Patent ID: 7664202
Filing Date: 2010-02-16
Classification: H03F

Abstract:
1. A transmission device using polar modulation, comprising: an amplitude/phase separation section for separating an input baseband modulation signal into a baseband amplitude modulation signal and a baseband phase modulation signal; a frequency synthesizer for performing phase modulation on a radio frequency carrier signal with the baseband phase modulation signal to generate a radio frequency phase modulated signal; a multiplier for multiplying the baseband amplitude modulation signal by a predetermined value; a first switching section and a second switching section for allowing the baseband amplitude modulation signal, obtained as a result of the multiplication and output from the multiplier, and a predetermined DC voltage signal to be input thereto, and selecting and outputting one of the signals; an amplitude modulation signal amplifier for supplying a supply voltage based on the signal which is output from the first switching section; a variable gain amplifier for amplifying the radio frequency phase modulated signal generated by the frequency synthesizer in accordance with the signal which is output from the second switching section; a radio frequency power amplifier for performing power amplification on the radio frequency phase modulated signal amplified by the variable gain amplifier, using the supply voltage supplied from the amplitude modulation signal amplifier; and a third switching section and a fourth switching section, respectively provided before and after the radio frequency power amplifier, for selecting either to output the radio frequency phase modulated signal amplified by the variable gain amplifier via the radio frequency power amplifier or to output the radio frequency phase modulated signal without using the radio frequency power amplifier; wherein the switching operation of the first through fourth switching sections is controlled in accordance with a power level of a signal which is to be output from the fourth switching section.