| 摘要 |
PROBLEM TO BE SOLVED: To provide a circuit configuration with which circuit scale is reduced and a high speed operation and high-accuracy compensation is realized in a nonlinear compensation circuit of an adaptive predistortion system having a local demodulator. SOLUTION: The fluctuation range of an input signal level is expressed with a plurality of signal level representative points, a compensation coefficient is calculated only at the representative points, and compensation coefficients at other levels are found by interpolation so that the circuit scale can be reduced and operations can be accelerated. Besides, concerning the calculation of the compensation coefficient, the calculation is recursively performed by a feedback loop using a cumulative multiplier so that high-accuracy compensation is enabled. |
