Patent ID: 8653902

Claim:
A transmission circuit comprising: a quadrature modulator that generates a vector modulation wave by quadrature-modulating an I signal, the I signal being an in-phase component of a modulation signal, and a Q signal, the Q signal being a quadrature-phase component of the modulation signal; a power amplifier that generates a transmission signal by amplifying the vector modulation wave according to power supply voltage; a low pass filter that generates a bandwidth limited envelope signal by performing bandwidth limitation on an envelope signal, the envelope signal being envelope information of the modulation signal; a delay section that generates a delayed envelope signal by delaying the envelope signal for a time corresponding to an amount of delay of the low pass filter; an offset control section that sets offset voltage based on the bandwidth limited envelope signal and the delayed envelope signal; an addition section that corrects the bandwidth limited envelope signal by adding the offset voltage to the bandwidth limited envelope signal, to generate a corrected envelope signal; and a power supply voltage control section that supplies voltage corresponding to the corrected envelope signal, as the power supply voltage, to the power amplifier; wherein the offset voltage is voltage that makes a level of the corrected envelope signal equal to or higher than a level of the delayed envelope signal.