VARIABLE GAIN AMPLIFYING DEVICE

PROBLEM TO BE SOLVED: To provide a variable gain amplifying device easily controlling gain characteristics and output power. SOLUTION: A variable gain amplifying device comprises: a first input terminal to which an input signal is inputted; an output terminal which outputs an amplified signal; an amplification unit including a switch stage and an amplification stage constituted of MOS transistors; and a controlling circuit that controls the gain by controlling turning-on and turning-off of the MOS transistors by outputting a control signal to gates of the MOS transistors on the switch stage. COPYRIGHT: (C)2009,JPO&INPIT