| 摘要 |
PURPOSE:To operate the bias circuit of an amplifier body after the uninverted (NF) of the amplifier body terminal becomes stable, speed up its output and smooth its rise, and reduce pop noises during power-on operation by stopping the operation of the bias circuit and charging capacitor connected to the NF terminal of the amplifier main body. CONSTITUTION:When the power source is turned on, the base voltage of a transistor (TR) 26 rises slowly with the time constant determined by a resistance 24 and a capacitor 25. Then, a TR38 is turned on by current mirror circuits 32 and 37, and a TR38 absorbs a current from the constant current source 1 of the amplifier body 50 to turn off TRs 4 and 5. Thus, the TR5 turns off and the NF terminal 20 is charged, so that the level at an output terminal 17 goes up to ''L''. Then, the TR5 turns on after the NF terminal 20 becomes stable (1VBE), so the output rises smoothly. |
