Patent ID: 8116699

Claim:
A transmitter comprising: a first transmitting circuit which corresponds to a signal of a first frequency band; a second transmitting circuit which corresponds to a signal of a second frequency band having a lower frequency band than the first frequency band; a first coupler which, disposed on an output signal line of the first transmitting circuit, branches and outputs part of an output signal from the first transmitting circuit; a second coupler which, disposed on an output line of the second transmitting circuit, branches and outputs part of an output signal from the second transmitting circuit; and a detector circuit detecting an input signal whose input terminal is coupled to a branched output terminal of the first coupler and a branched output terminal of the second coupler, wherein said input terminal is directly connected to the branched output terminal of the first coupler; and a filter circuit which, arranged between the input terminal and the branched output terminal of the second coupler, selectively passes a signal of the second frequency band.