TRANSMISSION POWER CONTROL CIRCUIT

摘要

A transmission power control circuit comprises a variable−gain amplifier (1) for amplifying a transmission wave with a gain corresponding to a control voltage VC from a power control unit (110). When the power (POUT) of a transmission wave falls within a measurement range of a detector circuit (3), the power control unit (110) carries out negative feedback of the detected voltage (VDET) with a control voltage feedback factor (K') set at 0 to bring the transmission power (POUT) close to a specified level by closed−loop control. On the other hand, when the transmission power (POUT) is out of the measurement range of the detector circuit (3), the power control unit (110) generates a control voltage (VC) by open−loop control based on a reference voltage VREF with a detection voltage feedback factor (K) set at 0.