| 摘要 |
PROBLEM TO BE SOLVED: To suppress reduction in output power or reduction in gain at a large power input, and to suppress reduction in gain or deterioration in distortion characteristics in the case that drift of a drain idle current is generated.SOLUTION: An amplifier circuit comprises: a power amplifier 11 including an FET 10 having an Si substrate or an SiC substrate and a nitride semiconductor layer formed on the Si substrate or the SiC substrate and having a gate terminal to which a high-frequency signal is input; a detector 12 detecting a drain idle current of the power amplifier; and a controller 14 outputting a gate bias voltage depending on the drain idle current to the gate terminal of the power amplifier in the case that the detected drain idle current is smaller than a predetermined value, and outputting a fixed gate bias voltage to the gate terminal of the power amplifier in the case that the detected drain idle current is the predetermined value or more. |
