POWER AMPLIFIER WITH MEASURING DEVICE OF OPERATION CURRENT

An HF power amplifier having an operating current measuring device is provided to reduce a load on an arbitrary power supply system by guaranteeing a coupling between the HF power amplifier and an evaluating unit. An HF power amplifier includes a measuring device for measuring an operating current. The HF power amplifier is divided into a main amplifier and a measuring amplifier having a scaling ratio smaller than that of the main amplifier. The main amplifier includes a first transistor(Amp1) with a base to receive an HF necessary signal, and has an operating point which is controlled by a first bias voltage(Vbias1). The measuring amplifier includes a second transistor(Amp2) with a base to receive the HF necessary signal, and an emitter. The emitter is connected to ground via a measuring resistor(Rshunt) to generate a measured voltage representing the operating current of the HF power amplifier. An adjusting member is provided to match a second bias voltage of the second transistor to the first bias voltage of the first transistor so that the operating point of the second transistor is adjusted. A load is connected to collectors of the first and second transistors.