Patent ID: 7881399

Claim:
A transmission circuit for generating and outputting a transmission signal based on input data, the transmission circuit comprising: a signal generation section for performing predetermined signal processing on the input data, thereby generating an amplitude signal and an angle-modulated signal; an amplitude calculation section for performing predetermined arithmetic processing on the amplitude signal, and outputting a resultant signal as a discrete value signal having a plurality of discrete values corresponding to a magnitude of the amplitude signal; a delta-sigma modulated signal generation section for delta-sigma modulating the amplitude signal in accordance with the discrete value signal, and outputting a resultant signal as a delta-sigma modulated signal; an amplitude amplifying section for outputting a signal corresponding to a magnitude of the delta-sigma modulated signal; and an amplitude modulation section for amplitude-modulating, by amplifying the angle-modulated signal in accordance with the signal outputted from the amplitude amplifying section, the angle-modulated signal, and outputting a resultant signal as a transmission signal having been angle-modulated and amplitude-modulated, wherein the amplitude calculation section retains at least one threshold value and two or more discrete values corresponding to the at least one threshold value, and determines, at predetermined time periods, whether or not the amplitude signal exceeds the at least one threshold value; selects, based on a determination result, a discrete value to be outputted; and outputs the selected discrete value as the discrete value signal.