Patent ID: 7944295

Claim:
A predistorter adapted to compensate for distortion generated in an amplifier, comprising: a level detection means for detecting a level of a signal input to said predistorter; a signal acquisition means for acquiring a signal output from the amplifier as a feedback signal; a correspondence acquisition means for independently updating predistortion coefficients of multiple polynomials in a set of orthogonal polynomials, the multiple polynomials being a function of the signal input to said predistorter and are mutually orthogonal, and for acquiring a correspondence between the level of the signal input to said predistorter and a control coefficient for predistortion based on the updated predistortion coefficients; and a predistortion executing means for applying distortion for predistortion to the signal input to said predistorter in accordance with the control coefficient for predistortion that corresponds to the level detected by said level detection means based on the correspondence acquired by said correspondence acquisition means, and outputting a distortion-applied-signal to the amplifier, wherein said correspondence acquisition means updates the predistortion coefficients of the multiple polynomials in the set of orthogonal polynomials so that a distortion component contained in the feedback signal acquired by said signal acquisition means is reduced, wherein said predistortion executing means comprises: a first predistortion executing means that serves as a memoryless predistorter adapted to compensate for AM-AM and AM-PM characteristics; and a second predistortion executing means that serves as a memory effect predistorter adapted to compensate for memory effects, wherein said first and second predistortion executing means are provided in parallel, and said correspondence acquisition means is adapted to update a predistortion coefficient for each of said first and second predistortion executing means expressed using the set of orthogonal polynomials, and to acquire a correspondence between the level of the signal input to said predistorter and a control coefficient for predistortion for each of said first and second predistortion executing means.