Abstract: Multi-mode power amplifiers that can support multiple radio technologies and/or multiple frequency bands are described. In one exemplary design, a first linear power amplifier supporting multiple radio technologies may be used to amplify a first RF input signal (e.g., for low band) and provide a first RF output signal. A second linear power amplifier also supporting the multiple radio technologies may be used to amplify a second RF input signal (e.g., for high band) and provide a second RF output signal. Each linear power amplifier may include multiple (e.g., three) chains coupled in parallel. Each chain may be selectable to amplify an RF input signal and provide an RF output signal for a respective range of output power levels. An RF input signal may be a phase modulated signal or a quadrature modulated signal and may be pre-distorted to account for non-linearity of the power amplifier.

Abstract: A method for measuring non-linear characteristics of a power amplifier is described. A calibration waveform is calculated during a testing procedure period. Amplitude characteristics of the calibration waveform at the output of the power amplifier are measured during the testing procedure period. Phase characteristics of the calibration waveform at the output of the power amplifier are measured during the testing procedure period. Pre-distortion techniques are configured based on the amplitude characteristics and the phase characteristics to be used during a normal operation period of a transmitter.

Abstract: Multi-mode power amplifiers that can support multiple radio technologies and/or multiple frequency bands are described. In one exemplary design, a first linear power amplifier supporting multiple radio technologies may be used to amplify a first RF input signal (e.g., for low band) and provide a first RF output signal. A second linear power amplifier also supporting the multiple radio technologies may be used to amplify a second RF input signal (e.g., for high band) and provide a second RF output signal. Each linear power amplifier may include multiple (e.g., three) chains coupled in parallel. Each chain may be selectable to amplify an RF input signal and provide an RF output signal for a respective range of output power levels. An RF input signal may be a phase modulated signal or a quadrature modulated signal and may be pre-distorted to account for non-linearity of the power amplifier.

Abstract: A method for measuring non-linear characteristics of a power amplifier is described. A calibration waveform is calculated during a testing procedure period. Amplitude characteristics of the calibration waveform at the output of the power amplifier are measured during the testing procedure period. Phase characteristics of the calibration waveform at the output of the power amplifier are measured during the testing procedure period. Pre-distortion techniques are configured based on the amplitude characteristics and the phase characteristics to be used during a normal operation period of a transmitter.