Patent ID: 7684514
Filing Date: 2010-03-23
Classification: H03F,H03G,H04B,H04L,H04W

Abstract:
1. A transmitter comprising: a quadrature modulation unit which inputs an in-phase component and a quadrature component of an input modulation signal and performs quadrature modulation; a variable gain amplification unit which amplifies an output of the quadrature modulation unit with a predetermined gain being controlled based on a gain control signal; and a power amplification unit which performs power amplification of an output of the variable gain amplification unit, wherein the power amplification unit has a linear mode for performing power amplification using a linear operation region in an input/output power characteristic and a saturation mode for performing power amplification using a saturation operation region in the input/output power characteristic, and wherein, if transmission output power of the power amplification unit is equal to or greater than a predetermined value, the output level of the variable gain amplification unit is adjusted, the power amplification unit is operated in the saturation mode, and a transmission output control signal amplitude-modulated based on an amplitude component of the input modulation signal is input to an output control input terminal of the power amplification unit for performing polar coordinate modulation; if the transmission output power is less than the predetermined value, the output level of the variable gain amplification unit is adjusted, the power amplification unit is operated in the linear mode, and a transmission output control signal of a predetermined level responsive to the transmission output power is input to the output control input terminal for performing linear amplification.