Apparatus and method for amplifying multi-mode power using pre-distorter

1. A method for amplifying power in a communication system, comprising steps of:

detecting a power level of a predetermined signal selected from among an input signal and an output signal;

adaptively changing a gate bias in accordance with the detected power level;

generating a pre-distortion component through operation of a single carrier mode or a multi-carrier mode in accordance with the changed gate bias; and

outputting only the predetermined signal after offsetting a distortion component generated during amplification of the predetermined signal by synthesizing the pre-distortion component with the distortion component.

2. The method as claimed in claim 1 , wherein the predetermined signal is determined to be a single carrier signal when the detected level exceeds a threshold and to be a multi-carrier signal when the detected level does not exceed the threshold.

3. The method as claimed in claim 2 , further comprising, when the predetermined signal is a single carrier signal, changing a class of the power amplifier to class B through control of the gate bias of the power amplifier, and generating and outputting a pre-distortion component corresponding to class B.

4. The method as claimed in claim 2 , further comprising, when the predetermined signal is a multi-carrier signal, changing a class of the power amplifier to class A through control of the gate bias of the power amplifier, and generating and outputting a pre-distortion component corresponding to class A.

5. An apparatus for amplifying power in a communication system, comprising:

a detection module which detects a power level of a predetermined signal selected from among an input signal and an output signal of a power amplifier and then transmits an operation mode control signal for the power amplifier;

a gate bias controller which controls a gate bias of the power amplifier in accordance with the detected power level; and

a power amplifier which operates in a class B region or a class A region in accordance with control by the gate bias controller to generate a pre-distortion component, offsets a distortion component generated during amplification of the predetermined signal by synthesizing the pre-distortion component with the distortion component, and outputs only the predetermined signal without distortion component.

6. The apparatus as claimed in claim 5 , wherein the detection module comprises an input signal detector for detecting the input signal input to the power amplifier.

7. The apparatus as claimed in claim 5 , wherein the detection module comprises an output signal detector for detecting the output signal output from the power amplifier.

8. The apparatus as claimed in claim 5 , wherein the detection module determines if the predetermined signal is a single carrier signal with a high power or a multi-carrier signal of a low power.

9. The apparatus as claimed in claim 5 , wherein, when the predetermined signal is a single carrier signal with a high power, the gate bias controller controls the gate bias of the power amplifier, so as to cause the power amplifier to operate in the class B region.

10. The apparatus as claimed in claim 5 , wherein, when the predetermined signal is a multi-carrier signal with a low power, the gate bias controller controls the gate bias of the power amplifier, so as to cause the power amplifier to operate in the class A region.

11. The apparatus as claimed in claim 5 , wherein the power amplifier comprises a drive amplifier using a Gallium Arsenic Field Effect Transistor (GaAs FET) and a main amplifier using a Laterally Diffused Metal Oxide Semiconductor (LDMOS) transistor.

12. The apparatus as claimed in claim 11 , wherein the drive amplifier operates as a single carrier power amplifier according to a gate bias of the GaAs FET.

13. The apparatus as claimed in claim 11 , wherein the drive amplifier operates as a multi-carrier power amplifier according to a gate bias of the GaAs FET.