| 摘要 |
PURPOSE:To realize stable, good-response gain control by controlling a gain so that an envelope signal obtained from the output of an amplifier is within a set range. CONSTITUTION:An input carrier is amplified by an amplifier 3, whose output is outputted to a terminal 7 and also inputted to an AM modulator 21. The carrier AM-modulated by the AM modulator 21 is inputted to a filter 22 for extracting the envelope signal. This envelope signal is inputted to an A/D converter 23. The feedback resistance network 26 of the amplifier is switched by the output signal of the amplifier 3 to vary the gain. Consequently, the level of the carrier is specified within a specific range. |
