Patent ID: 7006803

Claim:
A power amplification circuit for a communication device having a plurality of transmission frequency bands, comprising: a first amplification system for amplifying power of a modulation signal of a predetermined frequency band output from a single signal source without modification and outputting the amplified signal as a first transmission signal; and a second amplification system for converting the modulation signal of a predetermined frequency band output from said single signal source into a signal of a frequency band different from that of said first transmission signal, amplifying power of the converted signal and outputting the amplified output as a second transmission signal, wherein said second amplification system including a single local oscillation circuit for outputting a signal of a frequency band for the conversion into a frequency band different from a predetermined frequency band of the modulation signal output from said single signal source, and a single mixing circuit for mixing a signal whose frequency band is the same as that of the modulation signal output from said single signal source and an oscillation output of said local oscillation circuit.