| 摘要 |
PURPOSE:To prevent the generation of a DC shift during signal switching operation, and to reduce an IC-implemented chip in area by composing an active element of a npn transisitor for an changeover between two signals. CONSTITUTION:Emitters and collectors of transistors T1 and T2 are connected mutually; the common emitter is connected to constant current supply I1 and the cathode of diode D1, and the common collector is to the power supply. In the same way, T3 and T4 are connected together, and the anodes of D1 and D2 are connected together to the power supply via resistance R1. the current value of constant current supply I1 is equal to that of I2, and voltages Va and Vb applied to input terminals (a) and (b) are equal in DC component and different in AC component. Either Va or Vb is led out to the common anode between D1 and D2 corresponding to the control voltage applied to bases of T2 and T3. |
