| 摘要 |
PROBLEM TO BE SOLVED: To provide a gain changeable amplifier circuit and an input circuit allowing the gain to be switched over in a simple constitution. SOLUTION: The gain changeable amplifier circuit for amplifying an input signal at a different gain according to a control signal has a differential amplifier circuit (111) for outputting an output signal, i.e., the amplified input signal as it is fed, resistors (R12, R11; R31, R32; R41, R42, R43) connected to the differential amplifier circuit (111) for setting the gain, and gain switching circuits (112, 311, 312) for switching the connection of the resistors (R11; R31, R32; R41, R42, R43) according to the control signals (CNTL 11, CNTL 21, CNTL 31), thus switching the gain. COPYRIGHT: (C)2006,JPO&NCIPI
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