Patent attributes
A transmitter capable of carrying out a highly efficient polar coordinate modulation while maintaining an excellent distortion characteristic. When a high power amplifier is operated in a saturation mode to carry out a polar coordinate modulation, a switching control signal is set to be a multiplication, and a quadrature modulating digital signal and distortion data of a compensation table are multiplied, thereby adding a nonlinear distortion equivalent to that of the amplifier in a linear mode and compressing a peak factor of a modulating signal to enhance an efficiency of the polar coordinate modulation. When the amplifier is operated in the linear mode to carry out a linear amplification, the switching control signal is set to be a division and the quadrature modulating digital signal and the distortion data are divided, thereby adding a reverse distortion characteristic of the amplifier to carry out a nonlinear distortion compensation of the amplifier.
