| 摘要 |
PROBLEM TO BE SOLVED: To provide a technology for quickly restoring the gain of a variable gain amplifier to an original gain, even if the gain is quickly decreased by an attack operation due to a short-time large signal. SOLUTION: The automatic level adjusting circuit includes a level detecting section 30 for detecting the level of a digital signal converted from an analog signal by an A/D converter 20 and compares the detected level with a prescribed reference level, to detect attack and recovery; and a gain control section 40 for outputting a gain adjustment control signal, to adjust the gain of the variable gain amplifier 10 so that an output signal of the variable gain amplifier 10 reaches a prescribed signal level. The gain control section 40 generates a plurality of signals for carrying out gain adjustment control at different speeds, and selects and outputs the signal with a speed capable of obtaining the least gain among the signals as a gain adjustment control signal. COPYRIGHT: (C)2006,JPO&NCIPI
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