Device and method for linearizing transmitter in digital communication system

• US 6,373,902 B1
• Filed: 06/19/1998
• Issued: 04/16/2002
• Est. Priority Date: 06/19/1997
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Park, Jae-Sun, Ha, Ji-Won, Choi, Gin-Kyu
• Primary Examiner(s): CORRIELUS, JEAN B
• Application Number:
  US09/100,331
• Time in Patent Office: 1,397 Days
• Field of Search: 375/296, 375/295, 375/297, 375/259, 375/285, 375/254, 455/126, 455/115, 455/63, 330/49, 327/317, 332/123, 332/124, 332/159, 332/160, 332/162
• US Class Current: 375/296
• CPC Class Codes: H04L 27/367 using predistortion

Abstract

A device for linearizing a transmitter in a digital radio communication system. In the device, a predistortion lookup table stores predistortion data determined by measuring in advance distortion characteristics of the transmitter with respect to input baseband data. During transmission, the device synthesizes the input baseband data with the predistortion data to predistort the input data so as to compensate for the distortion characteristics caused by non-linear elements constituting the transmitter.

Claims

1. A device for linearizing a transmitter using a predistortion technique in a communication system, comprising:

a memory including a predistortion lookup table storing predistortion data determined by measuring, in advance, distortion characteristics of the transmitter with respect to input baseband data;

an address former accommodating a forming of an address of the memory depending on the input baseband data;

a filter coefficient generator adding a reference filter coefficient to the predistortion data output from the memory to generate predistortion filter coefficients; and

first and second baseband filters generating a predistorted baseband data output by predistorting and filtering the input baseband data according to said predistortion filter coefficients;

wherein the transmitter compensates for distortion characteristics caused by non-linear elements while the predistorted baseband data output from the baseband filters are modulated, up-converted, and amplified.

2. A device for linearizing a transmitter using a predistortion technique in a communication system, comprising:

a memory including a predistortion lookup table storing predistortion data determined by measuring, in advance, distortion characteristics of the transmitter with respect to input baseband data;

an address former accommodating a forming of an address of the memory depending on the input baseband data;

a filter coefficient generator adding a reference filter coefficient to the predistortion data output from the memory to generate predistortion filter coefficients; and

first and second baseband filters generating a predistorted baseband data output by predistorting and filtering the input baseband data according to said predistortion filter coefficients;

wherein the transmitter compensates for distortion characteristics caused by non-linear elements while the predistorted baseband data output from the baseband filters are modulated, up-converted, and amplified;

wherein said predistortion lookup table further storing said predistortion data according to a change of transmission power of the transmitter.

3. The device of claim 2, wherein said address former comprising:

a power control offset address mapper including a power offset address table generating an offset address according to the change of the transmission power, and mapping a current transmission power into the power offset address table to generate a power offset address; and

an address summer adding the power offset address to the baseband data to generate the address for the memory.

4. A device for linearizing a transmitter using a predistortion technique in a communication system, comprising:

a memory including a predistortion lookup table storing predistortion data determined by measuring, in advance, distortion characteristics of the transmitter with respect to input baseband data;

an address former accommodating a forming of an address of the memory depending on the input baseband data;

a filter coefficient generator adding a reference filter coefficient to the predistortion data output from the memory to generate predistortion filter coefficients; and

first and second baseband filters generating a predistorted baseband data output by predistorting and filtering the input baseband data according to said predistortion filter coefficients;

wherein the transmitter compensates for distortion characteristics caused by non-linear elements while the predistorted baseband data output from the baseband filters are modulated, up-converted, and amplified;

wherein said predistortion lookup table further storing said predistortion data according to a change of surrounding temperature of the transmitter.

5. The device of claim 4, wherein said address former comprising:

a temperature compensating offset address mapper including a temperature offset address table generating an offset address according to the change of the surrounding temperature, and mapping a current surrounding temperature into the temperature offset address table to generate a temperature offset address; and

an address summer adding the temperature offset address to the baseband data to generate the address for the memory.

6. A device for linearizing a transmitter using a predistortion technique in a communication system, comprising:

a memory including a predistortion lookup table storing predistortion data determined by measuring, in advance, distortion characteristics of said transmitter with respect to input baseband data;

an address former accommodating a forming of addresses for said memory depending on the input baseband data;

a multiplier accommodating a multiplying of the input baseband data by the predistortion data to generate predistorted baseband data;

a converter accommodating converting of an output of said multiplier to an analog baseband signal;

a lowpass filter accommodating a lowpass filtering of an output of said converter to produce a predistorted baseband transmission signal; and

said transmitter modulating, up-converting, and power-amplifying the predistorted baseband transmission signal, wherein said predistorted baseband transmission signal is offset by a distortion signal caused by non-linear elements of said transmitter, so that a final transmission signal is free from distortion;

wherein said predistortion lookup table further storing said predistortion data according to a change of transmission power of said transmitter;

wherein said address former comprising;

a power control offset address mapper including a power offset address table generating an offset address according to the change of the transmission power, and mapping a current transmission power into the power offset address table to generate a power offset address; and

an address summer adding the power offset address to the baseband data to generate each address for the memory.

7. A device for linearizing a transmitter using a predistortion technique in a communication system, comprising:

a memory including a predistortion lookup table storing predistortion data determined by measuring, in advance, distortion characteristics of said transmitter with respect to input baseband data;

an address former accommodating a forming of addresses for said memory depending on the input baseband data;

a multiplier accommodating a multiplying of the input baseband data by the predistortion data to generate predistorted baseband data;

a converter accommodating converting of an output of said multiplier to an analog baseband signal;

a lowpass filter accommodating a lowpass filtering of an output of said converter to produce a predistorted baseband transmission signal; and

said transmitter modulating, up-converting, and power-amplifying the predistorted baseband transmission signal, wherein said predistorted baseband transmission signal is offset by a distortion signal caused by non-linear elements of said transmitter, so that a final transmission signal is free from distortion;

wherein said predistortion lookup table further storing said predistortion data according to a change of surrounding temperature of said transmitter;

wherein said address former comprising;

a temperature compensating offset address mapper including a temperature offset address table generating an offset address according to the change of the surrounding temperature, and mapping a current surrounding temperature into the temperature offset address table to generate a temperature offset address; and

an address summer adding the temperature offset address to the baseband data to generate each address for the memory.

8. A device for linearizing a transmitter using a predistortion technique in a communication system, comprising:

a memory including a predistortion lookup table storing predistortion data determined by measuring, in advance, distortion characteristics of said transmitter with respect to input baseband data;

an address former accommodating forming of addresses for said memory depending on the input baseband data;

a converter accommodating converting the input baseband data to an analog baseband signal;

a multiplier accommodating multiplying the analog baseband signal by the predistortion data to generate a predistorted transmission signal;

a lowpass filter accommodating lowpass filtering of the predistorted transmission signal to produce a baseband transmission signal; and

said transmitter modulating, up-converting, and power-amplifying the baseband transmission signal, wherein said baseband transmission signal is offset by a distortion signal caused by non-linear elements of said transmitter, so that a final transmission signal is free from distortion.

9. A device for linearizing a transmitter using a predistortion technique in a communication system, comprising:

a memory including a predistortion lookup table storing predistortion data determined by measuring, in advance, distortion characteristics of said transmitter with respect to input baseband data;

an address former accommodating forming of addresses for said memory depending on the input baseband data;

a converter accommodating converting the input baseband data to an analog baseband signal;

a multiplier accommodating multiplying the analog baseband signal by the predistortion data to generate a predistorted transmission signal;

a lowpass filter accommodating lowpass filtering of the predistorted transmission signal to produce a baseband transmission signal; and

said transmitter modulating, up-converting, and power-amplifying the baseband transmission signal, wherein said baseband transmission signal is offset by a distortion signal caused by non-linear elements of said transmitter, so that a final transmission signal is free from distortion;

wherein said predistortion lookup table further storing said predistortion data according to a change of transmission power of said transmitter.

10. The device of claim 9, wherein said address former comprising:

a power control offset address mapper including a power offset address table generating an offset address according to the change of the transmission power, and mapping a current transmission power into the power offset address table to generate a power offset address; and

an address summer adding the power offset address to the baseband data to generate each address for said memory.

11. A device for linearizing a transmitter using a predistortion technique in a communication system, comprising:

a memory including a predistortion lookup table storing predistortion data determined by measuring, in advance, distortion characteristics of said transmitter with respect to input baseband data;

an address former accommodating forming of addresses for said memory depending on the input baseband data;

a converter accommodating converting the input baseband data to an analog baseband signal;

a multiplier accommodating multiplying the analog baseband signal by the predistortion data to generate a predistorted transmission signal;

a lowpass filter accommodating lowpass filtering of the predistorted transmission signal to produce a baseband transmission signal; and

said transmitter modulating, up-converting, and power-amplifying the baseband transmission signal, wherein said baseband transmission signal is offset by a distortion signal caused by non-linear elements of said transmitter, so that a final transmission signal is free from distortion;

wherein said predistortion lookup table further storing said predistortion data according to a change of surrounding temperature of said transmitter.

12. The device of claim 11, wherein said address former comprising:

a temperature compensating offset address mapper including a temperature offset address table generating an offset address according to the change of the surrounding temperature, and mapping a current surrounding temperature into the temperature offset address table to generate a temperature offset address; and

an address summer adding the temperature offset address to the baseband data to generate each address for said memory.

13. A method for linearizing a transmitter using a predistortion technique in a communication system having a predistortion lookup table for storing predistortion data determined by measuring, in advance, distortion characteristics of the transmitter with respect to input baseband data and transmission power, said method comprising the steps of:

forming an address according to the input baseband data and a transmission power control signal;

reading the predistortion data from the predistortion lookup table according to the address and outputting the read predistortion data as a filter coefficient; and

lowpass filtering the input baseband data and predistorting the baseband data according to said filter coefficient, so as to compensate the distortion characteristics caused by non-linear elements of the transmitter.