| 摘要 |
An Intermediate Frequency amplifier in a television receiver uses a dual gate field-effect transistor with an unbypassed source resistor. The dual gates are connected to a source of composite television signal and to a source of an automatic gain control signal. For weak signal conditions, the automatic gain control signal produces negative voltage feedback across the unbypassed source resistor, varying the output impedance of the field-effect transistor which is in parallel with a tuned circuit. The change in output impedance changes the Q of the tuned circuit and changes the response curve of the Intermediate Frequency amplifier.
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