Wireless communication apparatus

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 AGC amplifier which amplifies the signal subjected to frequency conversion according to the transmission output;
• a limiter which inputs the transmission signal amplified by said AGC amplifier to a power amplifier;
• a power amplifier which amplifies the transmission signal inputted from said limiter and outputs the transmission signal to said front-end unit;
• an envelope detection section which extracts and outputs amplitude information of the transmission signal inputted from said base band unit;
• and
• an amplitude modulation circuit which modulates a power supply voltage of said power amplifier based upon the amplitude information outputted from said envelope detection section,
• wherein said limiter applies clipping to the transmission signal amplified by said AGC amplifier in the case where an amplitude of the transmission signal amplified by said AGC amplifier is larger than a third threshold value,
• in the case where clipping is not applied by said limiter, said amplitude modulation circuit uses a linear region of said power amplifier to amplify the transmission signal amplified by said AGC amplifier to be linear, and
• in the case where clipping is applied by said limiter, said amplitude modulation circuit inputs a power supply voltage control signal, which corresponds to the amplitude information inputted from said envelope detection section, to said power amplifier, and uses a saturation region of said power amplifier to amplify the transmission signal amplified by said AGC amplifier.

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 conversion unit which separates the transmission signal inputted from said base band unit into a plurality of components and outputs the transmission signal;
• a quadrature modulator which subjects the transmission signal inputted from said conversion unit to frequency conversion;
• a power amplifier which amplifies the signal subjected to frequency conversion and outputs the signal to said front-end unit;
• and
• an amplitude modulation circuit which modulates a power supply voltage of said power amplifier based upon an output from said conversion unit;
• wherein said amplitude modulation circuit includes a combination of a first potential difference generation device, which steps up or steps down the power supply voltage of said power amplifier as required based upon an output from said conversion unit, and a second potential difference generation device which steps down the output voltage of said first potential difference generation device, and
• the circuit generates, in said conversion unit, first and second amplitude modulation control signals with respect to said first and second potential difference generation devices, respectively, based upon an amplitude modulation signal, transmission power level information, and transmission channel parameter setting information of the transmission signal.