Patent ID: 7180368
Filing Date: 2007-02-20
Classification: H03F

Abstract:
1. A distortion compensating circuit which detects distortion components generated in a power amplifying circuit amplifying power of a high frequency input signal according to an output signal and an input signal of the power amplifying circuit; and generates a distortion compensating signal according to the detected distortion components, said distortion compensating circuit comprising: an adjustment circuit which adjusts the input signal and the output signal so as to eliminate a level error, a phase error and a delay error between the input signal and the output signal; a distortion coefficient detection circuit which calculates an error signal representing the difference between the adjusted input signal and output signal, and calculates, from the calculated error signal and the input signal, at least a coefficient, specific to the power amplifying circuit, of a third-order intermodulation distortion partly constituting the detected distortion components and additionally a coefficient, specific to the power amplifying circuit, of a fifth-order intermodulation detected distortion partly constituting the distortion components and a coefficient, specific to the power amplifying circuit, of a seventh-order intermodulation distortion partly constituting the detected distortion components; and a distortion compensating signal generating circuit which generates, according to the calculated coefficients, a distortion compensating signal which is characteristically opposite in phase and gain to the intermodulation distortions.