In a transmitter apparatus of a mobile device, a radio frequency unit has transmitting terminals for sending wireless signals of different frequency bands. Transmission filters are respectively connected to the transmitting terminals and perform a filtering process for the signal of each frequency band. A first switch has a single output terminal and input terminals respectively connected to the transmission filters, performing a switching operation to connect one of the input terminals and the output terminal in response to a control signal. A power amplifier amplifies the signal transmitted through the output terminal of the first switch. A second switch has a single input terminal connected to the power amplifier, and output terminals corresponding to the transmission filters. The second switch performs a switching operation to connect the input terminal and one of the output terminals in response to the control signal.