Automatic gain control circuit
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsAkira Kawabe, Kouji Okamoto
Life of this patent
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Abstract
In a state where a PLL circuit is not locked, a gain control signal according to the difference between a peak value of a reproduced signal and the upper or lower limit value of the dynamic range of an A/D converter is given to a variable gain amplifier. In a state where the PLL circuit is locked, a gain control signal according to the difference between the reproduced signal and a reference value that corresponds to a level to which the reproduced signal belongs is given to the variable gain amplifier for each sampling point of the A/D converter. The variable gain amplifier amplifies the reproduced signal with a gain according to the gain control signal.
Claims10
An automatic gain control circuit, comprising:
- a variable gain amplifier for amplifying a reproduced signal from a recording medium;
- an A/D converter for quantizing the reproduced signal, which has been amplified by the variable gain amplifier;
- a clock generation circuit for generating a clock that is synchronized with the reproduced signal, which has been quantized by the A/D converter;
- an error calculation section for generating an error signal according to a difference between the reproduced signal, which has been quantized by the A/D converter, and one of n values (n is a positive integer) that corresponds to the reproduced signal, which has been quantized by the A/D converter, the n values being determined by a recording constraint and a recording format for the recording medium and a method for weighting the reproduced signal from the recording medium;
- and
- a control signal generation circuit for generating a gain control signal based on the error signal generated by the error calculation section, wherein:
- the A/D converter quantizes the reproduced signal, which has been amplified by the variable gain amplifier, in synchronism with the clock from the clock generation circuit;
- and
- the variable gain amplifier amplifies the reproduced signal from the recording medium with a gain according to a level of the gain control signal from the control signal generation circuit.
Dependencies are inferred from the claim text.