| 摘要 |
In an FM receiver including a plurality of cascaded amplifier stages for successively amplifying an IF signal to form a pulse signal which is demodulated to derive an audio signal, an auxiliary amplifier section beside the cascade is provided to amplify a signal developed at an intermediate point in the cascade to form a signal from which a control signal for controlling the gain of an RF amplifier. The auxiliary amplifier section includes a first linear amplifier including degenerative signal feedback followed in cascade by a second linear amplifier including a gain control arrangement. The latter is responsive to a logarithmic gain control signal generated by a logarithmic amplifier in response to the output signal of a peak detector following the auxiliary amplifier. The control signal has a relatively wide control range, e.g., 10 to 500 microvolts of RF input signal, suitable for controlling the gain of an RF stage.
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