| 摘要 |
PURPOSE:To enable to ensure on/off of the emitter follower output, by providing the switch which can turn on and off in parallel with the emitter resistance of an emitter follower circuit. CONSTITUTION:When the control voltage Vo is 0 volt, since the diode D1 is backward-biased with the emitter voltage of the transistor and the impedance is infinitive, a capacitor C is separated from the emitter resistance. Thus, the emitter follower circuit performs normal operation and the signal applied to an input terminal 3 appears at the output terminal 4. When the control voltage Vo is increased, the diode D1 is conductive and the emitter voltage is increased to cut off the transistor. Simultaneously, since the emitter is grounded with the capacitor C in AC manner, the signal appeared at the output terminal can surely be cut. |
