High frequency amplifier circuit permitting variable gain control

Abstract

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.

Dependencies are inferred from the claim text.