KR20020031356A - Feedforward linear method and apparatus of power amplifier - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method and a device for linearizing a feedforward of a power amplifier. In particular, a gain detection is used for a first loop of a feedforward circuit of a power amplifier, and a pilot is used for a second loop. The present invention relates to a method and apparatus for feedforward linearization of a power amplifier which stably controls linearization by removing asymmetrical characteristics of a transmission frequency band even in this changing signal. To this end, the feedforward linearization method of a power amplifier having a first loop and a second loop according to the present invention includes: an input signal input from a circuit preceding the power amplifier in the first loop and an error amplifier of the second loop. Detecting a gain by coupling an input signal and then removing a signal by controlling a phase and a magnitude such that a gain level is minimized; And a distortion removing process of coupling the input signal and the output signal of the error amplifier in the second loop to adjust the pilot signal to maintain constant magnitude and phase characteristics, thereby removing distortion.

Description

Feedforward Linearization Method and Apparatus of Power Amplifiers {FEEDFORWARD LINEAR METHOD AND APPARATUS OF POWER AMPLIFIER}

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method and a device for linearizing a feedforward of a power amplifier. In particular, a gain detection is used for a first loop of a feedforward circuit of a power amplifier, and a pilot is used for a second loop. The present invention relates to a method and apparatus for feedforward linearization of a power amplifier which stably controls linearization by removing asymmetrical characteristics of a transmission frequency band even in this changing signal.

As mobile communication technology shifts from the existing IS-95 method to the International Mobile Telecommunication (IMT-2000) method, a protocol specification for providing packet data is provided to provide high-speed packet data service in the existing voice-oriented service. It is becoming. To date, protocols with completed or ongoing specifications include 1X Evolution (1X EV-DO and 1X EV-DV). The 1X EV was initially named HDR (High Data Rate) and is a dedicated protocol for packet data transmission that is completely different from the existing IS-95 and IS-2000 wireless protocols. It is a protocol that maximizes the efficiency of use of wireless section and system by allocating and using dormant which is unique characteristic of packet data.

A power amplifier is used for secure RF signal transmission from the base station to the terminal, or secure RF signal transmission from the terminal to the base station. Signals used in the existing IS-95 protocol (hereinafter, referred to as IS-95 signals) are uniform. One power signal or a signal used in the present or future 1X EV protocol (hereinafter, referred to as a 1X EV signal) is a power signal having a large rate of change over time.

The IS-95 signal used in the conventional power amplifier has no problem in feedforward linearization when used in the conventional power amplifier circuits as shown in FIGS. 1A and 1B, but the 1X EV has a large instantaneous change rate in the existing power amplifier. When a signal having a large rate of change of a signal or an input signal is used, the linearity of the output (transmission band) relative to the input may be deteriorated.

A problem that occurs when a signal having a large instantaneous change rate is used in a feedforward linearization circuit of a conventional power amplifier will be described with reference to FIGS. 1A and 1B.

FIG. 1A illustrates a configuration of a first loop 1 of the conventional feedforward linear power amplifier, and FIG. 1B illustrates a configuration of a second loop 2 of the conventional feedforward linear amplifier.

In the first loop as shown in FIG. 1A, after the output signal of the power synthesizer of the front end is coupled, the output level is detected to control the output level to be minimum.

However, such a conventional power amplifier feed forward linearization circuit cannot determine whether the output level conversion value is due to a loop control or a signal change in a 1X EV signal having a large instantaneous rate of change or a signal in which an input signal changes rapidly. V) A problem arises that causes control.

In addition, in the second loop as shown in FIG. 1B, after the output of the final output stage is coupled, a pilot signal level is detected and a control operation is performed so that the level is minimized. This may minimize the pilot signal level, but may cause a problem of deterioration of linearity in the transmission band.

To prevent this phenomenon, the pilot frequency needs to be hopping and controlled, but the software burden is increased and the time required for stabilizing the loop is generated.

Accordingly, an object of the present invention is a feedforward linearization method of a power amplifier that stably controls linearization by removing asymmetrical characteristics of a transmission frequency band even in a signal having a varying input (1X EV signal, etc.) to solve the above problems; In providing a device.

1A is a view showing a first loop configuration of a conventional feedforward linear power amplifier;

Figure 1b is a view showing a second loop configuration of a conventional feed forward linear amplifier,

2 is a diagram illustrating a configuration of a feedforward linear power amplifier according to a preferred embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

1: input terminal 2: first coupler

3: vector modulator 4: main amplifier

5: D / A6: first controller

8: gain detector 9: third coupler

10: fourth coupler 11: first delay circuit

12: second coupler 13: pilot generator

14: fifth coupler 15: sixth coupler

16: second delay circuit 17: second vector modulator

18: error amplifier 19: eighth coupler

20: seventh coupler 21: the first pilot receiver

22: second controller 23: second pilot receiver

24: vector demodulator 25: ninth coupler

26: output terminal

In order to solve the above object, a feedforward linearization method of a power amplifier having a first loop and a second loop according to the first aspect of the present invention is:

In the first loop, a gain is detected by coupling an input signal input from a circuit preceding the power amplifier and an input signal input to the error amplifier of the second loop, and then a phase and a magnitude are set such that the gain level is minimized. A signal removing process of controlling to remove only the transmission signal component;

And a distortion removing process of coupling the input signal and the output signal of the error amplifier in the second loop to adjust the pilot signal to maintain constant magnitude and phase characteristics, thereby removing distortion.

In addition, in the feed forward linearization method of the power amplifier according to the second aspect of the present invention, the adjusting of the pilot signal to maintain the magnitude and phase characteristics of the pilot signal may be performed by coupling an input signal and an output signal of the error amplifier. The phase is characterized in that the characteristics of the transmission band are adjusted to have a desired value.

In addition, the feed forward linearization apparatus of the power amplifier according to the third aspect of the present invention:

A gain detector which detects a gain by coupling the input signal input from the circuit of the power amplifier step with the input signal input to the error amplifier, and outputs the detection result;

An analog / digital converter for converting and outputting gain levels of the input signal and the output signal detected by the gain detector into digital data;

Receiving digital data received from the analog-to-digital converter and determining gain and phase control signal values such that the gain level of the input signal and the output signal detected by the gain detector is minimized and outputting a digital control result value; 1 controller,

A digital / analog converter for converting and outputting the digital control result value processed by the first controller into an analog control signal;

A first loop including at least a first vector modulator that adjusts phase and magnitude based on an analog control signal from the digital / analog converter to remove only transmission signal components; And

The error amplifier amplifying an output signal from which the transmission signal component is removed from the first loop;

A first pilot receiver for extracting only a pilot signal component from a signal input to the error amplifier;

A second pilot receiver for extracting a pilot signal component of the changed signal via the error amplifier;

A vector demodulator for comparing pilot signals supplied from the first pilot receiver and the second pilot receiver and outputting a comparison result;

A second controller for outputting a phase and magnitude characteristic adjustment value so that the magnitude and phase of the pilot signal are kept constant through a comparison result supplied from the vector demodulator;

And a second loop including at least a second vector modulator for performing adjustment by controlling the magnitude and phase characteristic adjustment values for the pilot signal from the second controller.

In addition, the feed forward linearization apparatus of the power amplifier according to the fourth aspect of the present invention;

An input terminal for receiving a signal from a circuit before the power amplifier;

A first coupler for distributing the signal input from the input terminal;

A main amplifier for amplifying the input signal distributed from the first coupler and outputting the amplified result;

A gain detector which detects a gain by coupling an output signal from a third coupler output of the first coupler and a fourth coupler output of the sixth coupler, and outputs a detection result thereof;

An analog / digital converter converting the gain level detected by the gain detector into digital data and outputting the digital data;

Receiving digital data received from the analog-to-digital converter and determining a gain and phase control signal value such that the gain level of the input signal and the output signal detected by the gain detector is minimized and outputting a digital control result value; 1 controller,

A digital / analog converter for converting and outputting the digital control result value processed by the first controller into an analog control signal;

A first vector modulator for adjusting only phase and magnitude based on the analog control signal from the digital / analog converter to remove only the transmitted signal component;

A first delay circuit for delaying the signal distributed from the first coupler and supplying the delayed signal to the sixth coupler;

A fifth coupler operating as a directional coupler combining the signal from the main amplifier and the signal from the first delay circuit, the fifth coupler supplying an output signal from the main amplifier to the ninth coupler through a second delay circuit; 6 couplers,

The fifth coupler and the sixth coupler via the main amplifier from the first coupler so that the pilot signal oscillated in the pilot generator appears in both types of signals to be coupled in the fifth coupler and the sixth coupler, the directional coupler. A second coupler for injecting the pilot signal oscillated by the pilot generator into the signal path at any node on the path to the signal branch point in the circuit;

A second delay circuit for delaying a signal supplied from the fifth coupler and supplying the delayed signal to the ninth coupler;

An error amplifier for amplifying the output signal from the sixth coupler from which the transmission signal component has been removed and outputting the amplified result to the ninth coupler;

A first pilot receiver for extracting only pilot signal components of an output of the sixth coupler through a seventh coupler positioned in front of the error amplifier;

A second pilot receiver for extracting a pilot signal component of the changed signal via the error amplifier from an eighth coupler located at an output of the error amplifier;

A vector demodulator for comparing pilot signals supplied from the first pilot receiver and the second pilot receiver and outputting a comparison result;

A second controller for outputting a phase and magnitude characteristic adjustment value so that the magnitude and phase of the pilot signal are kept constant through a comparison result supplied from the vector demodulator;

A second vector modulator positioned between the error amplifier and the seventh coupler, the second vector modulator performing adjustment by controlling magnitude and phase characteristic adjustment values for a pilot signal from the second controller;

A ninth coupler outputting a signal supplied from the error amplifier and the second delay circuit, and

And an output terminal for supplying an output signal from the ninth coupler to a circuit of a next step.

In addition, the injection node of the second coupler according to the fifth aspect of the present invention is located between the vector modulator and the main amplifier.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same components have the same reference numerals as much as possible even if they are displayed on different drawings. Detailed descriptions of well-known functions and configurations that are determined to unnecessarily obscure the subject matter of the present invention will be omitted.

2 is a diagram illustrating a configuration of a feedforward linear power amplifier according to a preferred embodiment of the present invention, in which a signal input through the input terminal 1 from the circuit of the previous step (not shown) is input to the main amplifier 5. The circuit amplified by and output through the output terminal 26 is supplied to the circuit of the next stage. The feedforward linear power amplifier according to the preferred embodiment of the present invention has two kinds of signal paths in relation to the feedforward signal path. The first feedforward signal path (hereinafter referred to as "first loop") is The second feedforward signal path (hereinafter referred to as " second loop ") is operated as a signal cancellation loop and as a distortion cancellation loop. In addition, the signal cancellation loop (first loop) of the feedforward linear power amplifier according to an exemplary embodiment of the present invention includes an input terminal 1, a first coupler 2, a vector modulator 3, a main amplifier 4, D / A (5), first controller (6), A / D (7), gain detector (8), third coupler (9), first delay circuit (11), second coupler (12), pilot A generator 13, a fifth coupler 14, a sixth coupler 15, and the distortion elimination loop (second loop) comprises a fourth coupler 10, a second delay circuit 16, a second vector modulator. 17, an error amplifier 18, an eighth coupler 19, a seventh coupler 20, a first pilot receiver 21, a second controller 22, a second pilot receiver 23, a vector demodulator ( 24), the ninth coupler 25 and the output terminal (26).

The input terminal 1 applies a signal input from a circuit (modulator, etc.) of the previous step to the first coupler.

The first coupler 2 is used as a divider, and distributes the signal input from the input terminal 1 to the main amplifier 4 and the first delay circuit (11).

The main amplifier 4 amplifies the input signal distributed from the first coupler 2 and outputs the amplified result to the fifth coupler 14.

The gain detector 8 couples the input signal of the first coupler 2 with the output signal from the fourth coupler 10, which is the output of the sixth coupler 15, detects a gain, and detects the detected result. Supply to the A / D (7).

The A / D 7 converts the gain levels of the input signal and the output signal detected by the gain detector 8 into digital data and supplies them to the first controller 6.

The first controller 6 receives the digital data received from the A / D 7 and determines the gain and phase control signal values. The gain level of the input signal and the output signal detected by the gain detector 8 is determined. The gain and phase control signal (digital data) values are determined and sent to the D / A 5 so that the size of M is minimized. The first controller 6 sends a gain and phase control signal to the first vector modulator 3 to control phase and magnitude to remove only the transmitted signal components in the signal rejection loop (first loop).

The D / A 5 converts the digital control result value processed by the first controller 6 into an analog control signal and supplies it to the vector modulator 3.

The vector modulator 3 operates as a vector adjusting circuit and adjusts the phase and magnitude of the analog control signal from the D / A 5.

The first delay circuit 11 delays the signal distributed from the first coupler 2 and supplies the delayed signal to the sixth coupler 15.

The fifth coupler 14 and the sixth coupler 15 operate as a directional coupler for coupling the signal from the main amplifier 5 and the signal from the first delay circuit 11, and the main amplifier ( The output signal from 4) is supplied to the ninth coupler 25 through the second delay circuit 16.

The second coupler 12 causes the pilot signal oscillated by the pilot generator 13 to appear in both types of signals to be coupled by the fifth coupler 14 and the sixth coupler 15, which are the directional couplers. Oscillation in the pilot generator 13 in the signal path at any node on the path from one coupler 2 to the signal branch in the directional coupler 14, 15 via the main amplifier 40. Inject the pilot signal. For example, the injection node of the second coupler 12 is located between the vector modulator 3 and the main amplifier 4.

The second delay circuit 16 delays a signal supplied from the fifth coupler 14 and supplies the delayed signal to the ninth coupler 25.

The error amplifier 18 amplifies the output signal from the sixth coupler 15 from which the transmission signal component has been removed, and supplies the amplified result to the eighth coupler 19.

The first pilot receiver 21 extracts only a pilot signal component among the outputs of the sixth coupler 15 through the seventh coupler 20 and supplies it to the vector demodulator 28.

The second pilot receiver 23 extracts the characteristic (pilot signal component) of the changed signal via the error amplifier 18 and supplies it to the vector demodulator 24.

The vector demodulator 24 compares the pilot signals of the first pilot receiver 21 and the second pilot receiver 23 and supplies them to the second controller 22.

The second controller 22 adjusts the second vector modulator 30 to maintain a constant I / Q or A / Q characteristic of the pilot signal. That is, the second controller 22 couples the input signal of the error amplifier 18 and the output signal of the error amplifier 18 so that the magnitude and phase have a value when the characteristics of the transmission band are the best. The second vector modulator 17 is controlled to perform distortion removal.

The second vector modulator 17 is located between the error amplifier 18 and the seventh coupler 17 and controls the pilot signal I / Q or A / Q characteristic adjustment value of the second controller 22. By adjusting.

The ninth coupler 25 outputs a signal supplied from the error amplifier 18 and the second delay circuit 16 to an output terminal 26.

The output terminal 26 supplies the output signal from the ninth coupler 25 to the circuit of the next step.

In the feedforward linear power amplifier according to the preferred embodiment of the present invention, a feedforward linearization method of a power amplifier that stably controls linearization by removing asymmetrical characteristics of a transmission frequency band even in a signal whose input changes, such as a 1X EV signal, is provided. Explain.

As mentioned above, the feedforward linear power amplifier according to the present invention has two types of signals in relation to the feedforward signal path: a first loop that is a signal cancellation loop and a second loop that is a distortion cancellation loop connected to the first loop. There is a path.

The feed forward linearization method of the power amplifier according to the present invention first, in the first loop, which is a signal cancellation loop, gain detection is performed on a coupled signal of an input signal inputted from a circuit of a previous stage through an input terminal and an input signal of the error amplifier. To control the loop. In the second loop, which is a distortion elimination loop, the loop is controlled by detecting a pilot signal in a coupled signal of an input signal and an output signal of the error amplifier.

The loop control operation in the first loop and the loop control operation in the second loop will be described in more detail.

1. Loop control in the first loop:

The gain detector detects a gain detection result of an input signal distributed from the first coupler 2 and an input signal of the error amplifier 18 through the input terminal 1 from a circuit in front of the first controller 6. (8) and A / D (7), the gain and phase control signal is sent to the vector modulator (3) so that the magnitude of the gain level is minimized to control the phase and magnitude so that only the transmission signal component in the first loop is controlled. Remove

2. Loop control in the second loop:

The second controller 22 couples the input signal of the error amplifier 18 and the output signal of the error amplifier 18 so that the magnitude and phase have a value when the characteristic of the transmission band is the best. The two-vector modulator 17 is controlled to perform distortion removal. That is, in the second loop, the asymmetric characteristic of the transmission frequency band is eliminated by adjusting the pilot signal level to be kept constant, rather than controlling the pilot signal level to a minimum.

Therefore, the feed forward linearization method and apparatus of the power amplifier according to the present invention use gain detection for the first loop control of the feed forward circuit of the power amplifier and use a pilot for the second loop control, even in a signal whose input changes. The linearization is controlled stably by removing the asymmetrical characteristics of the transmission frequency band. According to the present invention, even when a 1X EV signal having a large instantaneous rate of change or a signal having a large rate of change of an input signal is used, the problem of deterioration of linearity in a transmission band can be solved, and the pilot frequency is hopped to prevent linearity deterioration as in the prior art. Control is unnecessary, so there is no software burden and no time is required to stabilize the loop. In addition, in the 1X EV signal having a large instantaneous rate of change or a signal in which the input signal changes at a high speed, an error control problem that cannot determine whether the output level shift value is caused by loop control or signal change is solved.

On the other hand, in the detailed description of the present invention has been described with reference to specific embodiments, of course, various modifications are possible without departing from the scope of the invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by the equivalents of the claims.

As described above, the present invention uses the gain detection for the first loop control of the feed forward circuit of the power amplifier and maintains the pilot level by using the pilot for the second loop control so that the transmission frequency band is maintained even in a signal whose input is changed. By eliminating the asymmetrical characteristic of, there is an advantage in that the linearization can be stably controlled.

In addition, the present invention can solve the problem of linearity deterioration in the transmission band even when using a 1X EV signal with a large instantaneous rate of change or a signal with a large rate of change of the input signal, hopping the pilot frequency to prevent the linearity deterioration as in the prior art It is not necessary to control while controlling, there is no software burden and there is no need for extra time to stabilize the loop.

In addition, the present invention solves the problem of false control that cannot determine whether the output level shift value is caused by a loop control or a signal change in a 1X EV signal having a large instantaneous rate of change or a signal whose input signal changes rapidly. Can be.

Claims (5)

In a feedforward linearization method of a power amplifier having a first loop and a second loop: In the first loop, a gain is detected by coupling an input signal input from a circuit preceding the power amplifier and an input signal input to the error amplifier of the second loop, and then the phase and the magnitude of the gain level are minimized. A signal removing process of controlling to remove only the transmission signal component; And a distortion removing step of removing distortion by coupling the input signal and the output signal of the error amplifier in the second loop to maintain a constant magnitude and phase characteristic of the pilot signal. Feedforward linearization method. The method of claim 1, Adjusting the pilot signal to maintain a constant magnitude and phase characteristics is characterized in that to adjust the magnitude and phase of the transmission band characteristics having a target value by coupling the input signal and the output signal of the error amplifier Feedforward linearization method of power amplifier. In feedforward linearizer of power amplifier: A gain detector which detects a gain by coupling an input signal input from the circuit of the power amplifier stage and an input signal input to an error amplifier, and outputs the detection result; An analog / digital converter for converting and outputting gain levels of the input signal and the output signal detected by the gain detector into digital data; Receiving digital data received from the analog-to-digital converter and determining a gain and phase control signal value such that the gain level of the input signal and the output signal detected by the gain detector is minimized and outputting a digital control result value; 1 controller, A digital / analog converter for converting and outputting the digital control result value processed by the first controller into an analog control signal; A first loop including at least a first vector modulator that adjusts phase and magnitude based on an analog control signal from the digital / analog converter to remove only transmission signal components; And The error amplifier amplifying an output signal from which the transmission signal component is removed from the first loop; A first pilot receiver for extracting only a pilot signal component from a signal input to the error amplifier; A second pilot receiver for extracting a pilot signal component of the changed signal via the error amplifier; A vector demodulator for comparing pilot signals supplied from the first pilot receiver and the second pilot receiver and outputting a comparison result; A second controller for outputting a phase and magnitude characteristic adjustment value so that the magnitude and phase of the pilot signal are kept constant through a comparison result supplied from the vector demodulator; And a second loop having at least a second vector modulator for performing adjustment by controlling the magnitude and phase characteristic adjustment values for the pilot signal from the second controller. 4. The apparatus of claim 3, wherein the feedforward linearization device of the power amplifier; An input terminal for receiving a signal from a circuit before the power amplifier; A first coupler for distributing the signal input from the input terminal; A main amplifier for amplifying the input signal distributed from the first coupler and outputting the amplified result; A gain detector for detecting a gain by coupling an output signal from a third coupler output of the first coupler and a fourth coupler output of the sixth coupler, and outputting a detection result; An analog / digital converter converting the gain level detected by the gain detector into digital data and outputting the digital data; Receiving digital data received from the analog-to-digital converter and determining gain and phase control signal values such that the gain level of the input signal and the output signal detected by the gain detector is minimized and outputting a digital control result value; 1 controller, A digital / analog converter for converting and outputting the digital control result value processed by the first controller into an analog control signal; A first vector modulator for adjusting only phase and magnitude based on the analog control signal from the digital / analog converter to remove only the transmitted signal component; A first delay circuit for delaying the signal distributed from the first coupler and supplying the delayed signal to the sixth coupler; A fifth coupler operating as a directional coupler combining the signal from the main amplifier and the signal from the first delay circuit, the fifth coupler supplying an output signal from the main amplifier to the ninth coupler through a second delay circuit; 6 couplers, The fifth coupler and the sixth coupler via the main amplifier from the first coupler so that the pilot signal oscillated in the pilot generator appears in both types of signals to be coupled in the fifth coupler and the sixth coupler, the directional coupler. A second coupler for injecting the pilot signal oscillated by the pilot generator into the signal path at any node on the path to the signal branch point in the circuit; A second delay circuit for delaying a signal supplied from the fifth coupler and supplying the delayed signal to the ninth coupler; An error amplifier for amplifying the output signal from the sixth coupler from which the transmission signal component has been removed and outputting the amplified result to the ninth coupler; A first pilot receiver for extracting only pilot signal components of an output of the sixth coupler through a seventh coupler positioned in front of the error amplifier; A second pilot receiver for extracting a pilot signal component of the changed signal via the error amplifier from an eighth coupler located at an output of the error amplifier; A vector demodulator for comparing pilot signals supplied from the first pilot receiver and the second pilot receiver and outputting a comparison result; A second controller for outputting a phase and magnitude characteristic adjustment value so that the magnitude and phase of the pilot signal are kept constant through a comparison result supplied from the vector demodulator; A second vector modulator positioned between the error amplifier and the seventh coupler, the second vector modulator performing adjustment by controlling magnitude and phase characteristic adjustment values for a pilot signal from the second controller; A ninth coupler outputting a signal supplied from the error amplifier and the second delay circuit, and And a circuit having an output terminal for supplying an output signal from the ninth coupler to a circuit of a next step. The method of claim 4, wherein And an injection node of the second coupler is positioned between the vector modulator and the main amplifier.