Patent ID: 7346318

Claim:
A radio communication system, comprising a high-frequency power amplifier component comprising a high-frequency power amplification circuit which comprises power amplifying transistors and is capable of operating in a first operation mode in which said power amplifying transistors amplify and output phase modulated high-frequency signals and in a second operation mode in which said power amplifying transistors amplify and output phase modulated and amplitude modulated high-frequency signals and a bias circuit which applies bias to said power amplifying transistors, said bias causing a changeover between idle currents flowing across said power amplifying transistors in said first operation mode and idle currents flowing across said power amplifying transistors in said second operation mode, wherein said bias circuit is configured to change the idle currents flowing across said power amplifying transistors, depending on the level of power supply voltage and the level of required output power, in said first operation mode, a second electronic component including a transmission/reception change-over circuit which changes over system operation between transmitting signals and receiving signals, and a third electronic component which modulates transmit signals and inputs modulated transmit signals to said high-frequency power amplifier component, wherein said third electronic component includes a gain control amplifier circuit which is able to control the amplitude of the transmit signals to be supplied to said high-frequency power amplifier component and supplies the signals with amplitude adjusted in accordance with the level of required output power through control of the gain of said gain control amplifier, depending on the level of required output power, to said high-frequency power amplifier component, when in either of said first operation mode and said second operation mode, wherein said third electronic component is configured to supply a signal to indicate which of said first operation mode and said second operation mode to said high-frequency power amplifier component, and wherein said third electronic component includes a storage means for storing table data to determine said control current, depending on the level of required output power, at least in said first operation mode.