Patent ID: 8599965

Claim:
A transmitter circuit that implements two modulation modes which are a polar modulation mode and a quadrature modulation mode, switches between the modulation modes according to an instruction, and generates a transmission signal, the transmitter circuit comprising: a signal generation section for transforming input data into an amplitude component signal and a phase component signal in the polar modulation mode, and transforming the input data into an in-phase component signal and a quadrature component signal in the quadrature modulation mode, to output an obtained signal; a first synthesizer section having a first VCO; a second synthesizer section having a second VCO that consumes less current than the first VCO; a mixer section; and an amplifier section, wherein the transmitter circuit operates in at least a first operation state, a second operation state, and a third operation state, in the first operation state, a modulation is performed in the polar modulation mode such that the first synthesizer section generates a phase-modulated signal based on the phase component signal, and the amplifier section performs amplification to combine the phase-modulated signal with the amplitude component signal, to generate the transmission signal, in the second operation state, a modulation is performed in the quadrature modulation mode such that the first synthesizer section generates a carrier wave, and the mixer section generates the transmission signal from the carrier wave, the in-phase component signal, and the quadrature component signal, in the third operation state, a modulation is performed in the quadrature modulation mode such that the second synthesizer section generates the carrier wave, and the mixer section generates the transmission signal from the carrier wave, the in-phase component signal, and the quadrature component signal, when an instruction for switching to a quadrature modulation is received in the first operation state, the transmitter circuit shifts to the second operation state, and the second synthesizer section is powered on, and after a predetermined time period has elapsed, the transmitter circuit shifts to the third operation state, and the first synthesizer section is powered off, and when an instruction for switching to a polar modulation is received in the third operation state, the first synthesizer section is powered on, and after a predetermined time period has elapsed, the transmitter circuit shifts to the first operation state, and the second synthesizer section is powered off.