| 摘要 |
<P>PROBLEM TO BE SOLVED: To compensate linear distortion irrespective of the magnitude of transmitted electric power by utilizing the features of an update system and a perturbation method upon calculating affine transformation coefficients. <P>SOLUTION: An analog quadrature modulator 22 outputs an output signal of an affine transformation unit 21 to an RF band and converts part of the signal to an IF band in a frequency converter 23. A digital quadrature detector 24 subjects the signal converted to the IF band to quadrature detection to eliminate a carrier component and outputs an IF frequency complex feedback signal. A control part 26 detects the level of the complex feedback signal, and when the level exceeds a certain threshold value, detects DC offset, a shift in gain ratio, and a shift in the degree of quadrature by means of a first CLC detection algorithm using an update formula to update the compensation coefficients of the affine transformation unit 21. In contrast, when the signal level is not more than the threshold value, the control part detects only DC offset by means of a second CLC detection algorithm using the perturbation method to update the compensation coefficients of the affine translation unit 21. <P>COPYRIGHT: (C)2008,JPO&INPIT |
