KR100688085B1 - Predistortion Linearizer apparatus for power amplifiers - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a predistortion linearization device for power amplification.

2. The technical problem to be solved by the invention

The present invention provides a predistortion linearization device for power amplification to increase the linearity of a power amplifier by compensating gain distortion (AM-AM) and phase distortion (AM-PM) of a power amplifier according to the magnitude of an input signal. Its purpose is to.

3. Summary of Solution to Invention

A predistortion linearization device for power amplification, comprising: amplifying means for increasing input power to compensate for insertion loss generated during phase and gain conversion; The bias resistance value includes a diode located on a line connecting the corresponding input terminal and the output terminal, a bias resistor and an inductor connected to the diode, and are selectively determined according to the phase change of the power amplifier to be linearized. And phase shifting means for increasing or decreasing the phase when the corresponding power increases with respect to the power input from the amplifying means according to the magnitude of the bias voltage of the diode; And gain converting means for increasing a gain which decreases with an increase in input power in said phase converting means.

4. Important uses of the invention

The present invention is used in power amplifiers and the like.

Predistortion, Linearization, Gain Distortion (AM-AM), Phase Distortion (AM-PM)

Description

Predistortion Linearizer apparatus for power amplifiers

1 is a configuration diagram of an embodiment of a predistortion linearization device for power amplification according to the present invention;

2 is a circuit diagram of an embodiment of a phase shifter in a predistortion linearization device for power amplification according to the present invention;

3 is an exemplary view illustrating a gain and a phase change according to a supply voltage change of a phase converter in a predistortion linearization device for power amplification according to the present invention;

4 is another exemplary diagram illustrating a gain and a phase change according to a supply voltage change of a phase converter in a predistortion linearization device for power amplification according to the present invention;

5 is an exemplary diagram illustrating a gain and a phase change according to a supply voltage change of a gain converter of a predistortion linearization device for power amplification according to the present invention;

FIG. 6 is an exemplary view showing a design result of an IMD3 of an amplifier including a pre-distortion linearization device for compensating a TWTA power amplifier and nonlinear characteristics in the present invention.

* Explanation of symbols for the main parts of the drawings

11: amplifier 12: phase shifter

13: gain converter 14: power amplifier

The present invention relates to a predistorter type linearizer for power amplification, and more particularly, gain distortion (AM-AM) and phase distortion (AM-) of a power amplifier according to the magnitude of an input signal of a microwave power amplifier. By compensating PM), a predistortion linearization device for increasing the linearity of a power amplifier is provided.

In general, an amplifier increases the power of an electrical signal input to the amplifier. An ideal amplifier should linearly increase the magnitude of the signal without distorting the input signal, but the nonlinear nature of the amplifier will cause distortion of the output signal.

The distortion generated by the amplifier is caused by the gain decrease and the phase change as the input signal increases.

As a method for improving the linearity of a power amplifier, predistortion, feed-forward, backoff, and feedback techniques are generally used. The dual predistortion linearizer is widely used because of the small efficiency, low cost, low cost, and low linearity.

Predistortion linearization technology is a field where a lot of research is being conducted at home and abroad. The pre-distortion linearizer using the common gate MESFET proposed by Allen Katz controls the gate voltage (Vg) and gate impedance (Zg) so that the desired nonlinear signal (the inverse of the AM-AM and AM-PM of the amplifier) To improve the linearity of the amplifier. It is composed of one active element and peripheral circuit, which has the advantage of compensating for gain and phase distortion at the same time. However, since the insertion loss is large, a large gain amplifier stage is required to compensate for this. There is a concern that the power consumption of the compensation amplifier may increase. In addition, the gain and phase is difficult to be compensated independently, there is a problem that is difficult to use optimally for all amplifiers.

Thus, W-M. The predistortion linearizer proposed by Zhang is a linearizer consisting of a MIC linearizer bridge, an amplifier stage, and a control stage. The linearizer bridge is composed of a linear phase shifter portion and a nonlinear portion to compensate for the AM-AM and AM-PM of the amplifier. . The linearizer of such a structure may have excellent linearity improvement effect, but it has a disadvantage of being realized at large and expensive by using two paths, and also because the gain compensation amount of the amplifier stage is large due to the increase of insertion loss due to the use of the coupler. This also has the disadvantage of increasing power consumption.

The present invention has been proposed to solve the above problems, and to compensate the gain distortion (AM-AM) and phase distortion (AM-PM) of the power amplifier according to the size of the input signal, the power to increase the linearity of the power amplifier The object is to provide a predistortion linearization device for amplification.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

An apparatus of the present invention for achieving the above object, the predistortion linearization device for power amplification, comprising: amplifying means for increasing the input power to compensate for the insertion loss occurring during the phase and gain conversion; The bias resistance value includes a diode located on a line connecting the corresponding input terminal and the output terminal, a bias resistor and an inductor connected to the diode, and are selectively determined according to the phase change of the power amplifier to be linearized. And phase shifting means for increasing or decreasing the phase when the corresponding power increases with respect to the power input from the amplifying means according to the magnitude of the bias voltage of the diode; And a gain converting means for increasing a gain which decreases with an increase in input power in the phase converting means.

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SUMMARY OF THE INVENTION The present invention provides a method for precompensating the nonlinearity of a microwave power amplifier, in which the gain distortion (AM-AM) and the phase distortion (AM-PM) of the power amplifier according to the magnitude of the input signal are placed in front of the power amplifier. In order to compensate for this, the gain converter and the phase converter may be configured to compensate for the insertion loss caused by the amplifier, thereby increasing the linearity of the power amplifier.

Therefore, in the present invention, the gain converter, the phase converter, and the amplifier are cascaded to optimally compensate for gain and phase by a desired amount, thereby providing a traveling wave tube amplifier (TWTA) and a solid state power amplifier (SSPA). Not only can be used for all amplification elements, etc., but it is simply configured in three stages.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, whereby those skilled in the art may easily implement the technical idea of the present invention. There will be. In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of an embodiment of a predistortion linearization device for power amplification according to the present invention.

As shown in FIG. 1, the predistortion linearization device for power amplification according to the present invention increases the input power of the predistortion linearization device, and occurs in the phase converter 12 and the gain converter 13. An amplifier 11 for compensating for insertion loss, a phase shifter 12 for increasing or decreasing a phase as the input power is increased, and a gain increasing as the input power is increased, for a phase change And a gain converter 13.

Referring to the operation of the predistortion linearization device for power amplification according to the present invention having the configuration as described above in detail as follows.

Predistortion linearizer according to the present invention is composed of an amplifier 11, a phase converter 12, a gain converter 13 as shown in FIG.

The input signal of the power amplifier 14 is generally on the order of 0 dBm (1 mW). However, most active devices used in the microwave band require an input power of 10 dBm (10 mW) or more in order to take full advantage of nonlinearity.

Accordingly, the predistortion linearizer according to the present invention increases the input power and provides the amplifier 11 at the very first stage to compensate for the insertion loss occurring in the phase converter 12 and the gain converter 13. use.

In addition, the phase shifter 12 used in the second stage of the predistortion linearizer uses a Schottky diode.

2 is a circuit diagram of an embodiment of a phase converter 12 of a predistortion linearization device for power amplification according to the present invention.

As shown in FIG. 2, the equivalent model of the Schottky diode may be represented by a parallel coupling of the resistor Rd and the capacitor Cp of the diode. In addition, the gain S21 of the phase converter 12 is expressed by the following [Equation 1] and [Equation 2].

Where Z ₀ is the characteristic impedance. The gain and phase change of the phase converter 12 according to the increase of the input power operate differently depending on the bias condition of the Schottky diode.

First, when the resistors R1 and R2 of the bias path of FIG. 2 are set to large values, when the input power to the Schottky diode increases, the current flowing through the diode increases, and the DC voltage applied to the diode decreases, thereby decreasing the equivalent capacitor. The dose will be reduced. In this case, the change amount of the capacitor Cp, which is an equivalent model of the diode, leads the gain and phase change of the phase converter 12. The gain change of Equation 1 decreases as the input power increases, and the phase change Increases with increasing input power.

Secondly, when the resistances R1 and R2 of the bias path of FIG. 2 are set to small values, when the input power to the Schottky diode increases, the current flowing through the diode becomes larger and the value of the equivalent resistance Rd decreases. . In this case, the change amount of the resistor Rd, which is an equivalent model of the diode, leads the gain and phase change of the phase converter 12. The gain change of Equation 1 increases as the input power increases, and the phase change is It decreases as the input power increases.

Here, the inductors L1 and L2 are necessary to prevent the signal from being bypassed when the resistors R1 and R2 are small. Therefore, the bias condition may be selectively determined according to the change of the phase change of the amplifier 11 to be linearized.

3 is an exemplary view illustrating a gain and a phase change according to a supply voltage change of a phase converter in a predistortion linearization device for power amplification according to the present invention, wherein a phase of a power amplifier whose phase decreases as the input power increases. To compensate for this, the resistors R1 and R2 of the bias path of the Schottky diode in the phase converter 12 are enlarged to 500 Ohm, and the gain and phase change according to the change of the power supply Vdd are shown.

As shown in FIG. 3, it can be seen that as the input power increases, the gain of the phase converter 12 decreases and the phase increases.

4 is another exemplary diagram illustrating a gain and a phase change according to a supply voltage change of a phase converter in a predistortion linearization device for power amplification according to the present invention, and the power amplifier 14 whose phase increases as the input power increases. In order to compensate for the phase of (), the resistances R1 and R2 of the bias path of the Schottky diode in the phase converter 12 are reduced to 10 Ohm, and the gain and phase change according to the change of the power supply Vdd are shown.

As shown in FIG. 4, it can be seen that as the input power increases, the gain of the phase converter 12 increases and the phase decreases.

All power amplifiers reduce their gain near their maximum output power as the input power increases. Therefore, there is a need for a compensation circuit that increases the gain as the input power increases. In the present invention, a "CLASS AB class amplifier" is used as the gain converter 13. Class AB amplifiers operate at low bias currents, and as the input power increases, the potential or current of the transistor transistor gate (in case of FET series transistors) or base (in case of BJT series transistors) is increased. As the operating current and gain increase, the gain reduction can be compensated for by increasing the input power of the power amplifier.

5 is an exemplary diagram illustrating a gain and a phase change according to a change in supply voltage of a gain converter of a predistortion linearization device for power amplification according to the present invention, and using a HEMT (High Electron Mobility Transistor) device of a FET series It shows the change of gain and phase according to the change of bias.

As shown in FIG. 5, when the gate bias is made smaller, more gain increases, and thus a bias capable of compensating for the gain reduction characteristic of the power amplifier 14 and the gain reduction or increase characteristic of the phase converter 12 is obtained. This is done by determining the voltage.

In addition, the phase change of the gain converter 13 is smaller than the phase change of the phase converter 12, but should be determined so as to be compensated as a whole so that an optimal predistortion linearization device may be realized.

FIG. 6 is an exemplary diagram illustrating a design result of a 3rd order intermodulation distortion (IMD3) diagram of an amplifier including a traveling wave tube amplifier (TWTA) power amplifier and a predistortion linearization device for compensating for nonlinear characteristics. FIG. The predistortion linearizer is designed to compensate for the nonlinear characteristics of the amplifier, and the design results of the IMD3 of the amplifier including the TWTA and the predistortion linearizer of the present invention are shown.

TWTA has the characteristic that the gain decreases and the phase decreases as the input single-tone power increases. As a result of optimally compensating this characteristic using the predistortion linearization device of the present invention, when two-tone power is applied as shown in FIG. 6, IMD3 is up to 10 dB or more compared to the characteristic of TWTA alone. Could improve.

Finally, the present invention has a cascade structure of three stages of amplification stage, phase shift stage, and gain shift stage, which is easy to implement and can be manufactured at low cost, light weight, and small size. This independent location allows any amplifier to optimally compensate for gain distortion (AM-AM) and phase distortion (AM-PM) characteristics.

As described above, the method of the present invention may be implemented as a program and stored in a recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.) in a computer-readable form. Since this process can be easily implemented by those skilled in the art will not be described in detail any more.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

In the present invention as described above, since the gain converter, the phase converter, and the amplifier are cascaded, the gain and phase can be optimally compensated by a desired amount. Thus, a traveling wave tube amplifier (TWTA) and a solid-state solid-state filter (SSPA) are used. Not only can be used for all amplification elements such as State Power Amplifier, but also consists of three stages, so that it can be manufactured in small size, light weight, and low cost in actual implementation.

Claims (5)

delete In the predistortion linearization device for power amplification, Amplifying means for increasing an input power to compensate for insertion loss occurring during phase and gain conversion; The bias resistance value includes a diode located on a line connecting the corresponding input terminal and the output terminal, a bias resistor and an inductor connected to the diode, and are selectively determined according to the phase change of the power amplifier to be linearized. And phase shifting means for increasing or decreasing the phase when the corresponding power increases with respect to the power input from the amplifying means according to the magnitude of the bias voltage of the diode; And Gain converting means for increasing a gain reduced with an increase in input power in said phase converting means; Predistortion linearization device for power amplification comprising a. The method of claim 2, The diode, A predistortion linearizer for power amplification, characterized in that it is a Schottky diode. The method of claim 2 or 3, The gain conversion means, As the input power increases, the potential or current of the gate of the amplifier transistor (in the case of the FET series transistor) or the base (in the case of the BJT series transistor) is increased to increase the operating current and the gain of the transistor, thereby making it the linearization target. Pre-distortion linearizer for power amplification, characterized in that the 'Class AB amplifier' to compensate for the gain of the power amplifier. delete

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