| 摘要 |
PURPOSE:To facilitate the formation of an IC and to obtain the distortionless maximum input level which is enough to both the 1st and 2nd amplifiers, by securing an AGC operation for the 1st and 2nd amplifiers with the AGC control voltage of a control voltage generating circuit. CONSTITUTION:The 1st voice signal supplied to an input terminal is amplified by the 1st amplifier 3. The 1st voice signal and the 2nd voice signal supplied to an input terminal 2 are amplified by the 2nd amplifier 4. A control voltage generating circuit 9 produces the AGC control voltage curresponding to the level of the output voice signal. The 1st and 2nd level control means 7 and 10 control the output voice signals of the amplifiers 3 and 4 at a certain level respectively by the AGC control voltage. As a result, a circuit can be converted into an IC without increasing the number of terminal pins. At the same time, the sufficient distortionless maximum input level is obtained for both amplifiers 3 and 4. |
