Patent ID: 7688156

Claim:
A transmission circuit for generating a transmission signal based on input data and outputting the transmission signal, the transmission circuit comprising: a signal generation section for generating an amplitude signal and a phase signal based on an amplitude component and a phase component obtained by performing signal processing on the data; a variable gain amplification section for amplifying or attenuating the amplitude signal with a controlled gain; a regulator for outputting a signal in accordance with a magnitude of the amplitude signal which is output from the variable gain amplification section; an angle modulation section for performing angle modulation on the phase signal and outputting the resultant signal as an angle-modulated signal; an amplitude modulation section for performing amplitude modulation on the angle-modulated signal with the signal which is output from the regulator into a modulated signal, attenuating the modulated signal with a controlled attenuation, and outputting the resultant signal as a transmission signal; and a control section for receiving power information representing a level of a power of a transmission signal to be output, and controlling a gain to be set in the variable gain amplification section and an attenuation to be set in the amplitude modulation section based on the power information; wherein the control section compares a value of the power information with at least one predetermined threshold value, and determines the gain to be set in the variable gain amplification section and the attenuation to be set in the amplitude modulation section based on the comparison result.