Apparatus and method of linearizing a power amplifier in a mobile radio communication system

A method of linearizing a power amplifier in a mobile radio communication system having a predistortion lookup table for storing predistortion data and a feedforward lookup table for storing feedforward control data, comprising the steps of

• linearizing an input signal by distorting the input signal using the stored predistortion data and controlling a gain of the predistorted input signal in accordance with the stored feedforward control data;
• power-amplifying and outputting the linearized input signal;
• producing an error signal by comparing a signal resulting from a feed-back of the output signal with a delayed input signal said delayed input signal generated by delaying the input signal;
• and
• updating the predistortion lookup table by adding the error signal to the predistortion data and storing the added data in the predistortion lookup table determined by the input data, and applying the error signal to an address of the feedforward lookup table.

An apparatus for linearizing a power amplifier in a mobile radio communication system, comprising:

• a predistortion lookup table for storing predistortion data;
• a feedforward lookup table for storing feedforward control data;
• an address generator for generating an address of the predistortion lookup table using an input signal;
• means for distorting the input signal by the predistortion data to generate a predistorted signal;
• a quadrature modulator for modulating the predistorted signal to generate a modulate d predistorted signal;
• a delay for delaying the modulated predistorted signal to generate a delayed modulated predistorted signal;
• a linearizer for removing a signal band by coupling the modulated predistorted signal, gain-controlling a filtered signal in accordance with the feedforward control data, and then coupling a gain-controlled signal to the delayed modulated predistorted signal;
• the power amplifier for power-amplifying an output of the linearizer to generate a power amplified signal;
• a quadrature demodulator for demodulating the power-amplified signal by coupling;
• an error detector for detecting an error between the input and output signals by comparing an output of the demodulator and a delayed input signal and outputting a corresponding error signal, said delayed input signal generated by delaying the input signal;
• a predistortion lookup table controller for updating the data of the predistortion lookup table which corresponds to a position of a present input data by adding the error signal from the error detector to an output of the predistortion lookup table;
• and
• a feedforward lookup table controller for controlling the feedforward lookup table to output corresponding feedforward control data by detecting a size of the error signal.