Patent ID: 7288986

Claim:
A communication semiconductor integrated circuit device comprising: a phase modulation circuit which provides a phase modulated signal in accordance with data to be transmitted; an amplitude circuit which provides an amplitude signal in accordance with the data to be transmitted; a first gain control amplifier which receives a first bias current, whose gain is determined in accordance with the first bias current, and which receives the amplitude signal and provides an output signal according to the amplitude signal to a circuit which receives the phase modulated signal and forms a transmission signal in accordance with the phase modulated signal and the output signal from the first gain control amplifier; and a first bias circuit which receives a first control signal and generates the first bias current to be supplied to the first gain control amplifier according to the first control signal, wherein the first bias circuit has a plurality of variable current circuits and the first bias current to be supplied to the first gain control amplifier is formed by combining currents from variable current circuits, and wherein the variable current circuits providing the currents to be combined are determined among the plurality of variable current circuits in accordance with the first control signal.