| 摘要 |
PURPOSE: A feedback variable gain amplifier is provided to improve the noise characteristics by reducing a parasitic capacitance of a FET(Field Effect Transistor) through a resistor and a capacitor of a variable resistor unit. CONSTITUTION: A gain control unit(GC2) includes a variable resistor unit(2100) and a broad-band matching unit(2300), which are connected in parallel to each other, and is connected between an input terminal(VIN) and an output terminal(VOUT) of an amplifier(AMP2). The amplifier(AMP2) includes a resistor(R21) and a first FET transistor(FET21), which are connected to each other. The input terminal(VIN) is connected to a gate of the first FET transistor(FET21) and the output terminal(VOUT) is connected to a connecting point of the first FET transistor(FET21) and the resistor(R21).
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