and the average voltage during the actual operation of the power amplifier 50. At this time, the temperature rise caused by the self-heating of the power amplifier 50 during the measurement can be made close to the temperature rise caused by the self-heating during the actual operation. As a result, the temperature conditions during the measurement can be made close to the temperature conditions during the actual operation.

[0070] Next, refer to FIG. 5A to FIG. 6B The accompanying drawings illustrate a measurement system based on a modified example of the first embodiment.

[0071] Figure 5A1 is a graph showing the waveform of a digital modulation signal DMS used in a measurement system based on a modified example. The pulse repetition period is marked as TC, and the pulse width is marked as PW. Although the duty ratio PW / TC is set to 1 / 2 in the first embodiment, it can also be set to a value other than 1 / 2. Figure 5A In the modification shown, the duty ratio PW / TC is set to 1 / 8. For example, the pulse width PW is 1 μs, and the pulse repetition period TC is 8 μs. Therefore, the duration of the non-measurement period in one cycle is 7 μs.

[0072] picture Figure 5A If the duty cycle is reduced, the proportion of the non-measurement period on the time axis becomes larger, as in the modification of . As a result, the ratio of the period in which the high-frequency input power Pin is set to the reference power level and the power supply voltage Vcc is set to the reference voltage level becomes larger. As a result, the temperature rise caused by self-heating in the measurement can be made closer to the temperature rise caused by self-heating in the actual operation. In order to make the temperature conditions in the measurement close to the temperature conditions in the actual operation, it is preferable to set the duty cycle to less than 1 / 2.

[0073] Figure 5B is a graph showing the waveform of a digital modulation signal DMS used in a measurement system based on another modified example. In this modified example, the repetition period TC of the pulse is equal to the pulse width PW. That is, the duty ratio PW / TC is 1. Therefore, on the time axis, there is no non-measurement period between two adjacent measurement periods.

[0074] picture Figure 5B As in the modification of the embodiment of the present invention, even if the duty ratio PW / TC is set to 1, the characteristics of the power amplifier 50 can be measured. In this modification, since there is no non-measurement period, the time required for measurement can be shortened. In addition, since there is no non-measurement period in which the high-frequency input power Pin is set to the reference power level and the power supply voltage Vcc is set to the reference voltage level, this modification is disadvantageous compared to the first embodiment from the viewpoint of making the temperature condition during measurement close to the temperature condition during actual operation.

[0075] In this modification, the order of occurrence of the pulses is adjusted so that the digital modulation signal DMS has one cycle Cm(i) ( Figure 2 ) is centered on the average value of the peak values ​​of multiple pulses in the time axis, and the peak value of one of the two adjacent pulses on the time axis is set below the average value, and the peak value of the other pulse is set above the average value. By adjusting the order of appearance of the pulses in this way, the temperature rise caused by the self-heating in the measurement can be balanced in time.

[0076] Fig. 6A1 is a graph showing waveforms of a digital modulation signal DMS and an envelope signal Env used in a measurement system according to another modified example. In the first embodiment, the pulse width of the digital modulation signal DMS is the same as the pulse width of the envelope signal Env. In contrast, in this modified example, the pulse width PWM of the digital modulation signal DMS is longer than the pulse width PWE of the envelope signal Env. The pulse repetition period TC is the same in the digital modulation signal DMS and the envelope signal Env.

[0077] On the time axis, the pulse of the envelope signal Env is included in the pulse of the digital modulation signal DMS. In addition, the comparison of the timing of the pulse of the envelope signal Env and the pulse of the digital modulation signal DMS is not based on the modulation signal generator 12 ( Figure 1 ) output time point, and from the envelope signal generator 20 ( Figure 1 ) is used as the reference not on the output time point of the power amplifier 50, but on the input time point to the power amplifier 50.

[0078] exist Fig. 6A In the modified example shown, the period within the pulse width range of the envelope signal Env is the measurement period Tmes. The characteristics of the power amplifier 50 are obtained based on the measured values ​​of the power of the high frequency output signal RFout, the power supply voltage Vcc, and the power supply current Icc in the measurement period Tmes.

[0079] In addition, although Fig. 6A In the modified example shown, the pulse width PWM of the digital modulation signal DMS is made longer than the pulse width PWE of the envelope signal Env, but conversely, the pulse width PWE of the envelope signal Env may be made longer than the pulse width PWM of the digital modulation signal DMS. In this case, it is sufficient to make the pulse of the digital modulation signal DMS included in the pulse of the envelope signal Env on the time axis.

[0080] Figure 6B Graphs showing waveforms of a digital modulation signal DMS and an envelope signal Env used in a measurement system according to yet another modified example. Fig. 6A In the variation shown in FIG. 1 , on the time axis, one of the pulses of the digital modulation signal DMS and the pulses of the envelope signal Env is included in the other. Figure 6B In the variation shown, a portion of the pulse of the digital modulation signal DMS overlaps a portion of the pulse of the envelope signal Env on the time axis. The magnitude relationship between the pulse width PWM of the digital modulation signal DMS and the pulse width PWE of the envelope signal Env is arbitrary. The period during which the pulses of the two overlap is the measurement period Tmes.

[0081] Even if like Fig. 6A as well as Figure 6B As in the modified example shown, the pulse width PWM of the digital modulation signal DMS and the pulse width PWE of the envelope signal Env are not made the same, and as in the first embodiment, the measurement time can be shortened and the temperature condition during measurement can be made close to the temperature condition during actual operation.

[0082] [Second embodiment]

[0083] Next, refer to Figure 7 A power amplifier evaluation method and a measurement system according to the second embodiment will be described. Figures 1 to 4C The common structure of the power amplifier evaluation method and measurement system according to the first embodiment shown in the figure is omitted.

[0084] Figure 7 This is a block diagram of a measurement system based on the second embodiment. In the first embodiment, the power supply 25 ( Figure 1 ) The power supply voltage Vcc supplied to the power amplifier 50 is changed based on the envelope signal Env, but in the second embodiment, the power supply 25 supplies a fixed constant power supply voltage Vcc to the power amplifier 50. Since the power supply voltage Vcc is constant, the waveform measuring device 30 does not need to measure the waveform of the power supply voltage Vcc but measures the waveform of the power supply current Icc.

[0085] In the second embodiment, the gain, phase, and power added efficiency are measured under the condition that the power supply voltage Vcc is constant.

[0086] Next, the excellent effect of the second embodiment is described. In the second embodiment, the high-frequency input signal RFin is generated by modulating the high-frequency signal RFC with a constant amplitude, so the measurement time can be shortened as in the first embodiment. Furthermore, by setting the duty cycle of the digital modulation signal DMS to less than 1 and setting a non-measurement period, the temperature condition during measurement can be made close to the temperature condition during actual operation as in the first embodiment. The measurement system based on the second embodiment can be used to evaluate the characteristics of the power amplifier 50 operating in the average power tracking (APT) mode.

[0087] The above-mentioned embodiments are for illustration only, and it is self-evident that partial replacement or combination of the structures shown in different embodiments can be performed. The same effects based on the same structure of multiple embodiments will not be mentioned one by one in each embodiment. Furthermore, the present invention is not limited to the above-mentioned embodiments. For example, various changes, improvements, combinations, etc. can be performed, which is obvious to those skilled in the art.

Claims

1. A method for evaluating a power amplifier, wherein: A high-frequency signal with constant amplitude is modulated by a digital modulation signal to generate a high-frequency input signal with a step-like amplitude change. The high frequency input signal is input to the power amplifier of the evaluation object, A period during which the amplitude of the high-frequency input signal is constant is set as a measurement period, and a high-frequency output signal from the power amplifier is measured in each of a plurality of measurement periods during which the amplitude of the high-frequency input signal is different. Two adjacent measurement periods are separated by a non-measurement period during which the high-frequency output signal is not measured.

2. The power amplifier evaluation method according to claim 1, wherein: In at least one of the non-measurement periods, the power of the high-frequency input signal is set to a constant reference power level, and in at least the non-measurement period, the power supply voltage supplied to the power amplifier is set to a constant reference voltage level.

3. The power amplifier evaluation method according to claim 1 or 2, wherein: The power supply voltage supplied to the power amplifier is made different corresponding to each of the plurality of measurement periods.

4. The power amplifier evaluation method according to claim 3, wherein: The power of the high-frequency input signal in each of the multiple measurement periods is set to an evaluation power level, the magnitude of the power supply voltage in each of the multiple measurement periods is set to an evaluation voltage level, and the high-frequency output signal from the power amplifier is measured using all combinations of the multiple evaluation power levels and the multiple evaluation voltage levels.

5. The power amplifier evaluation method according to claim 1 or 2, wherein: Furthermore, waveforms of a power supply voltage and a power supply current supplied to the power amplifier are measured, and characteristics of the power amplifier are obtained based on the measured values ​​of the power supply voltage and the power supply current and the measured value of the high-frequency output signal of the power amplifier.

6. The power amplifier evaluation method according to claim 1 or 2, wherein: The phase of the high-frequency output signal from the power amplifier is measured using the phase of the high-frequency signal before being modulated by the digital modulation signal as a reference.

7. The power amplifier evaluation method according to claim 1, wherein: The duty cycle of the digital modulation signal is less than 1 / 2.

8. A measurement system comprising: An input signal generator modulates a high-frequency signal with a constant amplitude with a digital modulation signal to generate a high-frequency input signal with a step-like amplitude change, and inputs the high-frequency input signal to a power amplifier of an evaluation object; A power supply for supplying a power supply voltage to the power amplifier; a waveform measuring device for measuring the waveforms of the voltage and current supplied from the power supply to the power amplifier; as well as The vector signal analyzer measures the power and phase of the output signal from the power amplifier during a plurality of measurement periods. Two adjacent measurement periods are separated by a non-measurement period during which the output signal is not measured.

9. The measuring system according to claim 8, wherein: It also has an envelope signal generator, which provides an envelope signal with a step-like voltage level change to the power supply. The power supply changes a voltage supplied to the power amplifier according to the envelope signal provided from the envelope signal generator.

10. The measuring system according to claim 8, wherein The duty cycle of the digital modulation signal is less than 1 / 2.

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