Patent ID: 6865399

Claim:
A dual-band type mobile telephone apparatus that can transmit and receive the band frequencies of the first and second radio frequency signal in different frequencies, comprising: a frequency selection switch provided on said apparatus body to select said first and second radio frequency signals; a driver amplifier having the frequency characteristic tuned with both frequency bands of said first and second radio frequency signals; a first RF power amplifier amplifying, with a first power transistor, the power of the first radio frequency signal amplified with said driver amplifier and then outputting the amplified signal to an antenna; a second RF power amplifier amplifying, with a second power transistor, the power of the second radio frequency signal amplified with said driver amplifier and then outputting the amplified signal to an antenna; a control unit interlocked with said frequency selection switch to output first and second bias control signals for selectively switching the operating condition of said first and second power transistors; first and second switching elements respectively connected in series in the input side of said first and second power transistors to be selected to conductive/non-conductive conditions interlocking with said first and second bias control signals; and a harmonics control circuit used in common for said first and second radio frequency signals that is set so that output terminals of said first and second power transistors terminate, interlocking with said first and second bias control signal, for the even number order harmonics of said first and second radio frequency signals or opens for the odd number order harmonics of the radio frequency signals.