AUTOMATIC LEVEL CONTROL CIRCUIT
First Claim
1. An automatic level control circuit comprising:
- a variable gain amplifier configured to amplify an input audio signal; and
a first control unit configured to monitor the level of the input audio signal, and to set the gain of the variable gain amplifier to a predetermined fixed value when the level is lower than a predetermined minimum threshold value.
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Accused Products
Abstract
A variable gain amplifier amplifies an input audio signal. A first control unit monitors the level of the input audio signal, and sets the gain of the variable gain amplifier to a predetermined fixed value when this level is lower than a predetermined minimum threshold. A second control unit monitors the level of an output signal VO of the variable gain amplifier. When this level exceeds a predetermined maximum threshold, the second control unit lowers the gain of the variable gain amplifier. When this level becomes smaller than this threshold, it raises the gain. When the level of the input audio signal is smaller than the minimum threshold, the first control unit disables the gain control operation of the variable gain amplifier controlled by the second control unit. A sub-amplifier amplifies the input audio signal. An output mixing unit mixes signals output from the variable gain amplifier and the sub-amplifier.
158 Citations
10 Claims
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1. An automatic level control circuit comprising:
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a variable gain amplifier configured to amplify an input audio signal; and a first control unit configured to monitor the level of the input audio signal, and to set the gain of the variable gain amplifier to a predetermined fixed value when the level is lower than a predetermined minimum threshold value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A gain control method for a variable gain amplifier configured to amplify an input audio signal, comprising:
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monitoring the level of the input audio signal, and setting the gain of the variable gain amplifier to a fixed value when the level of the input audio signal is smaller than a predetermined minimum threshold value, and monitoring the level of the output signal of the variable gain amplifier, lowering the gain of the variable gain amplifier when the level thus monitored exceeds a predetermined maximum threshold value, and raising the gain thereof when the level thus monitored becomes smaller than the maximum threshold value. - View Dependent Claims (10)
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Specification