JP7307449B2 - Active load pull measurement system - Google Patents

Description

The present invention relates to an active load pull measurement system suitable as a design technique for power amplifiers (microwave power amplifiers) used in the microwave region.

In order to obtain maximum output power (or maximum efficiency) in transistor-based microwave power amplifiers, it is common practice to design circuits using load-pull measurement systems. Usually, the maximum output (or maximum efficiency) of a transistor is obtained when it is operated in a non-linear region (for example, a region where the output approaches saturation) where it cannot be treated as a linear device. Therefore, it is necessary to measure with a load pull measurement system at the actual input signal level and design the optimum load impedance for the fundamental wave and harmonics. A commonly used load pull measurement system is a passive load pull that changes the load impedance by installing a mechanical passive tuner on the line connected to the output end of a DUT (device under test) such as a transistor. measurement system.

A passive load-pull measurement system changes the amplitude and phase of a reflected wave by mechanically (physically) changing the position of a probe that causes reflection close to a line in a passive tuner. However, since the loss due to the passive tuner is large, it is difficult to form a large reflected _wave load impedance for the DUT. be. In addition, since the phase of the reflected wave is changed by changing the position of the probe, changing the phase by 360 degrees increases the size of the device and takes time for measurement. can't

An active load-pull measurement system has been proposed to solve these problems. In the active load pull measurement system, as shown in FIG. 8 (and FIG. 10), the reference input signal is adjusted by the variable attenuator 141 (or 241) and the variable phase shifter 142 (or 242), and the adjusted The signal is amplified by an auxiliary amplifier 143 (or 243) to form a pseudo-reflected wave, which is injected into the output of the DUT via a circulator 144 (or 244). An output signal (output wave) from the DUT is absorbed by the terminating resistor 145 (or 245) via the circulator 144 (or 244). Since the active load pull measurement system controls the amplitude and phase of the pseudo-reflected wave with the variable attenuator 141 (or 241) and the variable phase shifter 142 (or 242), theoretically, the load impedance of the entire Smith chart can be electronically (without mechanical (physical) control).

Also, the active load pull measurement system can be configured using a network analyzer 6, a directional coupler 7, a bias T circuit 8, etc., as shown in FIG. 8 (and FIG. 10). A directional coupler 7 connected to the output terminal of the DUT extracts a signal (output wave) from the DUT to the load and a signal (reflected wave) from the load to the DUT on the line, and measures them with a network analyzer 6. By taking the ratio of , the reflection coefficient Γ _L of the load viewed from the DUT, that is, the load impedance can be obtained. Therefore, it is possible to observe the load impedance (reflection coefficient Γ _L ) in real time.

Conventional active load pull measurement systems are generally categorized into open loop and closed loop types. The open-loop type active load pull measurement system 101 uses a signal from an external signal source SG as shown in FIG. It uses the signal from the source. On the other hand, as shown in FIG. 10, the closed-loop active load pull measurement system 201 extracts (takes out) a portion of the DUT output signal via an extractor (directional coupler or circulator) 240 to obtain a reference signal. It is used for the input signal that becomes

An advantage of the open-loop type is that it has fewer components than the closed-loop type. Also, the specifications required for the auxiliary amplifier 143 that generates the pseudo-reflected wave are relatively simple hardware configuration because a general amplifier with high versatility equivalent to the maximum output power of the DUT can be used. It is feasible with In addition, the system operates stably. On the other hand, in the closed-loop type, the intensity of the injected pseudo-reflected wave follows changes in the output power. It is possible to measure the reflection coefficient _ΓL while drawing a circular curve close to a contour map.

In addition, in Patent Document 1, in addition to almost the same configuration as the open loop type active load pull measurement system shown in FIG. 8 of the present application, a discloses a configuration in which a transformer is provided between them. FIG. 1 of Patent Document 2 discloses a system whose basic configuration is almost the same as the open loop type active load pull measurement system shown in FIG. 8 of the present application. discloses a closed-loop type active load pull measurement system having substantially the same basic configuration as that shown in FIG. 10 of the present application. Further, FIG. 1 of Patent Document 3 discloses a system whose basic configuration is almost the same as the open-loop type active load pull measurement system shown in FIG. 8 of the present application. In addition to the basic configuration substantially similar to the open loop type active load pull measurement system shown in FIG. 8 of the present application, the figure shows a , with a passive tuner between them similar to that of the passive load pull measurement system described above.

JP 2004-271186 A Japanese Patent Publication No. 2006-528769 U.S. Pat. No. 9,213,056

However, both conventional open-loop and closed-loop active load pull measurement systems have problems in practical use as described below.

In the open-loop active load pull measurement system shown in FIG. 8, the amplitude of the spurious reflected wave injected into the DUT is injected independently of the amplitude of the output wave of the DUT. When the reflection coefficient Γ _L of the load is small, that is, when the amplitude of the injected pseudo-reflected wave is small, the phase change of the injected pseudo-reflected wave (phase change with constant amplitude) results in the reflection coefficient Γ Variation of _L is small. On the other hand, when the reflection coefficient Γ _L of the load is large, that is, when the amplitude of the injected pseudo-reflected wave is made as large as the output wave of the DUT, the reflection coefficient Γ _L greatly changes as shown in FIG. Situations in which the magnitude of Γ _L exceeds unity can also occur.

Therefore, in an open-loop active load-pull measurement system, to measure the entire Smith chart, the amplitude and phase must be set in small steps and measurements must be made at the combined points. Also, it is necessary that the magnitude of the reflection coefficient Γ _L does not exceed 1 so as not to damage the DUT. Therefore, the open-loop type active load pull measuring system is complicated to control the system. This problem is basically considered to be the same in the open-loop type active load pull measurement systems disclosed in Patent Documents 1 to 3 as well. In addition, in Patent Document 3, since the passive tuner is provided, the same problem as the passive load pull measurement system, such as an increase in the size of the device, remains.

On the other hand, a problem with the closed-loop active load-pull measurement system is that it is difficult to measure a region where the reflection coefficient _ΓL is large in practical use, as described below.

FIG. 11 shows the reflection coefficient Γ _L measured by changing the set value of the variable attenuator 241 in an experiment conducted by the inventors of the closed-loop active load-pull measurement system. The change in the reflection coefficient Γ _L in FIG. 11 is significantly different from the change in the reflection coefficient Γ _L in the open-loop active load-pull measurement system shown in FIG. , and by changing the amplitude, a circular curve close to a contour map is drawn. Here, the maximum size of the reflection coefficient _ΓL that can actually be realized is about 0.6, which is the limit. When the loop gain is increased by decreasing the attenuation of the variable attenuator 241 in an attempt to bring the reflection coefficient _ΓL closer to the periphery of the Smith chart, where the magnitude of the reflection coefficient _ΓL is close to 1, the loop system oscillates. Therefore, no further measurements are possible.

In Japanese Patent Application No. 2018-230466 previously filed by the inventor of the present application, both an open loop circuit unit corresponding to an open loop type active load pull measurement system and a closed loop circuit unit corresponding to a closed loop type active load pull measurement system are disclosed. We have proposed an active load-pull measurement system that can stably measure the reflection coefficient _ΓL in the entire region within 1 and that can be simplified and reduced in cost. Apart from the proposal, the inventor of the present application has based on the idea of using the output signal of the DUT in the closed-loop active load-pull measurement system and the idea of the basic configuration of the open-loop active load-pull measurement system. The inventors have researched an active load-pull measurement system that can stably measure in the entire range in which the magnitude of the coefficient _ΓL is 1 or less, and that can be simplified and reduced in cost, and devised the present invention.

The present invention has been made in view of such a reason, and its object is to be able to measure stably in all regions where the magnitude of the reflection coefficient _ΓL is 1 or less, and to simplify and reduce the cost as a system. To provide a possible active load pull measurement system.

In order to achieve the above object, the active load pull measurement system according to claim 1 comprises an oscillator, a phase synchronization section for phase-synchronizing the oscillator with an output signal of a device under test, and a pseudo reflected wave for generating the a pseudo-reflected wave injection section for injecting into a device under test; and a system control section, wherein the system control section controls the phase of the output signal of the oscillator using a variable phase shifter, The pseudo-reflected wave is generated by controlling the amplitude with a variable attenuator .

The active load pull measurement system according to claim 2 is the active load pull measurement system according to claim 1, wherein the oscillator is a voltage controlled oscillator, and the phase synchronization unit is an output signal of the device under test. and a phase comparator for comparing the phase of the output signal of the oscillator, and a loop filter for smoothing the output of the phase comparator and controlling the oscillator.

The active load pull measurement system according to claim 3 is the active load pull measurement system according to claim 2, wherein the phase synchronization unit includes a DUT output signal extractor for inputting an output signal of the device under test; a first frequency divider for dividing the signal from the DUT output signal extractor; and a second frequency divider for dividing the output signal of the oscillator, wherein the phase comparator The phase of the output signal of the frequency divider is compared with the phase of the output signal of the second frequency divider.

The active load pull measurement system according to claim 4 is the active load pull measurement system according to any one of claims 1 to 3, in which a part of the output signal of the device under test is extracted and converted into a DC voltage. wherein the pseudo-reflected wave injection unit includes a voltage-controlled variable gain amplifier, and the amplitude follower controls the gain of the voltage-controlled variable gain amplifier with the DC voltage. and

According to the active load pull measurement system of the present invention, it is possible to stably measure the reflection coefficient _ΓL over the entire range within 1, and it is possible to simplify the system and reduce the cost.

1 is a block diagram showing the configuration of an active load pull measurement system according to an embodiment of the invention; FIG. FIG. 3 is a block diagram showing a configuration in which the amplitude of a pseudo-reflected wave can follow variations in the amplitude of the output signal of the DUT by means of a circuit in the active load pull measurement system; 3 is a circuit diagram showing an example of a DC voltage conversion circuit in the configuration shown in FIG. 2 of the active load pull measurement system; FIG. 2 is a Smith chart showing the experimental reflection coefficient Γ _L of the configuration shown in FIG. 1 of the same active load pull measurement system; 3 is a Smith chart showing the experimental reflection coefficient Γ _L of the configuration shown in FIG. 2 of the same active load pull measurement system; 3 is a characteristic diagram showing the gain of the voltage-controlled variable gain amplifier with respect to the power input to the DC voltage generation circuit in the experiment of the active load pull measurement system shown in FIG. 2; FIG. 3 is a block diagram showing a configuration in which a plurality of sets of the oscillator, phase synchronization section, pseudo-reflected wave injection section, and amplitude tracking section shown in FIG. 2 of the active load pull measurement system are provided; FIG. 1 is a block diagram showing a conventional open-loop active load pull measurement system; FIG. FIG. 10 is a Smith chart showing _ΓL when changing the amplitude and phase of an injection wave in a conventional open-loop active load pull measurement system; FIG. 1 is a block diagram showing a conventional closed-loop active load pull measurement system; FIG. Fig. 10 is a Smith chart showing _ΓL when changing the amplitude and phase of the injection wave in an experiment of a conventional closed-loop active load pull measurement system;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. An active load pull measurement system 1 according to an embodiment of the present invention inputs a signal from an external signal source SG to an input terminal of a DUT (device under test) and obtains the optimum load impedance for the output signal of the DUT. . This active load pull measurement system 1 includes an oscillator 2, a phase synchronization section 3, and a pseudo-reflected wave injection section 4, as shown in FIG. The active load pull measurement system 1 can also include a system controller 5 , a network analyzer 6 , a directional coupler 7 and a bias T circuit 8 .

The phase of the oscillator 2 is controlled by a phase synchronization section 3 which will be described in detail later. Oscillator 2 may be a voltage controlled oscillator.

The phase synchronization section 3 synchronizes the phase of the oscillator 2 with the output signal of the DUT. The phase synchronization unit 3 receives the DUT output signal from the DUT output signal extractor 30 . The DUT output signal extractor 30 can be provided between the output terminal of the pseudo-reflected wave injector 4 (the output terminal of the auxiliary amplifier 43) and the output terminal of the DUT. The DUT output signal extractor 30 can use a circulator. The DUT output signal extractor 30 passes the pseudo-reflected wave output from the pseudo-reflected wave injection unit 4 (auxiliary amplifier 43 ), and directs the output signal of the DUT to the subsequent stage of the phase synchronization unit 3 . The input of the DUT output signal by the DUT output signal extractor 30 may be the input of a part of the DUT output signal (a part of the power) as well as the input of the entire DUT output signal.

The phase synchronization unit 3 can generate a signal in which the voltage level and the like of the input output signal of the DUT are adjusted through an attenuator 31 and an amplifier (limiter amplifier) 32 .

The phase synchronization unit 3 has a first frequency divider 33, a phase comparator 34, a loop filter 35, and a second frequency divider 36 when the oscillator 2 is a voltage-controlled oscillator. The first frequency divider 33 divides the signal from the DUT output signal extractor 30 so that the frequency becomes a predetermined frequency division ratio (1/N), and the second frequency divider 36 divides the frequency of the oscillator 2. The output signal is frequency-divided so that the frequency becomes a predetermined division ratio (1/N') (N and N' are natural numbers). The phase comparator 34 compares the phase of the output signal of the first frequency divider 33 and the phase of the output signal of the second frequency divider 36, that is, the phase of the output signal of the DUT and the output of the oscillator 2 Compare with the phase of the signal. The loop filter 35 smoothes the output of the phase comparator 34 and controls the oscillator 2 so that it follows the output signal of the DUT and is phase-locked.

Both or one of the frequency division ratio (1/N) of the first frequency divider 33 and the frequency division ratio (1/N') of the second frequency divider 36 is preferably variable. Then, for example, when N′=N, the fundamental wave (a signal of a frequency equal to the signal from the external signal source SG input to the input terminal of the DUT) can be a pseudo-reflected wave. It can be a pseudo-reflected wave of twice the harmonic of the wave. If the pseudo-reflected wave is only the fundamental wave, the frequency division ratio of the first frequency divider 33 and the frequency division ratio of the second frequency divider 36 may be fixed at N'=N, or both may be fixed. It is also possible to omit it.

The pseudo-reflected wave injection unit 4 controls the relative phase (in other words, the relative phase difference with the output signal of the DUT) and the amplitude with reference to the output signal of the oscillator 2 to generate the pseudo-reflected wave. and injects the pseudo-reflected wave toward the output terminal of the DUT. In other words, it can be said that the pseudo-reflected wave injection unit 4 uses the signal from the oscillator 2 instead of the signal from the external signal source SG in the basic configuration of the open loop type active load pull measurement system. Amplitude can be controlled by variable attenuator 41 and phase can be controlled by variable phase shifter 42 . Further, the pseudo-reflected wave injection unit 4 is provided with an auxiliary amplifier 43 so that it can be amplified and output.

Thus, the active load pull measurement system 1 utilizes the phase of the DUT's output signal and incorporates the concept of utilizing the DUT's output signal in a closed loop active load pull measurement system.

The system control unit 5 controls the variable attenuator 41 and the variable phase shifter 42 of the pseudo-reflected wave injection unit 4 according to a certain procedure of the active load pull measurement method. The system control unit 5 normally stores the procedure of the active load pull measurement method as a program, and the CPU executes the procedure.

As the network analyzer 6, a commercially available one with general specifications can be used. For the directional coupler 7, one with general specifications can be used. A directional coupler 7 connected to the output terminal of the DUT extracts a signal (output wave) from the DUT to the load and a signal (reflected wave) from the load to the DUT on the line, and measures them with a network analyzer 6. By taking the ratio of , the reflection coefficient _ΓL of the load seen from the DUT is calculated, and the load impedance is obtained from the reflection coefficient _ΓL . Therefore, it is possible to observe the load impedance (reflection coefficient Γ _L ) in real time. Bias T circuit 8 may be of the general specification for biasing the output of the DUT.

In the active load pull measurement system 1 described above, the oscillator 2 is phase-synchronized with the output signal of the DUT by the phase synchronization section 3, and once phase-synchronized, it oscillates at a different frequency as long as there is no loss of synchronization. will be gone. In addition, since the phase synchronization unit 3, the oscillator 2, and the pseudo-reflected wave injection unit 4 use the output signal of the DUT to generate the pseudo-reflected wave to be injected toward the output terminal of the DUT, at first glance, a loop may appear. Although there is a system that constitutes the loop, since the system that constitutes the loop is once disconnected from the phase synchronization unit 3 to the oscillator 2, it is possible to prevent the system that constitutes the loop from having a gain greater than 1 and oscillating. can. As a result, it is possible to stably measure the reflection coefficient _ΓL over the entire region within 1, and it is possible to simplify the system and reduce the cost.

Next, in the active load pull measurement system 1, an active load pull measurement system 1' will be described in which the amplitude of the pseudo-reflected wave can follow the fluctuation of the amplitude of the output signal of the DUT by means of a circuit. The active load pull measurement system 1' includes an oscillator 2, a phase synchronization section 3, a pseudo reflected wave injection section 4', and an amplitude tracking section 9, as shown in FIG. The active load pull measurement system 1 ′ can also include a system control section 5 , a network analyzer 6 , a directional coupler 7 and a bias T circuit 8 . The oscillator 2, the phase synchronization unit 3, the system control unit 5, the network analyzer 6, the directional coupler 7, and the bias T circuit 8 of the active load pull measurement system 1' are similar to those of the active load pull measurement system 1. can be used.

The pseudo-reflected wave injection portion 4' of the active load pull measurement system 1' includes a voltage controlled variable gain amplifier 44 therein (more specifically in the signal processing path). Other configurations of the pseudo reflected wave injection section 4 ′ are the same as those of the pseudo reflected wave injection section 4 described above. The voltage-controlled variable gain amplifier 44 can be provided in the front stage of the auxiliary amplifier 43, although it is not particularly limited. The gain of the voltage-controlled variable gain amplifier 44 is controlled by the amplitude follower 9 described below.

The amplitude follower 9 controls the gain of the voltage-controlled variable gain amplifier 44 with the output direct current (DC voltage) so that the amplitude of its output signal follows the amplitude of the output signal of the DUT. The amplitude follower 9 has a second DUT output signal extractor 90 , a DC voltage generation circuit 91 and a DC voltage conversion circuit 92 .

The amplitude follower 9 extracts (takes out) part of the DUT output signal (part of the power) input by the phase synchronization unit 3 by the second DUT output signal extractor 90 and inputs it. The second DUT output signal extractor 90 can use a directional coupler.

A DC voltage generation circuit 91 receives a portion of the DUT output signal (a portion of the power) through the second DUT output signal extractor 90 and generates a DC voltage according to the power. A commercially available RF power detector can be used as the DC voltage generation circuit 91 . Also, the DC voltage conversion circuit 92 converts the range of the DC voltage output by the DC voltage generation circuit 91 into a voltage range that can be properly controlled by the voltage controlled variable gain amplifier 44 . For example, as shown in FIG. 3, the DC voltage conversion circuit 92 includes an inverting amplifier 921 that inverts and amplifies the voltage input from the input terminal 92i with respect to a reference voltage, a bias voltage 922, and an output voltage of the inverting amplifier 921 and the bias voltage. 922 at a predetermined ratio, inverting and amplifying the result, and outputting the result to the output terminal 92o.

In the active load pull measurement system 1', the amplitude of the pseudo-reflected wave varies following variations in the amplitude of the output signal of the DUT. It is possible to prevent the amplitude of the output signal from becoming excessively large or small.

Experiments conducted by the inventors using the active load pull measurement systems 1 and 1' will be described. In the experiment, the signal from the external signal source SG was set at 2.45 GHz. 2.45 GHz is widely used for microwave heating, and the output impedance of a transistor, which is a DUT, becomes lower as the output increases, and becomes closer to a short circuit. It is not easy to design. EGN21C020MK, which is a gallium nitride high electron mobility transistor (GaN-HEMT) manufactured by Sumitomo Electric Device Innovations, Inc., was used as the DUT.

In FIG. 4, the amplitude of the pseudo-reflected wave is changed in three ways (the attenuation of the variable attenuator 41 is 20 dB, 18 dB, and 7 dB) in the active load pull measurement system 1, and the phase is set by the variable phase shifter 42 for each change. FIG. 10 is a Smith chart showing the reflection coefficient _ΓL measured by changing the angle. FIG. 5 shows that in the active load pull measurement system 1′, the amplitude of the pseudo-reflected wave is changed in four ways (the attenuation of the variable attenuator 41 is 20 dB, 18 dB, 7 dB, and 5 dB), and the phase is changed by the variable phase shifter for each change. 42 is a Smith chart showing the reflection coefficient _ΓL measured by changing the angle by a predetermined angle at 42. FIG. In the figure, ● indicates when the attenuation of the variable attenuator 41 is 20 dB, △ indicates when the attenuation of the variable attenuator 41 is 18 dB, ◆ indicates when the attenuation of the variable attenuator 41 is 7 dB, and □ indicates indicates the reflection coefficient _ΓL when the attenuation of the variable attenuator 41 is 5 dB.

In FIGS. 4 and 5, the data of the reflection coefficient Γ _L measured by changing the phase by a predetermined angle at each amplitude of the pseudo-reflected wave shows changes in the phase at substantially equal intervals, and the center of the Smith chart (Γ _L = A circular or arcuate shape centered around 0) is formed as a whole. As the amplitude of the pseudo-reflected wave is increased (the attenuation of the variable attenuator 41 is decreased), the circular or arc-shaped shape formed by the data of the reflection coefficient _ΓL on the Smith chart changes its diameter to While changing, it grows to the vicinity of the outer frame circle (the circle whose size of _ΓL is 1). That is, the reflection coefficient _ΓL can be measured up to a region where the magnitude is close to one. In FIG. 4, the area near the outer frame circle (the circle whose size _ΓL is 1) on the upper right side is the amplitude of the pseudo-reflected wave while the size of the reflection coefficient _ΓL does not exceed 1. is further increased (the attenuation of the variable attenuator 41 is decreased).

Note that in the measurement of FIG. 5, the DC voltage generation circuit 91 used an RF power detector LT5538 manufactured by Analog Devices. The gain of the voltage-controlled variable gain amplifier 44 with respect to the power input to the DC voltage generation circuit 91 shows favorable changes in the range of approximately -40 dBm to approximately -20 dBm as shown in FIG.

Although the active load pull measurement system according to the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiments, and can be modified within the scope of the claims. Various design modifications are possible. For example, although the above experiment was conducted for 2.45 GHz (fundamental wave), it is also applicable to its harmonics. It is also applicable to fundamental waves and harmonics of other frequencies.

It is also possible to simultaneously measure the fundamental wave and the harmonics, or the harmonics themselves. For example, like the active load pull measurement system 1'' shown in FIG. It is possible to provide a plurality of sets (two sets in FIG. 7) for fundamental waves or harmonics, and connect them with the power combiner 4A. The power combiner 4A can use, for example, a multiplexer. By setting the frequency division ratio of the second frequency divider 36 (or the frequency division ratio of the first frequency divider 33) of each phase synchronization section 3, it is possible to use it for the fundamental wave or for the harmonic wave. Of course, in the active load pull measurement system 1, a plurality of sets of the oscillator 2, the phase synchronization unit 3, and the pseudo reflected wave injection unit 4 are provided and connected by the power combiner 4A to form the active load pull measurement system 1''. You can also configure a system similar to

1, 1' active load pull measurement system 2 oscillator 3 phase synchronization section 30 DUT output signal extractor 31 attenuator 32 amplifier 33 first frequency divider 34 phase comparator 35 loop filter 36 second frequency divider 4, 4' pseudo Reflected wave injector 41 variable attenuator 42 variable phase shifter 43 auxiliary amplifier 44 voltage controlled variable gain amplifier 4A power combiner 5 system controller 6 network analyzer 7 directional coupler 8 bias T circuit 9 amplitude follower 90 second DUT output signal extractor 91 DC voltage generation circuit 92 DC voltage conversion circuit SG External signal source DUT Device under test

Claims (4)

an oscillator;
a phase synchronization unit that phase-synchronizes the oscillator with the output signal of the device under test;
a pseudo- reflected wave injector that generates a pseudo-reflected wave and injects it into the device under test;
a system control unit;
with
The system control unit controls the phase of the output signal of the oscillator with a variable phase shifter, controls the amplitude of the output signal of the oscillator with a variable attenuator, and generates the pseudo reflected wave. active load pull measurement system. The active load pull measurement system of claim 1,
the oscillator is a voltage controlled oscillator,
The phase synchronization section includes a phase comparator that compares the phase of the output signal of the device under test and the phase of the output signal of the oscillator, and a loop filter that smoothes the output of the phase comparator and controls the oscillator. An active load pull measurement system comprising: In the active load pull measurement system according to claim 2,
The phase synchronization section includes a DUT output signal extractor that inputs the output signal of the device under test, a first frequency divider that divides the signal from the DUT output signal extractor, and a divider that divides the output signal of the oscillator. and a second frequency divider,
The active load pull measurement system, wherein the phase comparator compares the phase of the output signal of the first frequency divider and the phase of the output signal of the second frequency divider. In the active load pull measurement system according to any one of claims 1 to 3,
further comprising an amplitude tracking unit that extracts a portion of the output signal of the device under test and converts it into a DC voltage;
The pseudo-reflected wave injection unit includes a voltage-controlled variable gain amplifier,
The active load pull measurement system, wherein the amplitude follower controls the gain of the voltage-controlled variable gain amplifier with the DC voltage.

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