| 摘要 |
PROBLEM TO BE SOLVED: To improve AGC operations to control an amplification factor (gain) of an amplifier. SOLUTION: An AGC detection circuit 10 detects a level of a reproduction signal and supplies a current I1 related to the level to a switching circuit 14. Further, a constant current generating circuit 16 supplies its generated constant current I also to the switching circuit 14. The switching circuit 14 outputs a constant current I at no signal and a current I1 at presence of the signal according to the detection result of a no-signal detection circuit 12. A current voltage conversion circuit 18 converts a current from the switching circuit 14 into a control voltage and supplies the control voltage to an AGC amplifier AP1 as a gain control signal. Thus, the gain setting in the AGC amplifier AP1 at no signal can be enhanced. COPYRIGHT: (C)2004,JPO&NCIPI
|
