Patent ID: 6081698
Filing Date: 2000-06-27
Classification: H01Q,H03C,H03F,H04B,H04L

Abstract:
A radio apparatus having a distortion compensating function in which transmission baseband signals comprising digital signals of I and Q components outputted by an arithmetic/control unit are converted to analog signals, the analog signals are applied to an orthogonal modulator via respective amplifiers, a reference carrier wave is orthogonally modulated by the transmission baseband signals to produce modulated waves for transmission, the modulated waves are caused to branch to an orthogonal detector, demodulated signals of I and Q components obtained by orthogonally detecting the modulated waves by said reference carrier wave are converted to respective digital signals to obtain reception baseband signals that are fed back to said arithmetic/control unit, and said arithmetic/control unit compares the baseband signals fed back and the transmission baseband signals and subjects the transmission baseband signals to pre-distortion processing based upon results of the comparison, thereby eliminating waveform distortion from the modulated waves for transmission, said apparatus comprising:a leakage carrier detector for detecting leakage carrier based upon offset of the orthogonal modulator;an offset detector for converting the leakage carrier to a direct current and generating a signal conforming to the offset; anda controller for generating a control signal based upon the offset detected and performing control in such a manner that the offset is minimized by changing an operating reference point of said amplifiers by said control signal to adjust input signal values of the I and Q components applied to said orthogonal modulator.