| 摘要 |
PURPOSE:To shorten settling time of input response and to stabilize an output signal by providing a muting circuit, a voltage-fluctuation preventing capacitor and through type capacitors whose other ends are made to be a DC voltage end, an output end and a grounding end, respectively. CONSTITUTION:When a power source is turned ON, a muting circuit Mc is operated. First and second switching element (field effect transistors) Q2 and Q3 which are connected to resistors R2 and R3 of first and second time constant circuits T1 and T2 in parallel are turned ON. DC blocking capacitors C1 and C2 are quickly charged. After a specified time, the elements Q2 and Q3 are turned OFF with a specified time difference. Thus delay in settling time of input response is shortened. The element Q3 is turned OFF after a specified time has elapsed from a time point when the element Q2 was turned OFF by the action of the circuit Mc. Therefore, the voltage fluctuation due to the DC offset of a first amplifier (initial stage) A1 and DC drift is suppressed. The voltage fluctuation in a power source line is suppressed and alleviated with a voltage-fluctuation preventing capacitor C6, a voltage-fluctuation preventing diode D3 and a through type capacitor C3. Mixing of noises into the amplifier output is prevented with through type capacitors C4 and C5, and stabilization is achieved. |
