Patent ID: 7778612

Claim:
A polar modulation circuit, comprising: a phase modulation section which generates a phase modulation signal based on a signal having at least a phase component in a baseband orthogonal signal generated from transmit data; an offset storage section which stores a DC offset of an output signal characteristic (AM-AM characteristic) relative to a control voltage in a steady state of an amplifier driven with a predetermined input high frequency signal amplitude value and a predetermined control voltage value; a coefficient storage section which stores a coefficient of the output signal characteristic; a first arithmetic circuit which adds or subtracts the DC offset stored in the offset storage section to/from an amplitude component of the baseband orthogonal signal; a second arithmetic circuit which multiplies or divides an output signal from the first arithmetic circuit by the coefficient stored in the coefficient storage section; an amplitude modulation section which generates an amplitude modulation signal based on an output signal from the second arithmetic circuit; and an amplifying section which synthesizes distortion-corrected transmit data by inputting the phase modulation signal as an input high frequency signal and inputting the amplitude modulation signal as a control signal.