Radio-frequency signal amplifier circuit, power amplifier module, front-end circuit, and communication device

摘要

A radio-frequency signal amplifier circuit that is used in a front-end circuit and that propagates a radio-frequency transmission signal and a radio-frequency reception signal is described. The amplifier circuit has an amplifier transistor, a bias circuit, a resistor, and an LC series resonance circuit. The LC series resonant circuit has one end that is connected to a node between the resistor and a signal input terminal, and has another end that is connected to a grounding terminal. A resonant frequency of the LC series resonance circuit is included in a difference frequency band between the frequencies of the transmission signal and the reception signal.