Patent ID: 6081694
Filing Date: 2000-06-27
Classification: H03F,H04B

Abstract:
A transmitter comprising:a power amplifying transistor for amplifying a transmitted signal;an input wide band matching circuit, connected to an input side of said power amplifying transistor, for matching a plurality of frequency bands;an output main matching circuit, connected to an output side of said power amplifying transistor, for matching said output side to one frequency band of said plurality of frequency bands;an antenna;an antenna switch for switching on/off a connection between the output side of said output main matching circuit and said antenna;a plurality of in-series transistors, connected to the output side of said output main matching circuit, for grounding the output side of said output main matching circuit when the signal is not transmitted; andan auxiliary matching circuit connected between the in-series connection of said plurality of transistors and ground,wherein said plurality of transistors can be on-off controlled, and when one frequency band other than said one frequency band of said plurality of frequency bands is used, the output side of said power amplifying transistor is matched to the one used frequency band by connecting a predetermined auxiliary matching circuit in all or a part of said auxiliary matching circuit to the output side of said output main matching circuit, under the on-off control in accordance with the used frequency band.