| 摘要 |
PURPOSE:To obtain a switch circuit having a small number of parts with no shock noise, by using the switch circuit of analog signals both as a B-class push-pull circuit. CONSTITUTION:The signal sent from the signal source 1 is amplified by the amplifier 2 and the supplied to the B-class push-pull circuit 11 via the DC blocking capacitor 13 to be delivered to the output terminal 4 via the DC blocking capacitor 3. The base potential (a) of the NPN transistor 18 is higher than the power supply voltage VCC by the forward voltage of diode, and the base potential (b) of the PNP transistor 19 becomes VCC-/2-VBE. The DC potential at the point C serving as an output is held at VCC/2, and the bias power source having the voltage of 1/2VCC is applied to the point C via the resistances 20. Thus no fluctuation is caused to the DC potential at the point C even by giving an on/off control the switching FET12 and then giving a control of nonconduction/conduction to the circuit 11. As a result, the shock noise can be prevented completely at the terminal 4. |
