Two-stage DC-coupled amplifier circuit

Two-stage DC-coupled amplifier circuit

 (2) Two-stage DC coupling amplifier circuit
    The two-stage DC coupling amplifier circuit is shown in Figure 100. It has
one more transistor than the single-tube direct coupling circuit. As can be seen from the figure, the collector voltage
(UCi) of VT1 is equal to the base voltage (Ubt) of the VT2 tube. Since the emitter voltage drop Uaeoz of VT2 is very small (0_7 V for the silicon tube and 0.3 V for the germanium tube ), the collector voltage of VT1 The electrode potential is also very low, making it difficult to work normally; on the other hand, the static base current of the VT2 tube will be too large, making the VI2 tube unable to work in the amplification area. This means that the DC coupling of two basic common-emitter amplifier circuits cannot amplify normally.