Device and method for controlling distortion characteristic of predistorter

• US 6,246,865 B1
• Filed: 02/04/1997
• Issued: 06/12/2001
• Est. Priority Date: 02/04/1997
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Lee, Dong-Woo
• Primary Examiner(s): Tsang, Fan
• Assistant Examiner(s): SMITH, SHEILA B
• Application Number:
  US08/789,232
• Time in Patent Office: 1,589 Days
• Field of Search: 332/107, 332/123, 332/159, 332/160, 332/124, 375/296, 375/297, 455/63, 455/67.3, 455/114, 455/115, 455/126, 455/70, 455/69, 330/149, 330/52
• US Class Current: 455/114.3
• CPC Class Codes: H01Q 11/12 Resonant antennas
• CPC Class Codes: H03D 7/00 Transference of modulation from one carrier to another, e.g. frequency-changing H03D9/00, H03D11/00 take precedence; dielectric amplifiers, magnetic amplifiers, parametric amplifiers used as a frequency-changers H03F
• CPC Class Codes: H04B 1/62 for providing a predistortion of the signal in the transmitter and corresponding correction in the receiver, e.g. for improving the signal/noise ratio

Abstract

A device and a method for meeting the distortion characteristic of a predistorter in accordance with the distortion characteristic of an output amplifier in a transmitter. The device controls the non-linear distortion characteristic of a predistorter in a radio communication transmitter which includes the predistorter for beforehand generating the non-linear distortion characteristic in opposition to non-linear distortion characteristics arising in an output amplifier, and up-converter for converting an output frequency of the predistorter into a radio frequency bandpass and outputting the converted frequency to the output amplifier. The device includes: a monitoring unit for monitoring the output level of the output amplifier; a storing unit for beforehand storing the non-linear distortion characteristics of the predistorter as digital data; a distortion controller for outputting and controlling given non-linear distortion characteristic digital data stored in the storing unit in correspondence with the output level of the monitoring unit; and a digital/analog converter for converting the non-linear distortion characteristic digital data outputted by the distortion controller into an analog signal and providing the converted data to the predistorter.

Claims

1. A device for controlling a non-linear distortion characteristic of a predistorter in a radio communication transmitter wherein said predistorter is connected via an up-converter to an output amplifier and generates the non-linear distortion characteristic in opposition to non-linear distortion characteristics arising in said output amplifier, and said up-converter converting an output frequency of said predistorter into a radio frequency bandpass and outputting said converted frequency to said output amplifier, said device comprising:

a monitoring unit connected to said output amplifier for monitoring an output level of said output amplifier and providing an output;

a storing unit for storing the non-linear distortion characteristics of said predistorter as digital data;

a distortion controller connected between said monitoring unit and said storing unit for outputting and controlling the digital data stored in said storing unit in correspondence with the output of said monitoring unit; and

a digital/analog converter connected between said storing unit and said predistorter for converting the digital data outputted by said distortion controller into an analog signal and providing said analog signal to said predistorter;

wherein said storing unit stores the digital data in a table including the output level of the output amplifier and at least one other quantity.

2. The device as recited in claim 1, wherein said storing unit maps EEPROM data are shown in following <

Table 1>

in correspondence with said output level of said output amplifier;

6. The device as recited in claim 1, wherein said at least one other quantity comprises a distortion control voltage.

7. The device as recited in claim 6, wherein said at least one other quantity comprises an address of the storing unit.

8. The device as recited in claim 7, wherein said at least one other quantity comprises electrically erasable and programmable read-only memory data.

9. The device as recited in claim 6, wherein said at least one other quantity comprises electrically erasable and programmable read-only memory data.

10. The device as recited in claim 1, wherein said at least one other quantity comprises an address of the storing unit.

11. The device as recited in claim 10, wherein said at least one other quantity comprises electrically erasable and programmable read-only memory data.

12. The device as recited in claim 1, wherein said at least one other quantity comprises electrically erasable and programmable read-only memory data.

3. A method for controlling a non-linear distortion characteristic of a predistorter in a radio communication transmitter, comprising the steps of:

(a) after setup of said transmitter, applying a two-tone signal as a modulation signal to the predistorter;

(b) passively adjusting a value of a distortion control voltage for non-linear distortion characteristics adjustment in said predistorter and applying said adjusted value to said predistorter in response to said step (a);

(c) analyzing a power spectrum of an output level of an output amplifier of said transmitter in response to said steps (a) and (b);

(d) measuring an output power control signal of said output amplifier when suppression of the non-linear distortion characteristics is sufficiently generated in said step (c);

(e) converting said output power signal into digital data corresponding to a distortion control voltage and storing said digital data;

(f) outputting given said digital data in response to said output power control signal of said output amplifier according to a modulation signal applied to said predistorter; and

(g) converting said digital data outputted in said step (f) into said distortion control voltage and applying said distortion control voltage to said predistorter.

4. The method as recited in claim 3, wherein said step (d) is performed by measuring said output power control signal of said output amplifier when the power spectrum in said step (c) is suppressed by an amount greater than 60 dBm.

5. A device for storing in a read-only memory digital data for controlling a non-linear distortion characteristic of a predistorter in a radio communication transmitter, said device comprising:

a two-tone generator having an output for generating a two-tone signal having a component identical to a component of a modulation signal applied to said predistorter;

a distortion control signal generator for generating a value of a distortion signal varied by a measure;

a predistorter having inputs connected to said output of said two-tone generator and to said distortion control signal generator for performing predistortion with inputs of said distortion control signal generated by said distortion control signal generator and said two-tone signal generated by said two-tone generator;

a frequency up-converter for converting an output frequency of said predistorter into a radio frequency bandpass and providing an output;

an output amplifier for amplifying the output of said frequency up-converter with a distortion characteristic opposite to said predistortion performed by said predistorter and providing an amplified output; and

a spectrum analyzer for analyzing a power level of said output amplifier through a power spectrum, measuring an output power control signal upon generation of largest inter-modulation signal suppression, converting said measured output power control signal into a binary logic value to provide a converter signal, and mapping said converter signal to a read-only memory.

13. In the radio communication transmitter which includes a predistorter, an up-converter connected to said predistorter, and an output amplifier connected to said up-converter;

a device for controlling a non-linear distortion characteristic of the predistorter, said device comprising;

monitoring means connected to said output amplifier for monitoring an output level of said output amplifier and providing a monitor output;

distortion controller means connected to said monitoring means and responding to said monitor output for providing digital data in correspondence to said monitor output; and

storing means for storing said digital data provided by said distortion controller means, said storing means providing a control output to said predistorter;

wherein said storing means stores the digital data in a table which includes the output level of the output amplifier and at least one other quantity.

14. The device as recited in claim 13, wherein said at least one other quantity comprises a distortion control voltage.

15. In the radio communication transmitter as recited in claim 14, wherein said at least one other quantity comprises an address of the storing unit.

16. In the radio communication transmitter as recited in claim 15, wherein said at least one other quantity comprises electrically erasable and programmable read-only memory data.

17. In the radio communication transmitter as recited in claim 14, wherein said at least one other quantity comprises electrically erasable and programmable read-only memory data.

18. In the radio communication transmitter as recited in claim 13, wherein said at least one other quantity comprises an address of the storing unit.

19. In the radio communication transmitter as recited in claim 18, wherein said at least one other quantity comprises electrically erasable and programmable read-only memory data.

20. In the radio communication transmitter as recited in claim 13, wherein said at least one other quantity comprises electrically erasable and programmable read-only memory data.

21. In the radio communication transmitter as recited in claim 13, wherein said storing means comprises an electronic erasable programmable read-only memory.

22. In the radio communication transmitter as recited in claim 13, further comprising converter means connected between said storing means and said predistorter for converting the digital data from said storing means to an analog signal comprising said control output provided to said predistorter.

23. In the radio communication transmitter which includes a predistorter, an up-converter connected to said predistorter, and an output amplifier connected to said up-converter;

a device for controlling a non-linear distortion characteristic of the predistorter, said device comprising;

two-tone generator means connected to an input of said predistorter for generating a two-tone signal having a component identical to a component of a modulation signal applied to said predistorter;

distortion control signal generator means connected to said predistorter for generating a distortion control signal which is provided to said predistorter; and

spectrum analyzer means connected to said output amplifier for analyzing a power level of said output amplifier through a power spectrum, for measuring an output power control signal, for converting said measured output control signal into a binary logic value to provide a converter signal, and for mapping said converter signal to a memory unit.

24. In the radio communication transmitter as recited in claim 23, said distortion control signal generator means comprising a voltage-divider.