彭义模电课件模拟电子技术第3章4-8节.pptVIP

For the CE circuit, the voltage and current gains are generally greater than 1. For the emitter-follower, the voltage gain is slightly less than 1, while current gains is greater than 1. For the CB circuit, the voltage gain is greater than 1, while the current gain is less than 1. The input resistance looking into the base terminal of a CE circuit may be in the low kilohm range; in an emitter follower, it is generally in the 50 to 100 kΩrange. The input resistance looking into the emitter of CB circuit is generally on the order of tens of ohms. The overall input resistance of both the common-emitter and emitter-follower circuits can be greatly affected by the bias circuitry. The output resistance of the emitter follower is generally in the range of a few ohms to tens of ohms. In contrast, the output resistance looking into the collector terminal of the collector terminal of the CE and CB circuits is very high. 例: 三级放大电路参量计算, 已知 β均为100, Rs = 500Ω, rbe1= 5.35 kΩ , rbe2 = 2.73kΩ , rbe3 = 1.41 kΩ. 1. 画出微变等效电路图; 2. 求 Ri, Ro, Av , Avs 多级放大器习题 Rb21 Rc1 T1 T2 Rb11 +VCC VO Rc2 vI RS Rb22 Re1 vs + _ + _ 60k Rb12 12k 12k 4.6k 26.6k 9.4k Re2 4k T3 Rb3 Re3 RL 6k 461k 4k 12k 0.5k 18V C1 C2 C3 C4 C5 C6 例3－8 画出图示电路的微变等效电路，图中设各电容的容抗均可忽略(注意标出电压电流的正方向)。 60. 解：(a) Rb1 + – RL rbe + – Rb2 b e c Rc Re – + RL ? Rc Rb1 +VCC – + Rb2 Cb2 Cb1 T 61. (b) +VCC + ? Rc Rb1 – + T Cb2 Cb1 Rb2 c e b (b) + – RC rbe + – Rb2 b e c Rb1 – 62. (c) + ? Rb1 +VCC – + T Cb2 Cb1 Rb3 Rb2 Re2 Re1 + – rbe Rb3 b e c Re1 Rb2 Rb1 – 63. (d) + – RC rbe + – Re e b c – + ? Rb1 Rc +VCC – + T C3 C1 Rb2 Re C2 64. 例3－9 求图示电路的输入电阻的表达式。 解：(a) Rc +VCC Rb2 T (a) Rb1 Re Ri 65. (b) Rc T (b) Rb Re Ri +VCC 66. (c) Rc +VCC T (c) Rb1 Ri Rb2 67. (d) (d) +VCC T1 Ri Rb1 Rb3 Re Rb2 T2 68. 例3－10 电路如图所示，设? =100，试求： (1)静态工作点； (2)电压放大倍数 (3)输入电阻Ri； (4)输出电阻Ro1和Ro2 69. 解：(1) + – Rb2 Rs Re T +VCC＝10V Rc Ro1 Ro2 Rb2 R1 20k? 15k? 2k? 2k? 2k? 70. (2) 71. (3) Ri = 8.2k? (4) Ro1 = Rc Ro2 72. 例3－11 电路如图所示，它是两个射极跟随器串接电路的交流通路，若每管的集电极电流IC=2.6mA，电