| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a transmitter apparatus performing a high-efficiency polar coordinate modulation while maintaining a good distortion characteristic. <P>SOLUTION: In the case of causing a large power amplifier 13 to operate in a saturation mode to perform a polar coordinate modulation, a switch control signal to be inputted to a multiplication/division switch terminal 33 is set to multiplication, whereby a distortion compensating part 17 multiplies quadrature modulated digital signals from I and Q input terminals 31 and 32 by distortion data from a compensation table 16, thereby adding a nonlinear distortion, which is equivalent to that during use of the large power amplifier 13 in a linear mode, to compress the peak factor of the modulated signals, thereby enhancing the efficiency of the polar coordinate modulation. In the case of causing the large power amplifier (13) to operate in a linear mode to perform a linear amplification, the switch control signal is set to division, whereby the distortion compensating part 17 divides the quadrature modulated digital signals by the distortion data, thereby adding a reverse distortion characteristic of the large power amplifier 13 to perform a nonlinear distortion compensation of the large power amplifier 13. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
