| 摘要 |
A variable gain amplifier includes one transistor and the other transistor which configures a differential transistor pair. An output signal voltage is taken out from a collector terminal of the one transistor. A first gain control signal to control a gain is supplied to the other transistor. The amplifier also includes a first voltage/current converter connected to a common emitter terminal of the one transistor and the other transistor, the first voltage/current converter having an input signal voltage supplied thereto, a power circuit which applies a constant bias voltage to a base terminal of the one transistor, and a capacitor connected to at least a base terminal of the other transistor.
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