Gain control amplifying circuit and recording and reproducing device

摘要: PROBLEM TO BE SOLVED: To hold frequency characteristics and DC constant irrelevantly to a variation in gain, gain control amplifier whose can be switched. SOLUTION: A voltage feedback type operational 10 is used as main amplification part. constitution composed of combination resistance elements 22 28 switches S24 S28 employed circuit 20 connected an inverted input terminal (-) the 10. Two-input/one-output are S28, signal Vi inputted one each switch other ground (GND) potential uninverted (+) Output terminals respective corresponding 24 for gain-switching. quantity held keep gain. COPYRIGHT: (C)2006,JPO&NCIPI