Linearization of a transmit amplifier

A method of compensating for predistortion of a transmit amplifier, said method comprising the steps of:

• scanning a plurality of transmit amplifier codes;
• generating a transmit amplifier output signal in accordance with each code scanned;
• providing controlled leakage of said transmit amplifier output signal to a receiver chain operative to demodulate said transmit amplifier output signal to yield I and Q samples therefrom;
• calculating amplitude and phase distortion values in accordance with said I and Q samples;
• and
• calibrating a predistortion table with said amplitude and phase distortion values.

A method of predistortion calibration of a transmit amplifier, said method comprising the steps of:

• stepping through a dynamic range of codes of said transmit amplifier;
• inputting each code to a transmit chain comprising a predistortion look up table (LUT) of transmit amplifier predistortion values to generate a radio frequency (RF) output signal in response thereto;
• demodulating said RF output signal to recover I and Q samples therefrom;
• calculating an instantaneous correction to the predistortion values stored in said predistortion LUT in accordance with said recovered I and Q values;
• and
• updating the contents of said predistortion LUT in accordance with said calculated instantaneous correction.

An apparatus for calibrating predistortion of a digitally controlled pre-power amplifier (DPA) and power amplifier (PA), comprising:

• means for stepping through a range of codes of said DPA;
• a transmit chain comprising a predistortion look up table (LUT) adapted to store a plurality of amplifier predistortion values, said transmit chain operative to generate a radio frequency (RF) output signal in response to each code;
• means for coupling said RF output signal to a receiver chain;
• said receive chain operative to demodulate said RF output signal to generate recovered I and Q samples therefrom;
• means for calculating corrections to the predistortion values stored in said predistortion LUT in accordance with said recovered I and Q values;
• and
• update means for updating the contents of said predistortion LUT in accordance with said calculated corrections.

A method of hybrid linearization compensation for use in a transceiver, said method comprising the steps of:

• first performing predistortion compensation during the ramp portion of a first end of a transmission burst to generate relative power level information feedback to update a predistortion look up table (LUT) thereby;
• second performing power control level (PCL) compensation during the ramp portion of a second end of said transmission burst to generate absolute power level information feedback and to update a power control LUT thereby;
• and
• tracking changes in said power control LUT over an operational range of said transceiver in accordance with said relative power level information feedback and said absolute power level information feedback.