| 摘要 |
A variable gain wideband bipolar monolithic amplifier has first and second bipolar transistors connected together in a Darlington configuration. A resistive shunt feedback loop connected between the output and the input of the amplifier controls the gain of the amplifier. The feedback loop includes a field effect transistor, formed on the same chip substantially by the same bipolar process as the bipolar transistors, for varying the impedance of the shunt feedback loop thereby varying the gain of the amplifier. The gain of the amplifier is controlled in response to the application of a control voltage to the gate of the FET. Further, the FET is dc biased for inhibiting the FET from drawing dc current.
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