Patent ID: 7110730

Claim:
An apparatus for mobile communication system which performs signal transmission by amplitude modulation and phase modulation, comprising: a power amplifier for amplifying a transmitting signal; a control circuit for controlling transmitting and receiving of signals and capable of supplying a predetermined characteristic data for a bias voltage or a power source voltage of said power amplifier; a radio frequency circuit for modulating the transmitting signal and demodulating a receiving signal; and a controllable voltage source which receives said predetermined characteristic data from said control circuit and provides said bias voltage or said power source voltage in accordance with said predetermined characteristic data, wherein said controllable voltage source includes a register for receiving and storing said predetermined characteristic data at a time of switching ON the apparatus and a digital to analog converter to output said bias voltage or said power source voltage based on said predetermined characteristic data stored in said register, and wherein said controllable voltage source is included in said radio frequency circuit, and a connection for setting said bias voltage or said power source voltage between said power amplifier and said radio frequency circuit or said control circuit is formed by an analog interface.