PROBLEM TO BE SOLVED: To provide a power amplifier circuit which has high power efficiency while suppressing a fluctuation of output power relatively to a fluctuation of a power supply voltage in a high-efficiency switching amplifier which operates in a radio frequency band.SOLUTION: A duty ratio control circuit 1 inputs an input signal Pin and a control voltage (a) and controls a duty ratio of a rectangular signal (b) to be outputted by the control voltage (a). A switching power amplifier 2 inputs the rectangular signal (b) having the duty ratio adjusted by the duty ratio control circuit 1. A detector 3 detects a level of an output signal Pout of the switching power amplifier 2 and outputs a detection voltage (d) corresponding to the level of the output signal Pout. A differential amplifier 4 inputs the detection voltage (d) from the detector 3 and a reference voltage (e) and outputs a signal of a differential therebetween as the control voltage (a).
|Patent number||JP2015211393 (A)|
|Publication status||Published - 24 Nov 2015|