存在问题 R B B XBi IR IR F1=Rb∥ R C R Bi R中R he +(1+B)R L Ok 5 T10k 2 Re 2k 2 Tak I 2k2 =R2 F=R∥ Rb,/I+(1+B)R存在问题 i b rbe i c βi b B C E Rs Rb Ui Rc RL i b rbe i c βi b B C Rb1 E 20kΩ Rc 2kΩ RL 6kΩ Rb2 10kΩ ui Re 2kΩ ( ) 1 L u be e R A r R    = − + + ' L u be R A r = − // i b be be r R r r =  o c r R= o c r R = 1 2 // //[ ( ) ] 1 i b b be e r R R r R = + + 