| 摘要 |
PROBLEM TO BE SOLVED: To provide a voltage-controlled variable amplifier capable of reducing costs, controlling the maximum amplitude without any distortion, and linearly adjusting gain. SOLUTION: The voltage-controlled variable amplifier comprises an operational amplifier OP that amplifies a voltage Vout3 (an input voltage) by a specific amplification factor and outputs a voltage Vout1 (an output voltage); an attenuation circuit that has an FET (a field effect transistor) (J6) and attenuates a voltage Vout2 for outputting as a voltage Vout3; and a negative-feedback circuit for allowing the voltage Vout1 to be subjected to negative feedback to a gate G of the FET (J6). In the attenuation circuit, attenuation is controlled according to the amount of the negative feedback of the output voltage to the gate G of the FET (J6). COPYRIGHT: (C)2005,JPO&NCIPI
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