Radio apparatus and offset compensating method

摘要

Disclosed is a radio apparatus in which modulating signals (I, Q signals) from an arithmetic/control unit are converted to analog signals, which are then applied to an orthogonal modulator. A modulated wave for transmission, which has been produced by orthogonally modulating a reference carrier wave by the modulating signals, is demodulated by the orthogonal detector. The arithmetic/control unit compares the modulating signals and the demodulated signals and, based upon the comparison, updates distortion compensation coefficients and applies pre-distortion processing to the modulating signal using the distortion compensation coefficients. Leakage carrier produced due to offset of the orthogonal modulator is detected and the arithmetic/control unit adjusts the level of the modulating signals or shifts the phase of the reference carrier wave in such a manner that the leakage carrier (offset) becomes zero.