| 摘要 |
PROBLEM TO BE SOLVED: To shorten the time required until a distortion compensating factor is updated at the time of adjusting a reference table. SOLUTION: A digital transmitter is provided with the reference table 11 prestoring distortion compensating factors, a table adjusting signal generating section 12 which generates a table adjusting signal, and a signal selecting section 13 which selects and outputs the table adjusting signal instead of a quadrature base-band signal when the table 11 is adjusted. The transmitter is also provided with a predistortion section 15 which compensates the distortion of the output signal of the signal selecting section 13 based on one of the distortion compensating factors stored on the table 11, a quadrature modulation section 17 which performs quadrature modulation on the output signal of the section 13, and an amplifying section 18 which amplifies the quadrature modulated signals. In addition, the transmitter is also provided with a quadrature demodulation section 19 which performs quadrature demodulation on part of the quadrature modulated signals by feeding back the part and a factor updating section 21 which updates the distortion compensating factor corresponding to the power value related to the output signal of the signal selecting section 13 and stored on the table 11 based on the comparative error of the quadrature demodulated signals and the output signal of the section 13. |
