Patent ID: 7505743

Claim:
A dual band transmitter in use for a dual band mobile communication terminal comprising: a first RF amplifier for amplifying the power of a high or first band signal at a first amplification factor that is determined according to a first bias voltage; a second RF amplifier for amplifying the power of a low or second band signal at a second amplification factor that is determined according to a second bias voltage; a first coupling capacitor for coupling an output signal from the first RF amplifier; a second coupling capacitor for coupling an output signal from the second RF amplifier; a filtering coupler having a first filter for affording high band pass to a first coupled signal from the first coupling capacitor and a second filter for affording low band pass to a second coupled signal from the second coupling capacitor; and a power amplifier controller for comparing the magnitude of a filtered signal from the filtering coupler with preset reference values to obtain difference values and adjusting the bias voltages of the first and second RF amplifiers based upon the difference values to control the first and second amplification factors.