| 摘要 |
PURPOSE:To adjust an AGC voltage generating circuit at only one point by inputting different channel signals to a single AGC voltage generating circuit, and thus obtaining AGC voltages for the respective channel signals. CONSTITUTION:A signal inputted to a terminal 1 is amplified by a variable gain amplifying circuit 3 and then outputted through a mixing part 5. Individual channel signals outputted from the variable gain amplifying circuit 3 are inputted to the 1st signal switching part through a signal superposition part 11. The 1st signal switching part supplies one of those channel signals to AGC voltage generating circuits 15 and 16 successively. Generated AGC voltages are fed back to variable gain amplifying circuits 3 for amplifying the prescribed channel signals by the 2nd signal switching part 13. Those feedback paths are provided with circuits which hold the individual AGC voltages temporarily and while they are changed over successively, the AGC voltages are held. |
