Method and device for digital linearization of power amplifier

Abstract

FIELD: radio engineering.SUBSTANCE: device for digital linearization of a power amplifier is proposed, comprising a power amplifier, a linearizer, a digital-to-analogue converter connected to the first output of the linearizer, for converting a digital linearized signal for setting the power amplifier into an analogue signal for adjusting the gain of the power amplifier. A digital frequency synthesizer is introduced, the input of which is connected to the second output of the linearizer, and the output is connected to the input of a power amplifier, to the output of which an attenuator, a signal conversion device that converts a high-frequency signal into a low-frequency analogue signal, and an analogue-to-digital converter, the output of which is connected to the input of the linearizer, are connected in series, and the linearizer records the value corresponding to the specified power at the output of the power amplifier, which is then compared with the current values of the power of the power amplifier, supplied to the linearizer from the output of the analogue-to-digital converter.EFFECT: simplification of the digital linearization device of a power amplifier.3 cl, 2 dwg

Description

[0001] This technical solution relates to radio engineering, in particular to the field of forming linear amplitude-frequency characteristics of amplifying paths of radio signals, and can be used in power amplifiers of portable small-sized radio stations to expand their frequency range.

[0002] A known method for linearizing a power amplifier in a mobile radio communication system has a look-up table for storing pre-distortion data and control data used to adjust the gain of the input signal (patent for invention RU No. 2172552, IPC H03F 1 / 32, H04B 1 / 62, H04B 7 / 26. Device and method for linearizing a power amplifier in a mobile radio communication system / HA Ji-Won (KR). Applicant and patent holder: SAMSUNG ELECTRONICS CO., LTD (KR). Application No. 2000108485 / 09 dated 08 / 05 / 1999, published on 08 / 28 / 2001. Bulletin No. 23).

[0003] This method linearizes the input signal by distorting the input signal using the stored pre-distortion data, amplifying the pre-distorted input signal according to the stored control data, and generating an error signal by comparing the signal obtained from the feedback output signal with the delayed input signal.

[0004] This procedure does not take into account the frequency component of the input signal and is complex, which entails the complication of the device implementing this method.

[0005] A known method for linearizing a power amplifier is performed in two stages. In the first stage, the power amplifier is prepared for production (operation), with the input signal being fed to a vector signal analyzer and to the power amplifier input. The converted signal from the power amplifier output is also fed to the vector signal analyzer, which measures the input and converted signals and transmits the measurement results to the lookup table generation module. At the second stage, the input signal is pre-distorted using lookup tables (patent for invention RU No. 2433522, IPC H03F 1 / 32. System and method for linearizing a power amplifier / Arkhipenkov V. Ya. (RU), Goreynov S. A. (RU), Melnikov A. O. (RU). Patent holder: SAMSUNG ELECTRONICS Co., LTD (KR). Application No. 2010115827 / 09 dated 21.04.2010, published 10.11.2011. Bulletin No. 31).

[0006] The disadvantages of this method are its complexity and the hardware uncertainty involved in performing numerous mathematical calculations. Furthermore, the constant gain of the power amplifier limits the dynamic range of the system.

[0007] The closest to the claimed method and device for digital linearization of a power amplifier is a linearized digital automatic gain control, including a method for linearized digital automatic gain control (AGC) in a radio communication device and a linearized digital control device for automatic gain control (AGC) in a radio communication device (patent for invention RU No. 2158474, IPC H03G 3 / 20. Linearized digital automatic gain control / Nathaniel B. WILSON (US). Applicant and patent holder: QWELCOMM INCORPORATED (US). Application No. 98107320 / 09 dated 09.16.1996 published 10.27.2000. Bulletin No. 30).

[0008] A method for linearized digital automatic gain control (AGC) in a radio communication device comprises an amplifier with an AGC of a transmitter (power amplifier), a linearizer of the transmitter (power amplifier), and the conversion of a linearized digital signal of tuning of the transmitter (power amplifier) ​​into an analog signal of adjustment of the gain of the amplifier with an AGC of a transmitter (power amplifier).

[0009] A linearized digital control device for automatic gain control (AGC) in a radio communication device comprises a transmitter AGC amplifier (power amplifier), a transmitter (power amplifier) ​​linearizer, a digital-to-analog converter connected to the transmitter (power amplifier) ​​linearizer, for converting a digital linearized tuning signal of the transmitter (power amplifier) ​​into an analog gain control signal of the transmitter AGC amplifier (power amplifier).

[0010] The disadvantages of both this method and the device are the complexity of implementation and the limited use of them, mainly in a cellular communication system, since the control signals for the power amplifier in a closed control loop come from the base station.

[0011] The technical result of the invention is a simplification of the method and device while simultaneously expanding the possibility of their use in a digital mobile radio (DMR) system in power amplifiers of portable small-sized radio stations.

[0012] Said technical result is achieved in that a digital linearization device for a power amplifier comprising a power amplifier with AGC (hereinafter referred to as a power amplifier), a power amplifier linearizer (hereinafter referred to as a linearizer), a digital-to-analog converter connected to the first output of the linearizer for converting a digital linearized signal for setting the power amplifier into an analog signal for adjusting the gain of the power amplifier, a digital frequency synthesizer is introduced, the input of which is connected to the second output of the linearizer, and the output is connected to the input of the power amplifier, to the output of which an attenuator is connected in series, a signal conversion device-analog converter connected to the first output of the linearizer for converting a digital linearized signal for setting the power amplifier into an analog signal for adjusting the gain of the power amplifier, a digital frequency synthesizer is introduced, the input of which is connected to the second output of the linearizer,and the output is connected to the input of a power amplifier, to the output of which an attenuator and a signal conversion device are connected in series, an analog converter connected to the first output of the linearizer for converting the digital linearized signal for setting the power amplifier into an analog signal for adjusting the gain of the power amplifier, a digital frequency synthesizer is introduced, the input of which is connected to the second output of the linearizer, and the output is connected to the input of the power amplifier, to the output of which an attenuator, a signal conversion device that ensures the conversion of a high-frequency signal into a low-frequency analog signal, and an analog-to-digital converter, the output of which is connected to the input of the linearizer, are connected in series, and the linearizer records a value corresponding to a specified power at the output of the power amplifier, which is then compared with the current values ​​of the power of the power amplifier, supplied to the linearizer from the output of the analog-to-digital converter.

[0013] The linearizer is designed as a multifunctional digital programmable microcontroller.

[0014] The specified technical result is achieved in that the method for digital linearization of a power amplifier, comprising converting a linearized digital signal for setting the power amplifier into an analog signal for adjusting the gain of the power amplifier, is characterized by the fact that it is performed in two successive stages, in the first of which an attenuator, a signal conversion device that ensures the conversion of a high-frequency signal into a low-frequency analog signal, and an analog-to-digital converter, the output of which is connected to the input of the linearizer, are connected in series to the output of the power amplifier, in the linearizer a value is recorded corresponding to a specified power at the output of the power amplifier, which is then compared with the current values ​​​​of the power amplifier, supplied to the linearizer from the output of the analog-to-digital converter,At the second stage, the digital frequency synthesizer sequentially discretely reconfigures the frequency of the signal at the input of the power amplifier over the entire operating range, and the linearizer at each of the discrete frequencies records in its memory, in the form of a table for adjusting the characteristics of the power amplifier, the values ​​of the control voltage at the output of the digital-to-analog converter, at which the output power at the output of the power amplifier will correspond to the specified value.

[0015] Fig. 1 shows a structural electrical circuit diagram of a digital linearization device for a power amplifier, which contains a power amplifier 1, a digital-to-analog converter 2, a digital frequency synthesizer 3, a linearizer 4 and a series-connected attenuator 5 connected to the output of the power amplifier 1, a signal conversion device 6 (for example, of the AD8361 type) and an analog-to-digital converter 7, the output of which is connected to the input of the linearizer 4.

[0016] In linearizer 4 (implemented in the form of a multifunctional digital programmable microcontroller, for example, type STM32F476RET6), the value corresponding to the specified power value at the output of power amplifier 1 (for example, type RA07M1317M) is fixed for comparison with the current values ​​of the power of power amplifier 1, coming to linearizer 4 from the output of analog-to-digital converter 7.

[0017] Before the practical use of the device, it undergoes preliminary linearization (tuning) in a manner characterized by the fact that the digital frequency synthesizer 3 sequentially discretely reconfigures the frequency of the signal at the input of the power amplifier 1 over the entire operating range, and the linearizer 4 at each of the discrete frequencies records in its memory, in the form of a table for adjusting the characteristics of the power amplifier 1, the values ​​​​of the control voltage at the output of the digital-to-analog converter 2, at which the output power at the output of the power amplifier 1 will correspond to the specified value.

[0018] After the linearization of the power amplifier 1 is completed, the data of the table for correcting the characteristics of the power amplifier 1 are recorded in the permanent memory of the linearizer 4, after which the digital linearization device of the power amplifier can be used in radio stations according to the simplified circuit shown in Fig. 2 in the mode of automatic gain control of the power amplifier over the entire operating frequency range, thereby equalizing its amplitude-frequency characteristic.

[0019] At the same time, the practical implementation of a power amplifier from only four microcircuits makes it possible to use it in portable small-sized radio stations.

Claims

1. A device for digital linearization of a power amplifier, comprising a power amplifier, a linearizer, a digital-to-analog converter connected to the first output of the linearizer, for converting a digital linearized signal for setting the power amplifier into an analog signal for adjusting the gain of the power amplifier, characterized in that a digital frequency synthesizer is introduced, the input of which is connected to the second output of the linearizer, and the output is connected to the input of the power amplifier, to the output of which an attenuator is connected in series, a signal conversion device that ensures the conversion of a high-frequency signal into a low-frequency analog signal, and an analog-to-digital converter, the output of which is connected to the input of the linearizer, and the linearizer records a value corresponding to a specified power at the output of the power amplifier, which it then compares with the current values ​​​​of the power amplifier, supplied to the linearizer from the output of the analog-to-digital converter.

2. The device according to paragraph 1, characterized in that the linearizer is made in the form of a multifunctional digital programmable microcontroller.

3. A method for digitally linearizing a power amplifier, comprising converting a linearized digital signal for setting the power amplifier into an analog signal for adjusting the gain of the power amplifier, characterized in that it is performed in two successive stages, in the first of which an attenuator, a signal conversion device that ensures the conversion of a high-frequency signal into a low-frequency analog signal, and an analog-to-digital converter, the output of which is connected to the input of the linearizer, are connected in series to the output of the power amplifier, in the linearizer a value is recorded corresponding to a specified power at the output of the power amplifier, which is then compared with the current values ​​of the power of the power amplifier supplied to the linearizer from the output of the analog-to-digital converter, in the second stage a digital frequency synthesizer sequentially discretely tunes the frequency of the signal at the input of the power amplifier over the entire operating range,and the linearizer at each of the discrete frequencies records in its memory, in the form of a table for adjusting the characteristics of the power amplifier, the values ​​of the control voltage at the output of the digital-to-analog converter, at which the output power at the output of the power amplifier will correspond to the specified value.

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