Patent ID: 7184491
Filing Date: 2007-02-27
Classification: H03F,H04B,H04L

Abstract:
1. A circuit which amplifies a transmission signal inputted from a base band unit according to a transmission output and outputs the transmission signal to a front-end unit in a wireless communication apparatus, the circuit comprising: a quadrature modulator which subjects the transmission signal inputted from said base band unit to frequency conversion; an automatic gain control amplifier (AGC) amplifier which amplifies the signal subjected to frequency conversion according to the transmission output; a power amplifier which amplifies the transmission signal amplified by said AGC amplifier and outputs the transmission signal to said front-end unit; and an amplitude modulation circuit which modulates a power supply voltage of said power amplifier, wherein, in the case where the transmission output of the transmission signal is larger than a predetermined threshold value, said amplitude modulation circuit inputs a power supply voltage control signal corresponding to an amplitude of the transmission signal to said power amplifier, and said power amplifier amplifies a signal, which is inputted based upon the power supply voltage control signal inputted from said amplitude modulation circuit, in an envelope elimination and restoration (EER) system, in the case where the transmission output of the transmission signal is equal to or smaller than the predetermined threshold value, said amplitude modulation circuit amplifies the transmission signal to be linear, and the predetermined threshold value is set based upon a linear region suitable for using said power amplifier as a linear power amplifier and a saturation region suitable for using said power amplifier as a saturation power amplifier, which are decided according to characteristics of said power amplifier.