Patent ID: 6329880
Filing Date: 2001-12-11
Classification: H03F

Abstract:
A transmitting circuit which comprises:a final stage amplifier amplifying an inputted radio frequency (RF) signal up to a specified transmission output, and capable of controlling consumption power and output distortion by a direct current (DC) voltage applied to a gate;a directional coupler having both a terminal capable of detecting output power outputted from said final stage amplifier and another terminal capable of detecting a reflected wave generated by mismatching between an output impedance of said final stage amplifier and a load impedance connected to an output side of said final stage amplifier;two first switches selecting said terminals of said directional coupler in a time division manner;a terminating resistor provided to correspond to each of said first switches, and terminating the terminal of said directional coupler unselected by said first switches;a detection diode converting each of the output power and the reflected wave obtained by said directional coupler into a DC voltage;a second switch selecting, switching and outputting one of the DC voltage with respect to said output power and the DC voltage with respect to said reflected wave obtained by said detection diode; andgate voltage control means for applying a gate voltage suited for said load impedance to said final stage amplifier in accordance with the DC voltage with respect to said reflected wave selected by said second switch.