| 摘要 |
PROBLEM TO BE SOLVED: To amplify a signal whose strength is greatly changed by one amplification means while keeping a response speed with respect to an input signal constant. SOLUTION: An amplifier 12 configures a feedback amplifier circuit with a resistor R1. A reference voltage generating circuit 14, a clamp circuit 15, an offset circuit 16, an inverted gain circuit 17, a field effect transistor (FET) 18, and a resistor R2 configure a gain control circuit for controlling the gain of the feedback amplifier circuit. The clamp circuit 15 clamps an input voltage to the signal amplifier 10 by using a reference voltage generated by the reference voltage generating circuit 14. The offset circuit 16 offsets an output voltage from the clamp circuit 15 toward a negative side. The inverted gain circuit 17 inverts the polarity of the output voltage of the offset circuit 16 to amplify the inverted output voltage. The field effect transistor 18 is activated by using the output voltage of the inverted gain circuit 17 for a control voltage and supplies a current to a feedback loop of the feedback amplifier circuit from a power supply V2 via the resistor R2. COPYRIGHT: (C)2006,JPO&NCIPI
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