System and method of baseband linearization for a class G radiofrequency power amplifier

A system of baseband linearization for a class G radiofrequency (RF) power amplifier, the linearization system comprising:

• a first input configured to receive an input digital baseband signal to be emitted comprising an in-phase component, I, and a quadrature component, Q;
• a first output configured to output a linearized output baseband digital signal to the class G RF power amplifier;
• a second input configured to receive a baseband digital signal coming from the output of the class G RF power amplifier;
• and
• a second output configured to output a digital power supply voltage selection signal to a DC-DC converter connected to the class G RF power amplifier;
• the linearization system further comprising:
• a module for selecting an amplifier power supply voltage, the input of the module for selecting the amplifier power supply voltage being connected to the first input of the linearization system and the output of the module for selecting the amplifier power supply voltage being connected to the second output of the linearization system, the module for selecting the amplifier power supply voltage being configured to select a power supply voltage from among at least two DC power supply voltages of the DC-DC converter as a function of the amplitude of the received input digital baseband signal to be emitted;
• a digital predistortion module connected to the first input of the linearization system and configured to perform a digital predistortion of the I and Q components of the received input digital baseband signal to be emitted;
• and
• a module for extracting predistortion coefficients, an input of the module for extracting predistortion coefficients being connected to the second input of the linearization system and configured to extract predistortion coefficients used by the digital predistortion module;
• wherein the linearization system further comprises:
• a digital filter with complex coefficients, the input of the digital filter with complex coefficients being connected to the output of the digital predistortion module and the output of the digital filter with complex coefficients being connected to the first output of the linearization system;
• and
• a module for extracting filter coefficients, an input of the module for extracting filter coefficients being connected to the second input of the linearization system and configured to extract filter coefficients used by the digital filter with complex coefficients;
• the module for extracting filter coefficients being configured to extract the filter coefficients as a function of the I and Q components of the received input digital baseband signal to be emitted, of the baseband digital signal coming from the output of the class G RF power amplifier, of the output of the digital filter with complex coefficients, and of the output of the digital predistortion module;
• the module for extracting filter coefficients comprising three time delay units, a gain calculating unit, a filter output expected signal calculating unit, two fast Fourier transform (FFT) units, a filter frequency response calculating unit and a filter coefficient extraction unit,
• the three time delay units respectively being configured to compensate propagation and processing times of the I and Q components of the received input digital baseband signal to be emitted, the output of the digital filter with complex coefficients and the output of the digital predistortion module,
• the gain calculating unit being configured to calculate the complex gain of the class G RF power amplifier from the delayed output of the digital filter with complex coefficients and the baseband digital signal coming from the output of the class G RF power amplifier,
• the filter output expected signal calculating unit being configured to calculate a signal to be generated by the digital filter with complex coefficients from the calculated complex gain and the delayed I and Q components of the received input digital baseband signal to be emitted,
• the two FFT units respectively being configured to calculate the Fourier transforms of the delayed output of the digital predistortion module and the signal to be generated by the digital filter with complex coefficients calculated by the filter output expected signal calculating unit,
• the filter frequency response calculating unit being configured to calculate the frequency response of the digital filter with complex coefficients to be generated from the Fourier transforms calculated by the FFT units, and
• the filter coefficient extraction unit being configured to extract the complex coefficients of the digital filter with complex coefficients to be synthesized as a function of the frequency response calculated by the filter frequency response calculating unit.