| 摘要 |
PURPOSE:To improve the stability after convergence by selecting the correction coefficient of a memory content so as to calculate plural kinds of the coefficients and outputting plural correction data of the memory content to a distortion advance correction means so as to reduce the convergence time of distortion compensation value. CONSTITUTION:Multiplier selector switches 322a, 322b in a correction quantity generating circuit 318 select a multiplier 320 for constant alpha1 for a t-sec from the start of operation of a distortion compensation circuit. Then the selector switches 322a, 322b select a multiplier 321 for constant alpha2 after the lapse of the time t-sec. Let an original constant of the multipliers be alpha, the relation of 0<alpha2<alpha<alpha1<=1 is in existence. Since the constant multiplied with a nonlinear distortion quantity generated by a power amplifier is larger (alpha<alpha1) for a time t-sec after the operation start of the distortion compensation circuit from the relation, the time when data stored in a rewritable memory 310 is converged into a predetermined value is reduced. Furthermore, since the constant multiplied with a nonlinear distortion quantity generated by a power amplifier is smaller (alpha2<alpha) after the lapse of a time t-sec, the data stored in the memory 310 are not deviated from a predetermined value. |
