| 摘要 |
PROBLEM TO BE SOLVED: To realize a variable gain amplifier which is strong against disturbance such as noise by expanding an output voltage range (dynamic range) and control voltage range, with no increase in power consumption. SOLUTION: The variable gain amplifier comprises a voltage current conversion circuit 1 which outputs a first positive current Iop1 and a first negative current Ion1 proportional to an input voltage, a variable gain part 4 which is controlled by a gain coefficient A (0<A<1) controlled by a control signal Vc after inputting of the first positive current Iop1 and the first negative current Ion1, and outputs four output currents including a second positive current Iop2 which is A-multiple of the first positive current Iop1, a third positive current Iop3 which is (1-A) multiple of the first positive current Iop1, a second negative current Ion2 which is A-multiple of the first negative current, and a third negative current Ion3 which is (1-A) multiple of the first negative current Ion1, and a voltage output part 5 in which both the second positive current Iop2 and the second negative current Ion2 or only any one of the third positive current Iop3 and the third negative current Iop3 is inputted for outputting a positive output voltage Vop and a negative output voltage Von. COPYRIGHT: (C)2005,JPO&NCIPI
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