JP2016131324A - Electrical characteristics measuring apparatus and measuring system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide electrical characteristics measuring apparatus and measuring system for evaluating the electrical characteristics of an amplifier for use in a broadcast/communication system at the time of modulation wave transmission, by a simple measurement system by non-modulated wave.SOLUTION: An electrical characteristics measuring apparatus includes an amplitude/phase comparator (network analyzer) including a signal generator 11 generating a first signal consisting of a non-modulated wave, and an amplitude/phase measuring unit 12 for measuring the amplitude and phase of an inputted signal, a signal generator 20 generating a second signal, and a synthesizer 30 for synthesizing the first and second signals. Input and output characteristics of a measured device are obtained based on the comparison result of the amplitude and phase for the frequency component of the first signal of output signals from the measured device 90.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electrical characteristic measurement apparatus and measurement system, and more particularly to an apparatus and system for measuring electrical characteristics of an amplifier that amplifies a modulated wave.

  In broadcasting / communication systems, etc., it is required to measure and grasp the electrical characteristics of the amplifier installed in the system in advance, set the optimum operating conditions based on the input / output power characteristics of the amplifier, etc., and perform signal amplification. ing.

  In recent years, in wireless communication systems such as broadcasting and communication, systems that use array antennas have been researched and developed from the viewpoint of effective use of power and effective use of frequency resources. In an array antenna, it is necessary to set and control the phase in order to form a highly accurate radiation pattern. Accordingly, it is also important to obtain input / output phase characteristics for signals actually used in a wireless communication system, that is, modulated waves.

  Until now, the measurement of the electrical characteristics generally used has been to measure the input / output characteristics of the amplifier using unmodulated waves and to measure the harmonic distortion characteristics of the amplifier. (Non-Patent Document 1).

  FIG. 4 shows a measurement system for evaluating input / output characteristics of an amplifier using an amplitude / phase comparator.

  The amplitude / phase comparator 10 includes a signal generation unit 11 and an amplitude / phase measurement unit 12 therein. The signal generator 11 can output a non-modulated wave (CW: continuous wave) with an arbitrary output power, and the amplitude / phase measurement unit 12 can output the non-modulated wave output by the signal generator 11. Using the wave as a reference signal, the amplitude and phase of the input signal are measured and compared. Such an amplitude / phase comparator 10 is generally commercially available as a network analyzer and can be easily obtained.

  At the time of measurement, an unmodulated wave that is an output of the amplitude / phase comparator 10 (signal generation unit 11) is input to an input terminal of an amplifier 90 that is a device to be measured, and the output of the amplifier 90 is an amplitude / phase comparator. 10 (amplitude / phase measurement unit 12). Thereby, the output power and the phase difference with respect to the input power of the amplifier 90 can be measured, and the input / output power characteristics and the input / output phase characteristics of the amplifier 90 when one unmodulated wave is used can be measured.

  In FIG. 4, the output of the amplitude / phase comparator 10 is directly input to the amplifier 90, which is the device under measurement, but power control is performed by interposing a variable attenuator (not shown) between them. May be. Further, a general network analyzer can also measure the reflected power of the device under test and can measure the S parameter of the device under test, etc., but the amplitude / phase comparator 10 in the drawing is detailed. The internal configuration and functions are omitted.

  FIG. 5 shows a measurement system for evaluating the harmonic distortion characteristics of the amplifier 90.

  The measurement system includes a first signal generator 21 that outputs an unmodulated wave having a first frequency, a second signal generator 22 that outputs an unmodulated wave having a second frequency different from the first frequency, and Synthesizer 30 adds (adds) the unmodulated wave of the first frequency and the unmodulated wave of the second frequency, attenuates the output of the synthesizer 30, and controls the input power of the amplifier 90 as the device under measurement The input side is constituted by the variable attenuator 40. The output of the amplifier 90, which is the device under measurement, is input to the spectrum analyzer 50. The spectrum analyzer 50 can measure and display the output power distribution of the amplifier 90 over a certain frequency range.

  Thereby, the output power of intermodulation waves (high-order distortion) such as third-order and fifth-order with respect to input power can be measured using two unmodulated waves, and the harmonic distortion characteristics of the amplifier 90 can be measured.

Takafumi Matsuzaki, Masaru Kamei, et al., “Evaluation of TWTA nonlinear characteristics on satellite for 8K UHDTV satellite broadcasting”, ITE Technical Report Vol.38, No.30, BCT2014-67 (Jul. 2014 ), pp.21-24

  In actual operation of broadcasting / communication systems, etc., data is superimposed on the modulated wave and transmitted, so that the modulated wave is input to and output from the amplifier. Therefore, in the broadcasting / communication system, output power is defined in a transmission signal used in actual operation, that is, a modulated wave.

  Amplifiers used in such broadcasting / communication systems are manufactured, evaluated, and implemented by manufacturers, not broadcasting / communication companies, and their characteristics are generally evaluated using unmodulated waves. Is. However, in a broadcasting / communication satellite system in which the amplifier of the satellite repeater operates at the maximum output power, when the modulated wave is actually transmitted, the amplifier output does not reach the maximum output power evaluated by the manufacturer as the unmodulated wave. There is a situation.

  This is because in an amplifier, there is a difference between the electrical characteristics when a modulated wave is input / output and the electrical characteristics when a non-modulated wave is input / output. In particular, it is known that as the operating point of the amplifier approaches the saturation level, the non-linear characteristic becomes stronger and the difference becomes larger (Non-Patent Document 1).

  The electrical characteristics of the amplifier when an unmodulated wave is input and output can be evaluated with a simple measurement system as shown in FIGS. On the other hand, the electrical characteristics of an amplifier when a modulated wave is input / output needs to be evaluated by a complicated measurement system using equipment corresponding to the actually transmitted modulated wave.

  FIG. 6 is an example of a measurement system for evaluating input / output power characteristics and input / output phase characteristics of an amplifier in a modulated wave. For the amplifier 90 which is a non-measuring device, a large number of devices 61 to 74 for generating and measuring a modulated wave to be transmitted are used.

  The measurement system includes a modulated wave generator 61 that generates a modulated wave, a distributor 62 that distributes the modulated wave in two, a signal generator 63 that generates a high frequency for shifting to a transmission frequency, and a mixed wave and a high frequency. A mixer (up-converter) 64, a filter 65 for removing components other than the transmitted modulated wave, a variable attenuator 66 for controlling the power of the modulated wave (input to the amplifier 90), and an unwanted wave component generated by the nonlinear characteristics of the amplifier 90 A filter 67 for limiting, a power meter 68 for detecting the output power of the amplifier 90, a signal generator 69 for generating a high frequency for returning the signal frequency, a mixer (down converter) 70 for mixing the amplifier output and the high frequency, and the original frequency band A filter 71 that removes the modulated waves other than the above, a phase shifter 72 that shifts the phase, a combiner 73 that synthesizes the input and output modulated waves, Beauty, the power meter 74 for detecting the combiner output, configured.

  An outline of the operation will be described. A modulated wave in the 1 GHz band generated by the modulated wave generator 61 is up-converted by the mixer 64 by a high frequency signal of 9 GHz, for example, generated from the signal generator 63, and only a necessary signal is selected by the filter 65, and the 10 GHz band is selected. It becomes a modulated wave. By controlling the power of this modulated wave with the variable attenuator 66, a modulated wave close to the actual operating condition is input to the amplifier 90 which is a non-measuring device.

  The output of the amplifier 90 is subjected to power measurement by a power meter 68 after limiting unwanted waves by a filter 67. By comparing the output power of the variable attenuator 66 (input of the amplifier 90) and the power measured by the power meter 68, the input / output power characteristics of the amplifier 90 can be measured.

  Further, the output of the amplifier 90 is down-converted by a mixer 70 using, for example, a high frequency signal of 9 GHz generated from the signal generator 69, and only a necessary signal is selected by a filter 71, and returned to a 1 GHz band modulation wave. The modulated wave that has passed through the amplifier 90 is phase-shifted by the phase shifter 72 (0 to 360 degrees), and is synthesized by the synthesizer 73 with the reference modulated wave generated by the modulated wave generator 61. When the power is observed with the power meter 74, the power changes between the peak and the null depending on the degree of phase shift. The phase shift of the two modulated waves is obtained from this change in power, and the input / output phase characteristics of the amplifier 90 can be measured.

  However, designing such a large-scale measurement system in order to obtain the input / output characteristics due to the modulated wave of the amplifier is burdensome, and a simpler measurement system is required.

  Accordingly, an object of the present invention, which has been made in view of the above problems, is to evaluate the electrical characteristics at the time of modulated wave transmission of an amplifier used in a broadcast / communication system, etc., with a simple measurement system using unmodulated waves. It is an object of the present invention to provide an electrical characteristic measuring apparatus and a measuring system that enable the above.

  It is known from experience that the electrical characteristics of an amplifier when a modulated wave is input / output shows the same tendency as the electrical characteristics of the amplifier when a plurality of signals are input / output. Therefore, the present invention compares the amplitude and phase of an output signal with respect to an input signal by using at least one unmodulated wave by two signal generators, and inputs / outputs the amplifier when the modulated wave is input / output. Easily evaluate characteristics.

  In order to solve the above problems, an electrical characteristic measurement apparatus according to the present invention includes a signal generator that generates a first signal composed of an unmodulated wave, an amplitude / phase comparator including an amplitude / phase measurement unit, A signal generator for generating a second signal different from the first signal; and a synthesizer for synthesizing the first signal and the second signal, wherein an output of the synthesizer is input to a device under test. And the output signal of the device under test is input to the amplitude / phase measurement unit, and the amplitude and phase of the frequency component of the first signal of the output signal are measured and compared with the input signal. The input / output characteristics of the device to be measured are obtained.

  The electrical characteristic measuring device preferably further includes a variable attenuator, and the output of the combiner is controlled by the variable attenuator to be an input signal of the device under measurement.

  In the electrical characteristic measuring apparatus, it is preferable that the second signal is an unmodulated wave having a frequency different from that of the first signal.

  In the electrical characteristic measuring apparatus, the device to be measured is an amplifier, and the input / output characteristic is preferably at least one of an input / output power characteristic and an input / output phase characteristic.

  In the electrical characteristic measuring apparatus, the amplitude / phase comparator is preferably a network analyzer.

  In order to solve the above problem, a measurement system according to the present invention combines a first signal composed of an unmodulated wave and a second signal different from the first signal, and An input / output characteristic of the device under test is obtained by comparing the amplitude and phase of the frequency component of the first signal of the output signal of the device under test as an input signal with the amplitude and phase of the input signal. Features.

  In the measurement system, it is preferable that the second signal is an unmodulated wave having a frequency different from that of the first signal.

  In the measurement system, the device to be measured is an amplifier, and the input / output characteristics are preferably at least one of input / output power characteristics and input / output phase characteristics.

  According to the electrical characteristic measuring apparatus and measuring system of the present invention, a simple measurement system using an unmodulated wave without using a modulated wave can be used to measure the electrical characteristics of an amplifier used in a broadcast / communication system at the time of modulated wave transmission. It becomes possible to evaluate with.

  In addition, a simple measurement system that can be prepared by the manufacturer makes it possible to obtain the input / output power characteristics of the amplifier considering the modulation wave transmission in actual operation. Can be used as is for configuration.

  In the present invention, since the input / output phase characteristics of the modulated wave can be obtained by using a plurality of unmodulated waves, the phase in the transmission signal used in actual operation can be easily set and controlled.

It is an example of the electrical property (input / output property of amplifier) measuring device of the present invention. It is a measurement result of the input-output power characteristic of the amplifier by this invention. It is a measurement result of the input-output phase characteristic of the amplifier by this invention. It is an example of a measurement system for evaluating input / output characteristics of an amplifier using a conventional unmodulated wave. It is an example of a measurement system for evaluating high frequency distortion characteristics of an amplifier using a conventional unmodulated wave. It is an example of a measurement system for evaluating input / output characteristics of an amplifier using a modulated wave.

  Embodiments of the present invention will be described below.

(Embodiment)
In FIG. 1, the example of the electrical property measuring apparatus in this invention is shown. The measuring apparatus 100 is an apparatus that evaluates electrical characteristics of an amplifier when a modulated wave is input / output using an unmodulated wave.

  The measuring apparatus 100 includes an amplitude / phase comparator 10, a signal generator 20, and a combiner 30. Furthermore, a variable attenuator 40 may be provided.

  The amplitude / phase comparator 10 includes a signal generation unit 11 and an amplitude / phase measurement unit 12 therein. The signal generator 11 can output a non-modulated wave (CW: continuous wave) with an arbitrary output power, and the amplitude / phase measurement unit 12 can output the non-modulated wave output by the signal generator 11. Using the wave as a reference signal, the amplitude and phase of the input signal are measured and compared. Such an amplitude / phase comparator 10 is generally commercially available as a network analyzer and can be easily obtained.

  The signal generator 20 can generate a signal different from the unmodulated wave output from the signal generator 11 of the amplitude / phase comparator 10 with an arbitrary output. The output signal of the signal generator 20 may be an unmodulated wave or another type of signal wave having an arbitrary waveform. However, in measurement, the frequency generated by the signal generator 11 Are preferably unmodulated waves of different frequencies.

  The synthesizer 30 synthesizes the unmodulated wave output from the signal generator 11 and the signal output from the signal generator 20.

  The variable attenuator 40 attenuates the output of the synthesizer 30 to an arbitrary level and controls the input power to the amplifier 90 that is the device under measurement. Since the signal generator 11 of the amplitude / phase comparator 10 and the signal generator 20 can each be output-controlled, the variable attenuator 40 is not essential. However, the signal generator 11 and the signal generator 20 are controlled so that the signal characteristics are more stable when the output power is not changed, and that the signal generator 11 and the signal generator 20 are simultaneously changed to have the same power. Therefore, it is desirable to control the output of the measuring apparatus 100 using the variable attenuator 40 for reasons such as difficulty in measurement. By using the variable attenuator, the input power to the amplifier 90 can be controlled while the outputs of the amplitude / phase comparator 10 and the signal generator 20 are stabilized, and accurate measurement can be performed.

  Next, an example of the operation of the measuring apparatus 100 will be described.

At the time of measurement, an unmodulated wave (first signal) having the first frequency f ₁ that is the output of the amplitude / phase comparator 10 (signal generator 11) is input to the synthesizer 30 and the signal generator 20 is also used. Thus, for example, an unmodulated wave (second signal) having a second frequency f ₂ different from the _first frequency f ₁ is output and input to the synthesizer 30. Note that the second signal output from the signal generator 20 is not limited to an unmodulated wave, and may be an arbitrary signal.

Here, it is desirable that the first frequency f ₁ and the second frequency f ₂ are close to the modulation wave when the amplifier 90 actually operates. For example, if the amplifier 90 is an amplifier used for satellite broadcasting, both the first frequency f ₁ and the second frequency f ₂ are in the 12 GHz band, and the difference between the two frequencies is 5 to 10 MHz. In addition, the power of the unmodulated wave (first signal) of the signal generator 11 and the power of the unmodulated wave (second signal) of the signal generator 20 can be freely selected. This facilitates correction of input / output power characteristics, which will be described later.

  The synthesizer 30 synthesizes and outputs two unmodulated waves without changing their respective frequencies, and inputs them to the amplifier 90 that is the device under measurement via the variable attenuator 40 as necessary. By using the variable attenuator 40, the output power of the measuring apparatus 100 (the input power of the amplifier 90) can be easily changed in a wide range from a small power to a large power at which the amplifier 90 exhibits nonlinear characteristics.

The amplifier 90 amplifies a combined wave of the unmodulated wave of the first frequency f _{1 and} the unmodulated wave of the second frequency f ₂ , and outputs the output signal to the amplitude / phase of the amplitude / phase comparator (network analyzer) 10. Input to the measurement unit 12.

The amplitude / phase comparator 10 selects the signal component of the first frequency f ₁ from the output signal of the amplifier 90, measures the power and phase, and determines the power and phase of the input signal of the amplifier 90 (in particular, the input signal). (The power and phase of the signal component of the first frequency f ₁ ). When the variable attenuator 40 is used, a power meter (not shown) is provided between the variable attenuator 40 and the amplifier 90 to obtain input power to the amplifier 90, and this is used for amplitude / phase measurement. The input / output power characteristics are obtained by comparison with the power obtained by the unit 12.

Thereby, the input / output power characteristic and the input / output phase characteristic of the amplifier 90 can be measured based on the output of the signal component of the first frequency f ₁ of the amplifier 90. Actually, since the unmodulated wave of the first frequency f _{1 and} the unmodulated wave of the second frequency f ₂ are inputted to the amplifier 90, the input / output power characteristic of the entire amplifier 90 is an amplitude / phase comparison. The characteristic obtained by the vessel 10 is corrected and obtained. For example, if the powers of two unmodulated waves are equal, it can be estimated that the entire amplifier 90 outputs twice as much power (in other words, the input of the first frequency f ₁ is half of the total input power). Therefore, correction is performed to double the input / output power characteristic obtained by the amplitude / phase comparator 10 (increase by 3.01 dB).

The input / output phase characteristic is determined by comparing the non-modulated wave generated by the signal generator 11 with the signal component of the first frequency f ₁ of the output signal of the amplifier 90 in the amplitude / phase comparator 10 to determine the phase difference. Ask. Since the phase characteristic is common to both unmodulated waves, the input / output phase characteristic obtained by the amplitude / phase comparator 10 becomes the phase characteristic of the amplifier 90 as it is.

  By using such a measuring apparatus 100, a first signal composed of an unmodulated wave that is an output of the amplitude / phase comparator 10 (signal generator 11) and a second signal that is an output of the signal generator 20 are used. To the input signal of the amplifier 90 as the device under test, and the amplitude and phase of the frequency component of the first signal of the output signal of the amplifier 90 are measured and compared with the input signal. A system for measuring electrical characteristics (at least one of input / output power characteristics and input / output phase characteristics) can be configured.

  In this way, it is possible to evaluate the input / output characteristics of the amplifier during modulated wave transmission using a plurality of signals including unmodulated waves.

(Measurement result)
2 and 3 show measurement results of input / output characteristics when a traveling wave tube amplifier (TWTA) is used as an amplifier and the present invention is applied.

  In the measurement, a network analyzer is used as the amplitude / phase comparator 10 constituting the measuring apparatus 100, and the signal generator 20 also outputs an unmodulated wave.

  Set the power level of the two unmodulated waves to be input to the amplifier that is the device under test, and output one of the unmodulated waves from the network analyzer, and input the output from the amplifier to the network analyzer. The pass characteristic (S parameter S21) was measured.

  FIG. 2 shows the input / output power characteristics measured by the measuring apparatus according to the present invention, and the input / output power characteristics of the same amplifier (TWTA) measured by one unmodulated wave by the measurement system of FIG.

  First, in the present invention, the result of measurement with the network analyzer (amplitude / phase comparator) 10 is the input / output characteristics indicated by the alternate long and short dash line (denoted as “one wave of two CW waves” in the figure). This characteristic is the output power characteristic of the amplifier for the signal of the frequency component of the network analyzer (signal generation unit 11) with respect to the power of the input signal of the amplifier. Here, since another unmodulated wave of the same power level is input to and output from the amplifier, the total output power of the amplifier is twice as large as the output power measured with one unmodulated wave (3 .01 dB increase). The corrected input / output characteristics are indicated by a solid line (denoted as “CW2 wave synthesis” in the figure).

  Compared with the measurement result of the input / output power characteristics of one unmodulated wave indicated by a broken line (denoted as “CW1 wave” in the figure) in FIG. 2, the input / output power characteristics obtained in the present invention are As the input power increases, the electrical characteristic that the output power decreases is obtained. This phenomenon is the same as the characteristic that the output power of the amplifier decreases when a modulated wave is input and output.

  Maximum output of input / output power characteristics (solid line) obtained by the present invention (relative output 9.79 dB when relative input is 0 dB) and maximum output of input / output power characteristics (dashed line) for one unmodulated wave (relative input) The difference from the relative output of 11.60 dB at 0 dB was 1.81 dB.

  This difference is 1.7 dB which is an actual measurement value of the difference between the maximum output power due to the unmodulated wave and the maximum output power due to the modulated wave in the satellite-mounted TWTA used in Non-Patent Document 1 (in the measurement result of Non-Patent Document 1). This is almost the same as the minimum output back-off (OBO) value that can be amplified.

  From this measurement result, the reliability of the measuring apparatus and measuring system according to the present invention could be confirmed.

  FIG. 3 shows the input / output phase characteristics measured by the measuring apparatus according to the present invention, and the input / output phase characteristics of the same amplifier (TWTA) measured by one unmodulated wave by the measurement system of FIG.

  According to the input / output phase characteristics (solid line, described as “CW2 wave”) obtained in the present invention, the input / output phase difference is 35.1 degrees at 0 dB relative input, whereas the input / output at one unmodulated wave. The phase characteristics (broken line, described as “CW1 wave”) had an input / output phase difference of 30.9 degrees at a relative input of 0 dB, and a phase difference of 4.2 degrees near the maximum output power. By using the input / output phase characteristics of two unmodulated waves obtained in the present invention, in a wireless communication system that synthesizes a plurality of modulated waves using an array antenna or the like, loss at the time of synthesis is reduced and more accurate radiation is achieved. Pattern formation and the like can be realized.

  In the description of the embodiment, the electrical characteristic measuring apparatus and measurement system of the present invention are used for measuring the input / output characteristics of an amplifier. However, the present invention is not limited to input / output of an electronic apparatus other than an amplifier to which a modulated wave signal is input. It can also be used to measure properties.

  Although the above embodiment has been described as a representative example, it will be apparent to those skilled in the art that many changes and substitutions can be made within the spirit and scope of the invention. Therefore, the present invention should not be construed as being limited by the above-described embodiments, and various modifications and changes can be made without departing from the scope of the claims. For example, a plurality of constituent blocks described in the embodiments can be combined into one, or one constituent block can be divided.

10 Amplitude / phase comparator (network analyzer)
DESCRIPTION OF SYMBOLS 11 Signal generator 12 Amplitude / phase measuring part 20, 21, 22 Signal generator 30 Synthesizer 40 Variable attenuator 50 Spectrum analyzer 61 Modulated wave generator 62 Divider 63 Signal generator 64 Mixer (upconverter)
65 Filter 66 Variable Attenuator 67 Filter 68 Power Meter 69 Signal Generator 70 Mixer (Down Converter)
71 Filter 72 Phase shifter 73 Synthesizer 74 Power meter 90 Amplifier (device under test)
100 measuring device

Claims (8)

An amplitude / phase comparator comprising a signal generator for generating a first signal composed of an unmodulated wave, and an amplitude / phase measurement unit;
A signal generator for generating a second signal different from the first signal;
A synthesizer that synthesizes the first signal and the second signal;
The output of the synthesizer is used as an input signal of the device under test, the output signal of the device under test is input to the amplitude / phase measurement unit, and the amplitude of the frequency component of the first signal of the output signal An electrical characteristic measuring device characterized in that a phase is measured and compared with the input signal to obtain an input / output characteristic of the device under measurement.   2. The electrical characteristic measuring apparatus according to claim 1, further comprising a variable attenuator, wherein the output of the synthesizer is controlled by the variable attenuator and used as an input signal of the device under measurement. apparatus.   3. The electrical characteristic measuring apparatus according to claim 1, wherein the second signal is an unmodulated wave having a frequency different from that of the first signal.   4. The electrical characteristic measuring apparatus according to claim 1, wherein the device under measurement is an amplifier, and the input / output characteristics are at least one of input / output power characteristics and input / output phase characteristics. A characteristic electrical property measuring device.   5. The electrical characteristic measuring apparatus according to claim 1, wherein the amplitude / phase comparator is configured by a network analyzer. 6.   A first signal composed of an unmodulated wave and a second signal different from the first signal are combined to be an input signal of the device under test, and the first signal of the output signal of the device under test A measurement system characterized in that an input / output characteristic of the device under test is obtained by comparing the amplitude and phase of the frequency component of the input signal with the amplitude and phase of the input signal.   The measurement system according to claim 6, wherein the second signal is an unmodulated wave having a frequency different from that of the first signal.   8. The measurement system according to claim 6, wherein the device under measurement is an amplifier, and the input / output characteristic is at least one of an input / output power characteristic and an input / output phase characteristic.

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