KR100328131B1 - Adaptive Feed-forward Linear Amplifier - Google Patents

Abstract

The present invention relates to a linear amplifier used in a communication system. In particular, the linearization of a feedforward linear amplifier without using a filter while implementing a feedforward linear amplifier having the best performance among the linear amplifiers that solves the linearity problem of conventional linear amplifiers. It provides an adaptive feedforward linear amplifier that controls the loop, which can change the center frequency of the feedforward linear amplifier by changing the frequency of the pilot signal, and the center frequency of the feedforward linear amplifier can be changed actively or passively. If it is necessary to develop a feedforward linear amplifier with a relatively small linearization band with a slight difference in center frequency, it is possible to automatically change the center frequency of the feedforward linear amplifier by changing only the frequency of the pilot signal. In this case, the pilot signal applied to the input of the feedforward linear amplifier appears at the output of the feedforward linear amplifier. Therefore, the pilot signal should be removed. It can be removed.

Description

Adaptive Feed-forward Linear Amplifier

The present invention relates to a linear power amplifier used in a communication system, and more particularly, to implement a feedforward linear amplifier having the best performance among linear amplifiers that solves the linearity problem of conventional linear amplifiers, but without using a filter. An adaptive feedforward linear amplifier that controls the linearization loop.

In general, power amplifiers in communication systems emphasize high linearity, high efficiency and ease of implementation. In particular, linearity of power amplifier is the main concern in digital mobile communication system. When power amplifier linearity is a problem, distortion signal (intermodulation signal) generated in power amplifier worsens the signal-to-noise ratio of the whole system. Acting as an interfering signal on the channel results in a decrease in the efficiency of frequency use and ultimately in the capacity of the entire system.

Accordingly, the linearity, efficiency and ease of implementation of power amplifiers used in transmitters in communication systems are of significant concern. In particular, in recent years, the linearity of the amplifier is the biggest problem due to the digitization of the analog system.

In general, linearization methods of power amplifiers include linearization methods such as analog feedback, Cartesian feedback, polar feedback, predistorter, and feedforward.

The linearization method having the best performance among such linearization methods is the feedforward linearization method, and the operation principle of the feedforward linear amplifier described above is shown in 2-tone spectrum in FIG. 1.

In FIG. 1, a 2-tone signal applied to a feedforward linear amplifier is divided into two paths by a power divider located at an input stage. Among the divided signals, the signal passing through the main amplifier has the original two-tone input signal and the distortion signal simultaneously due to the nonlinear characteristics of the main amplifier.

However, the signal passing through the time delay circuit in the first loop will only have insertion loss without distortion. The time delay circuit in the first loop equalizes the delay time for the input signal of the feedforward linear amplifier to reach the output stage of the subtraction circuit after passing through each path (upper path and lower path) in the first loop. Do it.

Thus, the signal passing through the main amplifier is divided by the directional coupler 1 into the input signal of the time delay circuit in the second loop and the input signal of the subtraction circuit. If the two-tone signal of the signal passing through the time delay circuit of the first loop (Signal Cancellation Loop) and the signal passing through the directional coupler 1 is the same in magnitude and has 180 phases at the output of the subtraction circuit At the output terminal of the subtraction circuit, the 2-tone signal applied to the feedforward linear amplifier is removed and only the distortion signal (intermodulation signal) generated from the main amplifier is present.

This distortion signal is again amplified without distortion (the magnitude of the signal is small enough not to cause distortion) through an error amplifier and then applied to directional coupler 2. After passing through directional coupler 1, the signal passing through the time delay circuit in the second loop (error cancellation loop) is a two-tone signal amplified by the main amplifier and a distortion signal generated by the nonlinear characteristics of the main amplifier. These signals are applied to the input signal of the directional coupler 2 in the second loop.

The time delay circuit in the second loop functions the same as the time delay circuit in the first loop. At the output of directional coupler 2, if the distortion signal amplified by the error amplifier and the error signal from the main amplifier are equal in magnitude and 180 degrees out of phase, the signal at the output of directional coupler 2 is applied to the feedforward linear amplifier. After that, only the 2-tone signal amplified by the main amplifier remains. Since these feedforward linear amplifiers have many components, they must be precisely sized, phased, and delayed in each linearization loop to ensure the desired performance.

In particular, as there are many and diverse components, they are sensitive to changes in the external environment, and a method for guaranteeing the performance of the feedforward linearization loop is required. If there is a way to actively monitor and control the performance of the linearization loop, it is possible to improve the reliability of the feedforward linear amplifier and to implement the feedforward linear amplifier. A linear amplifier using a control method of a feedforward linearization loop that actively responds to changes in the external environment is called an adaptive feedforward linear amplifier.

Representative methods of the above-described adaptive feedforward linear amplifier include several representative prior arts, which are illustrated in the accompanying FIGS. 2 to 4, and the technique illustrated in the accompanying FIG. 2 is described in US Pat. No. 4,580,105. The output stage of the feedforward linear amplifier monitors the strength of the pilot signal, and the variable attenuator A2 and phase shifter in the error cancellation loop (second linearization loop) to minimize the magnitude of the pilot signal at the output stage. P2) is a technology to control

In addition, the technique shown in FIG. 3 is described in US Pat. No. 5,307,022, which monitors the strength of the pilot signal at the output of the feedforward linear amplifier, and the signal is minimized at the output. It is a technique for controlling the variable attenuators A1 and A2 and the phase shifters P1 and P2 in the cancellation loop (first linearization loop) and the error cancellation loop (second linearization loop).

In addition, the technique shown in the accompanying FIG. 3 is described in US Pat. No. 5,166,634. The feedforward linear amplifier uses two pilot signals, each of which has a signal cancellation loop (first linearization loop) and It is used to monitor the operating status of the error cancellation loop (second linearization loop).

At this time, the control of the feedforward linearization loop using the pilot signal is performed by minimizing the size of the pilot signal at the detection point of the pilot signal.

2 and 3, the pilot signal is used to monitor and control the operation state of the linearization loop in the feedforward linear amplifier, but only in the error cancellation loop (second loop). Because of this, it is not easy to monitor and control the operation state of the signal cancellation loop (first loop).

In addition, the technique shown in FIG. 4 is a method to solve the above-mentioned problem, and to control and monitor the operating states of the signal cancellation loop (first loop) and error cancellation loop (second loop) by using two pilot signals. do.

In this case, the technique illustrated in FIG. 4 is a pilot 1 signal (pilot 1) applied through the directional coupler located at the input of the feed forward linear amplifier appears in the final output stage of the feed forward linear amplifier to remove this Bandpass filter is used, but there is a disadvantage that the output loss due to the insertion loss of the filter.

That is, the technique illustrated in FIG. 4, that is, US Pat. No. 5,166,634, illustrates a pilot 1 signal in an error cancellation loop (second loop) as another method of removing the pilot 1 signal appearing at the final output stage of the feedforward linear amplifier. 1) was reapplied and the pilot 1 signal was removed from the output of the feedforward linear amplifier by adjusting the magnitude and phase of the signal (pilot 1 applied to the error cancellation loop). There is no frequency change function of the 2 signal (pilot 2), and if the pilot 1 signal (pilot 1) is removed using a bandpass filter, the center frequency of the feedforward linear amplifier by changing the pilot frequency cannot be changed (bandpass). Change the center frequency of the filter), re-apply the pilot 1 signal (pilot 1) in the error cancellation loop (second loop) How to remove the first pilot signal (pilot 1) at the output end of the aeration has the disadvantage that not include a time delay circuit and not a wide frequency band pilot signal 1 (pilot 1) is removed from, because.

In addition, there is a disadvantage that the frequency of the input signal applied to the feedforward linear amplifier is not known.

An object of the present invention for solving the above problems is to implement a linear feed loop of the feed forward linear amplifier having the best performance among the linear amplifier to solve the linearity problem of conventional linear amplifiers without using a filter An adaptive feedforward linear amplifier is provided.

1 is an exemplary view for explaining the operation principle of the feedforward linear amplifier

2 is an exemplary diagram of linearization loop control of a conventional feedforward linear amplifier.

3 is an exemplary diagram of linearization loop control of a conventional feedforward linear amplifier.

4 is Exemplary linearization loop control of a conventional feedforward linear amplifier

5 is the cancellation performance of the linearization loop when there is a time delay mismatch of the linearization loop.

6A is a cancellation performance of a linearization loop in general, and a change in the center frequency of the linearization loop in the feedforward linear amplifier

6B shows the asymmetry of the linearization performance of the linearization loop in the feedforward linear amplifier.

7 is a pilot frequency change for checking the cancellation performance of the linearization loop

8 is an exemplary configuration diagram of an adaptive feedforward linear amplifier according to the present invention.

9 is a frequency and magnitude detection process of an input signal applied to a feedforward linear amplifier.

10 is a power synthesis block diagram of a feedforward linear amplifier.

11 is a variation of the adaptive feedforward linear amplifier shown in FIG.

12 is a bidirectional coupler

FIG. 13 shows another variant of the adaptive feedforward linear amplifier shown in FIG.

Figure 14 is an adaptive feedforward linear amplifier that does not use a pilot signal.

A feature of the present invention for achieving the above object, in the feed forward linear amplifier, the reference frequency by the pilot control signal to the center of the frequency band of the input signal to the first pilot signal, the second pilot signal and the pilot monitoring signal A pilot signal generating means for converting and outputting the first signal of the pilot signal generating means after receiving a signal of one of the signals distributed from the power of the input signal and changing the phase and magnitude of the corresponding signal by the first control signal; A first signal converting means for receiving a signal, mixing and outputting the signal, and a second pilot signal of one of the signals distributed from the power of the signal output from the first signal converting means, the second control signal, and the pilot signal generating means. After receiving the signal and changing the phase and magnitude of the signal distributed by the second control signal and mixed with the second pilot signal A second signal converting means for sampling the corresponding signal and the other signal among the signals distributed from the power of the signal output from the first signal converting means, after a predetermined time delay is received through the first delay element, and receiving the second signal. A third signal converting means for combining the sampled signal from the signal converting means and resampling the sampled signal; and outputting the first pilot signal input after a predetermined time delay through a second delay delay element by a third control signal; A fourth signal converting means for varying a phase and a magnitude according to a fourth control signal and outputting a signal combined with the sampled signal output from the third signal converting means according to a fourth control signal, and a predetermined time through a third delay delay element; The signal output from the second signal converting means input after the delay is combined with the signal output from the fourth signal converting means and sampled. The fifth signal converting means, and the signals output from the signals output from the fourth and fifth signal converting means and the power of the input signal, respectively, at different frequencies based on the pilot monitoring signal generated by the pilot signal generating means. Frequency conversion and power detection means for converting and detecting and outputting power of the corresponding signal, and receiving the signal output from the frequency conversion and power detection means and using it as a reference for linear amplification operation control, and a higher level control and monitoring device And control means for actively controlling the feedforward linearization loop by outputting various control signals for communicating with and controlling the pilot signal generating means and the first, second and fourth signal converting means.

As an additional feature of the present invention for achieving the above object, the first signal converting means receives a signal of one of the signals distributed in the power of the input signal and changes the phase and magnitude according to the first control signal. And first power coupling means for receiving, mixing, and outputting a signal generated by the first phase / size conversion means and a first pilot signal of the pilot signal generation means.

As another additional feature of the present invention for achieving the above object, the second signal converting means receives one of the signals distributed in the power of the signal output from the first signal converting means and according to the second control signal. Second phase-magnitude conversion means for varying phase and magnitude, and second power-combination means for receiving, mixing, and outputting a signal generated by the second phase / magnitude conversion means and a second pilot signal of the pilot signal generation means; And first power sampling means for receiving and sampling and outputting a signal output from the amplified second power coupling means.

As another additional feature of the present invention for achieving the above object, the third signal converting means transmits the other signal from among the signals distributed in the power of the signal output from the second signal converting means through the first delay delay element. Third power combining means for receiving input after a predetermined time delay and sampling the signal sampled by the third power sampling means, and second power sampling means for receiving and sampling the signal output from the third power combining means. It is to include.

In another aspect of the present invention for achieving the above object, the fourth signal converting means receives a first pilot signal of the pilot signal generating means after a predetermined time delay through a second delay delay element, and applies it to the third control signal. Third phase / magnitude converting means for varying phase and magnitude according to the present invention; fourth power for receiving, combining and outputting a sampling signal output from the third signal converting means and a signal output from the third phase / size converting means; And a fourth phase / size converting means for receiving a signal output from the fourth power combining means and varying a phase and a magnitude according to a fourth control signal.

In accordance with still another aspect of the present invention for achieving the above object, the fifth signal conversion means receives a signal output from the second signal conversion means after a predetermined time delay through a third delay delay element and the fourth signal. And fifth power combining means for amplifying, outputting, and combining the signals output from the signal converting means, and third power sampling means for receiving and sampling the signals output from the fifth power combining means. .

As another additional feature of the present invention for achieving the above object further comprises an isolator for transmitting the signal sampled in the fifth signal conversion means to the load side of the linear amplifier, but cut off the power signal reflected from the load side have.

As another additional feature of the present invention for achieving the above object, the frequency converting and power detecting means refers to a pilot monitoring signal generated by the pilot signal generating means for the other signal among the signals distributed in the power of the input signal. A first frequency conversion and power detection means for detecting and outputting power of a corresponding signal by converting to another frequency using a pilot monitoring signal generated by the pilot signal generation means based on a signal output from the second power sampling means. Second frequency conversion and power detection means for converting to another frequency and detecting and outputting power of the corresponding signal; and a signal output from the third power sampling means is different based on a pilot monitoring signal generated by the pilot signal generating means. 3rd week converting to frequency to detect and output the power of the signal It includes a wave number conversion and power detection means.

As another additional feature of the present invention for achieving the above object, each of the first to third frequency conversion and power detection means may convert a signal input based on a pilot monitoring signal generated by the pilot signal generation means into a different frequency. Frequency conversion means for converting and outputting, and a narrow band band pass filter and a log power detector, the power detecting means for receiving a frequency signal output from the frequency conversion means and detecting and outputting the power of the corresponding signal; .

An additional feature of the present invention for achieving the above object is that the third delay element, the phase / magnitude conversion means and the auxiliary amplification device are used, and a dual power coupling device is used to terminate the feedforward linear amplifier. One is to remove the pilot signal.

An additional feature of the present invention for achieving the above object is a means for changing the operating frequency of the linear amplifier to a specific frequency by changing the setting of the pilot signal generating means to change the frequency of the pilot signal, the frequency of the pilot signal By changing the frequency of the local oscillation signal generator of the frequency conversion device for detecting the pilot power, and by changing the operating frequency of the feed forward linear amplifier by detecting a pilot signal of the changed frequency accordingly.

According to another aspect of the present invention for achieving the above object, in a feed forward linear amplifier, a reference frequency is set by a pilot control signal so that a frequency band of an input signal is centered, and a first pilot signal, a second pilot signal, and a pilot monitoring signal. A first signal of the pilot signal generating means after receiving a signal of a pilot signal generating means for converting the signal into a signal and a signal distributed from the power of the input signal, and changing the phase and magnitude of the corresponding signal by the first control signal. A first signal converting means for receiving a pilot signal, mixing and outputting the first signal, and one of a signal distributed from the power of the signal output from the first signal converting means, a second control signal, and a second of the pilot signal generating means; The second pilot signal is received after varying the phase and magnitude of a signal distributed by the second control signal by receiving a pilot signal. And a second signal converting means for sampling the corresponding signal by mixing with the other signal, and receiving another signal from the signal distributed from the power of the signal output from the first signal converting means after a predetermined time delay through the first delay element. A third signal converting means for combining the sampled signal from the second signal converting means and resampling the sampled signal; and receiving a first pilot signal of the pilot signal generating means delayed by a predetermined time through a second delay delay element; Fourth signal converting means for varying phase and magnitude in accordance with a control signal, fifth signal converting means for varying phase and magnitude in accordance with a fourth control signal by receiving a signal output from the third signal converting means; The fourth signal is coupled to the signal of the second signal converting means and the fifth signal converting means which are input after a predetermined time delay through the three o'clock delay element. A sixth signal converting means for combining the signals output from the call converting means and sampling them, and outputting the signals outputted from the signals output from the fourth and sixth signal converting means and the power of the input signal, respectively; A frequency conversion and power detection means for converting to a different frequency based on the pilot monitoring signal generated by the signal to detect and output the power of the signal, and receiving the signal output from the frequency conversion and power detection means of linear amplification operation control It is used as a reference and actively feeds and outputs various control signals for communication with higher level control and monitoring devices and for controlling the pilot signal generating means and the first, second, fourth and fifth signal converting means. And control means for controlling the forward linearization loop.

As an additional feature of the present invention for achieving the above object, the first signal converting means receives a signal of one of the signals distributed in the power of the input signal and changes the phase and magnitude according to the first control signal. And first power coupling means for receiving, mixing, and outputting a signal generated by the first phase / size conversion means and a first pilot signal of the pilot signal generation means.

As another additional feature of the present invention for achieving the above object, the second signal converting means receives one of the signals distributed in the power of the signal output from the first signal converting means and according to the second control signal. Second phase-magnitude conversion means for varying phase and magnitude, and second power-combination means for receiving, mixing, and outputting a signal generated by the second phase / magnitude conversion means and a second pilot signal of the pilot signal generation means; And first power sampling means for receiving and sampling and outputting a signal output from the amplified second power coupling means.

As another additional feature of the present invention for achieving the above object, the third signal converting means transmits the other signal from among the signals distributed in the power of the signal output from the second signal converting means through the first delay delay element. Third power combining means for receiving input after a predetermined time delay and sampling the signal sampled by the third power sampling means, and second power sampling means for receiving and sampling the signal output from the third power combining means. It is to include.

In another aspect of the present invention for achieving the above object, the fourth signal converting means receives a first pilot signal of the pilot signal generating means after a predetermined time delay through a second delay delay element, and applies it to the third control signal. And third phase / magnitude converting means for varying phase and magnitude according to the present invention, and amplifying means for amplifying an output signal of the third phase / magnitude converting means.

In another aspect of the present invention for achieving the above object, the fifth signal converting means receives a signal output from the third signal converting means and changes a phase and a magnitude according to a fourth control signal. And an amplifying means for amplifying the output signal of the fourth phase / size converting means.

As another additional feature of the present invention for achieving the above object, the sixth signal converting means is combined with the fifth signal converting means and the signal of the second signal converting means input after a predetermined time delay through the third delay delay element. And a third power sampling means configured to receive and combine a signal output from the fourth signal converting means and a signal output from the fifth power coupling means, and then sample and output the combined power.

As another additional feature of the present invention for achieving the above object further comprises an isolator for transmitting the signal sampled by the sixth signal conversion means to the load side of the linear amplifier, but cut off the power signal reflected from the load side have.

As another additional feature of the present invention for achieving the above object, the frequency converting and power detecting means refers to a pilot monitoring signal generated by the pilot signal generating means for the other signal among the signals distributed in the power of the input signal. A first frequency conversion and power detection means for detecting and outputting power of a corresponding signal by converting to another frequency using a pilot monitoring signal generated by the pilot signal generation means based on a signal output from the second power sampling means. Second frequency conversion and power detection means for converting to another frequency and detecting and outputting power of the corresponding signal; and a signal output from the third power sampling means is different based on a pilot monitoring signal generated by the pilot signal generating means. Week 3 converts to frequency to detect and output the power of the signal It can be used, including conversion and power detecting means.

As another additional feature of the present invention for achieving the above object, each of the first to third frequency conversion and power detection means may convert a signal input based on a pilot monitoring signal generated by the pilot signal generation means into a different frequency. Frequency conversion means for converting and outputting, and a narrow band band pass filter and a log power detector, the power detecting means for receiving a frequency signal output from the frequency conversion means and detecting and outputting the power of the corresponding signal; .

An additional feature of the present invention for achieving the above object is that the third delay element, the phase / magnitude conversion means and the auxiliary amplification device are used, and a dual power coupling device is used to terminate the feedforward linear amplifier. One is to remove the pilot signal.

An additional feature of the present invention for achieving the above object is a means for changing the operating frequency of the linear amplifier to a specific frequency by changing the setting of the pilot signal generating means to change the frequency of the pilot signal, the frequency of the pilot signal By changing the frequency of the local oscillation signal generator of the frequency conversion device for detecting the pilot power, and by changing the operating frequency of the feed forward linear amplifier by detecting a pilot signal of the changed frequency accordingly.

Another feature of the present invention for achieving the above object, in the feed-forward linear amplifier, by converting the reference frequency to the first pilot signal and the pilot monitoring signal by the pilot control signal so that the frequency band of the input signal is the center output Receiving a signal from a pilot signal generating means and a signal distributed from the power of the input signal, and changing a phase and a magnitude of the corresponding signal by a first control signal, and then inputting a first pilot signal of the pilot signal generating means. A first signal converting means for receiving, mixing, and outputting a signal; one of a signal distributed from the power of the signal output from the first signal converting means, a second control signal, and a first pilot signal of the pilot signal generating means; The phase and magnitude of the signal distributed by the second control signal are varied and mixed with the second pilot signal. A second signal converting means for sampling a signal, and another signal of a signal distributed from the power of the signal output from the first signal converting means is input after a predetermined time delay through the first delay delay element, and the second signal converting is performed; A third signal converting means for combining the sampled signals from the means and resampling them, and outputting the first pilot signals inputted after a predetermined time delay through a second delay delay element by a third control signal; A fourth signal converting means for varying a phase and a magnitude according to a fourth control signal and outputting a signal combined with the sampled signal outputted from the third signal converting means after a predetermined time delay through the third delay delay element; Combining the signal output from the second signal converting means input with the signal output from the fourth signal converting means and sampling and outputting 5 signal converting means and the signals output from the signals output from the fourth and fifth signal converting means and the power of the input signal are respectively converted into different frequencies based on the pilot monitoring signal generated from the pilot signal generating means. Frequency conversion and power detection means for detecting and outputting the power of the signal, and the signal output from the frequency conversion and power detection means is used as a reference for the control of the linear amplification operation, and communication with the higher-level control and monitoring device And control means for actively controlling the feedforward linearization loop by outputting various control signals for controlling the pilot signal generating means and the first, second and fourth signal converting means.

A further feature of the present invention for achieving the above object is a feed forward linear amplifier comprising: a PLL means for converting a reference frequency into a specific frequency by a control signal and outputting the signal; A first phase / magnitude converting means for receiving a signal and varying a phase and a magnitude according to a first control signal, and a signal distributed from the power of the signal output from the first phase / magnitude converting means Second phase / magnitude converting means for receiving a phase and magnitude varying according to the second control signal, and first power sampling means for receiving and sampling an amplified signal of the signal generated by the second phase / magnitude converting means. And a predetermined time from the first time delay element to the other signal among the signals distributed in the power of the signal output from the first phase / size conversion means. A first power combining means for receiving a signal inputted after the delay and combining the signal sampled by the first power sampling means, and a second power sampling means for receiving the sample outputted from the first power combining means and sampling the same; A third phase / magnitude converting means for receiving a signal output from the second power sampling means and varying a phase and a magnitude according to a third control signal, and converting the signal output from the first power sampling means into a second delay delay element; Second power coupling means for receiving and amplifying amplified signals of a signal received after a predetermined time delay and output from the third phase / magnitude converting means, and outputted; The signal output from the three power sampling means is converted into a different frequency based on a specific frequency signal generated by the PLL means, respectively. Frequency conversion and power detection means for detecting and outputting the power of the power, and the signal output from the frequency conversion and power detection means is used as a reference for the control of the linear amplification operation, and communication with higher-level control and monitoring device and And control means for actively controlling a feedforward linearization loop by outputting various control signals for controlling the PLL means and the first to fourth phase / size conversion means.

First, a brief description of the technical spirit to be applied in the present invention, in general, when implementing an adaptive feedforward linear amplifier, it is necessary to monitor and control the operating state of the feedforward linearization loop.

At this time, the monitoring of the operation state of the feedforward linearization loop is a common method of using a pilot signal, but the method of removing the applied pilot signal is an important problem because the applied pilot signal appears at the output of the feedforward linear amplifier.

Therefore, even in the case of using a pilot signal, it is possible to change the operating frequency of the feedforward linear amplifier to a specific frequency of interest as long as it is possible to monitor and control the frequency-changed pilot signal while varying the frequency of the pilot signal. The invention was conceived.

In addition, the main cause of using the pilot signal to control the linearization loop of the adaptive feedforward linear amplifier is that the frequency of the signal applied to the feedforward linear amplifier is not known, and the linearization loop can be controlled without using the pilot signal. If there is, it is an idea of the present invention that the configuration of a high frequency (analog) circuit will be simpler than a feedforward linear amplifier using a pilot signal.

That is, if the above-mentioned conventional problems are solved without using a filter, there is no loss of output power of the feedforward linear amplifier and the frequency of the pilot signal can be changed, so that the control of the feedforward linearization loop will be easy. If there is a way to automatically know the frequency of the signal applied to the amplifier, it will be possible to maintain the linearization performance of the feedforward linear amplifier in the frequency band where the frequency of the signal is actively located.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

5 is a result of simulating the linearization performance of the linearization loop according to the difference of the delay time between each path in the loop, without the magnitude and phase imbalance of the signal on each path in the linearization loop, The linearization performance of the linearization loop for the case where only there exists is shown.

In FIG. 5, the time delay is expressed as the difference (err) of the physical length of each path in the loop at the center frequency fs. In addition, the performance of the linearization loop in FIG. 5 shows that the smaller the time delay, the better the linearization bandwidth and the linearization performance. Also, if there is only a time delay in the linearization loop, the linearization performance of the linearization loop is symmetrical about the center frequency.

In a real environment, there is a time delay between each path of the linearization loop, and there is also an imbalance in magnitude and phase between the signals passing through each path.

6A and 6B show the performance of the linearization loop in the above-described practical case. A remarkable thing in FIG. 6A shows that the linearization band is limited by time delay, and the center of the linearization loop according to the phase imbalance. You can see that this is moved. This fact indicates that the center frequency (operating frequency) of the feedforward linear amplifier can be changed.

Note also in FIG. 6B that the linearization performance of the linearization loop in the real environment is not symmetrical with respect to the center frequency. Therefore, when a pilot signal having one fixed frequency is applied to the linearization loop and the size of the pilot signal is monitored and controlled, the pilot signal may not have a desired performance in the linearization band (operating frequency) of the feedforward linear amplifier.

Therefore, in order to accurately monitor and control the operation state of the linearization loop, as shown in FIG. 7, it is necessary to monitor and control the magnitude of the pilot signal while changing the frequency of the pilot signal within the frequency band of interest.

That is, as shown in FIG. 7, the phase shifter and the variable attenuator in the linearization loop have the same and minimum magnitude of the pilot signal at Fa and Fb frequencies including the linearization band (between Fa to Fb frequency range in the case of pilot 1 signal). Must be controlled. In this case, the operating frequency of the feedforward linearization loop in FIG. 7 is Fa to Fb when the pilot 1 signal is used, and Fa 'to Fb' when the pilot 2 signal is used.

8 is an exemplary diagram of an adaptive feedforward linear amplifier according to the present invention. Referring to the configuration, there are two frequency synthesizers PLL1 and PLL2 for generating a pilot signal, and information for controlling the frequency synthesizer is shown in FIG. It is stored in the memory of the controller.

Signal generator 1 (PLL 1) generates a pilot 1 signal, signal generator 2 (PLL 2) generates a pilot 2 signal, and signal generator 3 (PLL3) generates frequency downlinkers 1, 2, and 3 (Mixer1, 2, 3). Generate a local oscillation signal (LO signal).

The pilot 1 signal is applied through the directional coupler 1 and the applied pilot 1 signal is monitored through the directional coupler 5 (or power divider). If each path in the first loop (signal rejection loop) passes, then the pilot 1 signal at the output of directional coupler 5 has the same magnitude, phase is 180 different, and the time delay is the same. There is no pilot 1 signal detected through the distributor.

As a result, the controller controls the phase shifter and the variable attenuator 2 so that the magnitude of the pilot 1 signal detected through the frequency down mixer 2 and the power detector 2 is kept to a minimum. .

This control and monitoring action maximizes the linearization performance of the first loop (signal rejection loop) of the feedforward linear amplifier.

However, the applied pilot 1 signal passes through delay line 2 in the second loop and appears at the output of the feedforward linear amplifier. Therefore, a means for removing pilot 1 from the output stage of the feedforward linear amplifier is needed.

In the accompanying FIG. 8, the pilot 1 signal is applied through the directional coupler 6 in the second loop of the feedforward linear amplifier, and the pilot 1 must be removed in a wide frequency range (not a pilot signal having a fixed frequency). As shown in Fig. 6, the frequency of the pilot has a band from Fa to Fb). The delay line 3, the phase shifter and the variable attenuator 4 are provided in the same manner as the feedforward linearization loop, so Removal performance was maximized.

The degree of removal of the pilot 1 signal at the output of the feedforward linear amplifier is monitored through the directional coupler 8. That is, the controller adjusts the phase shifter and the variable attenuator 4 so that the intensity of the pilot 1 signal detected through the directional coupler 8, the frequency downlinker 3, and the power detector 3 is minimized.

The pilot 2 signal to monitor the linearization performance of the second loop of the feedforward linear amplifier is applied through the directional coupler 2, the monitoring of the pilot 2 signal is made through the directional coupler 8, and the operation principle is to remove the pilot 1 signal. It is the same with the principle.

At this time, since the pilot 2 signal is monitored after the pilot 1 signal is removed from the output of the feedforward linear amplifier, the pilot 1 signal has no effect on the detection process of the pilot 2 signal.

In addition, there is no influence of the pilot 2 signal in the process of detecting the pilot 1 signal.

In FIG. 7, the frequency range of the pilot 2 signal is set to be wider than the frequency range of the pilot 1 signal. The reason for this is that the role of the first loop is to remove the signal and the second loop is to remove the error. Therefore, the linearization band of the second loop should be wider than the first loop in terms of the linearization band.

In this case, it can be seen that the center frequency of the feedforward linear amplifier can be changed through the attached FIG. 6, and if the frequency of the applied signal is known, the operation of the feedforward linear amplifier can be performed in a specific frequency band in which the signal exists. The center frequency of the feed forward linear amplifier may be changed by changing the frequency of the pilot signal according to the frequency of the signal applied to the feed forward linear amplifier.

Therefore, in order to detect the frequency and magnitude of the input signal of the feedforward linear amplifier as shown in FIG. 9, the local oscillation signal generator 3 (PLL 3) has a signal in a frequency band (interest frequency band) in which an input signal can exist. Are sweeped at a specific frequency interval F such that they appear at the intermediate frequency stage of frequency downlink mixer 1 (Mixer1), and information necessary for frequency sweep is received from the controller.

9 illustrates a process of detecting a frequency and a magnitude of a signal applied to a feedforward linear amplifier, wherein the center frequency (FIF) of the narrowband bandpass filter is fixed, and the controller already knows the frequency of the local oscillation signal generator. Since we know the magnitude of the signal, we can know the frequency of the signal.

That is, in the accompanying FIG. 8, the power detectors 1, 2 and 3 are constituted by a narrow band band pass filter and a log detector as shown in FIG.

After detecting the frequency and the magnitude of the signal applied to the feedforward linear amplifier as described above, in FIG. 8, the controller determines the frequencies of the pilot 1 signal generator PLL 1 and the pilot 2 signal generator PLL 2 in the frequency band of the input signal. Change the center and monitor the frequency-changed pilot 1 and 2 signals by changing the frequency of the signal generator 3 (PLL 3) providing the local oscillation signals of the frequency downlinker 2 and the frequency downlinker 3 according to the changed pilot frequency. Can be.

Thus, the basis for maximizing the performance of the feedforward linear amplifier in a specific frequency region by monitoring the magnitude of the frequency-changed pilot signal has been presented through the description in FIG. 6.

In addition, information on the frequency of the input signal of the feedforward linear amplifier may be obtained through a digital input / output device (Monitor & Test Port) inside the controller of FIG. 8.

In particular, when it is necessary to accurately detect the strength of the input signal of the feedforward linear amplifier, the memory device of the controller has a characteristic table of the frequency downlinker 1 and the power detector 1 of FIG. 8 in the frequency range of interest.

The characteristic tables of the frequency downlinker 1 and the power detector 1 are the magnitude of the signal and the power detector output voltage before frequency conversion with respect to the frequency, respectively. The magnitude of the input signal can be detected more accurately by using such a characteristic table. This characteristic table includes the details of the frequency down converter 2 and the power detector 2, the frequency down converter 3 and the power detector 3.

In addition, in Fig. 8, a phase shifter & variable attenuator 1 is used for power synthesis of a feedforward linear amplifier.

Through the digital monitor / test device of the controller, the information of the final synthesized output power after power synthesis of the feedforward linear amplifier and the output power of each feedforward linear amplifier are used to The phase shifter and the variable attenuator 1 are controlled by a controller in the feedforward linear amplifier so as to maximize power synthesis at the output stage of the power synthesizer.

10 shows a block diagram for power synthesis of a feedforward linear amplifier functioning as described above. In FIG. 10, information on power synthesis provided by the controller in the feedforward linear amplifier is provided through an RF controller & controller.

In addition, FIG. 11 is a modified method of removing the pilot 1 signal from the output stage of the feed forward linear amplifier of FIG. 8 to apply the pilot 1 signal to the second loop of the feed forward linear amplifier. ) Was used.

In this case, an additional amplifier (Aux. Amp) for amplifying the pilot 1 signal is necessary because the size of the pilot 1 signal applied to the second loop is small and is applied through the bidirectional coupler.

12, the structure of the bidirectional coupler is shown.

The bidirectional coupler has an advantage that the insertion loss is small because the physical length is shorter than when using two directional couplers.

13 also shows a block diagram for controlling the linearization loop of a feedforward linear amplifier without using a pilot signal. Since the frequency of the signal input in FIG. 13 can be known through the frequency downlinker 1 and the power detector 1, the linearization loop can be controlled without using a pilot signal.

The power detectors 1, 2, and 3 of FIG. 13 are composed of a narrowband bandpass filter and a log detector, and a method of controlling the linearization loop without using a pilot signal is as follows.

First, in order to grasp the frequency and magnitude of the signal applied to the feedforward linear amplifier, the local oscillation signal generator 1 (PLL1) of FIG. 13 uses a specific frequency such that a signal existing in the frequency range of interest appears as an intermediate frequency stage of the frequency downlinker. Sweep at intervals. This process is the same as the process shown in FIG. Information about the frequency of the local oscillation signal generator 1 is received from the controller.

In addition, the controller already knows information about the frequency of the local oscillation signal generator PLL1 and the intermediate frequency FIF of the frequency downlinker 1, and uses the analog voltage value applied from the power detector 1 to determine the feedforward linear amplifier. Know the frequency and magnitude of the input signal.

The controller also calculates the frequency of the distortion signal from the frequency of the input signal by internal calculation.

In addition, the directional coupler 3 monitors the magnitude of the input signal and the distortion signal of the feedforward linear amplifier. In this process, the controller sets the frequency of the local oscillation signal generator 1 (PLL1) so that the signal output from the intermediate frequency (IF) stage of the frequency downlink device 2 becomes the original input signal of the feedforward linear amplifier. This is performed by detecting the signal at each setting moment while setting the distortion signal to be output at the intermediate frequency stage of the frequency downlinker 2.

In addition, in the process of monitoring the magnitude of the input signal and the distortion signal of the feedforward linear amplifier through the directional coupler 3, the controller controls the variable attenuator and the phase shifter in the first loop to minimize the magnitude of the input signal of the feedforward linear amplifier. Adjust 2.

In addition, the monitoring and control of the second loop is performed by monitoring the magnitude of the input signal and the distortion signal of the feedforward linear amplifier through the directional coupler 3 and adjusting the variable attenuator and phase shifter 2 in the first loop. In this case, the variable attenuator and phase shifter 3 in the second linearization loop are adjusted to minimize the magnitude of the distortion signal detected by the directional coupler 5 located at the output of the feedforward linear amplifier.

Finally, in the accompanying FIG. 13, information on the input signal of the feedforward linear amplifier may be provided through the digital input / output device of the controller.

As described above, when the adaptive feedforward linear amplifier according to the present invention is provided, the center frequency of the feedforward linear amplifier can be changed by changing the frequency of the pilot signal, and the center frequency of the feedforward linear amplifier is changed actively or passively. .

In addition, when it is necessary to develop a feedforward linear amplifier having a relatively small linearization band with a slight difference in center frequency, the center frequency of the feedforward linear amplifier can be automatically changed by changing only the frequency of the pilot signal. In the case of using, the pilot signal applied to the input of the feedforward linear amplifier appears at the output of the feedforward linear amplifier and should be removed. Using the same method as the linearization loop in the feedforward, the pilot signal is most effectively used in a wide band. Can be removed.

Claims (25)

In a feed forward linear amplifier, Pilot signal generating means for converting a reference frequency into a first pilot signal, a second pilot signal, and a pilot monitoring signal by a pilot control signal so that the frequency band of the input signal is the center; A first signal that receives one of the signals distributed from the power of the input signal, varies the phase and magnitude of the corresponding signal by the first control signal, and then receives and mixes the first pilot signal of the pilot signal generating means and outputs the mixed signal; Signal conversion means; The signal divided by the second control signal is received by receiving one of the signals distributed from the power of the signal output from the first signal converting means, the second control signal, and the second pilot signal of the pilot signal generating means. Second signal converting means for varying a phase and a magnitude and mixing the second pilot signal to sample the corresponding signal; Receives another signal of the signal distributed from the power of the signal output from the first signal converting means after a predetermined time delay through the first delay delay element, combines the sampled signal from the second signal converting means, and resamples it. A third signal converting means for outputting the same; The first pilot signal input after the predetermined delay time through the second delay delay element is changed in phase and magnitude by a third control signal, and then the signal combined with the sampled signal output from the third signal converting means is fourth. Fourth signal converting means for varying the phase and the magnitude according to the control signal and outputting the variable; A fifth signal converting means for combining the signal output from the second signal converting means input after a predetermined time delay through a third delay delay element with the signal output from the fourth signal converting means and then sampling and outputting the sampled output signal; The signal distributed from the power output from the fourth and fifth signal conversion means and the power of the input signal are respectively converted into different frequencies based on the pilot monitoring signal generated from the pilot signal generating means to detect the power of the corresponding signal. Output frequency conversion and power detection means; And The signal output from the frequency converting and power detecting means is used as a reference for the control of the linear amplification operation, and the communication with the higher level control and monitoring device, the pilot signal generating means, and the first, second and fourth And control means for outputting various control signals for controlling the signal conversion means to actively control the feed forward linearization loop. The method of claim 1, The first signal converting means includes: first phase / magnitude converting means for receiving a signal of one of the signals distributed from the power of the input signal and varying a phase and a magnitude according to the first control signal; And a first power coupling means for receiving and mixing the signal generated by the first phase / magnitude converting means and the first pilot signal of the pilot signal generating means and outputting the mixed signal. The method of claim 1, The second signal converting means includes a second phase / size converting means for receiving a signal of one of the signals distributed from the power of the signal output from the first signal converting means and varying a phase and a magnitude according to the second control signal; ; Second power coupling means for receiving a signal generated by the second phase / magnitude converting means and a second pilot signal of the pilot signal generating means to mix and output the signal; And And a first power sampling means for receiving and sampling the signal output from the amplified second power coupling means. The method of claim 1, The third signal converting means receives another signal from among the signals distributed from the power of the signal output from the second signal converting means after a predetermined time delay through the first delay delay element, and is sampled by the third power sampling means. Third power coupling means for coupling and outputting a signal; And a second power sampling means for receiving and sampling the signal output from the third power coupling means. The method of claim 1, The fourth signal converting means may include a third phase / size converting means for receiving a first pilot signal of the pilot signal generating means after a predetermined time delay through a second delay delay element and varying a phase and a magnitude according to a third control signal; ; Fourth power combining means for receiving the sampling signal outputted from the third signal converting means and the signal outputted from the third phase / size converting means and receiving the combined signal; And And a fourth phase / size converting means for receiving a signal output from the fourth power coupling means and varying a phase and a magnitude according to a fourth control signal. The method of claim 1, The fifth signal converting means receives a signal output from the second signal converting means after a predetermined time delay through a third delay delay element, amplifies the signal output from the fourth signal converting means, receives, combines and outputs the signal. A fifth power coupling means; And a third power sampling means configured to receive and sample the signal output from the fifth power coupling means and output the sampled output signal. The method of claim 1, And an isolator for transmitting the signal sampled by the fifth signal converting means to the load side of the linear amplifier, and blocking the power signal reflected from the load side. The method according to any one of claims 1 to 6, The frequency converting and power detecting means converts one signal among the signals distributed from the power of the input signal into another frequency based on the pilot monitoring signal generated by the pilot signal generating means, and detects and outputs the power of the corresponding signal. First frequency conversion and power detection means; Second frequency conversion and power detection means for converting the signal output from the second power sampling means into another frequency based on the pilot monitoring signal generated by the pilot signal generation means to detect and output power of the corresponding signal; And And a third frequency converting and power detecting means for converting a signal output from the third power sampling means into another frequency based on a pilot monitoring signal generated by the pilot signal generating means to detect and output power of the corresponding signal. Adaptive feedforward linear amplifier, characterized in that. The method of claim 8, Each of the first to third frequency converting and power detecting means includes: frequency converting means for converting and outputting a signal input based on a pilot monitoring signal generated by the pilot signal generating means to another frequency; An adaptive feedforward linear amplifier comprising a narrow band band pass filter and a log power detector, the power detecting means receiving a frequency signal output from the frequency converting means and detecting and outputting power of the signal. The method according to any one of claims 1 to 6, An adaptive feedforward linear, using the third delay delay element, phase / magnitude conversion means and an auxiliary amplification device, and removing the first pilot signal at the end of the feedforward linear amplifier using a dual power coupling device. amplifier. The method according to any one of claims 1 to 6, A means for changing the operating frequency of the linear amplifier to a specific frequency by varying the setting of the pilot signal generating means to change the frequency of the pilot signal, and as the frequency of the pilot signal changes, the local oscillation signal of the frequency converter for detecting the pilot power. Adaptive feedforward linear amplifier, characterized in that for changing the frequency of the generator, thereby changing the operating frequency of the feedforward linear amplifier by detecting a pilot signal of the changed frequency. In a feed forward linear amplifier, Pilot signal generating means for converting a reference frequency into a first pilot signal, a second pilot signal, and a pilot monitoring signal by a pilot control signal so that the frequency band of the input signal is the center; A first signal that receives one of the signals distributed from the power of the input signal, varies the phase and magnitude of the corresponding signal by the first control signal, and then receives and mixes the first pilot signal of the pilot signal generating means and outputs the mixed signal; Signal conversion means; The signal divided by the second control signal is received by receiving one of the signals distributed from the power of the signal output from the first signal converting means, the second control signal, and the second pilot signal of the pilot signal generating means. Second signal converting means for varying a phase and a magnitude and mixing the second pilot signal to sample the corresponding signal; Receives another signal of the signal distributed from the power of the signal output from the first signal converting means after a predetermined time delay through the first delay delay element, combines the sampled signal from the second signal converting means, and resamples it. A third signal converting means for outputting the same; Fourth signal converting means for receiving a first pilot signal of the pilot signal generating means delayed by a second time delay element and varying a phase and a magnitude according to a third control signal; Fifth signal converting means for receiving a signal output from the third signal converting means and varying a phase and a magnitude according to a fourth control signal; Combining the signal of the second signal converting means and the fifth signal converting means inputted after a predetermined time delay through the third delay delay element, and combining the signal output from the fourth signal converting means with the combined signal, and sampling and outputting the combined signal; 6 signal converting means; The signal distributed from the power output from the fourth and sixth signal conversion means and the power of the input signal are respectively converted to different frequencies based on the pilot monitoring signal generated from the pilot signal generating means to detect the power of the corresponding signal. Output frequency conversion and power detection means; And The signal output from the frequency converting and power detecting means is used as a reference for the control of the linear amplification operation, and the communication with the higher level control and monitoring device, the pilot signal generating means, and the first, second and fourth And control means for actively controlling the feed forward linearization loop by outputting various control signals for controlling the fifth signal conversion means. The method of claim 12, The first signal converting means includes: first phase / magnitude converting means for receiving a signal of one of the signals distributed from the power of the input signal and varying a phase and a magnitude according to the first control signal; And a first power coupling means for receiving and mixing the signal generated by the first phase / magnitude converting means and the first pilot signal of the pilot signal generating means and outputting the mixed signal. The method of claim 12, The second signal converting means includes a second phase / size converting means for receiving a signal of one of the signals distributed from the power of the signal output from the first signal converting means and varying a phase and a magnitude according to the second control signal; ; Second power coupling means for receiving a signal generated by the second phase / magnitude converting means and a second pilot signal of the pilot signal generating means to mix and output the signal; And And a first power sampling means for receiving and sampling the signal output from the amplified second power coupling means. The method of claim 12, The third signal converting means receives another signal from among the signals distributed from the power of the signal output from the second signal converting means after a predetermined time delay through the first delay delay element, and is sampled by the third power sampling means. Third power coupling means for coupling and outputting a signal; And a second power sampling means for receiving and sampling the signal output from the third power coupling means. The method of claim 12, The fourth signal converting means may include a third phase / size converting means for receiving a first pilot signal of the pilot signal generating means after a predetermined time delay through a second delay delay element and varying a phase and a magnitude according to a third control signal; ; And an amplifying means for amplifying the output signal of the third phase / magnitude converting means. The method of claim 12, The fifth signal converting means includes: fourth phase / size converting means for receiving a signal output from the third signal converting means and varying a phase and a magnitude according to a fourth control signal; And an amplifying means for amplifying the output signal of said fourth phase / magnitude converting means. The method of claim 12, The sixth signal converting means includes: fifth power combining means for combining and outputting a signal of the second signal converting means input after a predetermined time delay through a third time delay element and the fifth signal converting means; And a third power sampling means configured to receive and combine the signal output from the fourth signal conversion means and the signal output from the fifth power coupling means, and then sample and output the combined signal. The method of claim 12, And an isolator which transmits the signal sampled by the sixth signal converting means to the load side of the linear amplifier, and cuts off the power signal reflected from the load side. The method according to any one of claims 12 to 18, The frequency converting and power detecting means converts one signal among the signals distributed from the power of the input signal into another frequency based on the pilot monitoring signal generated by the pilot signal generating means, and detects and outputs the power of the corresponding signal. First frequency conversion and power detection means; Second frequency conversion and power detection means for converting the signal output from the second power sampling means into another frequency based on the pilot monitoring signal generated by the pilot signal generation means to detect and output power of the corresponding signal; And And a third frequency converting and power detecting means for converting a signal output from the third power sampling means into another frequency based on a pilot monitoring signal generated by the pilot signal generating means to detect and output power of the corresponding signal. Adaptive feedforward linear amplifier, characterized in that. The method of claim 20, Each of the first to third frequency converting and power detecting means includes: frequency converting means for converting and outputting a signal input based on a pilot monitoring signal generated by the pilot signal generating means to another frequency; An adaptive feedforward linear amplifier comprising a narrow band band pass filter and a log power detector, the power detecting means receiving a frequency signal output from the frequency converting means and detecting and outputting power of the signal. The method according to any one of claims 12 to 18, An adaptive feedforward linear, using the third delay delay element, phase / magnitude conversion means and an auxiliary amplification device, and removing the first pilot signal at the end of the feedforward linear amplifier using a dual power coupling device. amplifier. The method according to any one of claims 12 to 18, A means for changing the operating frequency of the linear amplifier to a specific frequency by varying the setting of the pilot signal generating means to change the frequency of the pilot signal, and as the frequency of the pilot signal changes, the local oscillation signal of the frequency converter for detecting the pilot power. Adaptive feedforward linear amplifier, characterized in that for changing the frequency of the generator, thereby changing the operating frequency of the feedforward linear amplifier by detecting a pilot signal of the changed frequency. In a feed forward linear amplifier, Pilot signal generating means for converting the reference frequency into a first pilot signal and a pilot monitoring signal by a pilot control signal so that the frequency band of the input signal is the center; A first signal that receives one of the signals distributed from the power of the input signal, varies the phase and magnitude of the corresponding signal by the first control signal, and then receives and mixes the first pilot signal of the pilot signal generating means and outputs the mixed signal; Signal conversion means; One of the signals distributed from the power of the signal output from the first signal converting means and the second control signal and the first pilot signal of the pilot signal generating means are input to receive the signal divided by the second control signal. Second signal converting means for varying a phase and a magnitude and mixing the second pilot signal to sample the corresponding signal; Receives another signal of the signal distributed from the power of the signal output from the first signal converting means after a predetermined time delay through the first delay delay element, combines the sampled signal from the second signal converting means, and resamples it. A third signal converting means for outputting the same; The first pilot signal input after the predetermined delay time through the second delay delay element is changed in phase and magnitude by a third control signal, and then the signal combined with the sampled signal output from the third signal converting means is fourth. Fourth signal converting means for varying the phase and the magnitude according to the control signal and outputting the variable; A fifth signal converting means for combining the signal output from the second signal converting means input after a predetermined time delay through a third delay delay element with the signal output from the fourth signal converting means and then sampling and outputting the sampled output signal; The signal distributed from the power output from the fourth and fifth signal conversion means and the power of the input signal are respectively converted into different frequencies based on the pilot monitoring signal generated from the pilot signal generating means to detect the power of the corresponding signal. Output frequency conversion and power detection means; And The signal output from the frequency converting and power detecting means is used as a reference for the control of the linear amplification operation, and the communication with the higher level control and monitoring device, the pilot signal generating means, and the first, second and fourth And control means for outputting various control signals for controlling the signal conversion means to actively control the feed forward linearization loop. In a feed forward linear amplifier, PLL means for converting a reference frequency into a specific frequency and outputting the control signal; First phase / magnitude conversion means for receiving one of the signals distributed from the power of the input signal and varying phase and magnitude in accordance with the first control signal; Second phase / magnitude conversion means for receiving one of the signals distributed from the power of the signal output from the first phase / magnitude conversion means and varying phase and magnitude in accordance with a second control signal; First power sampling means for receiving and sampling the amplified signal of the signal generated by the second phase / magnitude converting means; The other signal, which is distributed from the power of the signal output from the first phase / size conversion means, is input after a predetermined time delay through the first delay delay element, and is output by combining the signal sampled by the first power sampling means. A first power coupling means; Second power sampling means for receiving a signal output from the first power coupling means and sampling the sample; Third phase / magnitude conversion means for receiving a signal output from the second power sampling means and varying a phase and a magnitude according to a third control signal; Second power coupling means for receiving a signal output from the first power sampling means after a predetermined time delay through a second delay delay element, receiving an amplified signal of the signal output from the third phase / size conversion means, and combining and outputting the signal; and; The signal distributed from the power of the input signal and the signal output from the second and third power sampling means are respectively converted into a different frequency based on a specific frequency signal generated by the PLL means to detect and output the power of the corresponding signal. Frequency conversion and power detection means; And The signal output from the frequency conversion and power detection means is used as a reference for linear amplification operation control, communication with higher level control and monitoring devices, the PLL means and the first to fourth phase / size conversion means. And control means for actively controlling the feedforward linearization loop by outputting various control signals for controlling them.