C b Bi R b2 20k2T10k2 Re 2k 3 2k2 0 +(+B)R i=ic+ir= bi R R R 已:a9i b rbe i c βi b B C Rb1 E 20kΩ Rc 2kΩ Rb2 10kΩ ui Re 2kΩ i i r o r 0 ( ) 1 i b be e u i r R  = = + + R b c c c u u i ic i i R R = + = + =  o c r R =