POWER AMPLIFIER HAVING CONSTANT EFFICIENCY

摘要

PURPOSE: A power amplifier having constant efficiency is provided to supply an output power having a constant efficiency regardless of the change of the input power by adjusting the power efficiency accordingly. CONSTITUTION: In a power amplifier, an input matcher(2) receives an input signal without a loss. The first transistor(Q1) amplifies the input signal received by the input matcher(2). An output matcher(4) sends out the output of the first transistor(Q1) without a loss. A power detector(10) detects the power level of the input signal received by the input matcher(2). A controller(8) produces a control voltage for adjusting amplification efficiency responding to the detected power level. A DC voltage adjuster(6) supplies the first transistor(Q1) with a DC voltage proportionate with the power level of the input signal.