POWER AMPLIFIER HAVING EFFECT THAT HIGH/LOW-OUTPUT MODE HAS OUTPUT IMPEDANCE MATCHING CIRCUIT

摘要

PURPOSE: A power amplifier is provided to reduce the power consumption by optimizing the output and the efficiency in a high-output mode and a low-output mode. CONSTITUTION: A first power amplifier(11) and a second power amplifier(12) are formed with HBTs(Heterojunction Bipolar Transistors) for amplifying RF signals. A current supply unit supplies the current to the first and the second power amplifiers. A switch(17) is used for switching an operation for supplying the current to the first power amplifier. A common input impedance matching circuit(21) is commonly connected between a base of the first power amplifier and an emitter of the second power amplifier in order to output RF signals to the first and the second power amplifiers. A common output impedance matching circuit(24) is commonly connected between output terminals of the first and the second power amplifiers in order to output the amplified RF signals.