The present invention is an amplifier circuit that permits variable gain
control, comprising an input terminal to which a high frequency input
signal is supplied; an amplifier transistor to the gate of which the high
frequency input signal supplied to the input terminal is supplied and
which generates an amplified signal at the drain side; and a variable
attenuator provided in a signal transmission line between the input
terminal and the gate of the amplifier transistor, in which a plurality
of attenuation units in which an attenuation capacitor and a switch
transistor are serially connected are provided in parallel between the
signal transmission line and a power supply, and the attenuation ratio of
which is variably controlled by controlling the conduction of the switch
transistor.