| 摘要 |
PURPOSE: A variable gain circuit employing a field effect transistor is provided to linearly adjust a gain in decibel representation for an external gain control signal that is received externally. CONSTITUTION: A variable gain circuit is provided with a first variable gain amplifier(101) that receives an input signal and provides an output of the amplified signal, a second variable gain amplifier(201) that receives the amplified signal and provides an output of an amplified output signal, a first gain control signal correction circuit(102) that provides an output of a first gain control signal(Vz1) to control the gain of the first variable gain amplifier(101) on the basis of an external gain control signal(VC) and a second gain control signal correction circuit(202) that provides an output of a second gain control signal(Vz2) to control the gain of the second variable gain amplifier(201) on the basis of the external gain control signal(VC).
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