Patent ID: 8354888
Filing Date: 2013-01-15
Classification: H03F

Abstract:
1. A power amplifier comprising: an input matching circuit having an input terminal and an output terminal; an amplifier transistor for amplifying an input signal received through the input matching circuit and output at the output terminal of the input matching circuit; means for varying a collector voltage applied to the amplifier transistor; a bias circuit for varying an idle current flowing in the amplifier transistor; and a compensation circuit including a first capacitor and a variable capacitance connected to the first capacitor, wherein the fist capacitor and the variable capacitance are connected to the output terminal of the input matching circuit, the compensation circuit varying capacitance at the output terminal of the input matching circuit to maintain phase shift and input reflection of the power amplifier constant when the collector voltage and the idle current vary, and to prevent a decrease in efficiency of the power amplifier due to changes in output power of the amplifier transistor.