| 摘要 |
PROBLEM TO BE SOLVED: To correct orthogonal distortion by providing a variable phase shifter that shifts the phase of a carrier, a Q detection circuit that receives a digital input signal and a carrier outputted from the variable phase shifter and obtains a base band Q signal, and a Q axis control circuit that controls the gain of the Q detection circuit. SOLUTION: The Q detection circuit 19 multiplies a carrier from a carrier oscillator 10 whose phase is shifted by a variable phase shifter 18 with an input signal to obtain a Q signal that is a base band signal. A Q axis control circuit 20 controls the gain and phase of the Q signal to control a phase shift quantity of the variable phase shifter 18 so as to maximize the vector quantity of the Q signal on a Q axis in the positive and negative directions. Then the Q axis control circuit 20 controls the Q detection circuit 19 in a way that a maximum amplitude of an I signal is equal to that of the Q signal, and the Q detection circuit 19 controls the gain of the outputted Q signal. Thus, even on the occurrence of phase distortion, the distortion can be corrected and the correction is made complete in a short time because the configuration is simple. |
