TRANSMITTER FOR WIRELESS DEVICE AND METHOD AND DEVICE FOR ENHANCING EFFICIENCY OF POWER AMPLIFIER IN THE TRANSMITTER

摘要

PROBLEM TO BE SOLVED: To provide a method and a device by which a nonlinear power amplifier with low power consumption can be employed in a transmitter. SOLUTION: The power amplifier of this invention is in operation in a linear mode to enhance the ISI(Inter-Symbol Interference) when the transmission power is low. When the input power is increased, the power amplifier is in operation in a nonlinear mode to reduce the power consumption. By changing a parameter of a root raised cosine filter, the shape of the signal is changed. A conventional filter parameter is used when the input level is low and a corrected filter parameter is employed when the input level is high. The power amplifier is characterized in that the two filter parameters are switched at the base band.