本发明提供一种射频功率放大器。射频功率放大器包括阻抗转换电路、电流单位增益放大器与输出匹配电路。阻抗转换电路接收第一输入功率信号且对应地输出第二输入功率信号，其中阻抗转换电路根据阻抗匹配参数来将电流单位增益放大器之输入阻抗转换为前级电路之输出阻抗，借此以提升前级电路的功率附加效率。电流单位增益放大器提供线性转阻以线性发送输入电流至输出阻抗进而产生线性输出功率，借此亦提升此电流单位增益放大器之功率附加效益，其中阻抗匹配参数根据第一系统电压、第二系统电压与预定功率增益值来决定。

A radio frequency (RF) power amplifier is disclosed. The RF power amplifier comprises an impedance transformation circuit, a current unit gain amplifier, an output match circuit. The impedance transformation circuit receives a first input power signal and outputs a second input power signal correspondingly, wherein the impedance transformation circuit transforms an input impedance to an output impedance according to an impedance matching parameter for increasing power added efficiency of a pre-stage circuit. The current unit gain amplifier provides a linear transimpedance so as to transmit in input current to an output impedance, and then generate linear output power also for increasing power added efficiency of the current unit gain amplifier, wherein the impedance matching parameter is determined by a first system voltage, a second system voltage and the predetermined power gain value.