| 摘要 |
PURPOSE:To suppress variation in input bias voltage even when an amplifier is turned on or off by generating a bias voltage and a bias current to the amplifier by different bias power sources. CONSTITUTION:A low voltage is impressed to a terminal 19 and a high voltage is impressed to a terminal 18 to turn a transistor (TR) Q5 on and a TRQ13 off. The base bias current supplied to a TRQ1 by turning on the TRQ5 is supplied not from a bias source through a resistance R3, but a bias current compensating circuit including TRs Q21-Q23. The resistance R3 only supplies the bias voltage. Therefore, even when the TRQ5 turns off, no voltage drop occurs across the resistance R3 and any pop voltage is not generated at an output terminal. |
