This paper proposed a method to promote power added efficiency of GaAs HBT power amplifier device.Based on analysis of the working state of power amplifier,the working mechanism and functional defects of adaptive biasing circuit and the effect of output feed on harmonic component,we improved feeding way of the input and output that we can adjust quiescent current conveniently after single power supply,and the second harmonic wave can be shorted by output power supply.This way will effectively promote the po...