由出备我 第11章基本放大电路 (2)放大电路的输入电阻和输出电阻r r=r= n[+(1+B)R1 LI EI 26 26 rn1≈300(1+B1 300+(1+60)×,92=1.04k9 2.14 El r,≈30092)+(2+n26 26(mⅤ 300+(1+375 =089k0 E2 17(mA) r2=RBI// rer a he2=0.89kQ2 2×0.89 1-2+0.89 0.62kQ n1∥/fma1+(1+月)R =3250k LI =r,≈R2=2k 0 回國(2) 放大电路的输入电阻ri和输出电阻ro   i i 1 B 1 be1 1 L1 r = r = R // r + (1+  )R L1 E1 i2 R = R // r 0.62kΩ 2 0.89 2 0.89 L1 = +  R = E1 be1 1 26 300 (1 ) I r  + +  Ω 1.04kΩ 2.14 26 300 (1 60) =       = + +  0.89kΩ 1.7(mA) 26(mV) = 300+(1+ 37.5) = E2 be2 2 26 300(Ω) ( 1) I r  +  + ri2 = RB 1  //RB 2  //rbe2  rbe2 = 0.89kΩ   i i 1 B 1 be1 1 L1 r = r = R // r + (1+  )R ro = ro2  RC2 = 2k = 32.50kΩ