Patent attributes
A system is provided for pre-distorting a transmit signal in a mobile terminal prior to amplification by a power amplifier to compensate for AM to AM and AM to PM distortion over an input value range. Pre-distortion circuitry includes both amplitude and phase pre-distortion circuitries. The amplitude pre-distortion circuitry distorts an amplitude component of a polar transmit signal using an amplitude compensation signal that essentially cancels the AM to AM distortion, and the phase pre-distortion circuitry distorts a phase component of the polar transmit signal using a phase compensation signal that essentially cancels the AM to PM distortion. The amplitude and phase compensation signals are generated based on corresponding sets of coefficients selected from a number of sets of coefficients defining polynomials describing compensation signals for each of at least two subsets of the input value range for each of two or more power levels of the power amplifier circuitry.
